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|
/*
* PPC Huge TLB Page Support for Kernel.
*
* Copyright (C) 2003 David Gibson, IBM Corporation.
* Copyright (C) 2011 Becky Bruce, Freescale Semiconductor
*
* Based on the IA-32 version:
* Copyright (C) 2002, Rohit Seth <rohit.seth@intel.com>
*/
#include <linux/mm.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>
#include <linux/export.h>
#include <linux/of_fdt.h>
#include <linux/memblock.h>
#include <linux/bootmem.h>
#include <linux/moduleparam.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/tlb.h>
#include <asm/setup.h>
#include <asm/hugetlb.h>
#include <asm/pte-walk.h>
#ifdef CONFIG_HUGETLB_PAGE
#define PAGE_SHIFT_64K 16
#define PAGE_SHIFT_512K 19
#define PAGE_SHIFT_8M 23
#define PAGE_SHIFT_16M 24
#define PAGE_SHIFT_16G 34
unsigned int HPAGE_SHIFT;
EXPORT_SYMBOL(HPAGE_SHIFT);
#define hugepd_none(hpd) (hpd_val(hpd) == 0)
pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr, unsigned long sz)
{
/*
* Only called for hugetlbfs pages, hence can ignore THP and the
* irq disabled walk.
*/
return __find_linux_pte(mm->pgd, addr, NULL, NULL);
}
static int __hugepte_alloc(struct mm_struct *mm, hugepd_t *hpdp,
unsigned long address, unsigned pdshift, unsigned pshift)
{
struct kmem_cache *cachep;
pte_t *new;
int i;
int num_hugepd;
if (pshift >= pdshift) {
cachep = hugepte_cache;
num_hugepd = 1 << (pshift - pdshift);
} else {
cachep = PGT_CACHE(pdshift - pshift);
num_hugepd = 1;
}
new = kmem_cache_zalloc(cachep, pgtable_gfp_flags(mm, GFP_KERNEL));
BUG_ON(pshift > HUGEPD_SHIFT_MASK);
BUG_ON((unsigned long)new & HUGEPD_SHIFT_MASK);
if (! new)
return -ENOMEM;
/*
* Make sure other cpus find the hugepd set only after a
* properly initialized page table is visible to them.
* For more details look for comment in __pte_alloc().
*/
smp_wmb();
spin_lock(&mm->page_table_lock);
/*
* We have multiple higher-level entries that point to the same
* actual pte location. Fill in each as we go and backtrack on error.
* We need all of these so the DTLB pgtable walk code can find the
* right higher-level entry without knowing if it's a hugepage or not.
*/
for (i = 0; i < num_hugepd; i++, hpdp++) {
if (unlikely(!hugepd_none(*hpdp)))
break;
else {
#ifdef CONFIG_PPC_BOOK3S_64
*hpdp = __hugepd(__pa(new) |
(shift_to_mmu_psize(pshift) << 2));
#elif defined(CONFIG_PPC_8xx)
*hpdp = __hugepd(__pa(new) | _PMD_USER |
(pshift == PAGE_SHIFT_8M ? _PMD_PAGE_8M :
_PMD_PAGE_512K) | _PMD_PRESENT);
#else
/* We use the old format for PPC_FSL_BOOK3E */
*hpdp = __hugepd(((unsigned long)new & ~PD_HUGE) | pshift);
#endif
}
}
/* If we bailed from the for loop early, an error occurred, clean up */
if (i < num_hugepd) {
for (i = i - 1 ; i >= 0; i--, hpdp--)
*hpdp = __hugepd(0);
kmem_cache_free(cachep, new);
}
spin_unlock(&mm->page_table_lock);
return 0;
}
/*
* These macros define how to determine which level of the page table holds
* the hpdp.
*/
#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
#define HUGEPD_PGD_SHIFT PGDIR_SHIFT
#define HUGEPD_PUD_SHIFT PUD_SHIFT
#endif
/*
* At this point we do the placement change only for BOOK3S 64. This would
* possibly work on other subarchs.
