From 1f62ed00a56bf01becaccd81bf30f2fcb0322fd2 Mon Sep 17 00:00:00 2001 From: Guo Ren Date: Thu, 6 Apr 2023 04:46:49 -0400 Subject: csky: mmu: Prevent spurious page faults C-SKY MMU would pre-fetch invalid pte entries, and it could work with flush_tlb_fix_spurious_fault, but the additional page fault exceptions would reduce performance. So flushing the entry of the TLB would prevent the following spurious page faults. Here is the test code: define DATA_LEN 4096 define COPY_NUM (504*100) unsigned char src[DATA_LEN*COPY_NUM] = {0}; unsigned char dst[DATA_LEN*COPY_NUM] = {0}; unsigned char func_src[DATA_LEN*COPY_NUM] = {0}; unsigned char func_dst[DATA_LEN*COPY_NUM] = {0}; void main(void) { int j; for (j = 0; j < COPY_NUM; j++) memcpy(&dst[j*DATA_LEN], &src[j*DATA_LEN], 4); } perf stat -e page-faults ./main.elf The amount of page fault traps would be reduced in half with the patch. Signed-off-by: Guo Ren Signed-off-by: Guo Ren --- arch/csky/abiv2/cacheflush.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/csky/abiv2') diff --git a/arch/csky/abiv2/cacheflush.c b/arch/csky/abiv2/cacheflush.c index 39c51399dd81..9923cd24db58 100644 --- a/arch/csky/abiv2/cacheflush.c +++ b/arch/csky/abiv2/cacheflush.c @@ -5,6 +5,7 @@ #include #include #include +#include void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, pte_t *pte) @@ -12,6 +13,8 @@ void update_mmu_cache(struct vm_area_struct *vma, unsigned long address, unsigned long addr; struct page *page; + flush_tlb_page(vma, address); + if (!pfn_valid(pte_pfn(*pte))) return; -- cgit v1.2.3