x86: PAT infrastructure patch

[deliverable/linux.git] / arch / x86 / mm / pageattr.c

/*
 * Copyright 2002 Andi Kleen, SuSE Labs.
 * Thanks to Ben LaHaise for precious feedback.
 */
#include <linux/highmem.h>
#include <linux/bootmem.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <linux/seq_file.h>
#include <linux/debugfs.h>

#include <asm/e820.h>
#include <asm/processor.h>
#include <asm/tlbflush.h>
#include <asm/sections.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/proto.h>

/*
 * The current flushing context - we pass it instead of 5 arguments:
 */
struct cpa_data {
        unsigned long   vaddr;
        pgprot_t        mask_set;
        pgprot_t        mask_clr;
        int             numpages;
        int             flushtlb;
        unsigned long   pfn;
};

#ifdef CONFIG_X86_64

static inline unsigned long highmap_start_pfn(void)
{
        return __pa(_text) >> PAGE_SHIFT;
}

static inline unsigned long highmap_end_pfn(void)
{
        return __pa(round_up((unsigned long)_end, PMD_SIZE)) >> PAGE_SHIFT;
}

#endif

#ifdef CONFIG_DEBUG_PAGEALLOC
# define debug_pagealloc 1
#else
# define debug_pagealloc 0
#endif

static inline int
within(unsigned long addr, unsigned long start, unsigned long end)
{
        return addr >= start && addr < end;
}

/*
 * Flushing functions
 */

/**
 * clflush_cache_range - flush a cache range with clflush
 * @addr:       virtual start address
 * @size:       number of bytes to flush
 *
 * clflush is an unordered instruction which needs fencing with mfence
 * to avoid ordering issues.
 */
void clflush_cache_range(void *vaddr, unsigned int size)
{
        void *vend = vaddr + size - 1;

        mb();

        for (; vaddr < vend; vaddr += boot_cpu_data.x86_clflush_size)
                clflush(vaddr);
        /*
         * Flush any possible final partial cacheline:
         */
        clflush(vend);

        mb();
}

static void __cpa_flush_all(void *arg)
{
        unsigned long cache = (unsigned long)arg;

        /*
         * Flush all to work around Errata in early athlons regarding
         * large page flushing.
         */
        __flush_tlb_all();

        if (cache && boot_cpu_data.x86_model >= 4)
                wbinvd();
}

static void cpa_flush_all(unsigned long cache)
{
        BUG_ON(irqs_disabled());

        on_each_cpu(__cpa_flush_all, (void *) cache, 1, 1);
}

static void __cpa_flush_range(void *arg)
{
        /*
         * We could optimize that further and do individual per page
         * tlb invalidates for a low number of pages. Caveat: we must
         * flush the high aliases on 64bit as well.
         */
        __flush_tlb_all();
}

static void cpa_flush_range(unsigned long start, int numpages, int cache)
{
        unsigned int i, level;
        unsigned long addr;

        BUG_ON(irqs_disabled());
        WARN_ON(PAGE_ALIGN(start) != start);

        on_each_cpu(__cpa_flush_range, NULL, 1, 1);

        if (!cache)
                return;

        /*
         * We only need to flush on one CPU,
         * clflush is a MESI-coherent instruction that
         * will cause all other CPUs to flush the same
         * cachelines:
         */
        for (i = 0, addr = start; i < numpages; i++, addr += PAGE_SIZE) {
                pte_t *pte = lookup_address(addr, &level);

                /*
                 * Only flush present addresses:
                 */
                if (pte && (pte_val(*pte) & _PAGE_PRESENT))
                        clflush_cache_range((void *) addr, PAGE_SIZE);
        }
}

/*
 * Certain areas of memory on x86 require very specific protection flags,
 * for example the BIOS area or kernel text. Callers don't always get this
 * right (again, ioremap() on BIOS memory is not uncommon) so this function
 * checks and fixes these known static required protection bits.
 */
static inline pgprot_t static_protections(pgprot_t prot, unsigned long address,
                                   unsigned long pfn)
{
        pgprot_t forbidden = __pgprot(0);

