linux/arch/arm64/mm/hugetlbpage.c
Anshuman Khandual f8b46c4b51 arm64/mm: Add pud_sect_supported()
Section mapping at PUD level is supported only on 4K pages and currently it
gets verified with explicit #ifdef or IS_ENABLED() constructs. This adds a
new helper pud_sect_supported() for this purpose, which particularly cleans
up the HugeTLB code path. It updates relevant switch statements with checks
for __PAGETABLE_PMD_FOLDED in order to avoid build failures caused with two
identical switch case values in those code blocks.

Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/1632130171-472-1-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Will Deacon <will@kernel.org>
2021-09-29 16:54:33 +01:00

521 lines
12 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* arch/arm64/mm/hugetlbpage.c
*
* Copyright (C) 2013 Linaro Ltd.
*
* Based on arch/x86/mm/hugetlbpage.c.
*/
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/pagemap.h>
#include <linux/err.h>
#include <linux/sysctl.h>
#include <asm/mman.h>
#include <asm/tlb.h>
#include <asm/tlbflush.h>
/*
* HugeTLB Support Matrix
*
* ---------------------------------------------------
* | Page Size | CONT PTE | PMD | CONT PMD | PUD |
* ---------------------------------------------------
* | 4K | 64K | 2M | 32M | 1G |
* | 16K | 2M | 32M | 1G | |
* | 64K | 2M | 512M | 16G | |
* ---------------------------------------------------
*/
/*
* Reserve CMA areas for the largest supported gigantic
* huge page when requested. Any other smaller gigantic
* huge pages could still be served from those areas.
*/
#ifdef CONFIG_CMA
void __init arm64_hugetlb_cma_reserve(void)
{
int order;
if (pud_sect_supported())
order = PUD_SHIFT - PAGE_SHIFT;
else
order = CONT_PMD_SHIFT + PMD_SHIFT - PAGE_SHIFT;
/*
* HugeTLB CMA reservation is required for gigantic
* huge pages which could not be allocated via the
* page allocator. Just warn if there is any change
* breaking this assumption.
*/
WARN_ON(order <= MAX_ORDER);
hugetlb_cma_reserve(order);
}
#endif /* CONFIG_CMA */
#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
bool arch_hugetlb_migration_supported(struct hstate *h)
{
size_t pagesize = huge_page_size(h);
switch (pagesize) {
#ifndef __PAGETABLE_PMD_FOLDED
case PUD_SIZE:
return pud_sect_supported();
#endif
case PMD_SIZE:
case CONT_PMD_SIZE:
case CONT_PTE_SIZE:
return true;
}
pr_warn("%s: unrecognized huge page size 0x%lx\n",
__func__, pagesize);
return false;
}
#endif
int pmd_huge(pmd_t pmd)
{
return pmd_val(pmd) && !(pmd_val(pmd) & PMD_TABLE_BIT);
}
int pud_huge(pud_t pud)
{
#ifndef __PAGETABLE_PMD_FOLDED
return pud_val(pud) && !(pud_val(pud) & PUD_TABLE_BIT);
#else
return 0;
#endif
}
/*
* Select all bits except the pfn
*/
static inline pgprot_t pte_pgprot(pte_t pte)
{
unsigned long pfn = pte_pfn(pte);
return __pgprot(pte_val(pfn_pte(pfn, __pgprot(0))) ^ pte_val(pte));
}
static int find_num_contig(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, size_t *pgsize)
{
pgd_t *pgdp = pgd_offset(mm, addr);
p4d_t *p4dp;
pud_t *pudp;
pmd_t *pmdp;
*pgsize = PAGE_SIZE;
p4dp = p4d_offset(pgdp, addr);
pudp = pud_offset(p4dp, addr);
pmdp = pmd_offset(pudp, addr);
if ((pte_t *)pmdp == ptep) {
*pgsize = PMD_SIZE;
return CONT_PMDS;
}
return CONT_PTES;
}
static inline int num_contig_ptes(unsigned long size, size_t *pgsize)
{
int contig_ptes = 0;
*pgsize = size;
switch (size) {
#ifndef __PAGETABLE_PMD_FOLDED
case PUD_SIZE:
if (pud_sect_supported())
contig_ptes = 1;
break;
#endif
case PMD_SIZE:
contig_ptes = 1;
break;
case CONT_PMD_SIZE:
*pgsize = PMD_SIZE;
contig_ptes = CONT_PMDS;
break;
case CONT_PTE_SIZE:
*pgsize = PAGE_SIZE;
contig_ptes = CONT_PTES;
break;
}
return contig_ptes;
}
/*
* Changing some bits of contiguous entries requires us to follow a
* Break-Before-Make approach, breaking the whole contiguous set
* before we can change any entries. See ARM DDI 0487A.k_iss10775,
* "Misprogramming of the Contiguous bit", page D4-1762.
*
* This helper performs the break step.
