mirror of
https://mirrors.bfsu.edu.cn/git/linux.git
synced 2024-12-05 10:04:12 +08:00
94036f4c88
Mapping dirty helpers have, so far, been only used on X86, but a port of vmwgfx to ARM64 exposed a problem which results in a compilation error on ARM64 systems: mm/mapping_dirty_helpers.c: In function `wp_clean_pud_entry': mm/mapping_dirty_helpers.c:172:32: error: implicit declaration of function `pud_dirty'; did you mean `pmd_dirty'? [-Werror=implicit-function-declaration] This is due to the fact that mapping_dirty_helpers code assumes that pud_dirty is always defined, which is not the case for architectures that don't define CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD. ARM64 arch is a little inconsistent when it comes to PUD hugepage helpers, e.g. it defines pud_young but not pud_dirty but regardless of that the core kernel code shouldn't assume that any of the PUD hugepage helpers are available unless CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD is defined. This prevents compilation errors whenever one of the drivers is ported to new architectures. Link: https://lkml.kernel.org/r/20210409165151.694574-1-zackr@vmware.com Signed-off-by: Zack Rusin <zackr@vmware.com> Reviewed-by: Thomas Hellstrm (Intel) <thomas_os@shipmail.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
354 lines
10 KiB
C
354 lines
10 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
#include <linux/pagewalk.h>
|
|
#include <linux/hugetlb.h>
|
|
#include <linux/bitops.h>
|
|
#include <linux/mmu_notifier.h>
|
|
#include <asm/cacheflush.h>
|
|
#include <asm/tlbflush.h>
|
|
|
|
/**
|
|
* struct wp_walk - Private struct for pagetable walk callbacks
|
|
* @range: Range for mmu notifiers
|
|
* @tlbflush_start: Address of first modified pte
|
|
* @tlbflush_end: Address of last modified pte + 1
|
|
* @total: Total number of modified ptes
|
|
*/
|
|
struct wp_walk {
|
|
struct mmu_notifier_range range;
|
|
unsigned long tlbflush_start;
|
|
unsigned long tlbflush_end;
|
|
unsigned long total;
|
|
};
|
|
|
|
/**
|
|
* wp_pte - Write-protect a pte
|
|
* @pte: Pointer to the pte
|
|
* @addr: The start of protecting virtual address
|
|
* @end: The end of protecting virtual address
|
|
* @walk: pagetable walk callback argument
|
|
*
|
|
* The function write-protects a pte and records the range in
|
|
* virtual address space of touched ptes for efficient range TLB flushes.
|
|
*/
|
|
static int wp_pte(pte_t *pte, unsigned long addr, unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
struct wp_walk *wpwalk = walk->private;
|
|
pte_t ptent = *pte;
|
|
|
|
if (pte_write(ptent)) {
|
|
pte_t old_pte = ptep_modify_prot_start(walk->vma, addr, pte);
|
|
|
|
ptent = pte_wrprotect(old_pte);
|
|
ptep_modify_prot_commit(walk->vma, addr, pte, old_pte, ptent);
|
|
wpwalk->total++;
|
|
wpwalk->tlbflush_start = min(wpwalk->tlbflush_start, addr);
|
|
wpwalk->tlbflush_end = max(wpwalk->tlbflush_end,
|
|
addr + PAGE_SIZE);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* struct clean_walk - Private struct for the clean_record_pte function.
|
|
* @base: struct wp_walk we derive from
|
|
* @bitmap_pgoff: Address_space Page offset of the first bit in @bitmap
|
|
* @bitmap: Bitmap with one bit for each page offset in the address_space range
|
|
* covered.