        /*
         * The BIOS area between 640k and 1Mb needs to be executable for
         * PCI BIOS based config access (CONFIG_PCI_GOBIOS) support.
         */
        if (within(pfn, BIOS_BEGIN >> PAGE_SHIFT, BIOS_END >> PAGE_SHIFT))
                pgprot_val(forbidden) |= _PAGE_NX;

        /*
         * The kernel text needs to be executable for obvious reasons
         * Does not cover __inittext since that is gone later on. On
         * 64bit we do not enforce !NX on the low mapping
         */
        if (within(address, (unsigned long)_text, (unsigned long)_etext))
                pgprot_val(forbidden) |= _PAGE_NX;

        /*
         * The .rodata section needs to be read-only. Using the pfn
         * catches all aliases.
         */
        if (within(pfn, __pa((unsigned long)__start_rodata) >> PAGE_SHIFT,
                   __pa((unsigned long)__end_rodata) >> PAGE_SHIFT))
                pgprot_val(forbidden) |= _PAGE_RW;

        prot = __pgprot(pgprot_val(prot) & ~pgprot_val(forbidden));

        return prot;
}

/*
 * Lookup the page table entry for a virtual address. Return a pointer
 * to the entry and the level of the mapping.
 *
 * Note: We return pud and pmd either when the entry is marked large
 * or when the present bit is not set. Otherwise we would return a
 * pointer to a nonexisting mapping.
 */
pte_t *lookup_address(unsigned long address, unsigned int *level)
{
        pgd_t *pgd = pgd_offset_k(address);
        pud_t *pud;
        pmd_t *pmd;

        *level = PG_LEVEL_NONE;

        if (pgd_none(*pgd))
                return NULL;

        pud = pud_offset(pgd, address);
        if (pud_none(*pud))
                return NULL;

        *level = PG_LEVEL_1G;
        if (pud_large(*pud) || !pud_present(*pud))
                return (pte_t *)pud;

        pmd = pmd_offset(pud, address);
        if (pmd_none(*pmd))
                return NULL;

        *level = PG_LEVEL_2M;
        if (pmd_large(*pmd) || !pmd_present(*pmd))
                return (pte_t *)pmd;

        *level = PG_LEVEL_4K;

        return pte_offset_kernel(pmd, address);
}

/*
 * Set the new pmd in all the pgds we know about:
 */
static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte)
{
        /* change init_mm */
        set_pte_atomic(kpte, pte);
#ifdef CONFIG_X86_32
        if (!SHARED_KERNEL_PMD) {
                struct page *page;

                list_for_each_entry(page, &pgd_list, lru) {
                        pgd_t *pgd;
                        pud_t *pud;
                        pmd_t *pmd;

                        pgd = (pgd_t *)page_address(page) + pgd_index(address);
                        pud = pud_offset(pgd, address);
                        pmd = pmd_offset(pud, address);
                        set_pte_atomic((pte_t *)pmd, pte);
                }
        }
#endif
}

static int
try_preserve_large_page(pte_t *kpte, unsigned long address,
                        struct cpa_data *cpa)
{
        unsigned long nextpage_addr, numpages, pmask, psize, flags, addr, pfn;
        pte_t new_pte, old_pte, *tmp;
        pgprot_t old_prot, new_prot;
        int i, do_split = 1;
        unsigned int level;

        spin_lock_irqsave(&pgd_lock, flags);
        /*
         * Check for races, another CPU might have split this page
         * up already:
         */
        tmp = lookup_address(address, &level);
        if (tmp != kpte)
                goto out_unlock;

        switch (level) {
        case PG_LEVEL_2M:
                psize = PMD_PAGE_SIZE;
                pmask = PMD_PAGE_MASK;
                break;
#ifdef CONFIG_X86_64
        case PG_LEVEL_1G:
                psize = PUD_PAGE_SIZE;
                pmask = PUD_PAGE_MASK;
                break;
#endif
        default:
                do_split = -EINVAL;
                goto out_unlock;
        }

