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For now, The existing API is prefixed with double underscore to become the arch-private API and the public API is just a simple wrapper that calls the private API. The public API implementation will subsequently be used to transparently manipulate the contiguous bit where appropriate. But since there are already some contig-aware users (e.g. hugetlb, kernel mapper), we must first ensure those users use the private API directly so that the future contig-bit manipulations in the public API do not interfere with those existing uses. arm64 did not previously define an arch-specific ptep_get(), so override the default version in the arch code, and also define the private __ptep_get() version. Currently they both do the same thing that the default version does (READ_ONCE()). Some arch users (hugetlb) were already using ptep_get() so convert those to the private API. While other callsites were doing direct READ_ONCE(), so convert those to use the appropriate (public/private) API too. There are some core kernel locations that directly dereference the ptep, so these will need to be updated separately. No behavioural changes intended. Signed-off-by: Ryan Roberts --- arch/arm64/include/asm/pgtable.h | 19 +++++++++++++++---- arch/arm64/kernel/efi.c | 2 +- arch/arm64/mm/fault.c | 4 ++-- arch/arm64/mm/hugetlbpage.c | 18 +++++++++--------- arch/arm64/mm/kasan_init.c | 2 +- arch/arm64/mm/mmu.c | 12 ++++++------ arch/arm64/mm/pageattr.c | 4 ++-- arch/arm64/mm/trans_pgd.c | 2 +- 8 files changed, 37 insertions(+), 26 deletions(-) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index ff79578fd806..31df4d73f9ac 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -275,6 +275,11 @@ static inline void __set_pte(pte_t *ptep, pte_t pte) } } +static inline pte_t __ptep_get(pte_t *ptep) +{ + return READ_ONCE(*ptep); +} + extern void __sync_icache_dcache(pte_t pteval); bool pgattr_change_is_safe(u64 old, u64 new); @@ -302,7 +307,7 @@ static inline void __check_safe_pte_update(struct mm_struct *mm, pte_t *ptep, if (!IS_ENABLED(CONFIG_DEBUG_VM)) return; - old_pte = READ_ONCE(*ptep); + old_pte = __ptep_get(ptep); if (!pte_valid(old_pte) || !pte_valid(pte)) return; @@ -339,7 +344,7 @@ static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, */ if (system_supports_mte() && pte_access_permitted(pte, false) && !pte_special(pte)) { - pte_t old_pte = READ_ONCE(*ptep); + pte_t old_pte = __ptep_get(ptep); /* * We only need to synchronise if the new PTE has tags enabled * or if swapping in (in which case another mapping may have @@ -893,7 +898,7 @@ static inline int __ptep_test_and_clear_young(struct vm_area_struct *vma, { pte_t old_pte, pte; - pte = READ_ONCE(*ptep); + pte = __ptep_get(ptep); do { old_pte = pte; pte = pte_mkold(pte); @@ -966,7 +971,7 @@ static inline void __ptep_set_wrprotect(struct mm_struct *mm, { pte_t old_pte, pte; - pte = READ_ONCE(*ptep); + pte = __ptep_get(ptep); do { old_pte = pte; pte = pte_wrprotect(pte); @@ -1120,6 +1125,12 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma, * private versions, which are prefixed with double underscore. */ +#define ptep_get ptep_get +static inline pte_t ptep_get(pte_t *ptep) +{ + return __ptep_get(ptep); +} + static inline void set_pte(pte_t *ptep, pte_t pte) { __set_pte(ptep, pte); diff --git a/arch/arm64/kernel/efi.c b/arch/arm64/kernel/efi.c index 7a28b6a08a82..9536fbce77a2 