|
|
* @start: Address_space page offset of first modified pte relative
|
|
* to @bitmap_pgoff
|
|
* @end: Address_space page offset of last modified pte relative
|
|
* to @bitmap_pgoff
|
|
*/
|
|
struct clean_walk {
|
|
struct wp_walk base;
|
|
pgoff_t bitmap_pgoff;
|
|
unsigned long *bitmap;
|
|
pgoff_t start;
|
|
pgoff_t end;
|
|
};
|
|
|
|
#define to_clean_walk(_wpwalk) container_of(_wpwalk, struct clean_walk, base)
|
|
|
|
/**
|
|
* clean_record_pte - Clean a pte and record its address space offset in a
|
|
* bitmap
|
|
* @pte: Pointer to the pte
|
|
* @addr: The start of virtual address to be clean
|
|
* @end: The end of virtual address to be clean
|
|
* @walk: pagetable walk callback argument
|
|
*
|
|
* The function cleans a pte and records the range in
|
|
* virtual address space of touched ptes for efficient TLB flushes.
|
|
* It also records dirty ptes in a bitmap representing page offsets
|
|
* in the address_space, as well as the first and last of the bits
|
|
* touched.
|
|
*/
|
|
static int clean_record_pte(pte_t *pte, unsigned long addr,
|
|
unsigned long end, struct mm_walk *walk)
|
|
{
|
|
struct wp_walk *wpwalk = walk->private;
|
|
struct clean_walk *cwalk = to_clean_walk(wpwalk);
|
|
pte_t ptent = *pte;
|
|
|
|
if (pte_dirty(ptent)) {
|
|
pgoff_t pgoff = ((addr - walk->vma->vm_start) >> PAGE_SHIFT) +
|
|
walk->vma->vm_pgoff - cwalk->bitmap_pgoff;
|
|
pte_t old_pte = ptep_modify_prot_start(walk->vma, addr, pte);
|
|
|
|
ptent = pte_mkclean(old_pte);
|
|
ptep_modify_prot_commit(walk->vma, addr, pte, old_pte, ptent);
|
|
|
|
wpwalk->total++;
|
|
wpwalk->tlbflush_start = min(wpwalk->tlbflush_start, addr);
|
|
wpwalk->tlbflush_end = max(wpwalk->tlbflush_end,
|
|
addr + PAGE_SIZE);
|
|
|
|
__set_bit(pgoff, cwalk->bitmap);
|
|
cwalk->start = min(cwalk->start, pgoff);
|
|
cwalk->end = max(cwalk->end, pgoff + 1);
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* wp_clean_pmd_entry - The pagewalk pmd callback.
|
|
*
|
|
* Dirty-tracking should take place on the PTE level, so
|
|
* WARN() if encountering a dirty huge pmd.
|
|
* Furthermore, never split huge pmds, since that currently
|
|
* causes dirty info loss. The pagefault handler should do
|
|
* that if needed.
|
|
*/
|
|
static int wp_clean_pmd_entry(pmd_t *pmd, unsigned long addr, unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
pmd_t pmdval = pmd_read_atomic(pmd);
|
|
|
|
if (!pmd_trans_unstable(&pmdval))
|
|
return 0;
|
|
|
|
if (pmd_none(pmdval)) {
|
|
walk->action = ACTION_AGAIN;
|
|
return 0;
|
|
}
|
|
|
|
/* Huge pmd, present or migrated */
|
|
walk->action = ACTION_CONTINUE;
|
|
if (pmd_trans_huge(pmdval) || pmd_devmap(pmdval))
|
|
WARN_ON(pmd_write(pmdval) || pmd_dirty(pmdval));
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* wp_clean_pud_entry - The pagewalk pud callback.
|
|
*
|
|
* Dirty-tracking should take place on the PTE level, so
|
|
* WARN() if encountering a dirty huge puds.
|
|
* Furthermore, never split huge puds, since that currently
|
|
* causes dirty info loss. The pagefault handler should do
|
|
* that if needed.
|
|
*/
|
|
static int wp_clean_pud_entry(pud_t *pud, unsigned long addr, unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
pud_t pudval = READ_ONCE(*pud);
|
|
|
|
if (!pud_trans_unstable(&pudval))
|
|
return 0;
|
|
|
|
if (pud_none(pudval)) {
|
|
walk->action = ACTION_AGAIN;
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
|
|
/* Huge pud */
|
|
walk->action = ACTION_CONTINUE;
|
|
if (pud_trans_huge(pudval) || pud_devmap(pudval))
|
|
WARN_ON(pud_write(pudval) || pud_dirty(pudval));
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* wp_clean_pre_vma - The pagewalk pre_vma callback.