        /*
         * Calculate the number of pages, which fit into this large
         * page starting at address:
         */
        nextpage_addr = (address + psize) & pmask;
        numpages = (nextpage_addr - address) >> PAGE_SHIFT;
        if (numpages < cpa->numpages)
                cpa->numpages = numpages;

        /*
         * We are safe now. Check whether the new pgprot is the same:
         */
        old_pte = *kpte;
        old_prot = new_prot = pte_pgprot(old_pte);

        pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
        pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);

        /*
         * old_pte points to the large page base address. So we need
         * to add the offset of the virtual address:
         */
        pfn = pte_pfn(old_pte) + ((address & (psize - 1)) >> PAGE_SHIFT);
        cpa->pfn = pfn;

        new_prot = static_protections(new_prot, address, pfn);

        /*
         * We need to check the full range, whether
         * static_protection() requires a different pgprot for one of
         * the pages in the range we try to preserve:
         */
        addr = address + PAGE_SIZE;
        pfn++;
        for (i = 1; i < cpa->numpages; i++, addr += PAGE_SIZE, pfn++) {
                pgprot_t chk_prot = static_protections(new_prot, addr, pfn);

                if (pgprot_val(chk_prot) != pgprot_val(new_prot))
                        goto out_unlock;
        }

        /*
         * If there are no changes, return. maxpages has been updated
         * above:
         */
        if (pgprot_val(new_prot) == pgprot_val(old_prot)) {
                do_split = 0;
                goto out_unlock;
        }

        /*
         * We need to change the attributes. Check, whether we can
         * change the large page in one go. We request a split, when
         * the address is not aligned and the number of pages is
         * smaller than the number of pages in the large page. Note
         * that we limited the number of possible pages already to
         * the number of pages in the large page.
         */
        if (address == (nextpage_addr - psize) && cpa->numpages == numpages) {
                /*
                 * The address is aligned and the number of pages
                 * covers the full page.
                 */
                new_pte = pfn_pte(pte_pfn(old_pte), canon_pgprot(new_prot));
                __set_pmd_pte(kpte, address, new_pte);
                cpa->flushtlb = 1;
                do_split = 0;
        }

out_unlock:
        spin_unlock_irqrestore(&pgd_lock, flags);

        return do_split;
}

static LIST_HEAD(page_pool);
static unsigned long pool_size, pool_pages, pool_low;
static unsigned long pool_used, pool_failed;

static void cpa_fill_pool(struct page **ret)
{
        gfp_t gfp = GFP_KERNEL;
        unsigned long flags;
        struct page *p;

        /*
         * Avoid recursion (on debug-pagealloc) and also signal
         * our priority to get to these pagetables:
         */
        if (current->flags & PF_MEMALLOC)
                return;
        current->flags |= PF_MEMALLOC;

        /*
         * Allocate atomically from atomic contexts:
         */
        if (in_atomic() || irqs_disabled() || debug_pagealloc)
                gfp =  GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN;

        while (pool_pages < pool_size || (ret && !*ret)) {
                p = alloc_pages(gfp, 0);
                if (!p) {
                        pool_failed++;
                        break;
                }
                /*
                 * If the call site needs a page right now, provide it:
                 */
                if (ret && !*ret) {
                        *ret = p;
                        continue;
                }
                spin_lock_irqsave(&pgd_lock, flags);
                list_add(&p->lru, &page_pool);
                pool_pages++;
                spin_unlock_irqrestore(&pgd_lock, flags);
        }

        current->flags &= ~PF_MEMALLOC;
}

#define SHIFT_MB                (20 - PAGE_SHIFT)
#define ROUND_MB_GB             ((1 << 10) - 1)
#define SHIFT_MB_GB             10
#define POOL_PAGES_PER_GB       16

void __init cpa_init(void)
{
        struct sysinfo si;
        unsigned long gb;

