linux/mm/percpu.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * mm/percpu.c - percpu memory allocator
   4 *
   5 * Copyright (C) 2009           SUSE Linux Products GmbH
   6 * Copyright (C) 2009           Tejun Heo <tj@kernel.org>
   7 *
   8 * Copyright (C) 2017           Facebook Inc.
   9 * Copyright (C) 2017           Dennis Zhou <dennisszhou@gmail.com>
  10 *
  11 * The percpu allocator handles both static and dynamic areas.  Percpu
  12 * areas are allocated in chunks which are divided into units.  There is
  13 * a 1-to-1 mapping for units to possible cpus.  These units are grouped
  14 * based on NUMA properties of the machine.
  15 *
  16 *  c0                           c1                         c2
  17 *  -------------------          -------------------        ------------
  18 * | u0 | u1 | u2 | u3 |        | u0 | u1 | u2 | u3 |      | u0 | u1 | u
  19 *  -------------------  ......  -------------------  ....  ------------
  20 *
  21 * Allocation is done by offsets into a unit's address space.  Ie., an
  22 * area of 512 bytes at 6k in c1 occupies 512 bytes at 6k in c1:u0,
  23 * c1:u1, c1:u2, etc.  On NUMA machines, the mapping may be non-linear
  24 * and even sparse.  Access is handled by configuring percpu base
  25 * registers according to the cpu to unit mappings and offsetting the
  26 * base address using pcpu_unit_size.
  27 *
  28 * There is special consideration for the first chunk which must handle
  29 * the static percpu variables in the kernel image as allocation services
  30 * are not online yet.  In short, the first chunk is structured like so:
  31 *
  32 *                  <Static | [Reserved] | Dynamic>
  33 *
  34 * The static data is copied from the original section managed by the
  35 * linker.  The reserved section, if non-zero, primarily manages static
  36 * percpu variables from kernel modules.  Finally, the dynamic section
  37 * takes care of normal allocations.
  38 *
  39 * The allocator organizes chunks into lists according to free size and
  40 * tries to allocate from the fullest chunk first.  Each chunk is managed
  41 * by a bitmap with metadata blocks.  The allocation map is updated on
  42 * every allocation and free to reflect the current state while the boundary
  43 * map is only updated on allocation.  Each metadata block contains
  44 * information to help mitigate the need to iterate over large portions
  45 * of the bitmap.  The reverse mapping from page to chunk is stored in
  46 * the page's index.  Lastly, units are lazily backed and grow in unison.
  47 *
  48 * There is a unique conversion that goes on here between bytes and bits.
  49 * Each bit represents a fragment of size PCPU_MIN_ALLOC_SIZE.  The chunk
  50 * tracks the number of pages it is responsible for in nr_pages.  Helper
  51 * functions are used to convert from between the bytes, bits, and blocks.
  52 * All hints are managed in bits unless explicitly stated.
  53 *
  54 * To use this allocator, arch code should do the following:
  55 *
  56 * - define __addr_to_pcpu_ptr() and __pcpu_ptr_to_addr() to translate
  57 *   regular address to percpu pointer and back if they need to be
  58 *   different from the default
  59 *
  60 * - use pcpu_setup_first_chunk() during percpu area initialization to
  61 *   setup the first chunk containing the kernel static percpu area
  62 */
  63
  64#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  65
  66#include <linux/bitmap.h>
  67#include <linux/memblock.h>
  68#include <linux/err.h>
  69#include <linux/lcm.h>
  70#include <linux/list.h>
  71#include <linux/log2.h>
  72#include <linux/mm.h>
  73#include <linux/module.h>
  74#include <linux/mutex.h>
  75#include <linux/percpu.h>
  76#include <linux/pfn.h>
  77#include <linux/slab.h>
  78#include <linux/spinlock.h>
  79#include <linux/vmalloc.h>
  80#include <linux/workqueue.h>
  81#include <linux/kmemleak.h>
  82#include <linux/sched.h>
  83
  84#include <asm/cacheflush.h>
  85#include <asm/sections.h>
  86#include <asm/tlbflush.h>
  87#include <asm/io.h>
  88
  89#define CREATE_TRACE_POINTS
  90#include <trace/events/percpu.h>
  91
  92#include "percpu-internal.h"
  93
  94/* the slots are sorted by free bytes left, 1-31 bytes share the same slot */
  95#define PCPU_SLOT_BASE_SHIFT            5
  96/* chunks in slots below this are subject to being sidelined on failed alloc */
  97#define PCPU_SLOT_FAIL_THRESHOLD        3
  98
  99#define PCPU_EMPTY_POP_PAGES_LOW        2
 100#define PCPU_EMPTY_POP_PAGES_HIGH       4
 101
 102#ifdef CONFIG_SMP
 103/* default addr <-> pcpu_ptr mapping, override in asm/percpu.h if necessary */
 104#ifndef __addr_to_pcpu_ptr
 105#define __addr_to_pcpu_ptr(addr)                                        \
 106        (void __percpu *)((unsigned long)(addr) -                       \
 107                          (unsigned long)pcpu_base_addr +               \
 108                          (unsigned long)__per_cpu_start)
 109#endif
 110#ifndef __pcpu_ptr_to_addr
 111#define __pcpu_ptr_to_addr(ptr)                                         \
 112        (void __force *)((unsigned long)(ptr) +                         \
 113                         (unsigned long)pcpu_base_addr -                \
 114                         (unsigned long)__per_cpu_start)
 115#endif
 116#else   /* CONFIG_SMP */
 117/* on UP, it's always identity mapped */
 118#define __addr_to_pcpu_ptr(addr)        (void __percpu *)(addr)
 119#define __pcpu_ptr_to_addr(ptr)         (void __force *)(ptr)
 120#endif  /* CONFIG_SMP */
 121
 122static int pcpu_unit_pages __ro_after_init;
 123static int pcpu_unit_size __ro_after_init;
 124static int pcpu_nr_units __ro_after_init;
 125static int pcpu_atom_size __ro_after_init;
 126int pcpu_nr_slots __ro_after_init;
 127static size_t pcpu_chunk_struct_size __ro_after_init;
 128
 129/* cpus with the lowest and highest unit addresses */
 130static unsigned int pcpu_low_unit_cpu __ro_after_init;
 131static unsigned int pcpu_high_unit_cpu __ro_after_init;
 132
 133/* the address of the first chunk which starts with the kernel static area */
 134void *pcpu_base_addr __ro_after_init;
 135EXPORT_SYMBOL_GPL(pcpu_base_addr);
 136
 137static const int *pcpu_unit_map __ro_after_init;                /* cpu -> unit */
 138const unsigned long *pcpu_unit_offsets __ro_after_init; /* cpu -> unit offset */
 139
 140/* group information, used for vm allocation */
 141static int pcpu_nr_groups __ro_after_init;
 142static const unsigned long *pcpu_group_offsets __ro_after_init;
 143static const size_t *pcpu_group_sizes __ro_after_init;
 144
 145/*
 146 * The first chunk which always exists.  Note that unlike other
 147 * chunks, this one can be allocated and mapped in several different
 148 * ways and thus often doesn't live in the vmalloc area.
 149 */
 150struct pcpu_chunk *pcpu_first_chunk __ro_after_init;
 151
 152/*
 153 * Optional reserved chunk.  This chunk reserves part of the first
 154 * chunk and serves it for reserved allocations.  When the reserved
 155 * region doesn't exist, the following variable is NULL.
 156 */
 157struct pcpu_chunk *pcpu_reserved_chunk __ro_after_init;
 158
 159DEFINE_SPINLOCK(pcpu_lock);     /* all internal data structures */
 160static DEFINE_MUTEX(pcpu_alloc_mutex);  /* chunk create/destroy, [de]pop, map ext */
 161
 162struct list_head *pcpu_slot __ro_after_init; /* chunk list slots */
 163
 164/* chunks which need their map areas extended, protected by pcpu_lock */
 165static LIST_HEAD(pcpu_map_extend_chunks);
 166
 167/*
 168 * The number of empty populated pages, protected by pcpu_lock.  The
 169 * reserved chunk doesn't contribute to the count.
 170 */
 171int pcpu_nr_empty_pop_pages;
 172
 173/*
 174 * The number of populated pages in use by the allocator, protected by
 175 * pcpu_lock.  This number is kept per a unit per chunk (i.e. when a page gets
 176 * allocated/deallocated, it is allocated/deallocated in all units of a chunk
 177 * and increments/decrements this count by 1).
 178 */
 179static unsigned long pcpu_nr_populated;
 180
 181/*
 182 * Balance work is used to populate or destroy chunks asynchronously.  We
 183 * try to keep the number of populated free pages between
 184 * PCPU_EMPTY_POP_PAGES_LOW and HIGH for atomic allocations and at most one
 185 * empty chunk.
 186 */
 187static void pcpu_balance_workfn(struct work_struct *work);
 188static DECLARE_WORK(pcpu_balance_work, pcpu_balance_workfn);
 189static bool pcpu_async_enabled __read_mostly;
 190static bool pcpu_atomic_alloc_failed;
 191
 192static void pcpu_schedule_balance_work(void)
 193{
 194        if (pcpu_async_enabled)
 195                schedule_work(&pcpu_balance_work);
 196}
 197
 198/**
 199 * pcpu_addr_in_chunk - check if the address is served from this chunk
 200 * @chunk: chunk of interest
 201 * @addr: percpu address
 202 *
 203 * RETURNS:
 204 * True if the address is served from this chunk.
 205 */
 206static bool pcpu_addr_in_chunk(struct pcpu_chunk *chunk, void *addr)
 207{
 208        void *start_addr, *end_addr;
 209
 210        if (!chunk)
 211                return false;
 212
 213        start_addr = chunk->base_addr + chunk->start_offset;
 214        end_addr = chunk->base_addr + chunk->nr_pages * PAGE_SIZE -
 215                   chunk->end_offset;
 216
 217        return addr >= start_addr && addr < end_addr;
 218}
 219
 220static int __pcpu_size_to_slot(int size)
 221{
 222        int highbit = fls(size);        /* size is in bytes */
 223        return max(highbit - PCPU_SLOT_BASE_SHIFT + 2, 1);
 224}
 225
 226static int pcpu_size_to_slot(int size)
 227{
 228        if (size == pcpu_unit_size)
 229                return pcpu_nr_slots - 1;
 230        return __pcpu_size_to_slot(size);
 231}
 232
 233static int pcpu_chunk_slot(const struct pcpu_chunk *chunk)
 234{
 235        const struct pcpu_block_md *chunk_md = &chunk->chunk_md;
 236
 237        if (chunk->free_bytes < PCPU_MIN_ALLOC_SIZE ||
 238            chunk_md->contig_hint == 0)
 239                return 0;
 240
 241        return pcpu_size_to_slot(chunk_md->contig_hint * PCPU_MIN_ALLOC_SIZE);
 242}
 243
 244/* set the pointer to a chunk in a page struct */
 245static void pcpu_set_page_chunk(struct page *page, struct pcpu_chunk *pcpu)
 246{
 247        page->index = (unsigned long)pcpu;
 248}
 249
 250/* obtain pointer to a chunk from a page struct */
 251static struct pcpu_chunk *pcpu_get_page_chunk(struct page *page)
 252{
 253        return (struct pcpu_chunk *)page->index;
 254}
 255
 256static int __maybe_unused pcpu_page_idx(unsigned int cpu, int page_idx)
 257{
 258        return pcpu_unit_map[cpu] * pcpu_unit_pages + page_idx;
 259}
 260
 261static unsigned long pcpu_unit_page_offset(unsigned int cpu, int page_idx)
 262{
 263        return pcpu_unit_offsets[cpu] + (page_idx << PAGE_SHIFT);
 264}
 265
 266static unsigned long pcpu_chunk_addr(struct pcpu_chunk *chunk,
 267                                     unsigned int cpu, int page_idx)
 268{
 269        return (unsigned long)chunk->base_addr +
 270               pcpu_unit_page_offset(cpu, page_idx);
 271}
 272
 273static void pcpu_next_unpop(unsigned long *bitmap, int *rs, int *re, int end)
 274{
 275        *rs = find_next_zero_bit(bitmap, end, *rs);
 276        *re = find_next_bit(bitmap, end, *rs + 1);
 277}
 278
 279static void pcpu_next_pop(unsigned long *bitmap, int *rs, int *re, int end)
 280{
 281        *rs = find_next_bit(bitmap, end, *rs);
 282        *re = find_next_zero_bit(bitmap, end, *rs + 1);
 283}
 284
 285/*
 286 * Bitmap region iterators.  Iterates over the bitmap between
 287 * [@start, @end) in @chunk.  @rs and @re should be integer variables
 288 * and will be set to start and end index of the current free region.
 289 */
 290#define pcpu_for_each_unpop_region(bitmap, rs, re, start, end)               \
 291        for ((rs) = (start), pcpu_next_unpop((bitmap), &(rs), &(re), (end)); \
 292             (rs) < (re);                                                    \
 293             (rs) = (re) + 1, pcpu_next_unpop((bitmap), &(rs), &(re), (end)))
 294
 295#define pcpu_for_each_pop_region(bitmap, rs, re, start, end)                 \
 296        for ((rs) = (start), pcpu_next_pop((bitmap), &(rs), &(re), (end));   \
 297             (rs) < (re);                                                    \
 298             (rs) = (re) + 1, pcpu_next_pop((bitmap), &(rs), &(re), (end)))
 299
 300/*
 301 * The following are helper functions to help access bitmaps and convert
 302 * between bitmap offsets to address offsets.
 303 */
 304static unsigned long *pcpu_index_alloc_map(struct pcpu_chunk *chunk, int index)
 305{
 306        return chunk->alloc_map +
 307               (index * PCPU_BITMAP_BLOCK_BITS / BITS_PER_LONG);
 308}
 309
 310static unsigned long pcpu_off_to_block_index(int off)
 311{
 312        return off / PCPU_BITMAP_BLOCK_BITS;
 313}
 314
 315static unsigned long pcpu_off_to_block_off(int off)
 316{
 317        return off & (PCPU_BITMAP_BLOCK_BITS - 1);
 318}
 319
 320static unsigned long pcpu_block_off_to_off(int index, int off)
 321{
 322        return index * PCPU_BITMAP_BLOCK_BITS + off;
 323}
 324
 325/*
 326 * pcpu_next_hint - determine which hint to use
 327 * @block: block of interest
 328 * @alloc_bits: size of allocation
 329 *
 330 * This determines if we should scan based on the scan_hint or first_free.
 331 * In general, we want to scan from first_free to fulfill allocations by
 332 * first fit.  However, if we know a scan_hint at position scan_hint_start
 333 * cannot fulfill an allocation, we can begin scanning from there knowing
 334 * the contig_hint will be our fallback.
 335 */
 336static int pcpu_next_hint(struct pcpu_block_md *block, int alloc_bits)
 337{
 338        /*
 339         * The three conditions below determine if we can skip past the
 340         * scan_hint.  First, does the scan hint exist.  Second, is the
 341         * contig_hint after the scan_hint (possibly not true iff
 342         * contig_hint == scan_hint).  Third, is the allocation request
 343         * larger than the scan_hint.
 344         */
 345        if (block->scan_hint &&
 346            block->contig_hint_start > block->scan_hint_start &&
 347            alloc_bits > block->scan_hint)
 348                return block->scan_hint_start + block->scan_hint;
 349
 350        return block->first_free;
 351}
 352
 353/**
 354 * pcpu_next_md_free_region - finds the next hint free area
 355 * @chunk: chunk of interest
 356 * @bit_off: chunk offset
 357 * @bits: size of free area
 358 *
 359 * Helper function for pcpu_for_each_md_free_region.  It checks
 360 * block->contig_hint and performs aggregation across blocks to find the
 361 * next hint.  It modifies bit_off and bits in-place to be consumed in the
 362 * loop.
