[PATCH v6 1/4] MIPS: Do not flush tlb page when updating PTE entry

[Bibo Mao]

It is not necessary to flush tlb page on all CPUs if suitable PTE
entry exists already during page fault handling, just updating
TLB is fine.

Here redefine flush_tlb_fix_spurious_fault as empty on MIPS system.
V6:
- Add update_mmu_tlb function as empty on all platform except mips
  system, we use this function to update local tlb for page fault
  smp-race handling
V5:
- define update_mmu_cache function specified on MIPS platform, and
  add page fault smp-race stats info
V4:
- add pte_sw_mkyoung function to implement readable privilege, and
  this function is  only in effect on MIPS system.
- add page valid bit judgement in function pte_modify
V3:
- add detailed changelog, modify typo issue in patch V2
v2:
- split flush_tlb_fix_spurious_fault and tlb update into two patches
- comments typo modification
- separate tlb update and add pte readable privilege into two patches

Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
---
 arch/mips/include/asm/pgtable.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/mips/include/asm/pgtable.h b/arch/mips/include/asm/pgtable.h
index 9b01d2d..0d625c2 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -478,6 +478,8 @@ static inline pgprot_t pgprot_writecombine(pgprot_t _prot)
 	return __pgprot(prot);
 }
 
+#define flush_tlb_fix_spurious_fault(vma, address) do { } while (0)
+
 /*
  * Conversion functions: convert a page and protection to a page entry,
  * and a page entry and page directory to the page they refer to.
-- 
1.8.3.1