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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 37510C0003 X-Stat-Signature: d3qaxb33f9m8hg8bairqqmf5pupjsts8 X-Rspam-User: X-HE-Tag: 1745993726-423525 X-HE-Meta: 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 HjEiTBJn bMfZSfGSBQGpTrI80CDeMoBVM9jq0iFhLBh7z8hb3n/p5hZaMFS+MazXaY5GVTQyBdA/cfnfxYYrLFTNyyi5siaN2qMvnNk8Vp1y7eEMIpIj9GxxvvRHkDIK9XuXsJaZjhl3h9fzHnJcg+7ILzyu9CWYfCvrR66PYeD2FF5Pw58ud/hKT+BWNlaoXaQXOXqG4HBL1U9Ds8r9ealt2WTQWpQ6pGpkWnKRrL2pcsPTkUHEqBzZcjLUQesSorNGk9UbVu91qavroVeWH6Iv8KMSQO9ETGg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 4/30/25 11:19, Dev Jain wrote: > > > On 30/04/25 11:13 am, Anshuman Khandual wrote: >> On 4/29/25 10:53, Dev Jain wrote: >>> Override the generic definition to use get_and_clear_full_ptes(), so that >>> we do a TLBI possibly only on the "contpte-edges" of the large PTE block, >>> instead of doing it for every contpte block, which happens for ptep_get_and_clear(). >> >> Could you please explain what does "contpte-edges" really signify in the >> context of large PTE blocks ? Also how TLBI operation only on these edges >> will never run into the risk of missing TLB invalidation of some other >> mapped areas ? > > We are doing a TLBI over the whole range already, in the mprotect code: > see tlb_flush_pte_range. What the arm64 internal API does, irrespective of the caller, is to do a TLBI for every contpte block in case of unfolding. We don't need that for the intermediate blocks because the caller does that. We do need a TLBI for the start and end contpte block, > because in case the range we are invalidating partially covers them, then the caller will not do a TLBI for the non-overlapped PTEs of the block. But is not splitting the TLBI flush responsibility between the callers (intermediate blocks) and the platform API (contpte-edges) - some what problematic from a semantics perspective, and will be more susceptible for missing TLB flushes etc ? > I'll explain some more in the changelog next version. > >> >>> >>> Signed-off-by: Dev Jain >>> --- >>>   arch/arm64/include/asm/pgtable.h |  5 +++++ >>>   arch/arm64/mm/mmu.c              | 12 +++++++++--- >>>   include/linux/pgtable.h          |  4 ++++ >>>   mm/pgtable-generic.c             | 16 +++++++++++----- >>>   4 files changed, 29 insertions(+), 8 deletions(-) >>> >>> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h >>> index 2a77f11b78d5..8872ea5f0642 100644 >>> --- a/arch/arm64/include/asm/pgtable.h >>> +++ b/arch/arm64/include/asm/pgtable.h >>> @@ -1553,6 +1553,11 @@ extern void ptep_modify_prot_commit(struct vm_area_struct *vma, >>>                       unsigned long addr, pte_t *ptep, >>>                       pte_t old_pte, pte_t new_pte); >>>   +#define modify_prot_start_ptes modify_prot_start_ptes >>> +extern pte_t modify_prot_start_ptes(struct vm_area_struct *vma, >>> +                    unsigned long addr, pte_t *ptep, >>> +                    unsigned int nr); >>> + >>>   #ifdef CONFIG_ARM64_CONTPTE >>>     /* >>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >>> index 8fcf59ba39db..fe60be8774f4 100644 >>> --- a/arch/arm64/mm/mmu.c >>> +++ b/arch/arm64/mm/mmu.c >>> @@ -1523,7 +1523,8 @@ static int __init prevent_bootmem_remove_init(void) >>>   early_initcall(prevent_bootmem_remove_init); >>>   #endif >>>   -pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) >>> +pte_t modify_prot_start_ptes(struct vm_area_struct *vma, unsigned long addr, >>> +                 pte_t *ptep, unsigned int nr) >>>   { >>>       if (alternative_has_cap_unlikely(ARM64_WORKAROUND_2645198)) { >>>           /* >>> @@ -1532,9 +1533,14 @@ pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte >>>            * in cases where cpu is affected with errata #2645198. >>>            */ >>>           if (pte_user_exec(ptep_get(ptep))) >>> -            return ptep_clear_flush(vma, addr, ptep); >>> +            return clear_flush_ptes(vma, addr, ptep, nr); >>>       } >>> -    return ptep_get_and_clear(vma->vm_mm, addr, ptep); >>> +    return get_and_clear_full_ptes(vma->vm_mm, addr, ptep, nr, 0); >>> +} >>> + >>> +pte_t ptep_modify_prot_start(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) >>> +{ >>> +    return modify_prot_start_ptes(vma, addr, ptep, 1); >>>   } >>>     void ptep_modify_prot_commit(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep, >>> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h >>> index ed287289335f..10cdb87ccecf 100644 >>> --- a/include/linux/pgtable.h >>> +++ b/include/linux/pgtable.h >>> @@ -828,6 +828,10 @@ extern pte_t ptep_clear_flush(struct vm_area_struct *vma, >>>                     pte_t *ptep); >>>   #endif >>>   +extern pte_t clear_flush_ptes(struct vm_area_struct *vma, >>> +                  unsigned long address, >>> +                  pte_t *ptep, unsigned int nr); >>> + >>>   #ifndef __HAVE_ARCH_PMDP_HUGE_CLEAR_FLUSH >>>   extern pmd_t pmdp_huge_clear_flush(struct vm_area_struct *vma, >>>                     unsigned long address, >>> diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c >>> index 5a882f2b10f9..e238f88c3cac 100644 >>> --- a/mm/pgtable-generic.c >>> +++ b/mm/pgtable-generic.c >>> @@ -90,17 +90,23 @@ int ptep_clear_flush_young(struct vm_area_struct *vma, >>>   } >>>   #endif >>>   -#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH >>> -pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address, >>> -               pte_t *ptep) >>> +pte_t clear_flush_ptes(struct vm_area_struct *vma, unsigned long address, >>> +               pte_t *ptep, unsigned int nr) >>>   { >>>       struct mm_struct *mm = (vma)->vm_mm; >>>       pte_t pte; >>> -    pte = ptep_get_and_clear(mm, address, ptep); >>> +    pte = get_and_clear_full_ptes(mm, address, ptep, nr, 0); >>>       if (pte_accessible(mm, pte)) >>> -        flush_tlb_page(vma, address); >>> +        flush_tlb_range(vma, address, address + nr * PAGE_SIZE); >>>       return pte; >>>   } >>> + >>> +#ifndef __HAVE_ARCH_PTEP_CLEAR_FLUSH >>> +pte_t ptep_clear_flush(struct vm_area_struct *vma, unsigned long address, >>> +               pte_t *ptep) >>> +{ >>> +    return clear_flush_ptes(vma, address, ptep, 1); >>> +} >>>   #endif >>>     #ifdef CONFIG_TRANSPARENT_HUGEPAGE >