|
|
*
|
|
* The pre_vma callback performs the cache flush, stages the tlb flush
|
|
* and calls the necessary mmu notifiers.
|
|
*/
|
|
static int wp_clean_pre_vma(unsigned long start, unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
struct wp_walk *wpwalk = walk->private;
|
|
|
|
wpwalk->tlbflush_start = end;
|
|
wpwalk->tlbflush_end = start;
|
|
|
|
mmu_notifier_range_init(&wpwalk->range, MMU_NOTIFY_PROTECTION_PAGE, 0,
|
|
walk->vma, walk->mm, start, end);
|
|
mmu_notifier_invalidate_range_start(&wpwalk->range);
|
|
flush_cache_range(walk->vma, start, end);
|
|
|
|
/*
|
|
* We're not using tlb_gather_mmu() since typically
|
|
* only a small subrange of PTEs are affected, whereas
|
|
* tlb_gather_mmu() records the full range.
|
|
*/
|
|
inc_tlb_flush_pending(walk->mm);
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* wp_clean_post_vma - The pagewalk post_vma callback.
|
|
*
|
|
* The post_vma callback performs the tlb flush and calls necessary mmu
|
|
* notifiers.
|
|
*/
|
|
static void wp_clean_post_vma(struct mm_walk *walk)
|
|
{
|
|
struct wp_walk *wpwalk = walk->private;
|
|
|
|
if (mm_tlb_flush_nested(walk->mm))
|
|
flush_tlb_range(walk->vma, wpwalk->range.start,
|
|
wpwalk->range.end);
|
|
else if (wpwalk->tlbflush_end > wpwalk->tlbflush_start)
|
|
flush_tlb_range(walk->vma, wpwalk->tlbflush_start,
|
|
wpwalk->tlbflush_end);
|
|
|
|
mmu_notifier_invalidate_range_end(&wpwalk->range);
|
|
dec_tlb_flush_pending(walk->mm);
|
|
}
|
|
|
|
/*
|
|
* wp_clean_test_walk - The pagewalk test_walk callback.
|
|
*
|
|
* Won't perform dirty-tracking on COW, read-only or HUGETLB vmas.
|
|
*/
|
|
static int wp_clean_test_walk(unsigned long start, unsigned long end,
|
|
struct mm_walk *walk)
|
|
{
|
|
unsigned long vm_flags = READ_ONCE(walk->vma->vm_flags);
|
|
|
|
/* Skip non-applicable VMAs */
|
|
if ((vm_flags & (VM_SHARED | VM_MAYWRITE | VM_HUGETLB)) !=
|
|
(VM_SHARED | VM_MAYWRITE))
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct mm_walk_ops clean_walk_ops = {
|
|
.pte_entry = clean_record_pte,
|
|
.pmd_entry = wp_clean_pmd_entry,
|
|
.pud_entry = wp_clean_pud_entry,
|
|
.test_walk = wp_clean_test_walk,
|
|
.pre_vma = wp_clean_pre_vma,
|
|
.post_vma = wp_clean_post_vma
|
|
};
|
|
|
|
static const struct mm_walk_ops wp_walk_ops = {
|
|
.pte_entry = wp_pte,
|
|
.pmd_entry = wp_clean_pmd_entry,
|
|
.pud_entry = wp_clean_pud_entry,
|
|
.test_walk = wp_clean_test_walk,
|
|
.pre_vma = wp_clean_pre_vma,
|
|
.post_vma = wp_clean_post_vma
|
|
};
|
|
|
|
/**
|
|
* wp_shared_mapping_range - Write-protect all ptes in an address space range
|
|
* @mapping: The address_space we want to write protect
|
|
* @first_index: The first page offset in the range
|
|
* @nr: Number of incremental page offsets to cover
|
|
*
|
|
* Note: This function currently skips transhuge page-table entries, since
|
|
* it's intended for dirty-tracking on the PTE level. It will warn on
|
|
* encountering transhuge write-enabled entries, though, and can easily be
|
|
* extended to handle them as well.
