// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * This file contains the routines for handling the MMU on those
 * PowerPC implementations where the MMU substantially follows the
 * architecture specification.  This includes the 6xx, 7xx, 7xxx,
 * and 8260 implementations but excludes the 8xx and 4xx.
 *  -- paulus
 *
 *  Derived from arch/ppc/mm/init.c:
 *    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
 */

#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/highmem.h>
#include <linux/memblock.h>

#include <asm/prom.h>
#include <asm/mmu.h>
#include <asm/machdep.h>
#include <asm/code-patching.h>
#include <asm/sections.h>

#include <mm/mmu_decl.h>

u8 __initdata early_hash[SZ_256K] __aligned(SZ_256K) = {0};

static struct hash_pte __initdata *Hash = (struct hash_pte *)early_hash;
static unsigned long __initdata Hash_size, Hash_mask;
static unsigned int __initdata hash_mb, hash_mb2;
unsigned long __initdata _SDR1;

struct ppc_bat BATS[8][2];      /* 8 pairs of IBAT, DBAT */

static struct batrange {        /* stores address ranges mapped by BATs */
        unsigned long start;
        unsigned long limit;
        phys_addr_t phys;
} bat_addrs[8];

#ifdef CONFIG_SMP
unsigned long mmu_hash_lock;
#endif

/*
 * Return PA for this VA if it is mapped by a BAT, or 0
 */
phys_addr_t v_block_mapped(unsigned long va)
{
        int b;
        for (b = 0; b < ARRAY_SIZE(bat_addrs); ++b)
                if (va >= bat_addrs[b].start && va < bat_addrs[b].limit)
                        return bat_addrs[b].phys + (va - bat_addrs[b].start);
        return 0;
}

/*
 * Return VA for a given PA or 0 if not mapped
 */
unsigned long p_block_mapped(phys_addr_t pa)
{
        int b;
        for (b = 0; b < ARRAY_SIZE(bat_addrs); ++b)
                if (pa >= bat_addrs[b].phys
                    && pa < (bat_addrs[b].limit-bat_addrs[b].start)
                              +bat_addrs[b].phys)
                        return bat_addrs[b].start+(pa-bat_addrs[b].phys);
        return 0;
}

static int find_free_bat(void)
{
        int b;
        int n = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4;

        for (b = 0; b < n; b++) {
                struct ppc_bat *bat = BATS[b];

                if (!(bat[1].batu & 3))
                        return b;
        }
        return -1;
}

/*
 * This function calculates the size of the larger block usable to map the
 * beginning of an area based on the start address and size of that area:
 * - max block size is 256 on 6xx.
 * - base address must be aligned to the block size. So the maximum block size
 *   is identified by the lowest bit set to 1 in the base address (for instance
 *   if base is 0x16000000, max size is 0x02000000).
 * - block size has to be a power of two. This is calculated by finding the
 *   highest bit set to 1.
 */
static unsigned int block_size(unsigned long base, unsigned long top)
{
        unsigned int max_size = SZ_256M;
        unsigned int base_shift = (ffs(base) - 1) & 31;
        unsigned int block_shift = (fls(top - base) - 1) & 31;

        return min3(max_size, 1U << base_shift, 1U << block_shift);
}

/*
 * Set up one of the IBAT (block address translation) register pairs.
 * The parameters are not checked; in particular size must be a power
 * of 2 between 128k and 256M.
 */
static void setibat(int index, unsigned long virt, phys_addr_t phys,
                    unsigned int size, pgprot_t prot)
{
        unsigned int bl = (size >> 17) - 1;
        int wimgxpp;
        struct ppc_bat *bat = BATS[index];
        unsigned long flags = pgprot_val(prot);

        if (!cpu_has_feature(CPU_FTR_NEED_COHERENT))
                flags &= ~_PAGE_COHERENT;

        wimgxpp = (flags & _PAGE_COHERENT) | (_PAGE_EXEC ? BPP_RX : BPP_XX);
        bat[0].batu = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */
        bat[0].batl = BAT_PHYS_ADDR(phys) | wimgxpp;
        if (flags & _PAGE_USER)
                bat[0].batu |= 1;       /* Vp = 1 */
}

static void clearibat(int index)
{
        struct ppc_bat *bat = BATS[index];

        bat[0].batu = 0;
        bat[0].batl = 0;
}

static unsigned long __init __mmu_mapin_ram(unsigned long base, unsigned long top)
{
        int idx;

        while ((idx = find_free_bat()) != -1 && base != top) {
                unsigned int size = block_size(base, top);

                if (size < 128 << 10)
                        break;
                setbat(idx, PAGE_OFFSET + base, base, size, PAGE_KERNEL_X);
                base += size;
        }

        return base;
}

unsigned long __init mmu_mapin_ram(unsigned long base, unsigned long top)
{
        unsigned long done;
        unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET;


        if (debug_pagealloc_enabled_or_kfence() || __map_without_bats) {
                pr_debug_once("Read-Write memory mapped without BATs\n");
                if (base >= border)
                        return base;
                if (top >= border)
                        top = border;
        }