        si_meminfo(&si);
        /*
         * Calculate the number of pool pages:
         *
         * Convert totalram (nr of pages) to MiB and round to the next
         * GiB. Shift MiB to Gib and multiply the result by
         * POOL_PAGES_PER_GB:
         */
        if (debug_pagealloc) {
                gb = ((si.totalram >> SHIFT_MB) + ROUND_MB_GB) >> SHIFT_MB_GB;
                pool_size = POOL_PAGES_PER_GB * gb;
        } else {
                pool_size = 1;
        }
        pool_low = pool_size;

        cpa_fill_pool(NULL);
        printk(KERN_DEBUG
               "CPA: page pool initialized %lu of %lu pages preallocated\n",
               pool_pages, pool_size);
}

static int split_large_page(pte_t *kpte, unsigned long address)
{
        unsigned long flags, pfn, pfninc = 1;
        unsigned int i, level;
        pte_t *pbase, *tmp;
        pgprot_t ref_prot;
        struct page *base;

        /*
         * Get a page from the pool. The pool list is protected by the
         * pgd_lock, which we have to take anyway for the split
         * operation:
         */
        spin_lock_irqsave(&pgd_lock, flags);
        if (list_empty(&page_pool)) {
                spin_unlock_irqrestore(&pgd_lock, flags);
                base = NULL;
                cpa_fill_pool(&base);
                if (!base)
                        return -ENOMEM;
                spin_lock_irqsave(&pgd_lock, flags);
        } else {
                base = list_first_entry(&page_pool, struct page, lru);
                list_del(&base->lru);
                pool_pages--;

                if (pool_pages < pool_low)
                        pool_low = pool_pages;
        }

        /*
         * Check for races, another CPU might have split this page
         * up for us already:
         */
        tmp = lookup_address(address, &level);
        if (tmp != kpte)
                goto out_unlock;

        pbase = (pte_t *)page_address(base);
#ifdef CONFIG_X86_32
        paravirt_alloc_pt(&init_mm, page_to_pfn(base));
#endif
        ref_prot = pte_pgprot(pte_clrhuge(*kpte));

#ifdef CONFIG_X86_64
        if (level == PG_LEVEL_1G) {
                pfninc = PMD_PAGE_SIZE >> PAGE_SHIFT;
                pgprot_val(ref_prot) |= _PAGE_PSE;
        }
#endif

        /*
         * Get the target pfn from the original entry:
         */
        pfn = pte_pfn(*kpte);
        for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc)
                set_pte(&pbase[i], pfn_pte(pfn, ref_prot));

        /*
         * Install the new, split up pagetable. Important details here:
         *
         * On Intel the NX bit of all levels must be cleared to make a
         * page executable. See section 4.13.2 of Intel 64 and IA-32
         * Architectures Software Developer's Manual).
         *
         * Mark the entry present. The current mapping might be
         * set to not present, which we preserved above.
         */
        ref_prot = pte_pgprot(pte_mkexec(pte_clrhuge(*kpte)));
        pgprot_val(ref_prot) |= _PAGE_PRESENT;
        __set_pmd_pte(kpte, address, mk_pte(base, ref_prot));
        base = NULL;

out_unlock:
        /*
         * If we dropped out via the lookup_address check under
         * pgd_lock then stick the page back into the pool:
         */
        if (base) {
                list_add(&base->lru, &page_pool);
                pool_pages++;
        } else
                pool_used++;
        spin_unlock_irqrestore(&pgd_lock, flags);

        return 0;
}

static int __change_page_attr(struct cpa_data *cpa, int primary)
{
        unsigned long address = cpa->vaddr;
        int do_split, err;
        unsigned int level;
        pte_t *kpte, old_pte;

repeat:
        kpte = lookup_address(address, &level);
        if (!kpte)
                return primary ? -EINVAL : 0;

        old_pte = *kpte;
        if (!pte_val(old_pte)) {
                if (!primary)
                        return 0;
                printk(KERN_WARNING "CPA: called for zero pte. "
                       "vaddr = %lx cpa->vaddr = %lx\n", address,
                       cpa->vaddr);
                WARN_ON(1);
                return -EINVAL;
        }

        if (level == PG_LEVEL_4K) {
                pte_t new_pte;
                pgprot_t new_prot = pte_pgprot(old_pte);
                unsigned long pfn = pte_pfn(old_pte);

                pgprot_val(new_prot) &= ~pgprot_val(cpa->mask_clr);
                pgprot_val(new_prot) |= pgprot_val(cpa->mask_set);

                new_prot = static_protections(new_prot, address, pfn);