 363 */
 364static void pcpu_next_md_free_region(struct pcpu_chunk *chunk, int *bit_off,
 365                                     int *bits)
 366{
 367        int i = pcpu_off_to_block_index(*bit_off);
 368        int block_off = pcpu_off_to_block_off(*bit_off);
 369        struct pcpu_block_md *block;
 370
 371        *bits = 0;
 372        for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
 373             block++, i++) {
 374                /* handles contig area across blocks */
 375                if (*bits) {
 376                        *bits += block->left_free;
 377                        if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
 378                                continue;
 379                        return;
 380                }
 381
 382                /*
 383                 * This checks three things.  First is there a contig_hint to
 384                 * check.  Second, have we checked this hint before by
 385                 * comparing the block_off.  Third, is this the same as the
 386                 * right contig hint.  In the last case, it spills over into
 387                 * the next block and should be handled by the contig area
 388                 * across blocks code.
 389                 */
 390                *bits = block->contig_hint;
 391                if (*bits && block->contig_hint_start >= block_off &&
 392                    *bits + block->contig_hint_start < PCPU_BITMAP_BLOCK_BITS) {
 393                        *bit_off = pcpu_block_off_to_off(i,
 394                                        block->contig_hint_start);
 395                        return;
 396                }
 397                /* reset to satisfy the second predicate above */
 398                block_off = 0;
 399
 400                *bits = block->right_free;
 401                *bit_off = (i + 1) * PCPU_BITMAP_BLOCK_BITS - block->right_free;
 402        }
 403}
 404
 405/**
 406 * pcpu_next_fit_region - finds fit areas for a given allocation request
 407 * @chunk: chunk of interest
 408 * @alloc_bits: size of allocation
 409 * @align: alignment of area (max PAGE_SIZE)
 410 * @bit_off: chunk offset
 411 * @bits: size of free area
 412 *
 413 * Finds the next free region that is viable for use with a given size and
 414 * alignment.  This only returns if there is a valid area to be used for this
 415 * allocation.  block->first_free is returned if the allocation request fits
 416 * within the block to see if the request can be fulfilled prior to the contig
 417 * hint.
 418 */
 419static void pcpu_next_fit_region(struct pcpu_chunk *chunk, int alloc_bits,
 420                                 int align, int *bit_off, int *bits)
 421{
 422        int i = pcpu_off_to_block_index(*bit_off);
 423        int block_off = pcpu_off_to_block_off(*bit_off);
 424        struct pcpu_block_md *block;
 425
 426        *bits = 0;
 427        for (block = chunk->md_blocks + i; i < pcpu_chunk_nr_blocks(chunk);
 428             block++, i++) {
 429                /* handles contig area across blocks */
 430                if (*bits) {
 431                        *bits += block->left_free;
 432                        if (*bits >= alloc_bits)
 433                                return;
 434                        if (block->left_free == PCPU_BITMAP_BLOCK_BITS)
 435                                continue;
 436                }
 437
 438                /* check block->contig_hint */
 439                *bits = ALIGN(block->contig_hint_start, align) -
 440                        block->contig_hint_start;
 441                /*
 442                 * This uses the block offset to determine if this has been
 443                 * checked in the prior iteration.
 444                 */
 445                if (block->contig_hint &&
 446                    block->contig_hint_start >= block_off &&
 447                    block->contig_hint >= *bits + alloc_bits) {
 448                        int start = pcpu_next_hint(block, alloc_bits);
 449
 450                        *bits += alloc_bits + block->contig_hint_start -
 451                                 start;
 452                        *bit_off = pcpu_block_off_to_off(i, start);
 453                        return;
 454                }
 455                /* reset to satisfy the second predicate above */
 456                block_off = 0;
 457
 458                *bit_off = ALIGN(PCPU_BITMAP_BLOCK_BITS - block->right_free,
 459                                 align);
 460                *bits = PCPU_BITMAP_BLOCK_BITS - *bit_off;
 461                *bit_off = pcpu_block_off_to_off(i, *bit_off);
 462                if (*bits >= alloc_bits)
 463                        return;
 464        }
 465
 466        /* no valid offsets were found - fail condition */
 467        *bit_off = pcpu_chunk_map_bits(chunk);
 468}
 469
 470/*
 471 * Metadata free area iterators.  These perform aggregation of free areas
 472 * based on the metadata blocks and return the offset @bit_off and size in
 473 * bits of the free area @bits.  pcpu_for_each_fit_region only returns when
 474 * a fit is found for the allocation request.
 475 */
 476#define pcpu_for_each_md_free_region(chunk, bit_off, bits)              \
 477        for (pcpu_next_md_free_region((chunk), &(bit_off), &(bits));    \
 478             (bit_off) < pcpu_chunk_map_bits((chunk));                  \
 479             (bit_off) += (bits) + 1,                                   \
 480             pcpu_next_md_free_region((chunk), &(bit_off), &(bits)))
 481
 482#define pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits)     \
 483        for (pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
 484                                  &(bits));                                   \
 485             (bit_off) < pcpu_chunk_map_bits((chunk));                        \
 486             (bit_off) += (bits),                                             \
 487             pcpu_next_fit_region((chunk), (alloc_bits), (align), &(bit_off), \
 488                                  &(bits)))
 489
 490/**
 491 * pcpu_mem_zalloc - allocate memory
 492 * @size: bytes to allocate
 493 * @gfp: allocation flags
 494 *
 495 * Allocate @size bytes.  If @size is smaller than PAGE_SIZE,
 496 * kzalloc() is used; otherwise, the equivalent of vzalloc() is used.
 497 * This is to facilitate passing through whitelisted flags.  The
 498 * returned memory is always zeroed.
 499 *
 500 * RETURNS:
 501 * Pointer to the allocated area on success, NULL on failure.
 502 */
 503static void *pcpu_mem_zalloc(size_t size, gfp_t gfp)
 504{
 505        if (WARN_ON_ONCE(!slab_is_available()))
 506                return NULL;
 507
 508        if (size <= PAGE_SIZE)
 509                return kzalloc(size, gfp);
 510        else
 511                return __vmalloc(size, gfp | __GFP_ZERO, PAGE_KERNEL);
 512}
 513
 514/**
 515 * pcpu_mem_free - free memory
 516 * @ptr: memory to free
 517 *
 518 * Free @ptr.  @ptr should have been allocated using pcpu_mem_zalloc().
 519 */
 520static void pcpu_mem_free(void *ptr)
 521{
 522        kvfree(ptr);
 523}
 524
 525static void __pcpu_chunk_move(struct pcpu_chunk *chunk, int slot,
 526                              bool move_front)
 527{
 528        if (chunk != pcpu_reserved_chunk) {
 529                if (move_front)
 530                        list_move(&chunk->list, &pcpu_slot[slot]);
 531                else
 532                        list_move_tail(&chunk->list, &pcpu_slot[slot]);
 533        }
 534}
 535
 536static void pcpu_chunk_move(struct pcpu_chunk *chunk, int slot)
 537{
 538        __pcpu_chunk_move(chunk, slot, true);
 539}
 540
 541/**
 542 * pcpu_chunk_relocate - put chunk in the appropriate chunk slot
 543 * @chunk: chunk of interest
 544 * @oslot: the previous slot it was on
 545 *
 546 * This function is called after an allocation or free changed @chunk.
 547 * New slot according to the changed state is determined and @chunk is
 548 * moved to the slot.  Note that the reserved chunk is never put on
 549 * chunk slots.
 550 *
 551 * CONTEXT:
 552 * pcpu_lock.
 553 */
 554static void pcpu_chunk_relocate(struct pcpu_chunk *chunk, int oslot)
 555{
 556        int nslot = pcpu_chunk_slot(chunk);
 557
 558        if (oslot != nslot)
 559                __pcpu_chunk_move(chunk, nslot, oslot < nslot);
 560}
 561
 562/*
 563 * pcpu_update_empty_pages - update empty page counters
 564 * @chunk: chunk of interest
 565 * @nr: nr of empty pages
 566 *
 567 * This is used to keep track of the empty pages now based on the premise
 568 * a md_block covers a page.  The hint update functions recognize if a block
 569 * is made full or broken to calculate deltas for keeping track of free pages.
 570 */
 571static inline void pcpu_update_empty_pages(struct pcpu_chunk *chunk, int nr)
 572{
 573        chunk->nr_empty_pop_pages += nr;
 574        if (chunk != pcpu_reserved_chunk)
 575                pcpu_nr_empty_pop_pages += nr;
 576}
 577
 578/*
 579 * pcpu_region_overlap - determines if two regions overlap
 580 * @a: start of first region, inclusive
 581 * @b: end of first region, exclusive
 582 * @x: start of second region, inclusive
 583 * @y: end of second region, exclusive
 584 *
 585 * This is used to determine if the hint region [a, b) overlaps with the
 586 * allocated region [x, y).
 587 */
 588static inline bool pcpu_region_overlap(int a, int b, int x, int y)
 589{
 590        return (a < y) && (x < b);
 591}
 592
 593/**
 594 * pcpu_block_update - updates a block given a free area
 595 * @block: block of interest
 596 * @start: start offset in block
 597 * @end: end offset in block
 598 *
 599 * Updates a block given a known free area.  The region [start, end) is
 600 * expected to be the entirety of the free area within a block.  Chooses
 601 * the best starting offset if the contig hints are equal.
 602 */
 603static void pcpu_block_update(struct pcpu_block_md *block, int start, int end)
 604{
 605        int contig = end - start;
 606
 607        block->first_free = min(block->first_free, start);
 608        if (start == 0)
 609                block->left_free = contig;
 610
 611        if (end == block->nr_bits)
 612                block->right_free = contig;
 613
 614        if (contig > block->contig_hint) {
 615                /* promote the old contig_hint to be the new scan_hint */
 616                if (start > block->contig_hint_start) {
 617                        if (block->contig_hint > block->scan_hint) {
 618                                block->scan_hint_start =
 619                                        block->contig_hint_start;
 620                                block->scan_hint = block->contig_hint;
 621                        } else if (start < block->scan_hint_start) {
 622                                /*
 623                                 * The old contig_hint == scan_hint.  But, the
 624                                 * new contig is larger so hold the invariant
 625                                 * scan_hint_start < contig_hint_start.
 626                                 */
 627                                block->scan_hint = 0;
 628                        }
 629                } else {
 630                        block->scan_hint = 0;
 631                }
 632                block->contig_hint_start = start;
 633                block->contig_hint = contig;
 634        } else if (contig == block->contig_hint) {
 635                if (block->contig_hint_start &&
 636                    (!start ||
 637                     __ffs(start) > __ffs(block->contig_hint_start))) {
 638                        /* start has a better alignment so use it */
 639                        block->contig_hint_start = start;
 640                        if (start < block->scan_hint_start &&
 641                            block->contig_hint > block->scan_hint)
 642                                block->scan_hint = 0;
 643                } else if (start > block->scan_hint_start ||
 644                           block->contig_hint > block->scan_hint) {
 645                        /*
 646                         * Knowing contig == contig_hint, update the scan_hint
 647                         * if it is farther than or larger than the current
 648                         * scan_hint.
 649                         */
 650                        block->scan_hint_start = start;
 651                        block->scan_hint = contig;
 652                }
 653        } else {
 654                /*
 655                 * The region is smaller than the contig_hint.  So only update
 656                 * the scan_hint if it is larger than or equal and farther than
 657                 * the current scan_hint.
 658                 */
 659                if ((start < block->contig_hint_start &&
 660                     (contig > block->scan_hint ||
 661                      (contig == block->scan_hint &&
 662                       start > block->scan_hint_start)))) {
 663                        block->scan_hint_start = start;
 664                        block->scan_hint = contig;
 665                }
 666        }
 667}
 668
 669/*
 670 * pcpu_block_update_scan - update a block given a free area from a scan
 671 * @chunk: chunk of interest
 672 * @bit_off: chunk offset
 673 * @bits: size of free area
 674 *
 675 * Finding the final allocation spot first goes through pcpu_find_block_fit()
 676 * to find a block that can hold the allocation and then pcpu_alloc_area()
 677 * where a scan is used.  When allocations require specific alignments,
 678 * we can inadvertently create holes which will not be seen in the alloc
 679 * or free paths.
 680 *
 681 * This takes a given free area hole and updates a block as it may change the
 682 * scan_hint.  We need to scan backwards to ensure we don't miss free bits
 683 * from alignment.
 684 */
 685static void pcpu_block_update_scan(struct pcpu_chunk *chunk, int bit_off,
 686                                   int bits)
 687{
 688        int s_off = pcpu_off_to_block_off(bit_off);
 689        int e_off = s_off + bits;
 690        int s_index, l_bit;
 691        struct pcpu_block_md *block;
 692
 693        if (e_off > PCPU_BITMAP_BLOCK_BITS)
 694                return;
 695
 696        s_index = pcpu_off_to_block_index(bit_off);
 697        block = chunk->md_blocks + s_index;
 698
 699        /* scan backwards in case of alignment skipping free bits */
 700        l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index), s_off);
 701        s_off = (s_off == l_bit) ? 0 : l_bit + 1;
 702
 703        pcpu_block_update(block, s_off, e_off);
 704}
 705
 706/**
 707 * pcpu_chunk_refresh_hint - updates metadata about a chunk
 708 * @chunk: chunk of interest
 709 * @full_scan: if we should scan from the beginning
 710 *
 711 * Iterates over the metadata blocks to find the largest contig area.
 712 * A full scan can be avoided on the allocation path as this is triggered
 713 * if we broke the contig_hint.  In doing so, the scan_hint will be before
 714 * the contig_hint or after if the scan_hint == contig_hint.  This cannot
 715 * be prevented on freeing as we want to find the largest area possibly
 716 * spanning blocks.
 717 */
 718static void pcpu_chunk_refresh_hint(struct pcpu_chunk *chunk, bool full_scan)
 719{
 720        struct pcpu_block_md *chunk_md = &chunk->chunk_md;
 721        int bit_off, bits;
 722
 723        /* promote scan_hint to contig_hint */
 724        if (!full_scan && chunk_md->scan_hint) {
 725                bit_off = chunk_md->scan_hint_start + chunk_md->scan_hint;
 726                chunk_md->contig_hint_start = chunk_md->scan_hint_start;
 727                chunk_md->contig_hint = chunk_md->scan_hint;
 728                chunk_md->scan_hint = 0;
 729        } else {
 730                bit_off = chunk_md->first_free;
 731                chunk_md->contig_hint = 0;
 732        }
 733
 734        bits = 0;
 735        pcpu_for_each_md_free_region(chunk, bit_off, bits) {
 736                pcpu_block_update(chunk_md, bit_off, bit_off + bits);
 737        }
 738}
 739
 740/**
 741 * pcpu_block_refresh_hint
 742 * @chunk: chunk of interest
 743 * @index: index of the metadata block
 744 *
 745 * Scans over the block beginning at first_free and updates the block
 746 * metadata accordingly.
