/*
 *  PowerPC version
 *    Copyright (C) 1995-1996 Gary Thomas (gdt@linuxppc.org)
 *
 *  Modifications by Paul Mackerras (PowerMac) (paulus@cs.anu.edu.au)
 *  and Cort Dougan (PReP) (cort@cs.nmt.edu)
 *    Copyright (C) 1996 Paul Mackerras
 *
 *  Derived from "arch/i386/mm/init.c"
 *    Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
 *
 *  Dave Engebretsen <engebret@us.ibm.com>
 *      Rework for PPC64 port.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  as published by the Free Software Foundation; either version
 *  2 of the License, or (at your option) any later version.
 *
 */

#undef DEBUG

#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/stddef.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/highmem.h>
#include <linux/idr.h>
#include <linux/nodemask.h>
#include <linux/module.h>
#include <linux/poison.h>
#include <linux/memblock.h>
#include <linux/hugetlb.h>
#include <linux/slab.h>

#include <asm/pgalloc.h>
#include <asm/page.h>
#include <asm/prom.h>
#include <asm/rtas.h>
#include <asm/io.h>
#include <asm/mmu_context.h>
#include <asm/pgtable.h>
#include <asm/mmu.h>
#include <asm/uaccess.h>
#include <asm/smp.h>
#include <asm/machdep.h>
#include <asm/tlb.h>
#include <asm/eeh.h>
#include <asm/processor.h>
#include <asm/mmzone.h>
#include <asm/cputable.h>
#include <asm/sections.h>
#include <asm/iommu.h>
#include <asm/vdso.h>

#include "mmu_decl.h"

#ifdef CONFIG_PPC_STD_MMU_64
#if PGTABLE_RANGE > USER_VSID_RANGE
#warning Limited user VSID range means pagetable space is wasted
#endif

#if (TASK_SIZE_USER64 < PGTABLE_RANGE) && (TASK_SIZE_USER64 < USER_VSID_RANGE)
#warning TASK_SIZE is smaller than it needs to be.
#endif
#endif /* CONFIG_PPC_STD_MMU_64 */

phys_addr_t memstart_addr = ~0;
EXPORT_SYMBOL_GPL(memstart_addr);
phys_addr_t kernstart_addr;
EXPORT_SYMBOL_GPL(kernstart_addr);

static void pgd_ctor(void *addr)
{
        memset(addr, 0, PGD_TABLE_SIZE);
}

static void pud_ctor(void *addr)
{
        memset(addr, 0, PUD_TABLE_SIZE);
}

static void pmd_ctor(void *addr)
{
        memset(addr, 0, PMD_TABLE_SIZE);
}

struct kmem_cache *pgtable_cache[MAX_PGTABLE_INDEX_SIZE];

/*
 * Create a kmem_cache() for pagetables.  This is not used for PTE
 * pages - they're linked to struct page, come from the normal free
 * pages pool and have a different entry size (see real_pte_t) to
 * everything else.  Caches created by this function are used for all
 * the higher level pagetables, and for hugepage pagetables.
 */
void pgtable_cache_add(unsigned shift, void (*ctor)(void *))
{
        char *name;
        unsigned long table_size = sizeof(void *) << shift;
        unsigned long align = table_size;

        /* When batching pgtable pointers for RCU freeing, we store
         * the index size in the low bits.  Table alignment must be
         * big enough to fit it.
         *
         * Likewise, hugeapge pagetable pointers contain a (different)
         * shift value in the low bits.  All tables must be aligned so
         * as to leave enough 0 bits in the address to contain it. */
        unsigned long minalign = max(MAX_PGTABLE_INDEX_SIZE + 1,
                                     HUGEPD_SHIFT_MASK + 1);
        struct kmem_cache *new;

        /* It would be nice if this was a BUILD_BUG_ON(), but at the
         * moment, gcc doesn't seem to recognize is_power_of_2 as a
         * constant expression, so so much for that. */
        BUG_ON(!is_power_of_2(minalign));
        BUG_ON((shift < 1) || (shift > MAX_PGTABLE_INDEX_SIZE));

        if (PGT_CACHE(shift))
                return; /* Already have a cache of this size */

        align = max_t(unsigned long, align, minalign);
        name = kasprintf(GFP_KERNEL, "pgtable-2^%d", shift);
        new = kmem_cache_create(name, table_size, align, 0, ctor);
        kfree(name);
        pgtable_cache[shift - 1] = new;
        pr_debug("Allocated pgtable cache for order %d\n", shift);
}


void pgtable_cache_init(void)
{
        pgtable_cache_add(PGD_INDEX_SIZE, pgd_ctor);
        pgtable_cache_add(PMD_CACHE_INDEX, pmd_ctor);
        /*
         * In all current configs, when the PUD index exists it's the
         * same size as either the pgd or pmd index except with THP enabled
         * on book3s 64
         */
        if (PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE))
                pgtable_cache_add(PUD_INDEX_SIZE, pud_ctor);

        if (!PGT_CACHE(PGD_INDEX_SIZE) || !PGT_CACHE(PMD_CACHE_INDEX))
                panic("Couldn't allocate pgtable caches");
        if (PUD_INDEX_SIZE && !PGT_CACHE(PUD_INDEX_SIZE))
                panic("Couldn't allocate pud pgtable caches");
}

