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Revert "FROMLIST: mm: x86, arm64: add arch_has_hw_pte_young()"

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This reverts commit 1861f17391.

To be replaced with upstream version.

Bug: 249601646
Change-Id: Ib992a9f199a9f30fbbf3f39537d87a8fb605c893
Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
This commit is contained in:
Kalesh Singh
2022-11-07 16:05:00 -08:00
parent 475108fadd
commit 970353b36e
4 changed files with 28 additions and 19 deletions
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14
arch/arm64/include/asm/pgtable.h
View File

@@ -1008,13 +1008,23 @@ static inline void update_mmu_cache(struct vm_area_struct *vma,
* page after fork() + CoW for pfn mappings. We don't always have a
* hardware-managed access flag on arm64.
*/
#define arch_has_hw_pte_young cpu_has_hw_af
static inline bool arch_faults_on_old_pte(void)
{
WARN_ON(preemptible());
return !cpu_has_hw_af();
}
#define arch_faults_on_old_pte arch_faults_on_old_pte
/*
* Experimentally, it's cheap to set the access flag in hardware and we
* benefit from prefaulting mappings as 'old' to start with.
*/
#define arch_wants_old_prefaulted_pte cpu_has_hw_af
static inline bool arch_wants_old_prefaulted_pte(void)
{
return !arch_faults_on_old_pte();
}
#define arch_wants_old_prefaulted_pte arch_wants_old_prefaulted_pte
#endif /* !__ASSEMBLY__ */

6
arch/x86/include/asm/pgtable.h
View File

@@ -1397,10 +1397,10 @@ static inline bool arch_has_pfn_modify_check(void)
return boot_cpu_has_bug(X86_BUG_L1TF);
}
#define arch_has_hw_pte_young arch_has_hw_pte_young
static inline bool arch_has_hw_pte_young(void)
#define arch_faults_on_old_pte arch_faults_on_old_pte
static inline bool arch_faults_on_old_pte(void)
{
return true;
return false;
}
#endif /* __ASSEMBLY__ */

13
include/linux/pgtable.h
View File

@@ -259,19 +259,6 @@ static inline int pmdp_clear_flush_young(struct vm_area_struct *vma,
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
#endif
#ifndef arch_has_hw_pte_young
/*
* Return whether the accessed bit is supported on the local CPU.
*
* This stub assumes accessing through an old PTE triggers a page fault.
* Architectures that automatically set the access bit should overwrite it.
*/
static inline bool arch_has_hw_pte_young(void)
{
return false;
}
#endif
#ifndef __HAVE_ARCH_PTEP_GET_AND_CLEAR
static inline pte_t ptep_get_and_clear(struct mm_struct *mm,
unsigned long address,

14
mm/memory.c
View File

@@ -122,6 +122,18 @@ int randomize_va_space __read_mostly =
2;
#endif
#ifndef arch_faults_on_old_pte
static inline bool arch_faults_on_old_pte(void)
{
/*
* Those arches which don't have hw access flag feature need to
* implement their own helper. By default, "true" means pagefault
* will be hit on old pte.
*/
return true;
}
#endif
#ifndef arch_wants_old_prefaulted_pte
static inline bool arch_wants_old_prefaulted_pte(void)
{
@@ -2904,7 +2916,7 @@ static inline bool cow_user_page(struct page *dst, struct page *src,
* On architectures with software "accessed" bits, we would
* take a double page fault, so mark it accessed here.
*/
if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) {
if (arch_faults_on_old_pte() && !pte_young(vmf->orig_pte)) {
pte_t entry;
vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);