 747 */
 748static void pcpu_block_refresh_hint(struct pcpu_chunk *chunk, int index)
 749{
 750        struct pcpu_block_md *block = chunk->md_blocks + index;
 751        unsigned long *alloc_map = pcpu_index_alloc_map(chunk, index);
 752        int rs, re, start;      /* region start, region end */
 753
 754        /* promote scan_hint to contig_hint */
 755        if (block->scan_hint) {
 756                start = block->scan_hint_start + block->scan_hint;
 757                block->contig_hint_start = block->scan_hint_start;
 758                block->contig_hint = block->scan_hint;
 759                block->scan_hint = 0;
 760        } else {
 761                start = block->first_free;
 762                block->contig_hint = 0;
 763        }
 764
 765        block->right_free = 0;
 766
 767        /* iterate over free areas and update the contig hints */
 768        pcpu_for_each_unpop_region(alloc_map, rs, re, start,
 769                                   PCPU_BITMAP_BLOCK_BITS) {
 770                pcpu_block_update(block, rs, re);
 771        }
 772}
 773
 774/**
 775 * pcpu_block_update_hint_alloc - update hint on allocation path
 776 * @chunk: chunk of interest
 777 * @bit_off: chunk offset
 778 * @bits: size of request
 779 *
 780 * Updates metadata for the allocation path.  The metadata only has to be
 781 * refreshed by a full scan iff the chunk's contig hint is broken.  Block level
 782 * scans are required if the block's contig hint is broken.
 783 */
 784static void pcpu_block_update_hint_alloc(struct pcpu_chunk *chunk, int bit_off,
 785                                         int bits)
 786{
 787        struct pcpu_block_md *chunk_md = &chunk->chunk_md;
 788        int nr_empty_pages = 0;
 789        struct pcpu_block_md *s_block, *e_block, *block;
 790        int s_index, e_index;   /* block indexes of the freed allocation */
 791        int s_off, e_off;       /* block offsets of the freed allocation */
 792
 793        /*
 794         * Calculate per block offsets.
 795         * The calculation uses an inclusive range, but the resulting offsets
 796         * are [start, end).  e_index always points to the last block in the
 797         * range.
 798         */
 799        s_index = pcpu_off_to_block_index(bit_off);
 800        e_index = pcpu_off_to_block_index(bit_off + bits - 1);
 801        s_off = pcpu_off_to_block_off(bit_off);
 802        e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
 803
 804        s_block = chunk->md_blocks + s_index;
 805        e_block = chunk->md_blocks + e_index;
 806
 807        /*
 808         * Update s_block.
 809         * block->first_free must be updated if the allocation takes its place.
 810         * If the allocation breaks the contig_hint, a scan is required to
 811         * restore this hint.
 812         */
 813        if (s_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
 814                nr_empty_pages++;
 815
 816        if (s_off == s_block->first_free)
 817                s_block->first_free = find_next_zero_bit(
 818                                        pcpu_index_alloc_map(chunk, s_index),
 819                                        PCPU_BITMAP_BLOCK_BITS,
 820                                        s_off + bits);
 821
 822        if (pcpu_region_overlap(s_block->scan_hint_start,
 823                                s_block->scan_hint_start + s_block->scan_hint,
 824                                s_off,
 825                                s_off + bits))
 826                s_block->scan_hint = 0;
 827
 828        if (pcpu_region_overlap(s_block->contig_hint_start,
 829                                s_block->contig_hint_start +
 830                                s_block->contig_hint,
 831                                s_off,
 832                                s_off + bits)) {
 833                /* block contig hint is broken - scan to fix it */
 834                if (!s_off)
 835                        s_block->left_free = 0;
 836                pcpu_block_refresh_hint(chunk, s_index);
 837        } else {
 838                /* update left and right contig manually */
 839                s_block->left_free = min(s_block->left_free, s_off);
 840                if (s_index == e_index)
 841                        s_block->right_free = min_t(int, s_block->right_free,
 842                                        PCPU_BITMAP_BLOCK_BITS - e_off);
 843                else
 844                        s_block->right_free = 0;
 845        }
 846
 847        /*
 848         * Update e_block.
 849         */
 850        if (s_index != e_index) {
 851                if (e_block->contig_hint == PCPU_BITMAP_BLOCK_BITS)
 852                        nr_empty_pages++;
 853
 854                /*
 855                 * When the allocation is across blocks, the end is along
 856                 * the left part of the e_block.
 857                 */
 858                e_block->first_free = find_next_zero_bit(
 859                                pcpu_index_alloc_map(chunk, e_index),
 860                                PCPU_BITMAP_BLOCK_BITS, e_off);
 861
 862                if (e_off == PCPU_BITMAP_BLOCK_BITS) {
 863                        /* reset the block */
 864                        e_block++;
 865                } else {
 866                        if (e_off > e_block->scan_hint_start)
 867                                e_block->scan_hint = 0;
 868
 869                        e_block->left_free = 0;
 870                        if (e_off > e_block->contig_hint_start) {
 871                                /* contig hint is broken - scan to fix it */
 872                                pcpu_block_refresh_hint(chunk, e_index);
 873                        } else {
 874                                e_block->right_free =
 875                                        min_t(int, e_block->right_free,
 876                                              PCPU_BITMAP_BLOCK_BITS - e_off);
 877                        }
 878                }
 879
 880                /* update in-between md_blocks */
 881                nr_empty_pages += (e_index - s_index - 1);
 882                for (block = s_block + 1; block < e_block; block++) {
 883                        block->scan_hint = 0;
 884                        block->contig_hint = 0;
 885                        block->left_free = 0;
 886                        block->right_free = 0;
 887                }
 888        }
 889
 890        if (nr_empty_pages)
 891                pcpu_update_empty_pages(chunk, -nr_empty_pages);
 892
 893        if (pcpu_region_overlap(chunk_md->scan_hint_start,
 894                                chunk_md->scan_hint_start +
 895                                chunk_md->scan_hint,
 896                                bit_off,
 897                                bit_off + bits))
 898                chunk_md->scan_hint = 0;
 899
 900        /*
 901         * The only time a full chunk scan is required is if the chunk
 902         * contig hint is broken.  Otherwise, it means a smaller space
 903         * was used and therefore the chunk contig hint is still correct.
 904         */
 905        if (pcpu_region_overlap(chunk_md->contig_hint_start,
 906                                chunk_md->contig_hint_start +
 907                                chunk_md->contig_hint,
 908                                bit_off,
 909                                bit_off + bits))
 910                pcpu_chunk_refresh_hint(chunk, false);
 911}
 912
 913/**
 914 * pcpu_block_update_hint_free - updates the block hints on the free path
 915 * @chunk: chunk of interest
 916 * @bit_off: chunk offset
 917 * @bits: size of request
 918 *
 919 * Updates metadata for the allocation path.  This avoids a blind block
 920 * refresh by making use of the block contig hints.  If this fails, it scans
 921 * forward and backward to determine the extent of the free area.  This is
 922 * capped at the boundary of blocks.
 923 *
 924 * A chunk update is triggered if a page becomes free, a block becomes free,
 925 * or the free spans across blocks.  This tradeoff is to minimize iterating
 926 * over the block metadata to update chunk_md->contig_hint.
 927 * chunk_md->contig_hint may be off by up to a page, but it will never be more
 928 * than the available space.  If the contig hint is contained in one block, it
 929 * will be accurate.
 930 */
 931static void pcpu_block_update_hint_free(struct pcpu_chunk *chunk, int bit_off,
 932                                        int bits)
 933{
 934        int nr_empty_pages = 0;
 935        struct pcpu_block_md *s_block, *e_block, *block;
 936        int s_index, e_index;   /* block indexes of the freed allocation */
 937        int s_off, e_off;       /* block offsets of the freed allocation */
 938        int start, end;         /* start and end of the whole free area */
 939
 940        /*
 941         * Calculate per block offsets.
 942         * The calculation uses an inclusive range, but the resulting offsets
 943         * are [start, end).  e_index always points to the last block in the
 944         * range.
 945         */
 946        s_index = pcpu_off_to_block_index(bit_off);
 947        e_index = pcpu_off_to_block_index(bit_off + bits - 1);
 948        s_off = pcpu_off_to_block_off(bit_off);
 949        e_off = pcpu_off_to_block_off(bit_off + bits - 1) + 1;
 950
 951        s_block = chunk->md_blocks + s_index;
 952        e_block = chunk->md_blocks + e_index;
 953
 954        /*
 955         * Check if the freed area aligns with the block->contig_hint.
 956         * If it does, then the scan to find the beginning/end of the
 957         * larger free area can be avoided.
 958         *
 959         * start and end refer to beginning and end of the free area
 960         * within each their respective blocks.  This is not necessarily
 961         * the entire free area as it may span blocks past the beginning
 962         * or end of the block.
 963         */
 964        start = s_off;
 965        if (s_off == s_block->contig_hint + s_block->contig_hint_start) {
 966                start = s_block->contig_hint_start;
 967        } else {
 968                /*
 969                 * Scan backwards to find the extent of the free area.
 970                 * find_last_bit returns the starting bit, so if the start bit
 971                 * is returned, that means there was no last bit and the
 972                 * remainder of the chunk is free.
 973                 */
 974                int l_bit = find_last_bit(pcpu_index_alloc_map(chunk, s_index),
 975                                          start);
 976                start = (start == l_bit) ? 0 : l_bit + 1;
 977        }
 978
 979        end = e_off;
 980        if (e_off == e_block->contig_hint_start)
 981                end = e_block->contig_hint_start + e_block->contig_hint;
 982        else
 983                end = find_next_bit(pcpu_index_alloc_map(chunk, e_index),
 984                                    PCPU_BITMAP_BLOCK_BITS, end);
 985
 986        /* update s_block */
 987        e_off = (s_index == e_index) ? end : PCPU_BITMAP_BLOCK_BITS;
 988        if (!start && e_off == PCPU_BITMAP_BLOCK_BITS)
 989                nr_empty_pages++;
 990        pcpu_block_update(s_block, start, e_off);
 991
 992        /* freeing in the same block */
 993        if (s_index != e_index) {
 994                /* update e_block */
 995                if (end == PCPU_BITMAP_BLOCK_BITS)
 996                        nr_empty_pages++;
 997                pcpu_block_update(e_block, 0, end);
 998
 999                /* reset md_blocks in the middle */
1000                nr_empty_pages += (e_index - s_index - 1);
1001                for (block = s_block + 1; block < e_block; block++) {
1002                        block->first_free = 0;
1003                        block->scan_hint = 0;
1004                        block->contig_hint_start = 0;
1005                        block->contig_hint = PCPU_BITMAP_BLOCK_BITS;
1006                        block->left_free = PCPU_BITMAP_BLOCK_BITS;
1007                        block->right_free = PCPU_BITMAP_BLOCK_BITS;
1008                }
1009        }
1010
1011        if (nr_empty_pages)
1012                pcpu_update_empty_pages(chunk, nr_empty_pages);
1013
1014        /*
1015         * Refresh chunk metadata when the free makes a block free or spans
1016         * across blocks.  The contig_hint may be off by up to a page, but if
1017         * the contig_hint is contained in a block, it will be accurate with
1018         * the else condition below.
1019         */
1020        if (((end - start) >= PCPU_BITMAP_BLOCK_BITS) || s_index != e_index)
1021                pcpu_chunk_refresh_hint(chunk, true);
1022        else
1023                pcpu_block_update(&chunk->chunk_md,
1024                                  pcpu_block_off_to_off(s_index, start),
1025                                  end);
1026}
1027
1028/**
1029 * pcpu_is_populated - determines if the region is populated
1030 * @chunk: chunk of interest
1031 * @bit_off: chunk offset
1032 * @bits: size of area
1033 * @next_off: return value for the next offset to start searching
1034 *
1035 * For atomic allocations, check if the backing pages are populated.
1036 *
1037 * RETURNS:
1038 * Bool if the backing pages are populated.
1039 * next_index is to skip over unpopulated blocks in pcpu_find_block_fit.
1040 */
1041static bool pcpu_is_populated(struct pcpu_chunk *chunk, int bit_off, int bits,
1042                              int *next_off)
1043{
1044        int page_start, page_end, rs, re;
1045
1046        page_start = PFN_DOWN(bit_off * PCPU_MIN_ALLOC_SIZE);
1047        page_end = PFN_UP((bit_off + bits) * PCPU_MIN_ALLOC_SIZE);
1048
1049        rs = page_start;
1050        pcpu_next_unpop(chunk->populated, &rs, &re, page_end);
1051        if (rs >= page_end)
1052                return true;
1053
1054        *next_off = re * PAGE_SIZE / PCPU_MIN_ALLOC_SIZE;
1055        return false;
1056}
1057
1058/**
1059 * pcpu_find_block_fit - finds the block index to start searching
1060 * @chunk: chunk of interest
1061 * @alloc_bits: size of request in allocation units
1062 * @align: alignment of area (max PAGE_SIZE bytes)
1063 * @pop_only: use populated regions only
1064 *
1065 * Given a chunk and an allocation spec, find the offset to begin searching
1066 * for a free region.  This iterates over the bitmap metadata blocks to
1067 * find an offset that will be guaranteed to fit the requirements.  It is
1068 * not quite first fit as if the allocation does not fit in the contig hint
1069 * of a block or chunk, it is skipped.  This errs on the side of caution
1070 * to prevent excess iteration.  Poor alignment can cause the allocator to
1071 * skip over blocks and chunks that have valid free areas.
1072 *
1073 * RETURNS:
1074 * The offset in the bitmap to begin searching.
1075 * -1 if no offset is found.
1076 */
1077static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits,
1078                               size_t align, bool pop_only)
1079{
1080        struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1081        int bit_off, bits, next_off;
1082
1083        /*
1084         * Check to see if the allocation can fit in the chunk's contig hint.
1085         * This is an optimization to prevent scanning by assuming if it
1086         * cannot fit in the global hint, there is memory pressure and creating
1087         * a new chunk would happen soon.
1088         */
1089        bit_off = ALIGN(chunk_md->contig_hint_start, align) -
1090                  chunk_md->contig_hint_start;
1091        if (bit_off + alloc_bits > chunk_md->contig_hint)
1092                return -1;
1093
1094        bit_off = pcpu_next_hint(chunk_md, alloc_bits);
1095        bits = 0;
1096        pcpu_for_each_fit_region(chunk, alloc_bits, align, bit_off, bits) {
1097                if (!pop_only || pcpu_is_populated(chunk, bit_off, bits,
1098                                                   &next_off))
1099                        break;
1100
1101                bit_off = next_off;
1102                bits = 0;
1103        }
1104
1105        if (bit_off == pcpu_chunk_map_bits(chunk))
1106                return -1;
1107
1108        return bit_off;
1109}
1110
1111/*
1112 * pcpu_find_zero_area - modified from bitmap_find_next_zero_area_off()
1113 * @map: the address to base the search on
1114 * @size: the bitmap size in bits
1115 * @start: the bitnumber to start searching at
1116 * @nr: the number of zeroed bits we're looking for
1117 * @align_mask: alignment mask for zero area
1118 * @largest_off: offset of the largest area skipped
1119 * @largest_bits: size of the largest area skipped
1120 *
1121 * The @align_mask should be one less than a power of 2.
1122 *
1123 * This is a modified version of bitmap_find_next_zero_area_off() to remember
1124 * the largest area that was skipped.  This is imperfect, but in general is
1125 * good enough.  The largest remembered region is the largest failed region
1126 * seen.  This does not include anything we possibly skipped due to alignment.
1127 * pcpu_block_update_scan() does scan backwards to try and recover what was
1128 * lost to alignment.  While this can cause scanning to miss earlier possible
1129 * free areas, smaller allocations will eventually fill those holes.
