From f85d2c104f167023736b0b06a79ddf06e3dc5a63 Mon Sep 17 00:00:00 2001 From: Will Deacon Date: Wed, 29 Jun 2022 10:53:49 +0100 Subject: [PATCH] arm64: hugetlb: Restore TLB invalidation for BBM on contiguous ptes Commit 42dbb8dc8f17 ("arm64/hugetlb: Drop TLB flush from get_clear_flush()") removed TLB invalidation from get_clear_flush() [now get_clear_contig()] on the basis that the core TLB invalidation code is aware of hugetlb mappings backed by contiguous page-table entries and will cover the correct virtual address range. However, this change also resulted in the TLB invalidation being removed from the "break" step in the break-before-make (BBM) sequence used internally by huge_ptep_set_{access_flags,wrprotect}(), therefore making the BBM sequence unsafe irrespective of later invalidation. Although the architecture is desperately unclear about how exactly contiguous ptes should be updated in a live page-table, restore TLB invalidation to our BBM sequence under the assumption that BBM is the right thing to be doing in the first place. Fixes: 42dbb8dc8f17 ("arm64/hugetlb: Drop TLB flush from get_clear_flush()") Cc: Ard Biesheuvel Cc: Steve Capper Cc: Anshuman Khandual Cc: Mike Kravetz Cc: Marc Zyngier Signed-off-by: Will Deacon Reviewed-by: Catalin Marinas Reviewed-by: Anshuman Khandual Link: https://lore.kernel.org/r/20220629095349.25748-1-will@kernel.org Signed-off-by: Catalin Marinas --- arch/arm64/mm/hugetlbpage.c | 30 +++++++++++++++++++++--------- 1 file changed, 21 insertions(+), 9 deletions(-) diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c index e2a5ec9fdc0db..3618ef3f6d818 100644 --- a/arch/arm64/mm/hugetlbpage.c +++ b/arch/arm64/mm/hugetlbpage.c @@ -214,6 +214,19 @@ static pte_t get_clear_contig(struct mm_struct *mm, return orig_pte; } +static pte_t get_clear_contig_flush(struct mm_struct *mm, + unsigned long addr, + pte_t *ptep, + unsigned long pgsize, + unsigned long ncontig) +{ + pte_t orig_pte = get_clear_contig(mm, addr, ptep, pgsize, ncontig); + struct vm_area_struct vma = TLB_FLUSH_VMA(mm, 0); + + flush_tlb_range(&vma, addr, addr + (pgsize * ncontig)); + return orig_pte; +} + /* * Changing some bits of contiguous entries requires us to follow a * Break-Before-Make approach, breaking the whole contiguous set @@ -447,19 +460,20 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma, int ncontig, i; size_t pgsize = 0; unsigned long pfn = pte_pfn(pte), dpfn; + struct mm_struct *mm = vma->vm_mm; 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); + ncontig = find_num_contig(mm, addr, ptep, &pgsize); dpfn = pgsize >> PAGE_SHIFT; if (!__cont_access_flags_changed(ptep, pte, ncontig)) return 0; - orig_pte = get_clear_contig(vma->vm_mm, addr, ptep, pgsize, ncontig); + orig_pte = get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig); /* Make sure we don't lose the dirty or young state */ if (pte_dirty(orig_pte)) @@ -470,7 +484,7 @@ int huge_ptep_set_access_flags(struct vm_area_struct *vma, 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)); + set_pte_at(mm, addr, ptep, pfn_pte(pfn, hugeprot)); return 1; } @@ -492,7 +506,7 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm, ncontig = find_num_contig(mm, addr, ptep, &pgsize); dpfn = pgsize >> PAGE_SHIFT; - pte = get_clear_contig(mm, addr, ptep, pgsize, ncontig); + pte = get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig); pte = pte_wrprotect(pte); hugeprot = pte_pgprot(pte); @@ -505,17 +519,15 @@ void huge_ptep_set_wrprotect(struct mm_struct *mm, pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { + struct mm_struct *mm = vma->vm_mm; size_t pgsize; int ncontig; - pte_t orig_pte; if (!pte_cont(READ_ONCE(*ptep))) return ptep_clear_flush(vma, addr, ptep); - ncontig = find_num_contig(vma->vm_mm, addr, ptep, &pgsize); - orig_pte = get_clear_contig(vma->vm_mm, addr, ptep, pgsize, ncontig); - flush_tlb_range(vma, addr, addr + pgsize * ncontig); - return orig_pte; + ncontig = find_num_contig(mm, addr, ptep, &pgsize); + return get_clear_contig_flush(mm, addr, ptep, pgsize, ncontig); } static int __init hugetlbpage_init(void) -- 2.39.5