100644 --- a/arch/arm64/kernel/efi.c +++ b/arch/arm64/kernel/efi.c @@ -106,7 +106,7 @@ static int __init set_permissions(pte_t *ptep, unsigned long addr, void *data) { struct set_perm_data *spd = data; const efi_memory_desc_t *md = spd->md; - pte_t pte = READ_ONCE(*ptep); + pte_t pte = __ptep_get(ptep); if (md->attribute & EFI_MEMORY_RO) pte = set_pte_bit(pte, __pgprot(PTE_RDONLY)); diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index f5a7a5ff6814..3193526b226d 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -177,7 +177,7 @@ static void show_pte(unsigned long addr) break; ptep = pte_offset_map(pmdp, addr); - pte = READ_ONCE(*ptep); + pte = __ptep_get(ptep); pr_cont(", pte=%016llx", pte_val(pte)); pte_unmap(ptep); } while(0); @@ -200,7 +200,7 @@ int __ptep_set_access_flags(struct vm_area_struct *vma, pte_t entry, int dirty) { pteval_t old_pteval, pteval; - pte_t pte = READ_ONCE(*ptep); + pte_t pte = __ptep_get(ptep); if (pte_same(pte, entry)) return 0; diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index 9a87b1c5661a..82b2036dbe2f 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -152,14 +152,14 @@ pte_t huge_ptep_get(pte_t *ptep) { int ncontig, i; size_t pgsize; - pte_t orig_pte = ptep_get(ptep); + pte_t orig_pte = __ptep_get(ptep); if (!pte_present(orig_pte) || !pte_cont(orig_pte)) return orig_pte; ncontig = num_contig_ptes(page_size(pte_page(orig_pte)), &pgsize); for (i = 0; i < ncontig; i++, ptep++) { - pte_t pte = ptep_get(ptep); + pte_t pte = __ptep_get(ptep); if (pte_dirty(pte)) orig_pte = pte_mkdirty(orig_pte); @@ -184,7 +184,7 @@ static pte_t get_clear_contig(struct mm_struct *mm, unsigned long pgsize, unsigned long ncontig) { - pte_t orig_pte = ptep_get(ptep); + pte_t orig_pte = __ptep_get(ptep); unsigned long i; for (i = 0; i < ncontig; i++, addr += pgsize, ptep++) { @@ -426,7 +426,7 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, { int ncontig; size_t pgsize; - pte_t orig_pte = ptep_get(ptep); + pte_t orig_pte = __ptep_get(ptep); if (!pte_cont(orig_pte)) return __ptep_get_and_clear(mm, addr, ptep); @@ -449,11 +449,11 @@ static int __cont_access_flags_changed(pte_t *ptep, pte_t pte, int ncontig) { int i; - if (pte_write(pte) != pte_write(ptep_get(ptep))) + if (pte_write(pte) != pte_write(__ptep_get(ptep))) return 1; for (i = 0; i < ncontig; i++) { - pte_t orig_pte = ptep_get(ptep + i); + pte_t orig_pte = __ptep_get(ptep + i); if (pte_dirty(pte) != pte_dirty(orig_pte)) return 1; @@ -510,7 +510,7 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm, size_t pgsize; pte_t pte; - if (!pte_cont(READ_ONCE(*ptep))) { + if (!pte_cont(__ptep_get(ptep))) { __ptep_set_wrprotect(mm, addr, ptep); return; } @@ -535,7 +535,7 @@ pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, size_t pgsize; int ncontig; - if (!pte_cont(READ_ONCE(*ptep))) + if (!pte_cont(__ptep_get(ptep))) return ptep_clear_flush(vma, addr, ptep); ncontig = find_num_contig(mm, addr, ptep, &pgsize); @@ -569,7 +569,7 @@ pte_t huge_ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr * when the permission changes from executable to non-executable * in cases where cpu is affected with errata #2645198. */ - if (pte_user_exec(READ_ONCE(*ptep))) + if (pte_user_exec(__ptep_get(ptep))) return huge_ptep_clear_flush(vma, addr, ptep); } return huge_ptep_get_and_clear(vma->vm_mm, addr, ptep); diff --git a/arch/arm64/mm/kasan_init.c b/arch/arm64/mm/kasan_init.c index 