1130 */
1131static unsigned long pcpu_find_zero_area(unsigned long *map,
1132                                         unsigned long size,
1133                                         unsigned long start,
1134                                         unsigned long nr,
1135                                         unsigned long align_mask,
1136                                         unsigned long *largest_off,
1137                                         unsigned long *largest_bits)
1138{
1139        unsigned long index, end, i, area_off, area_bits;
1140again:
1141        index = find_next_zero_bit(map, size, start);
1142
1143        /* Align allocation */
1144        index = __ALIGN_MASK(index, align_mask);
1145        area_off = index;
1146
1147        end = index + nr;
1148        if (end > size)
1149                return end;
1150        i = find_next_bit(map, end, index);
1151        if (i < end) {
1152                area_bits = i - area_off;
1153                /* remember largest unused area with best alignment */
1154                if (area_bits > *largest_bits ||
1155                    (area_bits == *largest_bits && *largest_off &&
1156                     (!area_off || __ffs(area_off) > __ffs(*largest_off)))) {
1157                        *largest_off = area_off;
1158                        *largest_bits = area_bits;
1159                }
1160
1161                start = i + 1;
1162                goto again;
1163        }
1164        return index;
1165}
1166
1167/**
1168 * pcpu_alloc_area - allocates an area from a pcpu_chunk
1169 * @chunk: chunk of interest
1170 * @alloc_bits: size of request in allocation units
1171 * @align: alignment of area (max PAGE_SIZE)
1172 * @start: bit_off to start searching
1173 *
1174 * This function takes in a @start offset to begin searching to fit an
1175 * allocation of @alloc_bits with alignment @align.  It needs to scan
1176 * the allocation map because if it fits within the block's contig hint,
1177 * @start will be block->first_free. This is an attempt to fill the
1178 * allocation prior to breaking the contig hint.  The allocation and
1179 * boundary maps are updated accordingly if it confirms a valid
1180 * free area.
1181 *
1182 * RETURNS:
1183 * Allocated addr offset in @chunk on success.
1184 * -1 if no matching area is found.
1185 */
1186static int pcpu_alloc_area(struct pcpu_chunk *chunk, int alloc_bits,
1187                           size_t align, int start)
1188{
1189        struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1190        size_t align_mask = (align) ? (align - 1) : 0;
1191        unsigned long area_off = 0, area_bits = 0;
1192        int bit_off, end, oslot;
1193
1194        lockdep_assert_held(&pcpu_lock);
1195
1196        oslot = pcpu_chunk_slot(chunk);
1197
1198        /*
1199         * Search to find a fit.
1200         */
1201        end = min_t(int, start + alloc_bits + PCPU_BITMAP_BLOCK_BITS,
1202                    pcpu_chunk_map_bits(chunk));
1203        bit_off = pcpu_find_zero_area(chunk->alloc_map, end, start, alloc_bits,
1204                                      align_mask, &area_off, &area_bits);
1205        if (bit_off >= end)
1206                return -1;
1207
1208        if (area_bits)
1209                pcpu_block_update_scan(chunk, area_off, area_bits);
1210
1211        /* update alloc map */
1212        bitmap_set(chunk->alloc_map, bit_off, alloc_bits);
1213
1214        /* update boundary map */
1215        set_bit(bit_off, chunk->bound_map);
1216        bitmap_clear(chunk->bound_map, bit_off + 1, alloc_bits - 1);
1217        set_bit(bit_off + alloc_bits, chunk->bound_map);
1218
1219        chunk->free_bytes -= alloc_bits * PCPU_MIN_ALLOC_SIZE;
1220
1221        /* update first free bit */
1222        if (bit_off == chunk_md->first_free)
1223                chunk_md->first_free = find_next_zero_bit(
1224                                        chunk->alloc_map,
1225                                        pcpu_chunk_map_bits(chunk),
1226                                        bit_off + alloc_bits);
1227
1228        pcpu_block_update_hint_alloc(chunk, bit_off, alloc_bits);
1229
1230        pcpu_chunk_relocate(chunk, oslot);
1231
1232        return bit_off * PCPU_MIN_ALLOC_SIZE;
1233}
1234
1235/**
1236 * pcpu_free_area - frees the corresponding offset
1237 * @chunk: chunk of interest
1238 * @off: addr offset into chunk
1239 *
1240 * This function determines the size of an allocation to free using
1241 * the boundary bitmap and clears the allocation map.
1242 */
1243static void pcpu_free_area(struct pcpu_chunk *chunk, int off)
1244{
1245        struct pcpu_block_md *chunk_md = &chunk->chunk_md;
1246        int bit_off, bits, end, oslot;
1247
1248        lockdep_assert_held(&pcpu_lock);
1249        pcpu_stats_area_dealloc(chunk);
1250
1251        oslot = pcpu_chunk_slot(chunk);
1252
1253        bit_off = off / PCPU_MIN_ALLOC_SIZE;
1254
1255        /* find end index */
1256        end = find_next_bit(chunk->bound_map, pcpu_chunk_map_bits(chunk),
1257                            bit_off + 1);
1258        bits = end - bit_off;
1259        bitmap_clear(chunk->alloc_map, bit_off, bits);
1260
1261        /* update metadata */
1262        chunk->free_bytes += bits * PCPU_MIN_ALLOC_SIZE;
1263
1264        /* update first free bit */
1265        chunk_md->first_free = min(chunk_md->first_free, bit_off);
1266
1267        pcpu_block_update_hint_free(chunk, bit_off, bits);
1268
1269        pcpu_chunk_relocate(chunk, oslot);
1270}
1271
1272static void pcpu_init_md_block(struct pcpu_block_md *block, int nr_bits)
1273{
1274        block->scan_hint = 0;
1275        block->contig_hint = nr_bits;
1276        block->left_free = nr_bits;
1277        block->right_free = nr_bits;
1278        block->first_free = 0;
1279        block->nr_bits = nr_bits;
1280}
1281
1282static void pcpu_init_md_blocks(struct pcpu_chunk *chunk)
1283{
1284        struct pcpu_block_md *md_block;
1285
1286        /* init the chunk's block */
1287        pcpu_init_md_block(&chunk->chunk_md, pcpu_chunk_map_bits(chunk));
1288
1289        for (md_block = chunk->md_blocks;
1290             md_block != chunk->md_blocks + pcpu_chunk_nr_blocks(chunk);
1291             md_block++)
1292                pcpu_init_md_block(md_block, PCPU_BITMAP_BLOCK_BITS);
1293}
1294
1295/**
1296 * pcpu_alloc_first_chunk - creates chunks that serve the first chunk
1297 * @tmp_addr: the start of the region served
1298 * @map_size: size of the region served
1299 *
1300 * This is responsible for creating the chunks that serve the first chunk.  The
1301 * base_addr is page aligned down of @tmp_addr while the region end is page
1302 * aligned up.  Offsets are kept track of to determine the region served. All
1303 * this is done to appease the bitmap allocator in avoiding partial blocks.
1304 *
1305 * RETURNS:
1306 * Chunk serving the region at @tmp_addr of @map_size.
1307 */
1308static struct pcpu_chunk * __init pcpu_alloc_first_chunk(unsigned long tmp_addr,
1309                                                         int map_size)
1310{
1311        struct pcpu_chunk *chunk;
1312        unsigned long aligned_addr, lcm_align;
1313        int start_offset, offset_bits, region_size, region_bits;
1314        size_t alloc_size;
1315
1316        /* region calculations */
1317        aligned_addr = tmp_addr & PAGE_MASK;
1318
1319        start_offset = tmp_addr - aligned_addr;
1320
1321        /*
1322         * Align the end of the region with the LCM of PAGE_SIZE and
1323         * PCPU_BITMAP_BLOCK_SIZE.  One of these constants is a multiple of
1324         * the other.
1325         */
1326        lcm_align = lcm(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE);
1327        region_size = ALIGN(start_offset + map_size, lcm_align);
1328
1329        /* allocate chunk */
1330        alloc_size = sizeof(struct pcpu_chunk) +
1331                BITS_TO_LONGS(region_size >> PAGE_SHIFT);
1332        chunk = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1333        if (!chunk)
1334                panic("%s: Failed to allocate %zu bytes\n", __func__,
1335                      alloc_size);
1336
1337        INIT_LIST_HEAD(&chunk->list);
1338
1339        chunk->base_addr = (void *)aligned_addr;
1340        chunk->start_offset = start_offset;
1341        chunk->end_offset = region_size - chunk->start_offset - map_size;
1342
1343        chunk->nr_pages = region_size >> PAGE_SHIFT;
1344        region_bits = pcpu_chunk_map_bits(chunk);
1345
1346        alloc_size = BITS_TO_LONGS(region_bits) * sizeof(chunk->alloc_map[0]);
1347        chunk->alloc_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1348        if (!chunk->alloc_map)
1349                panic("%s: Failed to allocate %zu bytes\n", __func__,
1350                      alloc_size);
1351
1352        alloc_size =
1353                BITS_TO_LONGS(region_bits + 1) * sizeof(chunk->bound_map[0]);
1354        chunk->bound_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1355        if (!chunk->bound_map)
1356                panic("%s: Failed to allocate %zu bytes\n", __func__,
1357                      alloc_size);
1358
1359        alloc_size = pcpu_chunk_nr_blocks(chunk) * sizeof(chunk->md_blocks[0]);
1360        chunk->md_blocks = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
1361        if (!chunk->md_blocks)
1362                panic("%s: Failed to allocate %zu bytes\n", __func__,
1363                      alloc_size);
1364
1365        pcpu_init_md_blocks(chunk);
1366
1367        /* manage populated page bitmap */
1368        chunk->immutable = true;
1369        bitmap_fill(chunk->populated, chunk->nr_pages);
1370        chunk->nr_populated = chunk->nr_pages;
1371        chunk->nr_empty_pop_pages = chunk->nr_pages;
1372
1373        chunk->free_bytes = map_size;
1374
1375        if (chunk->start_offset) {
1376                /* hide the beginning of the bitmap */
1377                offset_bits = chunk->start_offset / PCPU_MIN_ALLOC_SIZE;
1378                bitmap_set(chunk->alloc_map, 0, offset_bits);
1379                set_bit(0, chunk->bound_map);
1380                set_bit(offset_bits, chunk->bound_map);
1381
1382                chunk->chunk_md.first_free = offset_bits;
1383
1384                pcpu_block_update_hint_alloc(chunk, 0, offset_bits);
1385        }
1386
1387        if (chunk->end_offset) {
1388                /* hide the end of the bitmap */
1389                offset_bits = chunk->end_offset / PCPU_MIN_ALLOC_SIZE;
1390                bitmap_set(chunk->alloc_map,
1391                           pcpu_chunk_map_bits(chunk) - offset_bits,
1392                           offset_bits);
1393                set_bit((start_offset + map_size) / PCPU_MIN_ALLOC_SIZE,
1394                        chunk->bound_map);
1395                set_bit(region_bits, chunk->bound_map);
1396
1397                pcpu_block_update_hint_alloc(chunk, pcpu_chunk_map_bits(chunk)
1398                                             - offset_bits, offset_bits);
1399        }
1400
1401        return chunk;
1402}
1403
1404static struct pcpu_chunk *pcpu_alloc_chunk(gfp_t gfp)
1405{
1406        struct pcpu_chunk *chunk;
1407        int region_bits;
1408
1409        chunk = pcpu_mem_zalloc(pcpu_chunk_struct_size, gfp);
1410        if (!chunk)
1411                return NULL;
1412
1413        INIT_LIST_HEAD(&chunk->list);
1414        chunk->nr_pages = pcpu_unit_pages;
1415        region_bits = pcpu_chunk_map_bits(chunk);
1416
1417        chunk->alloc_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits) *
1418                                           sizeof(chunk->alloc_map[0]), gfp);
1419        if (!chunk->alloc_map)
1420                goto alloc_map_fail;
1421
1422        chunk->bound_map = pcpu_mem_zalloc(BITS_TO_LONGS(region_bits + 1) *
1423                                           sizeof(chunk->bound_map[0]), gfp);
1424        if (!chunk->bound_map)
1425                goto bound_map_fail;
1426
1427        chunk->md_blocks = pcpu_mem_zalloc(pcpu_chunk_nr_blocks(chunk) *
1428                                           sizeof(chunk->md_blocks[0]), gfp);
1429        if (!chunk->md_blocks)
1430                goto md_blocks_fail;
1431
1432        pcpu_init_md_blocks(chunk);
1433
1434        /* init metadata */
1435        chunk->free_bytes = chunk->nr_pages * PAGE_SIZE;
1436
1437        return chunk;
1438
1439md_blocks_fail:
1440        pcpu_mem_free(chunk->bound_map);
1441bound_map_fail:
1442        pcpu_mem_free(chunk->alloc_map);
1443alloc_map_fail:
1444        pcpu_mem_free(chunk);
1445
1446        return NULL;
1447}
1448
1449static void pcpu_free_chunk(struct pcpu_chunk *chunk)
1450{
1451        if (!chunk)
1452                return;
1453        pcpu_mem_free(chunk->md_blocks);
1454        pcpu_mem_free(chunk->bound_map);
1455        pcpu_mem_free(chunk->alloc_map);
1456        pcpu_mem_free(chunk);
1457}
1458
1459/**
1460 * pcpu_chunk_populated - post-population bookkeeping
1461 * @chunk: pcpu_chunk which got populated
1462 * @page_start: the start page
1463 * @page_end: the end page
1464 *
1465 * Pages in [@page_start,@page_end) have been populated to @chunk.  Update
1466 * the bookkeeping information accordingly.  Must be called after each
1467 * successful population.
1468 *
1469 * If this is @for_alloc, do not increment pcpu_nr_empty_pop_pages because it
1470 * is to serve an allocation in that area.
1471 */
1472static void pcpu_chunk_populated(struct pcpu_chunk *chunk, int page_start,
1473                                 int page_end)
1474{
1475        int nr = page_end - page_start;
1476
1477        lockdep_assert_held(&pcpu_lock);
1478
1479        bitmap_set(chunk->populated, page_start, nr);
1480        chunk->nr_populated += nr;
1481        pcpu_nr_populated += nr;
1482
1483        pcpu_update_empty_pages(chunk, nr);
1484}
1485
1486/**
1487 * pcpu_chunk_depopulated - post-depopulation bookkeeping
1488 * @chunk: pcpu_chunk which got depopulated
1489 * @page_start: the start page
1490 * @page_end: the end page
1491 *
1492 * Pages in [@page_start,@page_end) have been depopulated from @chunk.
1493 * Update the bookkeeping information accordingly.  Must be called after
1494 * each successful depopulation.
1495 */
1496static void pcpu_chunk_depopulated(struct pcpu_chunk *chunk,
1497                                   int page_start, int page_end)
1498{
1499        int nr = page_end - page_start;
1500
1501        lockdep_assert_held(&pcpu_lock);
1502
1503        bitmap_clear(chunk->populated, page_start, nr);
1504        chunk->nr_populated -= nr;
1505        pcpu_nr_populated -= nr;
1506
1507        pcpu_update_empty_pages(chunk, -nr);
1508}
1509
1510/*
1511 * Chunk management implementation.
1512 *
1513 * To allow different implementations, chunk alloc/free and
1514 * [de]population are implemented in a separate file which is pulled
1515 * into this file and compiled together.  The following functions
1516 * should be implemented.
1517 *
1518 * pcpu_populate_chunk          - populate the specified range of a chunk
1519 * pcpu_depopulate_chunk        - depopulate the specified range of a chunk
1520 * pcpu_create_chunk            - create a new chunk
1521 * pcpu_destroy_chunk           - destroy a chunk, always preceded by full depop
1522 * pcpu_addr_to_page            - translate address to physical address
1523 * pcpu_verify_alloc_info       - check alloc_info is acceptable during init
1524 */
1525static int pcpu_populate_chunk(struct pcpu_chunk *chunk,
1526                               int page_start, int page_end, gfp_t gfp);
1527static void pcpu_depopulate_chunk(struct pcpu_chunk *chunk,
1528                                  int page_start, int page_end);
1529static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp);
1530static void pcpu_destroy_chunk(struct pcpu_chunk *chunk);
1531static struct page *pcpu_addr_to_page(void *addr);
1532static int __init pcpu_verify_alloc_info(const struct pcpu_alloc_info *ai);
1533
1534#ifdef CONFIG_NEED_PER_CPU_KM
1535#include "percpu-km.c"
1536#else
1537#include "percpu-vm.c"
1538#endif
1539
1540/**
1541 * pcpu_chunk_addr_search - determine chunk containing specified address
1542 * @addr: address for which the chunk needs to be determined.