        if (!strict_kernel_rwx_enabled() || base >= border || top <= border)
                return __mmu_mapin_ram(base, top);

        done = __mmu_mapin_ram(base, border);
        if (done != border)
                return done;

        return __mmu_mapin_ram(border, top);
}

static bool is_module_segment(unsigned long addr)
{
        if (!IS_ENABLED(CONFIG_MODULES))
                return false;
        if (addr < ALIGN_DOWN(MODULES_VADDR, SZ_256M))
                return false;
        if (addr > ALIGN(MODULES_END, SZ_256M) - 1)
                return false;
        return true;
}

void mmu_mark_initmem_nx(void)
{
        int nb = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4;
        int i;
        unsigned long base = (unsigned long)_stext - PAGE_OFFSET;
        unsigned long top = (unsigned long)_etext - PAGE_OFFSET;
        unsigned long border = (unsigned long)__init_begin - PAGE_OFFSET;
        unsigned long size;

        for (i = 0; i < nb - 1 && base < top && top - base > (128 << 10);) {
                size = block_size(base, top);
                setibat(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_TEXT);
                base += size;
        }
        if (base < top) {
                size = block_size(base, top);
                size = max(size, 128UL << 10);
                if ((top - base) > size) {
                        size <<= 1;
                        if (strict_kernel_rwx_enabled() && base + size > border)
                                pr_warn("Some RW data is getting mapped X. "
                                        "Adjust CONFIG_DATA_SHIFT to avoid that.\n");
                }
                setibat(i++, PAGE_OFFSET + base, base, size, PAGE_KERNEL_TEXT);
                base += size;
        }
        for (; i < nb; i++)
                clearibat(i);

        update_bats();

        for (i = TASK_SIZE >> 28; i < 16; i++) {
                /* Do not set NX on VM space for modules */
                if (is_module_segment(i << 28))
                        continue;

                mtsr(mfsr(i << 28) | 0x10000000, i << 28);
        }
}

void mmu_mark_rodata_ro(void)
{
        int nb = mmu_has_feature(MMU_FTR_USE_HIGH_BATS) ? 8 : 4;
        int i;

        for (i = 0; i < nb; i++) {
                struct ppc_bat *bat = BATS[i];

                if (bat_addrs[i].start < (unsigned long)__init_begin)
                        bat[1].batl = (bat[1].batl & ~BPP_RW) | BPP_RX;
        }

        update_bats();
}

/*
 * Set up one of the I/D BAT (block address translation) register pairs.
 * The parameters are not checked; in particular size must be a power
 * of 2 between 128k and 256M.
 * On 603+, only set IBAT when _PAGE_EXEC is set
 */
void __init setbat(int index, unsigned long virt, phys_addr_t phys,
                   unsigned int size, pgprot_t prot)
{
        unsigned int bl;
        int wimgxpp;
        struct ppc_bat *bat;
        unsigned long flags = pgprot_val(prot);

        if (index == -1)
                index = find_free_bat();
        if (index == -1) {
                pr_err("%s: no BAT available for mapping 0x%llx\n", __func__,
                       (unsigned long long)phys);
                return;
        }
        bat = BATS[index];

        if ((flags & _PAGE_NO_CACHE) ||
            (cpu_has_feature(CPU_FTR_NEED_COHERENT) == 0))
                flags &= ~_PAGE_COHERENT;

        bl = (size >> 17) - 1;
        /* Do DBAT first */
        wimgxpp = flags & (_PAGE_WRITETHRU | _PAGE_NO_CACHE
                           | _PAGE_COHERENT | _PAGE_GUARDED);
        wimgxpp |= (flags & _PAGE_RW)? BPP_RW: BPP_RX;
        bat[1].batu = virt | (bl << 2) | 2; /* Vs=1, Vp=0 */
        bat[1].batl = BAT_PHYS_ADDR(phys) | wimgxpp;
        if (flags & _PAGE_USER)
                bat[1].batu |= 1;       /* Vp = 1 */
        if (flags & _PAGE_GUARDED) {
                /* G bit must be zero in IBATs */
                flags &= ~_PAGE_EXEC;
        }
        if (flags & _PAGE_EXEC)
                bat[0] = bat[1];
        else
                bat[0].batu = bat[0].batl = 0;

        bat_addrs[index].start = virt;
        bat_addrs[index].limit = virt + ((bl + 1) << 17) - 1;
        bat_addrs[index].phys = phys;
}

/*
 * Preload a translation in the hash table
 */
static void hash_preload(struct mm_struct *mm, unsigned long ea)
{
        pmd_t *pmd;

        if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
                return;
        pmd = pmd_off(mm, ea);
        if (!pmd_none(*pmd))
                add_hash_page(mm->context.id, ea, pmd_val(*pmd));
}