40125b217195..65074cf7f3a3 100644 --- a/arch/arm64/mm/kasan_init.c +++ b/arch/arm64/mm/kasan_init.c @@ -113,7 +113,7 @@ static void __init kasan_pte_populate(pmd_t *pmdp, unsigned long addr, memset(__va(page_phys), KASAN_SHADOW_INIT, PAGE_SIZE); next = addr + PAGE_SIZE; __set_pte(ptep, pfn_pte(__phys_to_pfn(page_phys), PAGE_KERNEL)); - } while (ptep++, addr = next, addr != end && pte_none(READ_ONCE(*ptep))); + } while (ptep++, addr = next, addr != end && pte_none(__ptep_get(ptep))); } static void __init kasan_pmd_populate(pud_t *pudp, unsigned long addr, diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c index 085a7e3eec98..d5dc36ff3827 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -176,7 +176,7 @@ static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end, ptep = pte_set_fixmap_offset(pmdp, addr); do { - pte_t old_pte = READ_ONCE(*ptep); + pte_t old_pte = __ptep_get(ptep); __set_pte(ptep, pfn_pte(__phys_to_pfn(phys), prot)); @@ -185,7 +185,7 @@ static void init_pte(pmd_t *pmdp, unsigned long addr, unsigned long end, * only allow updates to the permission attributes. */ BUG_ON(!pgattr_change_is_safe(pte_val(old_pte), - READ_ONCE(pte_val(*ptep)))); + pte_val(__ptep_get(ptep)))); phys += PAGE_SIZE; } while (ptep++, addr += PAGE_SIZE, addr != end); @@ -848,7 +848,7 @@ static void unmap_hotplug_pte_range(pmd_t *pmdp, unsigned long addr, do { ptep = pte_offset_kernel(pmdp, addr); - pte = READ_ONCE(*ptep); + pte = __ptep_get(ptep); if (pte_none(pte)) continue; @@ -981,7 +981,7 @@ static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr, do { ptep = pte_offset_kernel(pmdp, addr); - pte = READ_ONCE(*ptep); + pte = __ptep_get(ptep); /* * This is just a sanity check here which verifies that @@ -1000,7 +1000,7 @@ static void free_empty_pte_table(pmd_t *pmdp, unsigned long addr, */ ptep = pte_offset_kernel(pmdp, 0UL); for (i = 0; i < PTRS_PER_PTE; i++) { - if (!pte_none(READ_ONCE(ptep[i]))) + if (!pte_none(__ptep_get(ptep++))) return; } @@ -1470,7 +1470,7 @@ pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte * when the permission changes from executable to non-executable * in cases where cpu is affected with errata #2645198. */ - if (pte_user_exec(READ_ONCE(*ptep))) + if (pte_user_exec(ptep_get(ptep))) return ptep_clear_flush(vma, addr, ptep); } return ptep_get_and_clear(vma->vm_mm, addr, ptep); diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 057097acf9e0..624b0b0982e3 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -36,7 +36,7 @@ bool can_set_direct_map(void) static int change_page_range(pte_t *ptep, unsigned long addr, void *data) { struct page_change_data *cdata = data; - pte_t pte = READ_ONCE(*ptep); + pte_t pte = __ptep_get(ptep); pte = clear_pte_bit(pte, cdata->clear_mask); pte = set_pte_bit(pte, cdata->set_mask); @@ -246,5 +246,5 @@ bool kernel_page_present(struct page *page) return true; ptep = pte_offset_kernel(pmdp, addr); - return pte_valid(READ_ONCE(*ptep)); + return pte_valid(__ptep_get(ptep)); } diff --git a/arch/arm64/mm/trans_pgd.c b/arch/arm64/mm/trans_pgd.c index f9997b226614..b130a65092c1 100644 --- a/arch/arm64/mm/trans_pgd.c +++ b/arch/arm64/mm/trans_pgd.c @@ -32,7 +32,7 @@ static void *trans_alloc(struct trans_pgd_info *info) static void _copy_pte(pte_t *dst_ptep, pte_t *src_ptep, unsigned long addr) { - pte_t pte = READ_ONCE(*src_ptep); + pte_t pte = __ptep_get(src_ptep); if (pte_valid(pte)) { /* -- 2.25.1