1543 *
1544 * This is an internal function that handles all but static allocations.
1545 * Static percpu address values should never be passed into the allocator.
1546 *
1547 * RETURNS:
1548 * The address of the found chunk.
1549 */
1550static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
1551{
1552        /* is it in the dynamic region (first chunk)? */
1553        if (pcpu_addr_in_chunk(pcpu_first_chunk, addr))
1554                return pcpu_first_chunk;
1555
1556        /* is it in the reserved region? */
1557        if (pcpu_addr_in_chunk(pcpu_reserved_chunk, addr))
1558                return pcpu_reserved_chunk;
1559
1560        /*
1561         * The address is relative to unit0 which might be unused and
1562         * thus unmapped.  Offset the address to the unit space of the
1563         * current processor before looking it up in the vmalloc
1564         * space.  Note that any possible cpu id can be used here, so
1565         * there's no need to worry about preemption or cpu hotplug.
1566         */
1567        addr += pcpu_unit_offsets[raw_smp_processor_id()];
1568        return pcpu_get_page_chunk(pcpu_addr_to_page(addr));
1569}
1570
1571/**
1572 * pcpu_alloc - the percpu allocator
1573 * @size: size of area to allocate in bytes
1574 * @align: alignment of area (max PAGE_SIZE)
1575 * @reserved: allocate from the reserved chunk if available
1576 * @gfp: allocation flags
1577 *
1578 * Allocate percpu area of @size bytes aligned at @align.  If @gfp doesn't
1579 * contain %GFP_KERNEL, the allocation is atomic. If @gfp has __GFP_NOWARN
1580 * then no warning will be triggered on invalid or failed allocation
1581 * requests.
1582 *
1583 * RETURNS:
1584 * Percpu pointer to the allocated area on success, NULL on failure.
1585 */
1586static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
1587                                 gfp_t gfp)
1588{
1589        /* whitelisted flags that can be passed to the backing allocators */
1590        gfp_t pcpu_gfp = gfp & (GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN);
1591        bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
1592        bool do_warn = !(gfp & __GFP_NOWARN);
1593        static int warn_limit = 10;
1594        struct pcpu_chunk *chunk, *next;
1595        const char *err;
1596        int slot, off, cpu, ret;
1597        unsigned long flags;
1598        void __percpu *ptr;
1599        size_t bits, bit_align;
1600
1601        /*
1602         * There is now a minimum allocation size of PCPU_MIN_ALLOC_SIZE,
1603         * therefore alignment must be a minimum of that many bytes.
1604         * An allocation may have internal fragmentation from rounding up
1605         * of up to PCPU_MIN_ALLOC_SIZE - 1 bytes.
1606         */
1607        if (unlikely(align < PCPU_MIN_ALLOC_SIZE))
1608                align = PCPU_MIN_ALLOC_SIZE;
1609
1610        size = ALIGN(size, PCPU_MIN_ALLOC_SIZE);
1611        bits = size >> PCPU_MIN_ALLOC_SHIFT;
1612        bit_align = align >> PCPU_MIN_ALLOC_SHIFT;
1613
1614        if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE ||
1615                     !is_power_of_2(align))) {
1616                WARN(do_warn, "illegal size (%zu) or align (%zu) for percpu allocation\n",
1617                     size, align);
1618                return NULL;
1619        }
1620
1621        if (!is_atomic) {
1622                /*
1623                 * pcpu_balance_workfn() allocates memory under this mutex,
1624                 * and it may wait for memory reclaim. Allow current task
1625                 * to become OOM victim, in case of memory pressure.
1626                 */
1627                if (gfp & __GFP_NOFAIL)
1628                        mutex_lock(&pcpu_alloc_mutex);
1629                else if (mutex_lock_killable(&pcpu_alloc_mutex))
1630                        return NULL;
1631        }
1632
1633        spin_lock_irqsave(&pcpu_lock, flags);
1634
1635        /* serve reserved allocations from the reserved chunk if available */
1636        if (reserved && pcpu_reserved_chunk) {
1637                chunk = pcpu_reserved_chunk;
1638
1639                off = pcpu_find_block_fit(chunk, bits, bit_align, is_atomic);
1640                if (off < 0) {
1641                        err = "alloc from reserved chunk failed";
1642                        goto fail_unlock;
1643                }
1644
1645                off = pcpu_alloc_area(chunk, bits, bit_align, off);
1646                if (off >= 0)
1647                        goto area_found;
1648
1649                err = "alloc from reserved chunk failed";
1650                goto fail_unlock;
1651        }
1652
1653restart:
1654        /* search through normal chunks */
1655        for (slot = pcpu_size_to_slot(size); slot < pcpu_nr_slots; slot++) {
1656                list_for_each_entry_safe(chunk, next, &pcpu_slot[slot], list) {
1657                        off = pcpu_find_block_fit(chunk, bits, bit_align,
1658                                                  is_atomic);
1659                        if (off < 0) {
1660                                if (slot < PCPU_SLOT_FAIL_THRESHOLD)
1661                                        pcpu_chunk_move(chunk, 0);
1662                                continue;
1663                        }
1664
1665                        off = pcpu_alloc_area(chunk, bits, bit_align, off);
1666                        if (off >= 0)
1667                                goto area_found;
1668
1669                }
1670        }
1671
1672        spin_unlock_irqrestore(&pcpu_lock, flags);
1673
1674        /*
1675         * No space left.  Create a new chunk.  We don't want multiple
1676         * tasks to create chunks simultaneously.  Serialize and create iff
1677         * there's still no empty chunk after grabbing the mutex.
1678         */
1679        if (is_atomic) {
1680                err = "atomic alloc failed, no space left";
1681                goto fail;
1682        }
1683
1684        if (list_empty(&pcpu_slot[pcpu_nr_slots - 1])) {
1685                chunk = pcpu_create_chunk(pcpu_gfp);
1686                if (!chunk) {
1687                        err = "failed to allocate new chunk";
1688                        goto fail;
1689                }
1690
1691                spin_lock_irqsave(&pcpu_lock, flags);
1692                pcpu_chunk_relocate(chunk, -1);
1693        } else {
1694                spin_lock_irqsave(&pcpu_lock, flags);
1695        }
1696
1697        goto restart;
1698
1699area_found:
1700        pcpu_stats_area_alloc(chunk, size);
1701        spin_unlock_irqrestore(&pcpu_lock, flags);
1702
1703        /* populate if not all pages are already there */
1704        if (!is_atomic) {
1705                int page_start, page_end, rs, re;
1706
1707                page_start = PFN_DOWN(off);
1708                page_end = PFN_UP(off + size);
1709
1710                pcpu_for_each_unpop_region(chunk->populated, rs, re,
1711                                           page_start, page_end) {
1712                        WARN_ON(chunk->immutable);
1713
1714                        ret = pcpu_populate_chunk(chunk, rs, re, pcpu_gfp);
1715
1716                        spin_lock_irqsave(&pcpu_lock, flags);
1717                        if (ret) {
1718                                pcpu_free_area(chunk, off);
1719                                err = "failed to populate";
1720                                goto fail_unlock;
1721                        }
1722                        pcpu_chunk_populated(chunk, rs, re);
1723                        spin_unlock_irqrestore(&pcpu_lock, flags);
1724                }
1725
1726                mutex_unlock(&pcpu_alloc_mutex);
1727        }
1728
1729        if (pcpu_nr_empty_pop_pages < PCPU_EMPTY_POP_PAGES_LOW)
1730                pcpu_schedule_balance_work();
1731
1732        /* clear the areas and return address relative to base address */
1733        for_each_possible_cpu(cpu)
1734                memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size);
1735
1736        ptr = __addr_to_pcpu_ptr(chunk->base_addr + off);
1737        kmemleak_alloc_percpu(ptr, size, gfp);
1738
1739        trace_percpu_alloc_percpu(reserved, is_atomic, size, align,
1740                        chunk->base_addr, off, ptr);
1741
1742        return ptr;
1743
1744fail_unlock:
1745        spin_unlock_irqrestore(&pcpu_lock, flags);
1746fail:
1747        trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align);
1748
1749        if (!is_atomic && do_warn && warn_limit) {
1750                pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n",
1751                        size, align, is_atomic, err);
1752                dump_stack();
1753                if (!--warn_limit)
1754                        pr_info("limit reached, disable warning\n");
1755        }
1756        if (is_atomic) {
1757                /* see the flag handling in pcpu_blance_workfn() */
1758                pcpu_atomic_alloc_failed = true;
1759                pcpu_schedule_balance_work();
1760        } else {
1761                mutex_unlock(&pcpu_alloc_mutex);
1762        }
1763        return NULL;
1764}
1765
1766/**
1767 * __alloc_percpu_gfp - allocate dynamic percpu area
1768 * @size: size of area to allocate in bytes
1769 * @align: alignment of area (max PAGE_SIZE)
1770 * @gfp: allocation flags
1771 *
1772 * Allocate zero-filled percpu area of @size bytes aligned at @align.  If
1773 * @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can
1774 * be called from any context but is a lot more likely to fail. If @gfp
1775 * has __GFP_NOWARN then no warning will be triggered on invalid or failed
1776 * allocation requests.
1777 *
1778 * RETURNS:
1779 * Percpu pointer to the allocated area on success, NULL on failure.
1780 */
1781void __percpu *__alloc_percpu_gfp(size_t size, size_t align, gfp_t gfp)
1782{
1783        return pcpu_alloc(size, align, false, gfp);
1784}
1785EXPORT_SYMBOL_GPL(__alloc_percpu_gfp);
1786
1787/**
1788 * __alloc_percpu - allocate dynamic percpu area
1789 * @size: size of area to allocate in bytes
1790 * @align: alignment of area (max PAGE_SIZE)
1791 *
1792 * Equivalent to __alloc_percpu_gfp(size, align, %GFP_KERNEL).
1793 */
1794void __percpu *__alloc_percpu(size_t size, size_t align)
1795{
1796        return pcpu_alloc(size, align, false, GFP_KERNEL);
1797}
1798EXPORT_SYMBOL_GPL(__alloc_percpu);
1799
1800/**
1801 * __alloc_reserved_percpu - allocate reserved percpu area
1802 * @size: size of area to allocate in bytes
1803 * @align: alignment of area (max PAGE_SIZE)
1804 *
1805 * Allocate zero-filled percpu area of @size bytes aligned at @align
1806 * from reserved percpu area if arch has set it up; otherwise,
1807 * allocation is served from the same dynamic area.  Might sleep.
1808 * Might trigger writeouts.
1809 *
1810 * CONTEXT:
1811 * Does GFP_KERNEL allocation.
1812 *
1813 * RETURNS:
1814 * Percpu pointer to the allocated area on success, NULL on failure.
1815 */
1816void __percpu *__alloc_reserved_percpu(size_t size, size_t align)
1817{
1818        return pcpu_alloc(size, align, true, GFP_KERNEL);
1819}
1820
1821/**
1822 * pcpu_balance_workfn - manage the amount of free chunks and populated pages
1823 * @work: unused
1824 *
1825 * Reclaim all fully free chunks except for the first one.  This is also
1826 * responsible for maintaining the pool of empty populated pages.  However,
1827 * it is possible that this is called when physical memory is scarce causing
1828 * OOM killer to be triggered.  We should avoid doing so until an actual
1829 * allocation causes the failure as it is possible that requests can be
1830 * serviced from already backed regions.
1831 */
1832static void pcpu_balance_workfn(struct work_struct *work)
1833{
1834        /* gfp flags passed to underlying allocators */
1835        const gfp_t gfp = GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN;
1836        LIST_HEAD(to_free);
1837        struct list_head *free_head = &pcpu_slot[pcpu_nr_slots - 1];
1838        struct pcpu_chunk *chunk, *next;
1839        int slot, nr_to_pop, ret;
1840
1841        /*
1842         * There's no reason to keep around multiple unused chunks and VM
1843         * areas can be scarce.  Destroy all free chunks except for one.
1844         */
1845        mutex_lock(&pcpu_alloc_mutex);
1846        spin_lock_irq(&pcpu_lock);
1847
1848        list_for_each_entry_safe(chunk, next, free_head, list) {
1849                WARN_ON(chunk->immutable);
1850
1851                /* spare the first one */
1852                if (chunk == list_first_entry(free_head, struct pcpu_chunk, list))
1853                        continue;
1854
1855                list_move(&chunk->list, &to_free);
1856        }
1857
1858        spin_unlock_irq(&pcpu_lock);
1859
1860        list_for_each_entry_safe(chunk, next, &to_free, list) {
1861                int rs, re;
1862
1863                pcpu_for_each_pop_region(chunk->populated, rs, re, 0,
1864                                         chunk->nr_pages) {
1865                        pcpu_depopulate_chunk(chunk, rs, re);
1866                        spin_lock_irq(&pcpu_lock);
1867                        pcpu_chunk_depopulated(chunk, rs, re);
1868                        spin_unlock_irq(&pcpu_lock);
1869                }
1870                pcpu_destroy_chunk(chunk);
1871                cond_resched();
1872        }
1873
1874        /*
1875         * Ensure there are certain number of free populated pages for
1876         * atomic allocs.  Fill up from the most packed so that atomic
1877         * allocs don't increase fragmentation.  If atomic allocation
1878         * failed previously, always populate the maximum amount.  This
1879         * should prevent atomic allocs larger than PAGE_SIZE from keeping
1880         * failing indefinitely; however, large atomic allocs are not
1881         * something we support properly and can be highly unreliable and
1882         * inefficient.
1883         */
1884retry_pop:
1885        if (pcpu_atomic_alloc_failed) {
1886                nr_to_pop = PCPU_EMPTY_POP_PAGES_HIGH;
1887                /* best effort anyway, don't worry about synchronization */
1888                pcpu_atomic_alloc_failed = false;
1889        } else {
1890                nr_to_pop = clamp(PCPU_EMPTY_POP_PAGES_HIGH -
1891                                  pcpu_nr_empty_pop_pages,
1892                                  0, PCPU_EMPTY_POP_PAGES_HIGH);
1893        }
1894
1895        for (slot = pcpu_size_to_slot(PAGE_SIZE); slot < pcpu_nr_slots; slot++) {
1896                int nr_unpop = 0, rs, re;
1897
1898                if (!nr_to_pop)
1899                        break;
1900
1901                spin_lock_irq(&pcpu_lock);
1902                list_for_each_entry(chunk, &pcpu_slot[slot], list) {
1903                        nr_unpop = chunk->nr_pages - chunk->nr_populated;
1904                        if (nr_unpop)
1905                                break;
1906                }
1907                spin_unlock_irq(&pcpu_lock);
1908
1909                if (!nr_unpop)
1910                        continue;
1911
1912                /* @chunk can't go away while pcpu_alloc_mutex is held */
1913                pcpu_for_each_unpop_region(chunk->populated, rs, re, 0,
1914                                           chunk->nr_pages) {
1915                        int nr = min(re - rs, nr_to_pop);
1916
1917                        ret = pcpu_populate_chunk(chunk, rs, rs + nr, gfp);
1918                        if (!ret) {
1919                                nr_to_pop -= nr;
1920                                spin_lock_irq(&pcpu_lock);
1921                                pcpu_chunk_populated(chunk, rs, rs + nr);
1922                                spin_unlock_irq(&pcpu_lock);
1923                        } else {
1924                                nr_to_pop = 0;
1925                        }
1926
1927                        if (!nr_to_pop)
1928                                break;
1929                }
1930        }
1931
1932        if (nr_to_pop) {
1933                /* ran out of chunks to populate, create a new one and retry */
1934                chunk = pcpu_create_chunk(gfp);
1935                if (chunk) {
1936                        spin_lock_irq(&pcpu_lock);
1937                        pcpu_chunk_relocate(chunk, -1);
1938                        spin_unlock_irq(&pcpu_lock);
1939                        goto retry_pop;
1940                }
1941        }
1942
1943        mutex_unlock(&pcpu_alloc_mutex);
1944}
1945
1946/**
1947 * free_percpu - free percpu area
1948 * @ptr: pointer to area to free
1949 *
1950 * Free percpu area @ptr.