                /*
                 * We need to keep the pfn from the existing PTE,
                 * after all we're only going to change it's attributes
                 * not the memory it points to
                 */
                new_pte = pfn_pte(pfn, canon_pgprot(new_prot));
                cpa->pfn = pfn;
                /*
                 * Do we really change anything ?
                 */
                if (pte_val(old_pte) != pte_val(new_pte)) {
                        set_pte_atomic(kpte, new_pte);
                        cpa->flushtlb = 1;
                }
                cpa->numpages = 1;
                return 0;
        }

        /*
         * Check, whether we can keep the large page intact
         * and just change the pte:
         */
        do_split = try_preserve_large_page(kpte, address, cpa);
        /*
         * When the range fits into the existing large page,
         * return. cp->numpages and cpa->tlbflush have been updated in
         * try_large_page:
         */
        if (do_split <= 0)
                return do_split;

        /*
         * We have to split the large page:
         */
        err = split_large_page(kpte, address);
        if (!err) {
                cpa->flushtlb = 1;
                goto repeat;
        }

        return err;
}

static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias);

static int cpa_process_alias(struct cpa_data *cpa)
{
        struct cpa_data alias_cpa;
        int ret = 0;

        if (cpa->pfn > max_pfn_mapped)
                return 0;

        /*
         * No need to redo, when the primary call touched the direct
         * mapping already:
         */
        if (!within(cpa->vaddr, PAGE_OFFSET,
                    PAGE_OFFSET + (max_pfn_mapped << PAGE_SHIFT))) {

                alias_cpa = *cpa;
                alias_cpa.vaddr = (unsigned long) __va(cpa->pfn << PAGE_SHIFT);

                ret = __change_page_attr_set_clr(&alias_cpa, 0);
        }

#ifdef CONFIG_X86_64
        if (ret)
                return ret;
        /*
         * No need to redo, when the primary call touched the high
         * mapping already:
         */
        if (within(cpa->vaddr, (unsigned long) _text, (unsigned long) _end))
                return 0;

        /*
         * If the physical address is inside the kernel map, we need
         * to touch the high mapped kernel as well:
         */
        if (!within(cpa->pfn, highmap_start_pfn(), highmap_end_pfn()))
                return 0;

        alias_cpa = *cpa;
        alias_cpa.vaddr =
                (cpa->pfn << PAGE_SHIFT) + __START_KERNEL_map - phys_base;

        /*
         * The high mapping range is imprecise, so ignore the return value.
         */
        __change_page_attr_set_clr(&alias_cpa, 0);
#endif
        return ret;
}

static int __change_page_attr_set_clr(struct cpa_data *cpa, int checkalias)
{
        int ret, numpages = cpa->numpages;

        while (numpages) {
                /*
                 * Store the remaining nr of pages for the large page
                 * preservation check.
                 */
                cpa->numpages = numpages;

                ret = __change_page_attr(cpa, checkalias);
                if (ret)
                        return ret;

                if (checkalias) {
                        ret = cpa_process_alias(cpa);
                        if (ret)
                                return ret;
                }

