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arm64: mm: Make flush_tlb_fix_spurious_fault() a no-op

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Our use of broadcast TLB maintenance means that spurious page-faults
that have been handled already by another CPU do not require additional
TLB maintenance.

Make flush_tlb_fix_spurious_fault() a no-op and rely on the existing TLB
invalidation instead. Add an explicit flush_tlb_page() when making a page
dirty, as the TLB is permitted to cache the old read-only entry.

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Link: https://lore.kernel.org/r/20200728092220.GA21800@willie-the-truck
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Will Deacon 2020-09-30 13:20:40 +01:00
parent e676594115
commit 6a1bdb173f
2 changed files with 11 additions and 1 deletions
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8
arch/arm64/include/asm/pgtable.h
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@ -50,6 +50,14 @@ extern void __pgd_error(const char *file, int line, unsigned long val);
__flush_tlb_range(vma, addr, end, PUD_SIZE, false, 1)
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
/*
* Outside of a few very special situations (e.g. hibernation), we always
* use broadcast TLB invalidation instructions, therefore a spurious page
* fault on one CPU which has been handled concurrently by another CPU
* does not need to perform additional invalidation.
*/
#define flush_tlb_fix_spurious_fault(vma, address) do { } while (0)
/*
* ZERO_PAGE is a global shared page that is always zero: used
* for zero-mapped memory areas etc..

4
arch/arm64/mm/fault.c
View File

@ -218,7 +218,9 @@ int ptep_set_access_flags(struct vm_area_struct *vma,
pteval = cmpxchg_relaxed(&pte_val(*ptep), old_pteval, pteval);
} while (pteval != old_pteval);
flush_tlb_fix_spurious_fault(vma, address);
/* Invalidate a stale read-only entry */
if (dirty)
flush_tlb_page(vma, address);
return 1;
}