1951 *
1952 * CONTEXT:
1953 * Can be called from atomic context.
1954 */
1955void free_percpu(void __percpu *ptr)
1956{
1957        void *addr;
1958        struct pcpu_chunk *chunk;
1959        unsigned long flags;
1960        int off;
1961        bool need_balance = false;
1962
1963        if (!ptr)
1964                return;
1965
1966        kmemleak_free_percpu(ptr);
1967
1968        addr = __pcpu_ptr_to_addr(ptr);
1969
1970        spin_lock_irqsave(&pcpu_lock, flags);
1971
1972        chunk = pcpu_chunk_addr_search(addr);
1973        off = addr - chunk->base_addr;
1974
1975        pcpu_free_area(chunk, off);
1976
1977        /* if there are more than one fully free chunks, wake up grim reaper */
1978        if (chunk->free_bytes == pcpu_unit_size) {
1979                struct pcpu_chunk *pos;
1980
1981                list_for_each_entry(pos, &pcpu_slot[pcpu_nr_slots - 1], list)
1982                        if (pos != chunk) {
1983                                need_balance = true;
1984                                break;
1985                        }
1986        }
1987
1988        trace_percpu_free_percpu(chunk->base_addr, off, ptr);
1989
1990        spin_unlock_irqrestore(&pcpu_lock, flags);
1991
1992        if (need_balance)
1993                pcpu_schedule_balance_work();
1994}
1995EXPORT_SYMBOL_GPL(free_percpu);
1996
1997bool __is_kernel_percpu_address(unsigned long addr, unsigned long *can_addr)
1998{
1999#ifdef CONFIG_SMP
2000        const size_t static_size = __per_cpu_end - __per_cpu_start;
2001        void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2002        unsigned int cpu;
2003
2004        for_each_possible_cpu(cpu) {
2005                void *start = per_cpu_ptr(base, cpu);
2006                void *va = (void *)addr;
2007
2008                if (va >= start && va < start + static_size) {
2009                        if (can_addr) {
2010                                *can_addr = (unsigned long) (va - start);
2011                                *can_addr += (unsigned long)
2012                                        per_cpu_ptr(base, get_boot_cpu_id());
2013                        }
2014                        return true;
2015                }
2016        }
2017#endif
2018        /* on UP, can't distinguish from other static vars, always false */
2019        return false;
2020}
2021
2022/**
2023 * is_kernel_percpu_address - test whether address is from static percpu area
2024 * @addr: address to test
2025 *
2026 * Test whether @addr belongs to in-kernel static percpu area.  Module
2027 * static percpu areas are not considered.  For those, use
2028 * is_module_percpu_address().
2029 *
2030 * RETURNS:
2031 * %true if @addr is from in-kernel static percpu area, %false otherwise.
2032 */
2033bool is_kernel_percpu_address(unsigned long addr)
2034{
2035        return __is_kernel_percpu_address(addr, NULL);
2036}
2037
2038/**
2039 * per_cpu_ptr_to_phys - convert translated percpu address to physical address
2040 * @addr: the address to be converted to physical address
2041 *
2042 * Given @addr which is dereferenceable address obtained via one of
2043 * percpu access macros, this function translates it into its physical
2044 * address.  The caller is responsible for ensuring @addr stays valid
2045 * until this function finishes.
2046 *
2047 * percpu allocator has special setup for the first chunk, which currently
2048 * supports either embedding in linear address space or vmalloc mapping,
2049 * and, from the second one, the backing allocator (currently either vm or
2050 * km) provides translation.
2051 *
2052 * The addr can be translated simply without checking if it falls into the
2053 * first chunk. But the current code reflects better how percpu allocator
2054 * actually works, and the verification can discover both bugs in percpu
2055 * allocator itself and per_cpu_ptr_to_phys() callers. So we keep current
2056 * code.
2057 *
2058 * RETURNS:
2059 * The physical address for @addr.
2060 */
2061phys_addr_t per_cpu_ptr_to_phys(void *addr)
2062{
2063        void __percpu *base = __addr_to_pcpu_ptr(pcpu_base_addr);
2064        bool in_first_chunk = false;
2065        unsigned long first_low, first_high;
2066        unsigned int cpu;
2067
2068        /*
2069         * The following test on unit_low/high isn't strictly
2070         * necessary but will speed up lookups of addresses which
2071         * aren't in the first chunk.
2072         *
2073         * The address check is against full chunk sizes.  pcpu_base_addr
2074         * points to the beginning of the first chunk including the
2075         * static region.  Assumes good intent as the first chunk may
2076         * not be full (ie. < pcpu_unit_pages in size).
2077         */
2078        first_low = (unsigned long)pcpu_base_addr +
2079                    pcpu_unit_page_offset(pcpu_low_unit_cpu, 0);
2080        first_high = (unsigned long)pcpu_base_addr +
2081                     pcpu_unit_page_offset(pcpu_high_unit_cpu, pcpu_unit_pages);
2082        if ((unsigned long)addr >= first_low &&
2083            (unsigned long)addr < first_high) {
2084                for_each_possible_cpu(cpu) {
2085                        void *start = per_cpu_ptr(base, cpu);
2086
2087                        if (addr >= start && addr < start + pcpu_unit_size) {
2088                                in_first_chunk = true;
2089                                break;
2090                        }
2091                }
2092        }
2093
2094        if (in_first_chunk) {
2095                if (!is_vmalloc_addr(addr))
2096                        return __pa(addr);
2097                else
2098                        return page_to_phys(vmalloc_to_page(addr)) +
2099                               offset_in_page(addr);
2100        } else
2101                return page_to_phys(pcpu_addr_to_page(addr)) +
2102                       offset_in_page(addr);
2103}
2104
2105/**
2106 * pcpu_alloc_alloc_info - allocate percpu allocation info
2107 * @nr_groups: the number of groups
2108 * @nr_units: the number of units
2109 *
2110 * Allocate ai which is large enough for @nr_groups groups containing
2111 * @nr_units units.  The returned ai's groups[0].cpu_map points to the
2112 * cpu_map array which is long enough for @nr_units and filled with
2113 * NR_CPUS.  It's the caller's responsibility to initialize cpu_map
2114 * pointer of other groups.
2115 *
2116 * RETURNS:
2117 * Pointer to the allocated pcpu_alloc_info on success, NULL on
2118 * failure.
2119 */
2120struct pcpu_alloc_info * __init pcpu_alloc_alloc_info(int nr_groups,
2121                                                      int nr_units)
2122{
2123        struct pcpu_alloc_info *ai;
2124        size_t base_size, ai_size;
2125        void *ptr;
2126        int unit;
2127
2128        base_size = ALIGN(struct_size(ai, groups, nr_groups),
2129                          __alignof__(ai->groups[0].cpu_map[0]));
2130        ai_size = base_size + nr_units * sizeof(ai->groups[0].cpu_map[0]);
2131
2132        ptr = memblock_alloc(PFN_ALIGN(ai_size), PAGE_SIZE);
2133        if (!ptr)
2134                return NULL;
2135        ai = ptr;
2136        ptr += base_size;
2137
2138        ai->groups[0].cpu_map = ptr;
2139
2140        for (unit = 0; unit < nr_units; unit++)
2141                ai->groups[0].cpu_map[unit] = NR_CPUS;
2142
2143        ai->nr_groups = nr_groups;
2144        ai->__ai_size = PFN_ALIGN(ai_size);
2145
2146        return ai;
2147}
2148
2149/**
2150 * pcpu_free_alloc_info - free percpu allocation info
2151 * @ai: pcpu_alloc_info to free
2152 *
2153 * Free @ai which was allocated by pcpu_alloc_alloc_info().
2154 */
2155void __init pcpu_free_alloc_info(struct pcpu_alloc_info *ai)
2156{
2157        memblock_free_early(__pa(ai), ai->__ai_size);
2158}
2159
2160/**
2161 * pcpu_dump_alloc_info - print out information about pcpu_alloc_info
2162 * @lvl: loglevel
2163 * @ai: allocation info to dump
2164 *
2165 * Print out information about @ai using loglevel @lvl.
2166 */
2167static void pcpu_dump_alloc_info(const char *lvl,
2168                                 const struct pcpu_alloc_info *ai)
2169{
2170        int group_width = 1, cpu_width = 1, width;
2171        char empty_str[] = "--------";
2172        int alloc = 0, alloc_end = 0;
2173        int group, v;
2174        int upa, apl;   /* units per alloc, allocs per line */
2175
2176        v = ai->nr_groups;
2177        while (v /= 10)
2178                group_width++;
2179
2180        v = num_possible_cpus();
2181        while (v /= 10)
2182                cpu_width++;
2183        empty_str[min_t(int, cpu_width, sizeof(empty_str) - 1)] = '\0';
2184
2185        upa = ai->alloc_size / ai->unit_size;
2186        width = upa * (cpu_width + 1) + group_width + 3;
2187        apl = rounddown_pow_of_two(max(60 / width, 1));
2188
2189        printk("%spcpu-alloc: s%zu r%zu d%zu u%zu alloc=%zu*%zu",
2190               lvl, ai->static_size, ai->reserved_size, ai->dyn_size,
2191               ai->unit_size, ai->alloc_size / ai->atom_size, ai->atom_size);
2192
2193        for (group = 0; group < ai->nr_groups; group++) {
2194                const struct pcpu_group_info *gi = &ai->groups[group];
2195                int unit = 0, unit_end = 0;
2196
2197                BUG_ON(gi->nr_units % upa);
2198                for (alloc_end += gi->nr_units / upa;
2199                     alloc < alloc_end; alloc++) {
2200                        if (!(alloc % apl)) {
2201                                pr_cont("\n");
2202                                printk("%spcpu-alloc: ", lvl);
2203                        }
2204                        pr_cont("[%0*d] ", group_width, group);
2205
2206                        for (unit_end += upa; unit < unit_end; unit++)
2207                                if (gi->cpu_map[unit] != NR_CPUS)
2208                                        pr_cont("%0*d ",
2209                                                cpu_width, gi->cpu_map[unit]);
2210                                else
2211                                        pr_cont("%s ", empty_str);
2212                }
2213        }
2214        pr_cont("\n");
2215}
2216
2217/**
2218 * pcpu_setup_first_chunk - initialize the first percpu chunk
2219 * @ai: pcpu_alloc_info describing how to percpu area is shaped
2220 * @base_addr: mapped address
2221 *
2222 * Initialize the first percpu chunk which contains the kernel static
2223 * percpu area.  This function is to be called from arch percpu area
2224 * setup path.
2225 *
2226 * @ai contains all information necessary to initialize the first
2227 * chunk and prime the dynamic percpu allocator.
2228 *
2229 * @ai->static_size is the size of static percpu area.
2230 *
2231 * @ai->reserved_size, if non-zero, specifies the amount of bytes to
2232 * reserve after the static area in the first chunk.  This reserves
2233 * the first chunk such that it's available only through reserved
2234 * percpu allocation.  This is primarily used to serve module percpu
2235 * static areas on architectures where the addressing model has
2236 * limited offset range for symbol relocations to guarantee module
2237 * percpu symbols fall inside the relocatable range.
2238 *
2239 * @ai->dyn_size determines the number of bytes available for dynamic
2240 * allocation in the first chunk.  The area between @ai->static_size +
2241 * @ai->reserved_size + @ai->dyn_size and @ai->unit_size is unused.
2242 *
2243 * @ai->unit_size specifies unit size and must be aligned to PAGE_SIZE
2244 * and equal to or larger than @ai->static_size + @ai->reserved_size +
2245 * @ai->dyn_size.
2246 *
2247 * @ai->atom_size is the allocation atom size and used as alignment
2248 * for vm areas.
2249 *
2250 * @ai->alloc_size is the allocation size and always multiple of
2251 * @ai->atom_size.  This is larger than @ai->atom_size if
2252 * @ai->unit_size is larger than @ai->atom_size.
2253 *
2254 * @ai->nr_groups and @ai->groups describe virtual memory layout of
2255 * percpu areas.  Units which should be colocated are put into the
2256 * same group.  Dynamic VM areas will be allocated according to these
2257 * groupings.  If @ai->nr_groups is zero, a single group containing
2258 * all units is assumed.
2259 *
2260 * The caller should have mapped the first chunk at @base_addr and
2261 * copied static data to each unit.
2262 *
2263 * The first chunk will always contain a static and a dynamic region.
2264 * However, the static region is not managed by any chunk.  If the first
2265 * chunk also contains a reserved region, it is served by two chunks -
2266 * one for the reserved region and one for the dynamic region.  They
2267 * share the same vm, but use offset regions in the area allocation map.
2268 * The chunk serving the dynamic region is circulated in the chunk slots
2269 * and available for dynamic allocation like any other chunk.