*/
pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr, unsigned long sz)
{
pgd_t *pg;
pud_t *pu;
pmd_t *pm;
hugepd_t *hpdp = NULL;
unsigned pshift = __ffs(sz);
unsigned pdshift = PGDIR_SHIFT;
addr &= ~(sz-1);
pg = pgd_offset(mm, addr);
#ifdef CONFIG_PPC_BOOK3S_64
if (pshift == PGDIR_SHIFT)
/* 16GB huge page */
return (pte_t *) pg;
else if (pshift > PUD_SHIFT)
/*
* We need to use hugepd table
*/
hpdp = (hugepd_t *)pg;
else {
pdshift = PUD_SHIFT;
pu = pud_alloc(mm, pg, addr);
if (pshift == PUD_SHIFT)
return (pte_t *)pu;
else if (pshift > PMD_SHIFT)
hpdp = (hugepd_t *)pu;
else {
pdshift = PMD_SHIFT;
pm = pmd_alloc(mm, pu, addr);
if (pshift == PMD_SHIFT)
/* 16MB hugepage */
return (pte_t *)pm;
else
hpdp = (hugepd_t *)pm;
}
}
#else
if (pshift >= HUGEPD_PGD_SHIFT) {
hpdp = (hugepd_t *)pg;
} else {
pdshift = PUD_SHIFT;
pu = pud_alloc(mm, pg, addr);
if (pshift >= HUGEPD_PUD_SHIFT) {
hpdp = (hugepd_t *)pu;
} else {
pdshift = PMD_SHIFT;
pm = pmd_alloc(mm, pu, addr);
hpdp = (hugepd_t *)pm;
}
}
#endif
if (!hpdp)
return NULL;
BUG_ON(!hugepd_none(*hpdp) && !hugepd_ok(*hpdp));
if (hugepd_none(*hpdp) && __hugepte_alloc(mm, hpdp, addr, pdshift, pshift))
return NULL;
return hugepte_offset(*hpdp, addr, pdshift);
}
#ifdef CONFIG_PPC_BOOK3S_64
/*
* Tracks gpages after the device tree is scanned and before the
* huge_boot_pages list is ready on pseries.
*/
#define MAX_NUMBER_GPAGES 1024
__initdata static u64 gpage_freearray[MAX_NUMBER_GPAGES];
__initdata static unsigned nr_gpages;
/*
* Build list of addresses of gigantic pages. This function is used in early
* boot before the buddy allocator is setup.
*/
void __init pseries_add_gpage(u64 addr, u64 page_size, unsigned long number_of_pages)
{
if (!addr)
return;
while (number_of_pages > 0) {
gpage_freearray[nr_gpages] = addr;
nr_gpages++;
number_of_pages--;
addr += page_size;
}
}
int __init pseries_alloc_bootmem_huge_page(struct hstate *hstate)
{
struct huge_bootmem_page *m;
if (nr_gpages == 0)
return 0;
m = phys_to_virt(gpage_freearray[--nr_gpages]);
gpage_freearray[nr_gpages] = 0;
list_add(&m->list, &huge_boot_pages);
m->hstate = hstate;
return 1;
}
#endif
int __init alloc_bootmem_huge_page(struct hstate *h)
{
#ifdef CONFIG_PPC_BOOK3S_64
if (firmware_has_feature(FW_FEATURE_LPAR) && !radix_enabled())
return pseries_alloc_bootmem_huge_page(h);
#endif
return __alloc_bootmem_huge_page(h);
}
#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
#define HUGEPD_FREELIST_SIZE \
((PAGE_SIZE - sizeof(struct hugepd_freelist)) / sizeof(pte_t))
struct hugepd_freelist {
struct rcu_head rcu;
unsigned int index;
void *ptes[0];
};
static DEFINE_PER_CPU(struct hugepd_freelist *, hugepd_freelist_cur);
static void hugepd_free_rcu_callback(struct rcu_head *head)
{
struct hugepd_freelist *batch =
container_of(head, struct hugepd_freelist, rcu);
unsigned int i;
for (i = 0; i < batch->index; i++)
kmem_cache_free(hugepte_cache, batch->ptes[i]);
free_page((unsigned long)batch);
}
static void hugepd_free(struct mmu_gather *tlb, void *hugepte)
{
struct hugepd_freelist **batchp;
batchp = &get_cpu_var(hugepd_freelist_cur);
if (atomic_read(&tlb->mm->mm_users) < 2 ||
mm_is_thread_local(tlb->mm)) {
kmem_cache_free(hugepte_cache, hugepte);
put_cpu_var(hugepd_freelist_cur);
return;
}
if (*batchp == NULL) {
*batchp = (struct hugepd_freelist *)__get_free_page(GFP_ATOMIC);
(*batchp)->index = 0;
}
(*batchp)->ptes[(*batchp)->index++] = hugepte;
if ((*batchp)->index == HUGEPD_FREELIST_SIZE) {
call_rcu_sched(&(*batchp)->rcu, hugepd_free_rcu_callback);
*batchp = NULL;
}
put_cpu_var(hugepd_freelist_cur);
}
#else
static inline void hugepd_free(struct mmu_gather *tlb, void *hugepte) {}