#ifdef CONFIG_SPARSEMEM_VMEMMAP
/*
 * Given an address within the vmemmap, determine the pfn of the page that
 * represents the start of the section it is within.  Note that we have to
 * do this by hand as the proffered address may not be correctly aligned.
 * Subtraction of non-aligned pointers produces undefined results.
 */
static unsigned long __meminit vmemmap_section_start(unsigned long page)
{
        unsigned long offset = page - ((unsigned long)(vmemmap));

        /* Return the pfn of the start of the section. */
        return (offset / sizeof(struct page)) & PAGE_SECTION_MASK;
}

/*
 * Check if this vmemmap page is already initialised.  If any section
 * which overlaps this vmemmap page is initialised then this page is
 * initialised already.
 */
static int __meminit vmemmap_populated(unsigned long start, int page_size)
{
        unsigned long end = start + page_size;
        start = (unsigned long)(pfn_to_page(vmemmap_section_start(start)));

        for (; start < end; start += (PAGES_PER_SECTION * sizeof(struct page)))
                if (pfn_valid(page_to_pfn((struct page *)start)))
                        return 1;

        return 0;
}

/* On hash-based CPUs, the vmemmap is bolted in the hash table.
 *
 * On Book3E CPUs, the vmemmap is currently mapped in the top half of
 * the vmalloc space using normal page tables, though the size of
 * pages encoded in the PTEs can be different
 */

#ifdef CONFIG_PPC_BOOK3E
static int __meminit vmemmap_create_mapping(unsigned long start,
                                            unsigned long page_size,
                                            unsigned long phys)
{
        /* Create a PTE encoding without page size */
        unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
                _PAGE_KERNEL_RW;

        /* PTEs only contain page size encodings up to 32M */
        BUG_ON(mmu_psize_defs[mmu_vmemmap_psize].enc > 0xf);

        /* Encode the size in the PTE */
        flags |= mmu_psize_defs[mmu_vmemmap_psize].enc << 8;

        /* For each PTE for that area, map things. Note that we don't
         * increment phys because all PTEs are of the large size and
         * thus must have the low bits clear
         */
        for (i = 0; i < page_size; i += PAGE_SIZE)
                BUG_ON(map_kernel_page(start + i, phys, flags));

        return 0;
}

#ifdef CONFIG_MEMORY_HOTPLUG
static void vmemmap_remove_mapping(unsigned long start,
                                   unsigned long page_size)
{
}
#endif
#else /* CONFIG_PPC_BOOK3E */
static int __meminit vmemmap_create_mapping(unsigned long start,
                                            unsigned long page_size,
                                            unsigned long phys)
{
        int rc = htab_bolt_mapping(start, start + page_size, phys,
                                   pgprot_val(PAGE_KERNEL),
                                   mmu_vmemmap_psize, mmu_kernel_ssize);
        if (rc < 0) {
                int rc2 = htab_remove_mapping(start, start + page_size,
                                              mmu_vmemmap_psize,
                                              mmu_kernel_ssize);
                BUG_ON(rc2 && (rc2 != -ENOENT));
        }
        return rc;
}

#ifdef CONFIG_MEMORY_HOTPLUG
static void vmemmap_remove_mapping(unsigned long start,
                                   unsigned long page_size)
{
        int rc = htab_remove_mapping(start, start + page_size,
                                     mmu_vmemmap_psize,
                                     mmu_kernel_ssize);
        BUG_ON((rc < 0) && (rc != -ENOENT));
        WARN_ON(rc == -ENOENT);
}
#endif

#endif /* CONFIG_PPC_BOOK3E */

struct vmemmap_backing *vmemmap_list;
static struct vmemmap_backing *next;
static int num_left;
static int num_freed;

static __meminit struct vmemmap_backing * vmemmap_list_alloc(int node)
{
        struct vmemmap_backing *vmem_back;
        /* get from freed entries first */
        if (num_freed) {
                num_freed--;
                vmem_back = next;
                next = next->list;

                return vmem_back;
        }

        /* allocate a page when required and hand out chunks */
        if (!num_left) {
                next = vmemmap_alloc_block(PAGE_SIZE, node);
                if (unlikely(!next)) {
                        WARN_ON(1);
                        return NULL;
                }
                num_left = PAGE_SIZE / sizeof(struct vmemmap_backing);
        }

        num_left--;

        return next++;
}

static __meminit void vmemmap_list_populate(unsigned long phys,
                                            unsigned long start,
                                            int node)
{
        struct vmemmap_backing *vmem_back;

        vmem_back = vmemmap_list_alloc(node);
        if (unlikely(!vmem_back)) {
                WARN_ON(1);
                return;
        }

        vmem_back->phys = phys;
        vmem_back->virt_addr = start;
        vmem_back->list = vmemmap_list;

        vmemmap_list = vmem_back;
}

int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
{
        unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;