*/
static pte_t get_clear_flush(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep,
unsigned long pgsize,
unsigned long ncontig)
{
pte_t orig_pte = huge_ptep_get(ptep);
bool valid = pte_valid(orig_pte);
unsigned long i, saddr = addr;
for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) {
pte_t pte = ptep_get_and_clear(mm, addr, ptep);
/*
* If HW_AFDBM is enabled, then the HW could turn on
* the dirty or accessed bit for any page in the set,
* so check them all.
*/
if (pte_dirty(pte))
orig_pte = pte_mkdirty(orig_pte);
if (pte_young(pte))
orig_pte = pte_mkyoung(orig_pte);
}
if (valid) {
struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
flush_tlb_range(&vma, saddr, addr);
}
return orig_pte;
}
/*
* Changing some bits of contiguous entries requires us to follow a
* Break-Before-Make approach, breaking the whole contiguous set
* before we can change any entries. See ARM DDI 0487A.k_iss10775,
* "Misprogramming of the Contiguous bit", page D4-1762.
*
* This helper performs the break step for use cases where the
* original pte is not needed.
*/
static void clear_flush(struct mm_struct *mm,
unsigned long addr,
pte_t *ptep,
unsigned long pgsize,
unsigned long ncontig)
{
struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0);
unsigned long i, saddr = addr;
for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
pte_clear(mm, addr, ptep);
flush_tlb_range(&vma, saddr, addr);
}
void set_huge_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte)
{
size_t pgsize;
int i;
int ncontig;
unsigned long pfn, dpfn;
pgprot_t hugeprot;
/*
* Code needs to be expanded to handle huge swap and migration
* entries. Needed for HUGETLB and MEMORY_FAILURE.
*/
WARN_ON(!pte_present(pte));
if (!pte_cont(pte)) {
set_pte_at(mm, addr, ptep, pte);
return;
}
ncontig = find_num_contig(mm, addr, ptep, &pgsize);
pfn = pte_pfn(pte);
dpfn = pgsize >> PAGE_SHIFT;
hugeprot = pte_pgprot(pte);
clear_flush(mm, addr, ptep, pgsize, ncontig);
for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
}
void set_huge_swap_pte_at(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, pte_t pte, unsigned long sz)
{
int i, ncontig;
size_t pgsize;
ncontig = num_contig_ptes(sz, &pgsize);
for (i = 0; i < ncontig; i++, ptep++)
set_pte(ptep, pte);
}
pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
unsigned long addr, unsigned long sz)
{
pgd_t *pgdp;
p4d_t *p4dp;
pud_t *pudp;
pmd_t *pmdp;
pte_t *ptep = NULL;
pgdp = pgd_offset(mm, addr);
p4dp = p4d_offset(pgdp, addr);
pudp = pud_alloc(mm, p4dp, addr);
if (!pudp)
return NULL;
if (sz == PUD_SIZE) {
ptep = (pte_t *)pudp;
} else if (sz == (CONT_PTE_SIZE)) {
pmdp = pmd_alloc(mm, pudp, addr);
if (!pmdp)
return NULL;
WARN_ON(addr & (sz - 1));
/*
* Note that if this code were ever ported to the
* 32-bit arm platform then it will cause trouble in
* the case where CONFIG_HIGHPTE is set, since there
* will be no pte_unmap() to correspond with this
* pte_alloc_map().
*/
ptep = pte_alloc_map(mm, pmdp, addr);
} else if (sz == PMD_SIZE) {
if (want_pmd_share(vma, addr) && pud_none(READ_ONCE(*pudp)))
ptep = huge_pmd_share(mm, vma, addr, pudp);
else
ptep = (pte_t *)pmd_alloc(mm, pudp, addr);
} else if (sz == (CONT_PMD_SIZE)) {
pmdp = pmd_alloc(mm, pudp, addr);
WARN_ON(addr & (sz - 1));
return (pte_t *)pmdp;
}
return ptep;
}
pte_t *huge_pte_offset(struct mm_struct *mm,
unsigned long addr, unsigned long sz)
{
pgd_t *pgdp;
p4d_t *p4dp;
pud_t *pudp, pud;
pmd_t *pmdp, pmd;
pgdp = pgd_offset(mm, addr);
if (!pgd_present(READ_ONCE(*pgdp)))
return NULL;
p4dp = p4d_offset(pgdp, addr);
if (!p4d_present(READ_ONCE(*p4dp)))
return NULL;
pudp = pud_offset(p4dp, addr);
pud = READ_ONCE(*pudp);
if (sz != PUD_SIZE && pud_none(pud))
return NULL;
/* hugepage or swap? */
if (pud_huge(pud) || !pud_present(pud))
return (pte_t *)pudp;
/* table; check the next level */
if (sz == CONT_PMD_SIZE)
addr &= CONT_PMD_MASK;
pmdp = pmd_offset(pudp, addr);
pmd = READ_ONCE(*pmdp);
if (!(sz == PMD_SIZE || sz == CONT_PMD_SIZE) &&
pmd_none(pmd))
return NULL;
if (pmd_huge(pmd) || !pmd_present(pmd))
return (pte_t *)pmdp;
if (sz == CONT_PTE_SIZE)
return pte_offset_kernel(pmdp, (addr & CONT_PTE_MASK));
return NULL;
}
pte_t arch_make_huge_pte(pte_t entry, unsigned int shift, vm_flags_t flags)
{
size_t pagesize = 1UL << shift;
if (pagesize == CONT_PTE_SIZE) {
entry = pte_mkcont(entry);
} else if (pagesize == CONT_PMD_SIZE) {
entry = pmd_pte(pmd_mkcont(pte_pmd(entry)));
} else if (pagesize != PUD_SIZE && pagesize != PMD_SIZE) {
pr_warn("%s: unrecognized huge page size 0x%lx\n",
__func__, pagesize);
}
return entry;
}
void huge_pte_clear(struct mm_struct *mm, unsigned long addr,
pte_t *ptep, unsigned long sz)
{
int i, ncontig;
size_t pgsize;
ncontig = num_contig_ptes(sz, &pgsize);
for (i = 0; i < ncontig; i++, addr += pgsize, ptep++)
pte_clear(mm, addr, ptep);
}
pte_t huge_ptep_get_and_clear(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
int ncontig;
size_t pgsize;
pte_t orig_pte = huge_ptep_get(ptep);
if (!pte_cont(orig_pte))
return ptep_get_and_clear(mm, addr, ptep);
ncontig = find_num_contig(mm, addr, ptep, &pgsize);
return get_clear_flush(mm, addr, ptep, pgsize, ncontig);
}
/*
* huge_ptep_set_access_flags will update access flags (dirty, accesssed)
* and write permission.