#endif
static void free_hugepd_range(struct mmu_gather *tlb, hugepd_t *hpdp, int pdshift,
unsigned long start, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
pte_t *hugepte = hugepd_page(*hpdp);
int i;
unsigned long pdmask = ~((1UL << pdshift) - 1);
unsigned int num_hugepd = 1;
unsigned int shift = hugepd_shift(*hpdp);
/* Note: On fsl the hpdp may be the first of several */
if (shift > pdshift)
num_hugepd = 1 << (shift - pdshift);
start &= pdmask;
if (start < floor)
return;
if (ceiling) {
ceiling &= pdmask;
if (! ceiling)
return;
}
if (end - 1 > ceiling - 1)
return;
for (i = 0; i < num_hugepd; i++, hpdp++)
*hpdp = __hugepd(0);
if (shift >= pdshift)
hugepd_free(tlb, hugepte);
else
pgtable_free_tlb(tlb, hugepte, pdshift - shift);
}
static void hugetlb_free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
pmd_t *pmd;
unsigned long next;
unsigned long start;
start = addr;
do {
unsigned long more;
pmd = pmd_offset(pud, addr);
next = pmd_addr_end(addr, end);
if (!is_hugepd(__hugepd(pmd_val(*pmd)))) {
/*
* if it is not hugepd pointer, we should already find
* it cleared.
*/
WARN_ON(!pmd_none_or_clear_bad(pmd));
continue;
}
/*
* Increment next by the size of the huge mapping since
* there may be more than one entry at this level for a
* single hugepage, but all of them point to
* the same kmem cache that holds the hugepte.
*/
more = addr + (1 << hugepd_shift(*(hugepd_t *)pmd));
if (more > next)
next = more;
free_hugepd_range(tlb, (hugepd_t *)pmd, PMD_SHIFT,
addr, next, floor, ceiling);
} while (addr = next, addr != end);
start &= PUD_MASK;
if (start < floor)
return;
if (ceiling) {
ceiling &= PUD_MASK;
if (!ceiling)
return;
}
if (end - 1 > ceiling - 1)
return;
pmd = pmd_offset(pud, start);
pud_clear(pud);
pmd_free_tlb(tlb, pmd, start);
mm_dec_nr_pmds(tlb->mm);
}
static void hugetlb_free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
pud_t *pud;
unsigned long next;
unsigned long start;
start = addr;
do {
pud = pud_offset(pgd, addr);
next = pud_addr_end(addr, end);
if (!is_hugepd(__hugepd(pud_val(*pud)))) {
if (pud_none_or_clear_bad(pud))
continue;
hugetlb_free_pmd_range(tlb, pud, addr, next, floor,
ceiling);
} else {
unsigned long more;
/*
* Increment next by the size of the huge mapping since
* there may be more than one entry at this level for a
* single hugepage, but all of them point to
* the same kmem cache that holds the hugepte.
*/
more = addr + (1 << hugepd_shift(*(hugepd_t *)pud));
if (more > next)
next = more;
free_hugepd_range(tlb, (hugepd_t *)pud, PUD_SHIFT,
addr, next, floor, ceiling);
}
} while (addr = next, addr != end);
start &= PGDIR_MASK;
if (start < floor)
return;
if (ceiling) {
ceiling &= PGDIR_MASK;
if (!ceiling)
return;
}
if (end - 1 > ceiling - 1)
return;
pud = pud_offset(pgd, start);
pgd_clear(pgd);
pud_free_tlb(tlb, pud, start);
mm_dec_nr_puds(tlb->mm);
}
/*
* This function frees user-level page tables of a process.
*/
void hugetlb_free_pgd_range(struct mmu_gather *tlb,
unsigned long addr, unsigned long end,
unsigned long floor, unsigned long ceiling)
{
pgd_t *pgd;
unsigned long next;
/*
* Because there are a number of different possible pagetable
* layouts for hugepage ranges, we limit knowledge of how
* things should be laid out to the allocation path
* (huge_pte_alloc(), above). Everything else works out the
* structure as it goes from information in the hugepd
* pointers. That means that we can't here use the
* optimization used in the normal page free_pgd_range(), of
* checking whether we're actually covering a large enough
* range to have to do anything at the top level of the walk
* instead of at the bottom.