                /*
                 * Adjust the number of pages with the result of the
                 * CPA operation. Either a large page has been
                 * preserved or a single page update happened.
                 */
                BUG_ON(cpa->numpages > numpages);
                numpages -= cpa->numpages;
                cpa->vaddr += cpa->numpages * PAGE_SIZE;
        }
        return 0;
}

static inline int cache_attr(pgprot_t attr)
{
        return pgprot_val(attr) &
                (_PAGE_PAT | _PAGE_PAT_LARGE | _PAGE_PWT | _PAGE_PCD);
}

static int change_page_attr_set_clr(unsigned long addr, int numpages,
                                    pgprot_t mask_set, pgprot_t mask_clr)
{
        struct cpa_data cpa;
        int ret, cache, checkalias;

        /*
         * Check, if we are requested to change a not supported
         * feature:
         */
        mask_set = canon_pgprot(mask_set);
        mask_clr = canon_pgprot(mask_clr);
        if (!pgprot_val(mask_set) && !pgprot_val(mask_clr))
                return 0;

        /* Ensure we are PAGE_SIZE aligned */
        if (addr & ~PAGE_MASK) {
                addr &= PAGE_MASK;
                /*
                 * People should not be passing in unaligned addresses:
                 */
                WARN_ON_ONCE(1);
        }

        cpa.vaddr = addr;
        cpa.numpages = numpages;
        cpa.mask_set = mask_set;
        cpa.mask_clr = mask_clr;
        cpa.flushtlb = 0;

        /* No alias checking for _NX bit modifications */
        checkalias = (pgprot_val(mask_set) | pgprot_val(mask_clr)) != _PAGE_NX;

        ret = __change_page_attr_set_clr(&cpa, checkalias);

        /*
         * Check whether we really changed something:
         */
        if (!cpa.flushtlb)
                goto out;

        /*
         * No need to flush, when we did not set any of the caching
         * attributes:
         */
        cache = cache_attr(mask_set);

        /*
         * On success we use clflush, when the CPU supports it to
         * avoid the wbindv. If the CPU does not support it and in the
         * error case we fall back to cpa_flush_all (which uses
         * wbindv):
         */
        if (!ret && cpu_has_clflush)
                cpa_flush_range(addr, numpages, cache);
        else
                cpa_flush_all(cache);

out:
        cpa_fill_pool(NULL);

        return ret;
}

static inline int change_page_attr_set(unsigned long addr, int numpages,
                                       pgprot_t mask)
{
        return change_page_attr_set_clr(addr, numpages, mask, __pgprot(0));
}

static inline int change_page_attr_clear(unsigned long addr, int numpages,
                                         pgprot_t mask)
{
        return change_page_attr_set_clr(addr, numpages, __pgprot(0), mask);
}

int set_memory_uc(unsigned long addr, int numpages)
{
        return change_page_attr_set(addr, numpages,
                                    __pgprot(_PAGE_CACHE_UC));
}
EXPORT_SYMBOL(set_memory_uc);

int set_memory_wb(unsigned long addr, int numpages)
{
        return change_page_attr_clear(addr, numpages,
                                      __pgprot(_PAGE_CACHE_MASK));
}
EXPORT_SYMBOL(set_memory_wb);

int set_memory_x(unsigned long addr, int numpages)
{
        return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_NX));
}
EXPORT_SYMBOL(set_memory_x);

int set_memory_nx(unsigned long addr, int numpages)
{
        return change_page_attr_set(addr, numpages, __pgprot(_PAGE_NX));
}
EXPORT_SYMBOL(set_memory_nx);

int set_memory_ro(unsigned long addr, int numpages)
{
        return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_RW));
}

int set_memory_rw(unsigned long addr, int numpages)
{
        return change_page_attr_set(addr, numpages, __pgprot(_PAGE_RW));
}

int set_memory_np(unsigned long addr, int numpages)
{
        return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_PRESENT));
}

int set_pages_uc(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_uc(addr, numpages);
}
EXPORT_SYMBOL(set_pages_uc);

int set_pages_wb(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_wb(addr, numpages);
}
EXPORT_SYMBOL(set_pages_wb);

int set_pages_x(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_x(addr, numpages);
}
EXPORT_SYMBOL(set_pages_x);

int set_pages_nx(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_nx(addr, numpages);
}
EXPORT_SYMBOL(set_pages_nx);