2270 */
2271void __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
2272                                   void *base_addr)
2273{
2274        size_t size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2275        size_t static_size, dyn_size;
2276        struct pcpu_chunk *chunk;
2277        unsigned long *group_offsets;
2278        size_t *group_sizes;
2279        unsigned long *unit_off;
2280        unsigned int cpu;
2281        int *unit_map;
2282        int group, unit, i;
2283        int map_size;
2284        unsigned long tmp_addr;
2285        size_t alloc_size;
2286
2287#define PCPU_SETUP_BUG_ON(cond) do {                                    \
2288        if (unlikely(cond)) {                                           \
2289                pr_emerg("failed to initialize, %s\n", #cond);          \
2290                pr_emerg("cpu_possible_mask=%*pb\n",                    \
2291                         cpumask_pr_args(cpu_possible_mask));           \
2292                pcpu_dump_alloc_info(KERN_EMERG, ai);                   \
2293                BUG();                                                  \
2294        }                                                               \
2295} while (0)
2296
2297        /* sanity checks */
2298        PCPU_SETUP_BUG_ON(ai->nr_groups <= 0);
2299#ifdef CONFIG_SMP
2300        PCPU_SETUP_BUG_ON(!ai->static_size);
2301        PCPU_SETUP_BUG_ON(offset_in_page(__per_cpu_start));
2302#endif
2303        PCPU_SETUP_BUG_ON(!base_addr);
2304        PCPU_SETUP_BUG_ON(offset_in_page(base_addr));
2305        PCPU_SETUP_BUG_ON(ai->unit_size < size_sum);
2306        PCPU_SETUP_BUG_ON(offset_in_page(ai->unit_size));
2307        PCPU_SETUP_BUG_ON(ai->unit_size < PCPU_MIN_UNIT_SIZE);
2308        PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->unit_size, PCPU_BITMAP_BLOCK_SIZE));
2309        PCPU_SETUP_BUG_ON(ai->dyn_size < PERCPU_DYNAMIC_EARLY_SIZE);
2310        PCPU_SETUP_BUG_ON(!ai->dyn_size);
2311        PCPU_SETUP_BUG_ON(!IS_ALIGNED(ai->reserved_size, PCPU_MIN_ALLOC_SIZE));
2312        PCPU_SETUP_BUG_ON(!(IS_ALIGNED(PCPU_BITMAP_BLOCK_SIZE, PAGE_SIZE) ||
2313                            IS_ALIGNED(PAGE_SIZE, PCPU_BITMAP_BLOCK_SIZE)));
2314        PCPU_SETUP_BUG_ON(pcpu_verify_alloc_info(ai) < 0);
2315
2316        /* process group information and build config tables accordingly */
2317        alloc_size = ai->nr_groups * sizeof(group_offsets[0]);
2318        group_offsets = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2319        if (!group_offsets)
2320                panic("%s: Failed to allocate %zu bytes\n", __func__,
2321                      alloc_size);
2322
2323        alloc_size = ai->nr_groups * sizeof(group_sizes[0]);
2324        group_sizes = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2325        if (!group_sizes)
2326                panic("%s: Failed to allocate %zu bytes\n", __func__,
2327                      alloc_size);
2328
2329        alloc_size = nr_cpu_ids * sizeof(unit_map[0]);
2330        unit_map = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2331        if (!unit_map)
2332                panic("%s: Failed to allocate %zu bytes\n", __func__,
2333                      alloc_size);
2334
2335        alloc_size = nr_cpu_ids * sizeof(unit_off[0]);
2336        unit_off = memblock_alloc(alloc_size, SMP_CACHE_BYTES);
2337        if (!unit_off)
2338                panic("%s: Failed to allocate %zu bytes\n", __func__,
2339                      alloc_size);
2340
2341        for (cpu = 0; cpu < nr_cpu_ids; cpu++)
2342                unit_map[cpu] = UINT_MAX;
2343
2344        pcpu_low_unit_cpu = NR_CPUS;
2345        pcpu_high_unit_cpu = NR_CPUS;
2346
2347        for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
2348                const struct pcpu_group_info *gi = &ai->groups[group];
2349
2350                group_offsets[group] = gi->base_offset;
2351                group_sizes[group] = gi->nr_units * ai->unit_size;
2352
2353                for (i = 0; i < gi->nr_units; i++) {
2354                        cpu = gi->cpu_map[i];
2355                        if (cpu == NR_CPUS)
2356                                continue;
2357
2358                        PCPU_SETUP_BUG_ON(cpu >= nr_cpu_ids);
2359                        PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
2360                        PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
2361
2362                        unit_map[cpu] = unit + i;
2363                        unit_off[cpu] = gi->base_offset + i * ai->unit_size;
2364
2365                        /* determine low/high unit_cpu */
2366                        if (pcpu_low_unit_cpu == NR_CPUS ||
2367                            unit_off[cpu] < unit_off[pcpu_low_unit_cpu])
2368                                pcpu_low_unit_cpu = cpu;
2369                        if (pcpu_high_unit_cpu == NR_CPUS ||
2370                            unit_off[cpu] > unit_off[pcpu_high_unit_cpu])
2371                                pcpu_high_unit_cpu = cpu;
2372                }
2373        }
2374        pcpu_nr_units = unit;
2375
2376        for_each_possible_cpu(cpu)
2377                PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
2378
2379        /* we're done parsing the input, undefine BUG macro and dump config */
2380#undef PCPU_SETUP_BUG_ON
2381        pcpu_dump_alloc_info(KERN_DEBUG, ai);
2382
2383        pcpu_nr_groups = ai->nr_groups;
2384        pcpu_group_offsets = group_offsets;
2385        pcpu_group_sizes = group_sizes;
2386        pcpu_unit_map = unit_map;
2387        pcpu_unit_offsets = unit_off;
2388
2389        /* determine basic parameters */
2390        pcpu_unit_pages = ai->unit_size >> PAGE_SHIFT;
2391        pcpu_unit_size = pcpu_unit_pages << PAGE_SHIFT;
2392        pcpu_atom_size = ai->atom_size;
2393        pcpu_chunk_struct_size = sizeof(struct pcpu_chunk) +
2394                BITS_TO_LONGS(pcpu_unit_pages) * sizeof(unsigned long);
2395
2396        pcpu_stats_save_ai(ai);
2397
2398        /*
2399         * Allocate chunk slots.  The additional last slot is for
2400         * empty chunks.
2401         */
2402        pcpu_nr_slots = __pcpu_size_to_slot(pcpu_unit_size) + 2;
2403        pcpu_slot = memblock_alloc(pcpu_nr_slots * sizeof(pcpu_slot[0]),
2404                                   SMP_CACHE_BYTES);
2405        if (!pcpu_slot)
2406                panic("%s: Failed to allocate %zu bytes\n", __func__,
2407                      pcpu_nr_slots * sizeof(pcpu_slot[0]));
2408        for (i = 0; i < pcpu_nr_slots; i++)
2409                INIT_LIST_HEAD(&pcpu_slot[i]);
2410
2411        /*
2412         * The end of the static region needs to be aligned with the
2413         * minimum allocation size as this offsets the reserved and
2414         * dynamic region.  The first chunk ends page aligned by
2415         * expanding the dynamic region, therefore the dynamic region
2416         * can be shrunk to compensate while still staying above the
2417         * configured sizes.
2418         */
2419        static_size = ALIGN(ai->static_size, PCPU_MIN_ALLOC_SIZE);
2420        dyn_size = ai->dyn_size - (static_size - ai->static_size);
2421
2422        /*
2423         * Initialize first chunk.
2424         * If the reserved_size is non-zero, this initializes the reserved
2425         * chunk.  If the reserved_size is zero, the reserved chunk is NULL
2426         * and the dynamic region is initialized here.  The first chunk,
2427         * pcpu_first_chunk, will always point to the chunk that serves
2428         * the dynamic region.
2429         */
2430        tmp_addr = (unsigned long)base_addr + static_size;
2431        map_size = ai->reserved_size ?: dyn_size;
2432        chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2433
2434        /* init dynamic chunk if necessary */
2435        if (ai->reserved_size) {
2436                pcpu_reserved_chunk = chunk;
2437
2438                tmp_addr = (unsigned long)base_addr + static_size +
2439                           ai->reserved_size;
2440                map_size = dyn_size;
2441                chunk = pcpu_alloc_first_chunk(tmp_addr, map_size);
2442        }
2443
2444        /* link the first chunk in */
2445        pcpu_first_chunk = chunk;
2446        pcpu_nr_empty_pop_pages = pcpu_first_chunk->nr_empty_pop_pages;
2447        pcpu_chunk_relocate(pcpu_first_chunk, -1);
2448
2449        /* include all regions of the first chunk */
2450        pcpu_nr_populated += PFN_DOWN(size_sum);
2451
2452        pcpu_stats_chunk_alloc();
2453        trace_percpu_create_chunk(base_addr);
2454
2455        /* we're done */
2456        pcpu_base_addr = base_addr;
2457}
2458
2459#ifdef CONFIG_SMP
2460
2461const char * const pcpu_fc_names[PCPU_FC_NR] __initconst = {
2462        [PCPU_FC_AUTO]  = "auto",
2463        [PCPU_FC_EMBED] = "embed",
2464        [PCPU_FC_PAGE]  = "page",
2465};
2466
2467enum pcpu_fc pcpu_chosen_fc __initdata = PCPU_FC_AUTO;
2468
2469static int __init percpu_alloc_setup(char *str)
2470{
2471        if (!str)
2472                return -EINVAL;
2473
2474        if (0)
2475                /* nada */;
2476#ifdef CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK
2477        else if (!strcmp(str, "embed"))
2478                pcpu_chosen_fc = PCPU_FC_EMBED;
2479#endif
2480#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2481        else if (!strcmp(str, "page"))
2482                pcpu_chosen_fc = PCPU_FC_PAGE;
2483#endif
2484        else
2485                pr_warn("unknown allocator %s specified\n", str);
2486
2487        return 0;
2488}
2489early_param("percpu_alloc", percpu_alloc_setup);
2490
2491/*
2492 * pcpu_embed_first_chunk() is used by the generic percpu setup.
2493 * Build it if needed by the arch config or the generic setup is going
2494 * to be used.
2495 */
2496#if defined(CONFIG_NEED_PER_CPU_EMBED_FIRST_CHUNK) || \
2497        !defined(CONFIG_HAVE_SETUP_PER_CPU_AREA)
2498#define BUILD_EMBED_FIRST_CHUNK
2499#endif
2500
2501/* build pcpu_page_first_chunk() iff needed by the arch config */
2502#if defined(CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK)
2503#define BUILD_PAGE_FIRST_CHUNK
2504#endif
2505
2506/* pcpu_build_alloc_info() is used by both embed and page first chunk */
2507#if defined(BUILD_EMBED_FIRST_CHUNK) || defined(BUILD_PAGE_FIRST_CHUNK)
2508/**
2509 * pcpu_build_alloc_info - build alloc_info considering distances between CPUs
2510 * @reserved_size: the size of reserved percpu area in bytes
2511 * @dyn_size: minimum free size for dynamic allocation in bytes
2512 * @atom_size: allocation atom size
2513 * @cpu_distance_fn: callback to determine distance between cpus, optional
2514 *
2515 * This function determines grouping of units, their mappings to cpus
2516 * and other parameters considering needed percpu size, allocation
2517 * atom size and distances between CPUs.
2518 *
2519 * Groups are always multiples of atom size and CPUs which are of
2520 * LOCAL_DISTANCE both ways are grouped together and share space for
2521 * units in the same group.  The returned configuration is guaranteed
2522 * to have CPUs on different nodes on different groups and >=75% usage
2523 * of allocated virtual address space.
2524 *
2525 * RETURNS:
2526 * On success, pointer to the new allocation_info is returned.  On
2527 * failure, ERR_PTR value is returned.
2528 */
2529static struct pcpu_alloc_info * __init pcpu_build_alloc_info(
2530                                size_t reserved_size, size_t dyn_size,
2531                                size_t atom_size,
2532                                pcpu_fc_cpu_distance_fn_t cpu_distance_fn)
2533{
2534        static int group_map[NR_CPUS] __initdata;
2535        static int group_cnt[NR_CPUS] __initdata;
2536        const size_t static_size = __per_cpu_end - __per_cpu_start;
2537        int nr_groups = 1, nr_units = 0;
2538        size_t size_sum, min_unit_size, alloc_size;
2539        int upa, max_upa, uninitialized_var(best_upa);  /* units_per_alloc */
2540        int last_allocs, group, unit;
2541        unsigned int cpu, tcpu;
2542        struct pcpu_alloc_info *ai;
2543        unsigned int *cpu_map;
2544
2545        /* this function may be called multiple times */
2546        memset(group_map, 0, sizeof(group_map));
2547        memset(group_cnt, 0, sizeof(group_cnt));
2548
2549        /* calculate size_sum and ensure dyn_size is enough for early alloc */
2550        size_sum = PFN_ALIGN(static_size + reserved_size +
2551                            max_t(size_t, dyn_size, PERCPU_DYNAMIC_EARLY_SIZE));
2552        dyn_size = size_sum - static_size - reserved_size;
2553
2554        /*
2555         * Determine min_unit_size, alloc_size and max_upa such that
2556         * alloc_size is multiple of atom_size and is the smallest
2557         * which can accommodate 4k aligned segments which are equal to
2558         * or larger than min_unit_size.
2559         */
2560        min_unit_size = max_t(size_t, size_sum, PCPU_MIN_UNIT_SIZE);
2561
2562        /* determine the maximum # of units that can fit in an allocation */
2563        alloc_size = roundup(min_unit_size, atom_size);
2564        upa = alloc_size / min_unit_size;
2565        while (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2566                upa--;
2567        max_upa = upa;
2568
2569        /* group cpus according to their proximity */
2570        for_each_possible_cpu(cpu) {
2571                group = 0;
2572        next_group:
2573                for_each_possible_cpu(tcpu) {
2574                        if (cpu == tcpu)
2575                                break;
2576                        if (group_map[tcpu] == group && cpu_distance_fn &&
2577                            (cpu_distance_fn(cpu, tcpu) > LOCAL_DISTANCE ||
2578                             cpu_distance_fn(tcpu, cpu) > LOCAL_DISTANCE)) {
2579                                group++;
2580                                nr_groups = max(nr_groups, group + 1);
2581                                goto next_group;
2582                        }
2583                }
2584                group_map[cpu] = group;
2585                group_cnt[group]++;
2586        }
2587
2588        /*
2589         * Wasted space is caused by a ratio imbalance of upa to group_cnt.
2590         * Expand the unit_size until we use >= 75% of the units allocated.
2591         * Related to atom_size, which could be much larger than the unit_size.
2592         */
2593        last_allocs = INT_MAX;
2594        for (upa = max_upa; upa; upa--) {
2595                int allocs = 0, wasted = 0;
2596
2597                if (alloc_size % upa || (offset_in_page(alloc_size / upa)))
2598                        continue;
2599
2600                for (group = 0; group < nr_groups; group++) {
2601                        int this_allocs = DIV_ROUND_UP(group_cnt[group], upa);
2602                        allocs += this_allocs;
2603                        wasted += this_allocs * upa - group_cnt[group];
2604                }
2605
2606                /*
2607                 * Don't accept if wastage is over 1/3.  The
2608                 * greater-than comparison ensures upa==1 always
2609                 * passes the following check.
2610                 */
2611                if (wasted > num_possible_cpus() / 3)
2612                        continue;
2613
2614                /* and then don't consume more memory */
2615                if (allocs > last_allocs)
2616                        break;
2617                last_allocs = allocs;
2618                best_upa = upa;
2619        }
2620        upa = best_upa;
2621
2622        /* allocate and fill alloc_info */
2623        for (group = 0; group < nr_groups; group++)
2624                nr_units += roundup(group_cnt[group], upa);
2625
2626        ai = pcpu_alloc_alloc_info(nr_groups, nr_units);
2627        if (!ai)
2628                return ERR_PTR(-ENOMEM);
2629        cpu_map = ai->groups[0].cpu_map;
2630
2631        for (group = 0; group < nr_groups; group++) {
2632                ai->groups[group].cpu_map = cpu_map;
2633                cpu_map += roundup(group_cnt[group], upa);
2634        }
2635
2636        ai->static_size = static_size;
2637        ai->reserved_size = reserved_size;
2638        ai->dyn_size = dyn_size;
2639        ai->unit_size = alloc_size / upa;
2640        ai->atom_size = atom_size;
2641        ai->alloc_size = alloc_size;
2642
2643        for (group = 0, unit = 0; group < nr_groups; group++) {
2644                struct pcpu_group_info *gi = &ai->groups[group];
2645
2646                /*
2647                 * Initialize base_offset as if all groups are located
2648                 * back-to-back.  The caller should update this to
2649                 * reflect actual allocation.
2650                 */
2651                gi->base_offset = unit * ai->unit_size;
2652
2653                for_each_possible_cpu(cpu)
2654                        if (group_map[cpu] == group)
2655                                gi->cpu_map[gi->nr_units++] = cpu;
2656                gi->nr_units = roundup(gi->nr_units, upa);
2657                unit += gi->nr_units;
2658        }
2659        BUG_ON(unit != nr_units);
2660
2661        return ai;
2662}
2663#endif /* BUILD_EMBED_FIRST_CHUNK || BUILD_PAGE_FIRST_CHUNK */
2664
2665#if defined(BUILD_EMBED_FIRST_CHUNK)
2666/**
2667 * pcpu_embed_first_chunk - embed the first percpu chunk into bootmem
2668 * @reserved_size: the size of reserved percpu area in bytes
2669 * @dyn_size: minimum free size for dynamic allocation in bytes
2670 * @atom_size: allocation atom size
2671 * @cpu_distance_fn: callback to determine distance between cpus, optional
2672 * @alloc_fn: function to allocate percpu page
2673 * @free_fn: function to free percpu page
2674 *
2675 * This is a helper to ease setting up embedded first percpu chunk and
2676 * can be called where pcpu_setup_first_chunk() is expected.