*
* To make sense of this, you should probably go read the big
* block comment at the top of the normal free_pgd_range(),
* too.
*/
do {
next = pgd_addr_end(addr, end);
pgd = pgd_offset(tlb->mm, addr);
if (!is_hugepd(__hugepd(pgd_val(*pgd)))) {
if (pgd_none_or_clear_bad(pgd))
continue;
hugetlb_free_pud_range(tlb, pgd, addr, next, floor, ceiling);
} else {
unsigned long more;
/*
* Increment next by the size of the huge mapping since
* there may be more than one entry at the pgd level
* for a single hugepage, but all of them point to the
* same kmem cache that holds the hugepte.
*/
more = addr + (1 << hugepd_shift(*(hugepd_t *)pgd));
if (more > next)
next = more;
free_hugepd_range(tlb, (hugepd_t *)pgd, PGDIR_SHIFT,
addr, next, floor, ceiling);
}
} while (addr = next, addr != end);
}
struct page *follow_huge_pd(struct vm_area_struct *vma,
unsigned long address, hugepd_t hpd,
int flags, int pdshift)
{
pte_t *ptep;
spinlock_t *ptl;
struct page *page = NULL;
unsigned long mask;
int shift = hugepd_shift(hpd);
struct mm_struct *mm = vma->vm_mm;
retry:
ptl = &mm->page_table_lock;
spin_lock(ptl);
ptep = hugepte_offset(hpd, address, pdshift);
if (pte_present(*ptep)) {
mask = (1UL << shift) - 1;
page = pte_page(*ptep);
page += ((address & mask) >> PAGE_SHIFT);
if (flags & FOLL_GET)
get_page(page);
} else {
if (is_hugetlb_entry_migration(*ptep)) {
spin_unlock(ptl);
__migration_entry_wait(mm, ptep, ptl);
goto retry;
}
}
spin_unlock(ptl);
return page;
}
static unsigned long hugepte_addr_end(unsigned long addr, unsigned long end,
unsigned long sz)
{
unsigned long __boundary = (addr + sz) & ~(sz-1);
return (__boundary - 1 < end - 1) ? __boundary : end;
}
int gup_huge_pd(hugepd_t hugepd, unsigned long addr, unsigned pdshift,
unsigned long end, int write, struct page **pages, int *nr)
{
pte_t *ptep;
unsigned long sz = 1UL << hugepd_shift(hugepd);
unsigned long next;
ptep = hugepte_offset(hugepd, addr, pdshift);
do {
next = hugepte_addr_end(addr, end, sz);
if (!gup_hugepte(ptep, sz, addr, end, write, pages, nr))
return 0;
} while (ptep++, addr = next, addr != end);
return 1;
}
#ifdef CONFIG_PPC_MM_SLICES
unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
unsigned long len, unsigned long pgoff,
unsigned long flags)
{
struct hstate *hstate = hstate_file(file);
int mmu_psize = shift_to_mmu_psize(huge_page_shift(hstate));
#ifdef CONFIG_PPC_RADIX_MMU
if (radix_enabled())
return radix__hugetlb_get_unmapped_area(file, addr, len,
pgoff, flags);
#endif
return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1);
}
#endif
unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
{
#ifdef CONFIG_PPC_MM_SLICES
/* With radix we don't use slice, so derive it from vma*/
if (!radix_enabled()) {
unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
return 1UL << mmu_psize_to_shift(psize);
}
#endif
if (!is_vm_hugetlb_page(vma))
return PAGE_SIZE;
return huge_page_size(hstate_vma(vma));
}
static inline bool is_power_of_4(unsigned long x)
{
if (is_power_of_2(x))
return (__ilog2(x) % 2) ? false : true;
return false;
}
static int __init add_huge_page_size(unsigned long long size)
{
int shift = __ffs(size);
int mmu_psize;
/* Check that it is a page size supported by the hardware and
* that it fits within pagetable and slice limits. */
if (size <= PAGE_SIZE)
return -EINVAL;
#if defined(CONFIG_PPC_FSL_BOOK3E)
if (!is_power_of_4(size))
return -EINVAL;
#elif !defined(CONFIG_PPC_8xx)
if (!is_power_of_2(size) || (shift > SLICE_HIGH_SHIFT))
return -EINVAL;
#endif
if ((mmu_psize = shift_to_mmu_psize(shift)) < 0)
return -EINVAL;
#ifdef CONFIG_PPC_BOOK3S_64
/*
* We need to make sure that for different page sizes reported by
* firmware we only add hugetlb support for page sizes that can be
* supported by linux page table layout.