/*
 * This is called at the end of handling a user page fault, when the
 * fault has been handled by updating a PTE in the linux page tables.
 * We use it to preload an HPTE into the hash table corresponding to
 * the updated linux PTE.
 *
 * This must always be called with the pte lock held.
 */
void update_mmu_cache(struct vm_area_struct *vma, unsigned long address,
                      pte_t *ptep)
{
        if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
                return;
        /*
         * We don't need to worry about _PAGE_PRESENT here because we are
         * called with either mm->page_table_lock held or ptl lock held
         */

        /* We only want HPTEs for linux PTEs that have _PAGE_ACCESSED set */
        if (!pte_young(*ptep) || address >= TASK_SIZE)
                return;

        /* We have to test for regs NULL since init will get here first thing at boot */
        if (!current->thread.regs)
                return;

        /* We also avoid filling the hash if not coming from a fault */
        if (TRAP(current->thread.regs) != 0x300 && TRAP(current->thread.regs) != 0x400)
                return;

        hash_preload(vma->vm_mm, address);
}

/*
 * Initialize the hash table and patch the instructions in hashtable.S.
 */
void __init MMU_init_hw(void)
{
        unsigned int n_hpteg, lg_n_hpteg;

        if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
                return;

        if ( ppc_md.progress ) ppc_md.progress("hash:enter", 0x105);

#define LG_HPTEG_SIZE   6               /* 64 bytes per HPTEG */
#define SDR1_LOW_BITS   ((n_hpteg - 1) >> 10)
#define MIN_N_HPTEG     1024            /* min 64kB hash table */

        /*
         * Allow 1 HPTE (1/8 HPTEG) for each page of memory.
         * This is less than the recommended amount, but then
         * Linux ain't AIX.
         */
        n_hpteg = total_memory / (PAGE_SIZE * 8);
        if (n_hpteg < MIN_N_HPTEG)
                n_hpteg = MIN_N_HPTEG;
        lg_n_hpteg = __ilog2(n_hpteg);
        if (n_hpteg & (n_hpteg - 1)) {
                ++lg_n_hpteg;           /* round up if not power of 2 */
                n_hpteg = 1 << lg_n_hpteg;
        }
        Hash_size = n_hpteg << LG_HPTEG_SIZE;

        /*
         * Find some memory for the hash table.
         */
        if ( ppc_md.progress ) ppc_md.progress("hash:find piece", 0x322);
        Hash = memblock_alloc(Hash_size, Hash_size);
        if (!Hash)
                panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
                      __func__, Hash_size, Hash_size);
        _SDR1 = __pa(Hash) | SDR1_LOW_BITS;

        pr_info("Total memory = %lldMB; using %ldkB for hash table\n",
                (unsigned long long)(total_memory >> 20), Hash_size >> 10);


        Hash_mask = n_hpteg - 1;
        hash_mb2 = hash_mb = 32 - LG_HPTEG_SIZE - lg_n_hpteg;
        if (lg_n_hpteg > 16)
                hash_mb2 = 16 - LG_HPTEG_SIZE;
}

void __init MMU_init_hw_patch(void)
{
        unsigned int hmask = Hash_mask >> (16 - LG_HPTEG_SIZE);
        unsigned int hash = (unsigned int)Hash - PAGE_OFFSET;

        if (!mmu_has_feature(MMU_FTR_HPTE_TABLE))
                return;

        if (ppc_md.progress)
                ppc_md.progress("hash:patch", 0x345);
        if (ppc_md.progress)
                ppc_md.progress("hash:done", 0x205);

        /* WARNING: Make sure nothing can trigger a KASAN check past this point */

        /*
         * Patch up the instructions in hashtable.S:create_hpte
         */
        modify_instruction_site(&patch__hash_page_A0, 0xffff, hash >> 16);
        modify_instruction_site(&patch__hash_page_A1, 0x7c0, hash_mb << 6);
        modify_instruction_site(&patch__hash_page_A2, 0x7c0, hash_mb2 << 6);
        modify_instruction_site(&patch__hash_page_B, 0xffff, hmask);
        modify_instruction_site(&patch__hash_page_C, 0xffff, hmask);

        /*
         * Patch up the instructions in hashtable.S:flush_hash_page
         */
        modify_instruction_site(&patch__flush_hash_A0, 0xffff, hash >> 16);
        modify_instruction_site(&patch__flush_hash_A1, 0x7c0, hash_mb << 6);
        modify_instruction_site(&patch__flush_hash_A2, 0x7c0, hash_mb2 << 6);
        modify_instruction_site(&patch__flush_hash_B, 0xffff, hmask);
}

void setup_initial_memory_limit(phys_addr_t first_memblock_base,
                                phys_addr_t first_memblock_size)
{
        /* We don't currently support the first MEMBLOCK not mapping 0
         * physical on those processors
         */
        BUG_ON(first_memblock_base != 0);

        memblock_set_current_limit(min_t(u64, first_memblock_size, SZ_256M));
}

void __init print_system_hash_info(void)
{
        pr_info("Hash_size         = 0x%lx\n", Hash_size);
        if (Hash_mask)
                pr_info("Hash_mask         = 0x%lx\n", Hash_mask);
}

void __init early_init_mmu(void)
{
}