*
* For a contiguous huge pte range we need to check whether or not write
* permission has to change only on the first pte in the set. Then for
* all the contiguous ptes we need to check whether or not there is a
* discrepancy between dirty or young.
*/
static int __cont_access_flags_changed(pte_t *ptep, pte_t pte, int ncontig)
{
int i;
if (pte_write(pte) != pte_write(huge_ptep_get(ptep)))
return 1;
for (i = 0; i < ncontig; i++) {
pte_t orig_pte = huge_ptep_get(ptep + i);
if (pte_dirty(pte) != pte_dirty(orig_pte))
return 1;
if (pte_young(pte) != pte_young(orig_pte))
return 1;
}
return 0;
}
int huge_ptep_set_access_flags(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep,
pte_t pte, int dirty)
{
int ncontig, i;
size_t pgsize = 0;
unsigned long pfn = pte_pfn(pte), dpfn;
pgprot_t hugeprot;
pte_t orig_pte;
if (!pte_cont(pte))
return ptep_set_access_flags(vma, addr, ptep, pte, dirty);
ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
dpfn = pgsize >> PAGE_SHIFT;
if (!__cont_access_flags_changed(ptep, pte, ncontig))
return 0;
orig_pte = get_clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
/* Make sure we don't lose the dirty or young state */
if (pte_dirty(orig_pte))
pte = pte_mkdirty(pte);
if (pte_young(orig_pte))
pte = pte_mkyoung(pte);
hugeprot = pte_pgprot(pte);
for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
set_pte_at(vma->vm_mm, addr, ptep, pfn_pte(pfn, hugeprot));
return 1;
}
void huge_ptep_set_wrprotect(struct mm_struct *mm,
unsigned long addr, pte_t *ptep)
{
unsigned long pfn, dpfn;
pgprot_t hugeprot;
int ncontig, i;
size_t pgsize;
pte_t pte;
if (!pte_cont(READ_ONCE(*ptep))) {
ptep_set_wrprotect(mm, addr, ptep);
return;
}
ncontig = find_num_contig(mm, addr, ptep, &pgsize);
dpfn = pgsize >> PAGE_SHIFT;
pte = get_clear_flush(mm, addr, ptep, pgsize, ncontig);
pte = pte_wrprotect(pte);
hugeprot = pte_pgprot(pte);
pfn = pte_pfn(pte);
for (i = 0; i < ncontig; i++, ptep++, addr += pgsize, pfn += dpfn)
set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot));
}
void huge_ptep_clear_flush(struct vm_area_struct *vma,
unsigned long addr, pte_t *ptep)
{
size_t pgsize;
int ncontig;
if (!pte_cont(READ_ONCE(*ptep))) {
ptep_clear_flush(vma, addr, ptep);
return;
}
ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize);
clear_flush(vma->vm_mm, addr, ptep, pgsize, ncontig);
}
static int __init hugetlbpage_init(void)
{
if (pud_sect_supported())
hugetlb_add_hstate(PUD_SHIFT - PAGE_SHIFT);
hugetlb_add_hstate(CONT_PMD_SHIFT - PAGE_SHIFT);
hugetlb_add_hstate(PMD_SHIFT - PAGE_SHIFT);
hugetlb_add_hstate(CONT_PTE_SHIFT - PAGE_SHIFT);
return 0;
}
arch_initcall(hugetlbpage_init);
bool __init arch_hugetlb_valid_size(unsigned long size)
{
switch (size) {
#ifndef __PAGETABLE_PMD_FOLDED
case PUD_SIZE:
return pud_sect_supported();
#endif
case CONT_PMD_SIZE:
case PMD_SIZE:
case CONT_PTE_SIZE:
return true;
}
return false;
}