* For now we have
* Radix: 2M
* Hash: 16M and 16G
*/
if (radix_enabled()) {
if (mmu_psize != MMU_PAGE_2M) {
if (cpu_has_feature(CPU_FTR_POWER9_DD1) ||
(mmu_psize != MMU_PAGE_1G))
return -EINVAL;
}
} else {
if (mmu_psize != MMU_PAGE_16M && mmu_psize != MMU_PAGE_16G)
return -EINVAL;
}
#endif
BUG_ON(mmu_psize_defs[mmu_psize].shift != shift);
/* Return if huge page size has already been setup */
if (size_to_hstate(size))
return 0;
hugetlb_add_hstate(shift - PAGE_SHIFT);
return 0;
}
static int __init hugepage_setup_sz(char *str)
{
unsigned long long size;
size = memparse(str, &str);
if (add_huge_page_size(size) != 0) {
hugetlb_bad_size();
pr_err("Invalid huge page size specified(%llu)\n", size);
}
return 1;
}
__setup("hugepagesz=", hugepage_setup_sz);
struct kmem_cache *hugepte_cache;
static int __init hugetlbpage_init(void)
{
int psize;
#if !defined(CONFIG_PPC_FSL_BOOK3E) && !defined(CONFIG_PPC_8xx)
if (!radix_enabled() && !mmu_has_feature(MMU_FTR_16M_PAGE))
return -ENODEV;
#endif
for (psize = 0; psize < MMU_PAGE_COUNT; ++psize) {
unsigned shift;
unsigned pdshift;
if (!mmu_psize_defs[psize].shift)
continue;
shift = mmu_psize_to_shift(psize);
#ifdef CONFIG_PPC_BOOK3S_64
if (shift > PGDIR_SHIFT)
continue;
else if (shift > PUD_SHIFT)
pdshift = PGDIR_SHIFT;
else if (shift > PMD_SHIFT)
pdshift = PUD_SHIFT;
else
pdshift = PMD_SHIFT;
#else
if (shift < HUGEPD_PUD_SHIFT)
pdshift = PMD_SHIFT;
else if (shift < HUGEPD_PGD_SHIFT)
pdshift = PUD_SHIFT;
else
pdshift = PGDIR_SHIFT;
#endif
if (add_huge_page_size(1ULL << shift) < 0)
continue;
/*
* if we have pdshift and shift value same, we don't
* use pgt cache for hugepd.
*/
if (pdshift > shift)
pgtable_cache_add(pdshift - shift, NULL);
#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
else if (!hugepte_cache) {
/*
* Create a kmem cache for hugeptes. The bottom bits in
* the pte have size information encoded in them, so
* align them to allow this
*/
hugepte_cache = kmem_cache_create("hugepte-cache",
sizeof(pte_t),
HUGEPD_SHIFT_MASK + 1,
0, NULL);
if (hugepte_cache == NULL)
panic("%s: Unable to create kmem cache "
"for hugeptes\n", __func__);
}
#endif
}
#if defined(CONFIG_PPC_FSL_BOOK3E) || defined(CONFIG_PPC_8xx)
/* Default hpage size = 4M on FSL_BOOK3E and 512k on 8xx */
if (mmu_psize_defs[MMU_PAGE_4M].shift)
HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_4M].shift;
else if (mmu_psize_defs[MMU_PAGE_512K].shift)
HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_512K].shift;
#else
/* Set default large page size. Currently, we pick 16M or 1M
* depending on what is available
*/
if (mmu_psize_defs[MMU_PAGE_16M].shift)
HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_16M].shift;
else if (mmu_psize_defs[MMU_PAGE_1M].shift)
HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_1M].shift;
else if (mmu_psize_defs[MMU_PAGE_2M].shift)
HPAGE_SHIFT = mmu_psize_defs[MMU_PAGE_2M].shift;
#endif
return 0;
}
arch_initcall(hugetlbpage_init);
void flush_dcache_icache_hugepage(struct page *page)
{
int i;
void *start;
BUG_ON(!PageCompound(page));
for (i = 0; i < (1UL << compound_order(page)); i++) {
if (!PageHighMem(page)) {
__flush_dcache_icache(page_address(page+i));
} else {
start = kmap_atomic(page+i);
__flush_dcache_icache(start);
kunmap_atomic(start);
}
}
}
#endif /* CONFIG_HUGETLB_PAGE */
/*
* We have 4 cases for pgds and pmds:
* (1) invalid (all zeroes)
* (2) pointer to next table, as normal; bottom 6 bits == 0
* (3) leaf pte for huge page _PAGE_PTE set
* (4) hugepd pointer, _PAGE_PTE = 0 and bits [2..6] indicate size of table
*
* So long as we atomically load page table pointers we are safe against teardown,
* we can follow the address down to the the page and take a ref on it.