int set_pages_ro(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_ro(addr, numpages);
}

int set_pages_rw(struct page *page, int numpages)
{
        unsigned long addr = (unsigned long)page_address(page);

        return set_memory_rw(addr, numpages);
}

#ifdef CONFIG_DEBUG_PAGEALLOC

static int __set_pages_p(struct page *page, int numpages)
{
        struct cpa_data cpa = { .vaddr = (unsigned long) page_address(page),
                                .numpages = numpages,
                                .mask_set = __pgprot(_PAGE_PRESENT | _PAGE_RW),
                                .mask_clr = __pgprot(0)};

        return __change_page_attr_set_clr(&cpa, 1);
}

static int __set_pages_np(struct page *page, int numpages)
{
        struct cpa_data cpa = { .vaddr = (unsigned long) page_address(page),
                                .numpages = numpages,
                                .mask_set = __pgprot(0),
                                .mask_clr = __pgprot(_PAGE_PRESENT | _PAGE_RW)};

        return __change_page_attr_set_clr(&cpa, 1);
}

void kernel_map_pages(struct page *page, int numpages, int enable)
{
        if (PageHighMem(page))
                return;
        if (!enable) {
                debug_check_no_locks_freed(page_address(page),
                                           numpages * PAGE_SIZE);
        }

        /*
         * If page allocator is not up yet then do not call c_p_a():
         */
        if (!debug_pagealloc_enabled)
                return;

        /*
         * The return value is ignored as the calls cannot fail.
         * Large pages are kept enabled at boot time, and are
         * split up quickly with DEBUG_PAGEALLOC. If a splitup
         * fails here (due to temporary memory shortage) no damage
         * is done because we just keep the largepage intact up
         * to the next attempt when it will likely be split up:
         */
        if (enable)
                __set_pages_p(page, numpages);
        else
                __set_pages_np(page, numpages);

        /*
         * We should perform an IPI and flush all tlbs,
         * but that can deadlock->flush only current cpu:
         */
        __flush_tlb_all();

        /*
         * Try to refill the page pool here. We can do this only after
         * the tlb flush.
         */
        cpa_fill_pool(NULL);
}

#ifdef CONFIG_DEBUG_FS
static int dpa_show(struct seq_file *m, void *v)
{
        seq_puts(m, "DEBUG_PAGEALLOC\n");
        seq_printf(m, "pool_size     : %lu\n", pool_size);
        seq_printf(m, "pool_pages    : %lu\n", pool_pages);
        seq_printf(m, "pool_low      : %lu\n", pool_low);
        seq_printf(m, "pool_used     : %lu\n", pool_used);
        seq_printf(m, "pool_failed   : %lu\n", pool_failed);

        return 0;
}

static int dpa_open(struct inode *inode, struct file *filp)
{
        return single_open(filp, dpa_show, NULL);
}

static const struct file_operations dpa_fops = {
        .open           = dpa_open,
        .read           = seq_read,
        .llseek         = seq_lseek,
        .release        = single_release,
};

int __init debug_pagealloc_proc_init(void)
{
        struct dentry *de;

        de = debugfs_create_file("debug_pagealloc", 0600, NULL, NULL,
                                 &dpa_fops);
        if (!de)
                return -ENOMEM;

        return 0;
}
__initcall(debug_pagealloc_proc_init);
#endif

#ifdef CONFIG_HIBERNATION

bool kernel_page_present(struct page *page)
{
        unsigned int level;
        pte_t *pte;

        if (PageHighMem(page))
                return false;

        pte = lookup_address((unsigned long)page_address(page), &level);
        return (pte_val(*pte) & _PAGE_PRESENT);
}

#endif /* CONFIG_HIBERNATION */

#endif /* CONFIG_DEBUG_PAGEALLOC */

/*
 * The testcases use internal knowledge of the implementation that shouldn't
 * be exposed to the rest of the kernel. Include these directly here.
 */
#ifdef CONFIG_CPA_DEBUG
#include "pageattr-test.c"
#endif