        /* Align to the page size of the linear mapping. */
        start = _ALIGN_DOWN(start, page_size);

        pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);

        for (; start < end; start += page_size) {
                void *p;
                int rc;

                if (vmemmap_populated(start, page_size))
                        continue;

                p = vmemmap_alloc_block(page_size, node);
                if (!p)
                        return -ENOMEM;

                vmemmap_list_populate(__pa(p), start, node);

                pr_debug("      * %016lx..%016lx allocated at %p\n",
                         start, start + page_size, p);

                rc = vmemmap_create_mapping(start, page_size, __pa(p));
                if (rc < 0) {
                        pr_warning(
                                "vmemmap_populate: Unable to create vmemmap mapping: %d\n",
                                rc);
                        return -EFAULT;
                }
        }

        return 0;
}

#ifdef CONFIG_MEMORY_HOTPLUG
static unsigned long vmemmap_list_free(unsigned long start)
{
        struct vmemmap_backing *vmem_back, *vmem_back_prev;

        vmem_back_prev = vmem_back = vmemmap_list;

        /* look for it with prev pointer recorded */
        for (; vmem_back; vmem_back = vmem_back->list) {
                if (vmem_back->virt_addr == start)
                        break;
                vmem_back_prev = vmem_back;
        }

        if (unlikely(!vmem_back)) {
                WARN_ON(1);
                return 0;
        }

        /* remove it from vmemmap_list */
        if (vmem_back == vmemmap_list) /* remove head */
                vmemmap_list = vmem_back->list;
        else
                vmem_back_prev->list = vmem_back->list;

        /* next point to this freed entry */
        vmem_back->list = next;
        next = vmem_back;
        num_freed++;

        return vmem_back->phys;
}

void __ref vmemmap_free(unsigned long start, unsigned long end)
{
        unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;

        start = _ALIGN_DOWN(start, page_size);

        pr_debug("vmemmap_free %lx...%lx\n", start, end);

        for (; start < end; start += page_size) {
                unsigned long addr;

                /*
                 * the section has already be marked as invalid, so
                 * vmemmap_populated() true means some other sections still
                 * in this page, so skip it.
                 */
                if (vmemmap_populated(start, page_size))
                        continue;

                addr = vmemmap_list_free(start);
                if (addr) {
                        struct page *page = pfn_to_page(addr >> PAGE_SHIFT);

                        if (PageReserved(page)) {
                                /* allocated from bootmem */
                                if (page_size < PAGE_SIZE) {
                                        /*
                                         * this shouldn't happen, but if it is
                                         * the case, leave the memory there
                                         */
                                        WARN_ON_ONCE(1);
                                } else {
                                        unsigned int nr_pages =
                                                1 << get_order(page_size);
                                        while (nr_pages--)
                                                free_reserved_page(page++);
                                }
                        } else
                                free_pages((unsigned long)(__va(addr)),
                                                        get_order(page_size));

                        vmemmap_remove_mapping(start, page_size);
                }
        }
}
#endif
void register_page_bootmem_memmap(unsigned long section_nr,
                                  struct page *start_page, unsigned long size)
{
}

/*
 * We do not have access to the sparsemem vmemmap, so we fallback to
 * walking the list of sparsemem blocks which we already maintain for
 * the sake of crashdump. In the long run, we might want to maintain
 * a tree if performance of that linear walk becomes a problem.
 *
 * realmode_pfn_to_page functions can fail due to:
 * 1) As real sparsemem blocks do not lay in RAM continously (they
 * are in virtual address space which is not available in the real mode),
 * the requested page struct can be split between blocks so get_page/put_page
 * may fail.
 * 2) When huge pages are used, the get_page/put_page API will fail
 * in real mode as the linked addresses in the page struct are virtual
 * too.
 */
struct page *realmode_pfn_to_page(unsigned long pfn)
{
        struct vmemmap_backing *vmem_back;
        struct page *page;
        unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
        unsigned long pg_va = (unsigned long) pfn_to_page(pfn);

        for (vmem_back = vmemmap_list; vmem_back; vmem_back = vmem_back->list) {
                if (pg_va < vmem_back->virt_addr)
                        continue;

                /* After vmemmap_list entry free is possible, need check all */
                if ((pg_va + sizeof(struct page)) <=
                                (vmem_back->virt_addr + page_size)) {
                        page = (struct page *) (vmem_back->phys + pg_va -
                                vmem_back->virt_addr);
                        return page;
                }
        }

        /* Probably that page struct is split between real pages */
        return NULL;
}
EXPORT_SYMBOL_GPL(realmode_pfn_to_page);

#elif defined(CONFIG_FLATMEM)

struct page *realmode_pfn_to_page(unsigned long pfn)
{
        struct page *page = pfn_to_page(pfn);
        return page;
}
EXPORT_SYMBOL_GPL(realmode_pfn_to_page);

#endif /* CONFIG_SPARSEMEM_VMEMMAP/CONFIG_FLATMEM */