* This function need to be called with interrupts disabled. We use this variant
* when we have MSR[EE] = 0 but the paca->irq_soft_mask = IRQS_ENABLED
*/
pte_t *__find_linux_pte(pgd_t *pgdir, unsigned long ea,
bool *is_thp, unsigned *hpage_shift)
{
pgd_t pgd, *pgdp;
pud_t pud, *pudp;
pmd_t pmd, *pmdp;
pte_t *ret_pte;
hugepd_t *hpdp = NULL;
unsigned pdshift = PGDIR_SHIFT;
if (hpage_shift)
*hpage_shift = 0;
if (is_thp)
*is_thp = false;
pgdp = pgdir + pgd_index(ea);
pgd = READ_ONCE(*pgdp);
/*
* Always operate on the local stack value. This make sure the
* value don't get updated by a parallel THP split/collapse,
* page fault or a page unmap. The return pte_t * is still not
* stable. So should be checked there for above conditions.
*/
if (pgd_none(pgd))
return NULL;
else if (pgd_huge(pgd)) {
ret_pte = (pte_t *) pgdp;
goto out;
} else if (is_hugepd(__hugepd(pgd_val(pgd))))
hpdp = (hugepd_t *)&pgd;
else {
/*
* Even if we end up with an unmap, the pgtable will not
* be freed, because we do an rcu free and here we are
* irq disabled
*/
pdshift = PUD_SHIFT;
pudp = pud_offset(&pgd, ea);
pud = READ_ONCE(*pudp);
if (pud_none(pud))
return NULL;
else if (pud_huge(pud)) {
ret_pte = (pte_t *) pudp;
goto out;
} else if (is_hugepd(__hugepd(pud_val(pud))))
hpdp = (hugepd_t *)&pud;
else {
pdshift = PMD_SHIFT;
pmdp = pmd_offset(&pud, ea);
pmd = READ_ONCE(*pmdp);
/*
* A hugepage collapse is captured by pmd_none, because
* it mark the pmd none and do a hpte invalidate.
*/
if (pmd_none(pmd))
return NULL;
if (pmd_trans_huge(pmd) || pmd_devmap(pmd)) {
if (is_thp)
*is_thp = true;
ret_pte = (pte_t *) pmdp;
goto out;
}
if (pmd_huge(pmd)) {
ret_pte = (pte_t *) pmdp;
goto out;
} else if (is_hugepd(__hugepd(pmd_val(pmd))))
hpdp = (hugepd_t *)&pmd;
else
return pte_offset_kernel(&pmd, ea);
}
}
if (!hpdp)
return NULL;
ret_pte = hugepte_offset(*hpdp, ea, pdshift);
pdshift = hugepd_shift(*hpdp);
out:
if (hpage_shift)
*hpage_shift = pdshift;
return ret_pte;
}
EXPORT_SYMBOL_GPL(__find_linux_pte);
int gup_hugepte(pte_t *ptep, unsigned long sz, unsigned long addr,
unsigned long end, int write, struct page **pages, int *nr)
{
unsigned long pte_end;
struct page *head, *page;
pte_t pte;
int refs;
pte_end = (addr + sz) & ~(sz-1);
if (pte_end < end)
end = pte_end;
pte = READ_ONCE(*ptep);
if (!pte_access_permitted(pte, write))
return 0;
/* hugepages are never "special" */
VM_BUG_ON(!pfn_valid(pte_pfn(pte)));
refs = 0;
head = pte_page(pte);
page = head + ((addr & (sz-1)) >> PAGE_SHIFT);
do {
VM_BUG_ON(compound_head(page) != head);
pages[*nr] = page;
(*nr)++;
page++;
refs++;
} while (addr += PAGE_SIZE, addr != end);
if (!page_cache_add_speculative(head, refs)) {
*nr -= refs;
return 0;
}
if (unlikely(pte_val(pte) != pte_val(*ptep))) {
/* Could be optimized better */
*nr -= refs;
while (refs--)
put_page(head);
return 0;
}
return 1;
}
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