2677 *
2678 * If this function is used to setup the first chunk, it is allocated
2679 * by calling @alloc_fn and used as-is without being mapped into
2680 * vmalloc area.  Allocations are always whole multiples of @atom_size
2681 * aligned to @atom_size.
2682 *
2683 * This enables the first chunk to piggy back on the linear physical
2684 * mapping which often uses larger page size.  Please note that this
2685 * can result in very sparse cpu->unit mapping on NUMA machines thus
2686 * requiring large vmalloc address space.  Don't use this allocator if
2687 * vmalloc space is not orders of magnitude larger than distances
2688 * between node memory addresses (ie. 32bit NUMA machines).
2689 *
2690 * @dyn_size specifies the minimum dynamic area size.
2691 *
2692 * If the needed size is smaller than the minimum or specified unit
2693 * size, the leftover is returned using @free_fn.
2694 *
2695 * RETURNS:
2696 * 0 on success, -errno on failure.
2697 */
2698int __init pcpu_embed_first_chunk(size_t reserved_size, size_t dyn_size,
2699                                  size_t atom_size,
2700                                  pcpu_fc_cpu_distance_fn_t cpu_distance_fn,
2701                                  pcpu_fc_alloc_fn_t alloc_fn,
2702                                  pcpu_fc_free_fn_t free_fn)
2703{
2704        void *base = (void *)ULONG_MAX;
2705        void **areas = NULL;
2706        struct pcpu_alloc_info *ai;
2707        size_t size_sum, areas_size;
2708        unsigned long max_distance;
2709        int group, i, highest_group, rc = 0;
2710
2711        ai = pcpu_build_alloc_info(reserved_size, dyn_size, atom_size,
2712                                   cpu_distance_fn);
2713        if (IS_ERR(ai))
2714                return PTR_ERR(ai);
2715
2716        size_sum = ai->static_size + ai->reserved_size + ai->dyn_size;
2717        areas_size = PFN_ALIGN(ai->nr_groups * sizeof(void *));
2718
2719        areas = memblock_alloc(areas_size, SMP_CACHE_BYTES);
2720        if (!areas) {
2721                rc = -ENOMEM;
2722                goto out_free;
2723        }
2724
2725        /* allocate, copy and determine base address & max_distance */
2726        highest_group = 0;
2727        for (group = 0; group < ai->nr_groups; group++) {
2728                struct pcpu_group_info *gi = &ai->groups[group];
2729                unsigned int cpu = NR_CPUS;
2730                void *ptr;
2731
2732                for (i = 0; i < gi->nr_units && cpu == NR_CPUS; i++)
2733                        cpu = gi->cpu_map[i];
2734                BUG_ON(cpu == NR_CPUS);
2735
2736                /* allocate space for the whole group */
2737                ptr = alloc_fn(cpu, gi->nr_units * ai->unit_size, atom_size);
2738                if (!ptr) {
2739                        rc = -ENOMEM;
2740                        goto out_free_areas;
2741                }
2742                /* kmemleak tracks the percpu allocations separately */
2743                kmemleak_free(ptr);
2744                areas[group] = ptr;
2745
2746                base = min(ptr, base);
2747                if (ptr > areas[highest_group])
2748                        highest_group = group;
2749        }
2750        max_distance = areas[highest_group] - base;
2751        max_distance += ai->unit_size * ai->groups[highest_group].nr_units;
2752
2753        /* warn if maximum distance is further than 75% of vmalloc space */
2754        if (max_distance > VMALLOC_TOTAL * 3 / 4) {
2755                pr_warn("max_distance=0x%lx too large for vmalloc space 0x%lx\n",
2756                                max_distance, VMALLOC_TOTAL);
2757#ifdef CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK
2758                /* and fail if we have fallback */
2759                rc = -EINVAL;
2760                goto out_free_areas;
2761#endif
2762        }
2763
2764        /*
2765         * Copy data and free unused parts.  This should happen after all
2766         * allocations are complete; otherwise, we may end up with
2767         * overlapping groups.
2768         */
2769        for (group = 0; group < ai->nr_groups; group++) {
2770                struct pcpu_group_info *gi = &ai->groups[group];
2771                void *ptr = areas[group];
2772
2773                for (i = 0; i < gi->nr_units; i++, ptr += ai->unit_size) {
2774                        if (gi->cpu_map[i] == NR_CPUS) {
2775                                /* unused unit, free whole */
2776                                free_fn(ptr, ai->unit_size);
2777                                continue;
2778                        }
2779                        /* copy and return the unused part */
2780                        memcpy(ptr, __per_cpu_load, ai->static_size);
2781                        free_fn(ptr + size_sum, ai->unit_size - size_sum);
2782                }
2783        }
2784
2785        /* base address is now known, determine group base offsets */
2786        for (group = 0; group < ai->nr_groups; group++) {
2787                ai->groups[group].base_offset = areas[group] - base;
2788        }
2789
2790        pr_info("Embedded %zu pages/cpu s%zu r%zu d%zu u%zu\n",
2791                PFN_DOWN(size_sum), ai->static_size, ai->reserved_size,
2792                ai->dyn_size, ai->unit_size);
2793
2794        pcpu_setup_first_chunk(ai, base);
2795        goto out_free;
2796
2797out_free_areas:
2798        for (group = 0; group < ai->nr_groups; group++)
2799                if (areas[group])
2800                        free_fn(areas[group],
2801                                ai->groups[group].nr_units * ai->unit_size);
2802out_free:
2803        pcpu_free_alloc_info(ai);
2804        if (areas)
2805                memblock_free_early(__pa(areas), areas_size);
2806        return rc;
2807}
2808#endif /* BUILD_EMBED_FIRST_CHUNK */
2809
2810#ifdef BUILD_PAGE_FIRST_CHUNK
2811/**
2812 * pcpu_page_first_chunk - map the first chunk using PAGE_SIZE pages
2813 * @reserved_size: the size of reserved percpu area in bytes
2814 * @alloc_fn: function to allocate percpu page, always called with PAGE_SIZE
2815 * @free_fn: function to free percpu page, always called with PAGE_SIZE
2816 * @populate_pte_fn: function to populate pte
2817 *
2818 * This is a helper to ease setting up page-remapped first percpu
2819 * chunk and can be called where pcpu_setup_first_chunk() is expected.
2820 *
2821 * This is the basic allocator.  Static percpu area is allocated
2822 * page-by-page into vmalloc area.
2823 *
2824 * RETURNS:
2825 * 0 on success, -errno on failure.
2826 */
2827int __init pcpu_page_first_chunk(size_t reserved_size,
2828                                 pcpu_fc_alloc_fn_t alloc_fn,
2829                                 pcpu_fc_free_fn_t free_fn,
2830                                 pcpu_fc_populate_pte_fn_t populate_pte_fn)
2831{
2832        static struct vm_struct vm;
2833        struct pcpu_alloc_info *ai;
2834        char psize_str[16];
2835        int unit_pages;
2836        size_t pages_size;
2837        struct page **pages;
2838        int unit, i, j, rc = 0;
2839        int upa;
2840        int nr_g0_units;
2841
2842        snprintf(psize_str, sizeof(psize_str), "%luK", PAGE_SIZE >> 10);
2843
2844        ai = pcpu_build_alloc_info(reserved_size, 0, PAGE_SIZE, NULL);
2845        if (IS_ERR(ai))
2846                return PTR_ERR(ai);
2847        BUG_ON(ai->nr_groups != 1);
2848        upa = ai->alloc_size/ai->unit_size;
2849        nr_g0_units = roundup(num_possible_cpus(), upa);
2850        if (WARN_ON(ai->groups[0].nr_units != nr_g0_units)) {
2851                pcpu_free_alloc_info(ai);
2852                return -EINVAL;
2853        }
2854
2855        unit_pages = ai->unit_size >> PAGE_SHIFT;
2856
2857        /* unaligned allocations can't be freed, round up to page size */
2858        pages_size = PFN_ALIGN(unit_pages * num_possible_cpus() *
2859                               sizeof(pages[0]));
2860        pages = memblock_alloc(pages_size, SMP_CACHE_BYTES);
2861        if (!pages)
2862                panic("%s: Failed to allocate %zu bytes\n", __func__,
2863                      pages_size);
2864
2865        /* allocate pages */
2866        j = 0;
2867        for (unit = 0; unit < num_possible_cpus(); unit++) {
2868                unsigned int cpu = ai->groups[0].cpu_map[unit];
2869                for (i = 0; i < unit_pages; i++) {
2870                        void *ptr;
2871
2872                        ptr = alloc_fn(cpu, PAGE_SIZE, PAGE_SIZE);
2873                        if (!ptr) {
2874                                pr_warn("failed to allocate %s page for cpu%u\n",
2875                                                psize_str, cpu);
2876                                goto enomem;
2877                        }
2878                        /* kmemleak tracks the percpu allocations separately */
2879                        kmemleak_free(ptr);
2880                        pages[j++] = virt_to_page(ptr);
2881                }
2882        }
2883
2884        /* allocate vm area, map the pages and copy static data */
2885        vm.flags = VM_ALLOC;
2886        vm.size = num_possible_cpus() * ai->unit_size;
2887        vm_area_register_early(&vm, PAGE_SIZE);
2888
2889        for (unit = 0; unit < num_possible_cpus(); unit++) {
2890                unsigned long unit_addr =
2891                        (unsigned long)vm.addr + unit * ai->unit_size;
2892
2893                for (i = 0; i < unit_pages; i++)
2894                        populate_pte_fn(unit_addr + (i << PAGE_SHIFT));
2895
2896                /* pte already populated, the following shouldn't fail */
2897                rc = __pcpu_map_pages(unit_addr, &pages[unit * unit_pages],
2898                                      unit_pages);
2899                if (rc < 0)
2900                        panic("failed to map percpu area, err=%d\n", rc);
2901
2902                /*
2903                 * FIXME: Archs with virtual cache should flush local
2904                 * cache for the linear mapping here - something
2905                 * equivalent to flush_cache_vmap() on the local cpu.
2906                 * flush_cache_vmap() can't be used as most supporting
2907                 * data structures are not set up yet.
2908                 */
2909
2910                /* copy static data */
2911                memcpy((void *)unit_addr, __per_cpu_load, ai->static_size);
2912        }
2913
2914        /* we're ready, commit */
2915        pr_info("%d %s pages/cpu s%zu r%zu d%zu\n",
2916                unit_pages, psize_str, ai->static_size,
2917                ai->reserved_size, ai->dyn_size);
2918
2919        pcpu_setup_first_chunk(ai, vm.addr);
2920        goto out_free_ar;
2921
2922enomem:
2923        while (--j >= 0)
2924                free_fn(page_address(pages[j]), PAGE_SIZE);
2925        rc = -ENOMEM;
2926out_free_ar:
2927        memblock_free_early(__pa(pages), pages_size);
2928        pcpu_free_alloc_info(ai);
2929        return rc;
2930}
2931#endif /* BUILD_PAGE_FIRST_CHUNK */
2932
2933#ifndef CONFIG_HAVE_SETUP_PER_CPU_AREA
2934/*
2935 * Generic SMP percpu area setup.
2936 *
2937 * The embedding helper is used because its behavior closely resembles
2938 * the original non-dynamic generic percpu area setup.  This is
2939 * important because many archs have addressing restrictions and might
2940 * fail if the percpu area is located far away from the previous
2941 * location.  As an added bonus, in non-NUMA cases, embedding is
2942 * generally a good idea TLB-wise because percpu area can piggy back
2943 * on the physical linear memory mapping which uses large page
2944 * mappings on applicable archs.
2945 */
2946unsigned long __per_cpu_offset[NR_CPUS] __read_mostly;
2947EXPORT_SYMBOL(__per_cpu_offset);
2948
2949static void * __init pcpu_dfl_fc_alloc(unsigned int cpu, size_t size,
2950                                       size_t align)
2951{
2952        return  memblock_alloc_from(size, align, __pa(MAX_DMA_ADDRESS));
2953}
2954
2955static void __init pcpu_dfl_fc_free(void *ptr, size_t size)
2956{
2957        memblock_free_early(__pa(ptr), size);
2958}
2959
2960void __init setup_per_cpu_areas(void)
2961{
2962        unsigned long delta;
2963        unsigned int cpu;
2964        int rc;
2965
2966        /*
2967         * Always reserve area for module percpu variables.  That's
2968         * what the legacy allocator did.
2969         */
2970        rc = pcpu_embed_first_chunk(PERCPU_MODULE_RESERVE,
2971                                    PERCPU_DYNAMIC_RESERVE, PAGE_SIZE, NULL,
2972                                    pcpu_dfl_fc_alloc, pcpu_dfl_fc_free);
2973        if (rc < 0)
2974                panic("Failed to initialize percpu areas.");
2975
2976        delta = (unsigned long)pcpu_base_addr - (unsigned long)__per_cpu_start;
2977        for_each_possible_cpu(cpu)
2978                __per_cpu_offset[cpu] = delta + pcpu_unit_offsets[cpu];
2979}
2980#endif  /* CONFIG_HAVE_SETUP_PER_CPU_AREA */
2981
2982#else   /* CONFIG_SMP */
2983
2984/*
2985 * UP percpu area setup.
2986 *
2987 * UP always uses km-based percpu allocator with identity mapping.
2988 * Static percpu variables are indistinguishable from the usual static
2989 * variables and don't require any special preparation.
2990 */
2991void __init setup_per_cpu_areas(void)
2992{
2993        const size_t unit_size =
2994                roundup_pow_of_two(max_t(size_t, PCPU_MIN_UNIT_SIZE,
2995                                         PERCPU_DYNAMIC_RESERVE));
2996        struct pcpu_alloc_info *ai;
2997        void *fc;
2998
2999        ai = pcpu_alloc_alloc_info(1, 1);
3000        fc = memblock_alloc_from(unit_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS));
3001        if (!ai || !fc)
3002                panic("Failed to allocate memory for percpu areas.");
3003        /* kmemleak tracks the percpu allocations separately */
3004        kmemleak_free(fc);
3005
3006        ai->dyn_size = unit_size;
3007        ai->unit_size = unit_size;
3008        ai->atom_size = unit_size;
3009        ai->alloc_size = unit_size;
3010        ai->groups[0].nr_units = 1;
3011        ai->groups[0].cpu_map[0] = 0;
3012
3013        pcpu_setup_first_chunk(ai, fc);
3014        pcpu_free_alloc_info(ai);
3015}
3016
3017#endif  /* CONFIG_SMP */
3018
3019/*
3020 * pcpu_nr_pages - calculate total number of populated backing pages
3021 *
3022 * This reflects the number of pages populated to back chunks.  Metadata is
3023 * excluded in the number exposed in meminfo as the number of backing pages
3024 * scales with the number of cpus and can quickly outweigh the memory used for
3025 * metadata.  It also keeps this calculation nice and simple.
3026 *
3027 * RETURNS:
3028 * Total number of populated backing pages in use by the allocator.
3029 */
3030unsigned long pcpu_nr_pages(void)
3031{
3032        return pcpu_nr_populated * pcpu_nr_units;
3033}
3034
3035/*
3036 * Percpu allocator is initialized early during boot when neither slab or
3037 * workqueue is available.  Plug async management until everything is up
3038 * and running.
3039 */
3040static int __init percpu_enable_async(void)
3041{
3042        pcpu_async_enabled = true;
3043        return 0;
3044}
3045subsys_initcall(percpu_enable_async);
3046