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| author | Nicholas Piggin <npiggin@gmail.com> | 2018-06-01 13:01:16 +0300 |
|---|---|---|
| committer | Michael Ellerman <mpe@ellerman.id.au> | 2018-06-03 13:40:35 +0300 |
| commit | 6d8278c414cb24ac2b424f50afa99d13a49064b7 (patch) | |
| tree | 134aa8513feb83e37aac3033a0588eebad1efb8a /arch/powerpc/include/asm/book3s | |
| parent | e5f7cb58c2b77a0249c2028b6d1ec4d6d420816d (diff) | |
| download | linux-6d8278c414cb24ac2b424f50afa99d13a49064b7.tar.xz | |
powerpc/64s/radix: do not flush TLB on spurious fault
In the case of a spurious fault (which can happen due to a race with
another thread that changes the page table), the default Linux mm code
calls flush_tlb_page for that address. This is not required because
the pte will be re-fetched. Hash does not wire this up to a hardware
TLB flush for this reason. This patch avoids the flush for radix.
>From Power ISA v3.0B, p.1090:
Setting a Reference or Change Bit or Upgrading Access Authority
(PTE Subject to Atomic Hardware Updates)
If the only change being made to a valid PTE that is subject to
atomic hardware updates is to set the Refer- ence or Change bit to
1 or to add access authorities, a simpler sequence suffices
because the translation hardware will refetch the PTE if an access
is attempted for which the only problems were reference and/or
change bits needing to be set or insufficient access authority.
The nest MMU on POWER9 does not re-fetch the PTE after such an access
attempt before faulting, so address spaces with a coprocessor
attached will continue to flush in these cases.
This reduces tlbies for a kernel compile workload from 0.95M to 0.90M.
fork --fork --exec benchmark improved 0.5% (12300->12400).
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/include/asm/book3s')
| -rw-r--r-- | arch/powerpc/include/asm/book3s/64/tlbflush.h | 12 |
1 files changed, 11 insertions, 1 deletions
diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush.h b/arch/powerpc/include/asm/book3s/64/tlbflush.h index 0cac17253513..ebf572ea621e 100644 --- a/arch/powerpc/include/asm/book3s/64/tlbflush.h +++ b/arch/powerpc/include/asm/book3s/64/tlbflush.h @@ -4,7 +4,7 @@ #define MMU_NO_CONTEXT ~0UL - +#include <linux/mm_types.h> #include <asm/book3s/64/tlbflush-hash.h> #include <asm/book3s/64/tlbflush-radix.h> @@ -137,6 +137,16 @@ static inline void flush_all_mm(struct mm_struct *mm) #define flush_tlb_page(vma, addr) local_flush_tlb_page(vma, addr) #define flush_all_mm(mm) local_flush_all_mm(mm) #endif /* CONFIG_SMP */ + +#define flush_tlb_fix_spurious_fault flush_tlb_fix_spurious_fault +static inline void flush_tlb_fix_spurious_fault(struct vm_area_struct *vma, + unsigned long address) +{ + /* See ptep_set_access_flags comment */ + if (atomic_read(&vma->vm_mm->context.copros) > 0) + flush_tlb_page(vma, address); +} + /* * flush the page walk cache for the address */ |