|
|
*
|
|
* Return: The number of ptes actually write-protected. Note that
|
|
* already write-protected ptes are not counted.
|
|
*/
|
|
unsigned long wp_shared_mapping_range(struct address_space *mapping,
|
|
pgoff_t first_index, pgoff_t nr)
|
|
{
|
|
struct wp_walk wpwalk = { .total = 0 };
|
|
|
|
i_mmap_lock_read(mapping);
|
|
WARN_ON(walk_page_mapping(mapping, first_index, nr, &wp_walk_ops,
|
|
&wpwalk));
|
|
i_mmap_unlock_read(mapping);
|
|
|
|
return wpwalk.total;
|
|
}
|
|
EXPORT_SYMBOL_GPL(wp_shared_mapping_range);
|
|
|
|
/**
|
|
* clean_record_shared_mapping_range - Clean and record all ptes in an
|
|
* address space range
|
|
* @mapping: The address_space we want to clean
|
|
* @first_index: The first page offset in the range
|
|
* @nr: Number of incremental page offsets to cover
|
|
* @bitmap_pgoff: The page offset of the first bit in @bitmap
|
|
* @bitmap: Pointer to a bitmap of at least @nr bits. The bitmap needs to
|
|
* cover the whole range @first_index..@first_index + @nr.
|
|
* @start: Pointer to number of the first set bit in @bitmap.
|
|
* is modified as new bits are set by the function.
|
|
* @end: Pointer to the number of the last set bit in @bitmap.
|
|
* none set. The value is modified as new bits are set by the function.
|
|
*
|
|
* Note: When this function returns there is no guarantee that a CPU has
|
|
* not already dirtied new ptes. However it will not clean any ptes not
|
|
* reported in the bitmap. The guarantees are as follows:
|
|
* a) All ptes dirty when the function starts executing will end up recorded
|
|
* in the bitmap.
|
|
* b) All ptes dirtied after that will either remain dirty, be recorded in the
|
|
* bitmap or both.
|
|
*
|
|
* If a caller needs to make sure all dirty ptes are picked up and none
|
|
* additional are added, it first needs to write-protect the address-space
|
|
* range and make sure new writers are blocked in page_mkwrite() or
|
|
* pfn_mkwrite(). And then after a TLB flush following the write-protection
|
|
* pick up all dirty bits.
|
|
*
|
|
* Note: This function currently skips transhuge page-table entries, since
|
|
* it's intended for dirty-tracking on the PTE level. It will warn on
|
|
* encountering transhuge dirty entries, though, and can easily be extended
|
|
* to handle them as well.
|
|
*
|
|
* Return: The number of dirty ptes actually cleaned.
|
|
*/
|
|
unsigned long clean_record_shared_mapping_range(struct address_space *mapping,
|
|
pgoff_t first_index, pgoff_t nr,
|
|
pgoff_t bitmap_pgoff,
|
|
unsigned long *bitmap,
|
|
pgoff_t *start,
|
|
pgoff_t *end)
|
|
{
|
|
bool none_set = (*start >= *end);
|
|
struct clean_walk cwalk = {
|
|
.base = { .total = 0 },
|
|
.bitmap_pgoff = bitmap_pgoff,
|
|
.bitmap = bitmap,
|
|
.start = none_set ? nr : *start,
|
|
.end = none_set ? 0 : *end,
|
|
};
|
|
|
|
i_mmap_lock_read(mapping);
|
|
WARN_ON(walk_page_mapping(mapping, first_index, nr, &clean_walk_ops,
|
|
&cwalk.base));
|
|
i_mmap_unlock_read(mapping);
|
|
|
|
*start = cwalk.start;
|
|
*end = cwalk.end;
|
|
|
|
return cwalk.base.total;
|
|
}
|
|
EXPORT_SYMBOL_GPL(clean_record_shared_mapping_range);
|