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authorWill Deacon <will@kernel.org>2022-06-29 10:53:49 +0100
committerCatalin Marinas <catalin.marinas@arm.com>2022-07-01 18:29:26 +0100
commit410982303772993a86bb7a9cfa7ece34522b2636 (patch)
treeb5ece703f4811290655a3556d7c3d5c7167796b2
parentc50f11c6196f45c92ca48b16a5071615d4ae0572 (diff)
arm64: hugetlb: Restore TLB invalidation for BBM on contiguous ptes
Commit fb396bb459c1 ("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: fb396bb459c1 ("arm64/hugetlb: Drop TLB flush from get_clear_flush()") Cc: Ard Biesheuvel <ardb@kernel.org> Cc: Steve Capper <steve.capper@arm.com> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Marc Zyngier <maz@kernel.org> Signed-off-by: Will Deacon <will@kernel.org> Reviewed-by: Catalin Marinas <catalin.marinas@arm.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Link: https://lore.kernel.org/r/20220629095349.25748-1-will@kernel.org Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
-rw-r--r--arch/arm64/mm/hugetlbpage.c30
1 files changed, 21 insertions, 9 deletions
diff --git a/arch/arm64/mm/hugetlbpage.c b/arch/arm64/mm/hugetlbpage.c
index e2a5ec9fdc0d..3618ef3f6d81 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)