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1f62ed00a5
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 <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
70 lines
1.4 KiB
C
70 lines
1.4 KiB
C
// SPDX-License-Identifier: GPL-2.0
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// Copyright (C) 2018 Hangzhou C-SKY Microsystems co.,ltd.
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/fs.h>
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#include <linux/pagemap.h>
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#include <linux/syscalls.h>
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#include <linux/spinlock.h>
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#include <asm/page.h>
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#include <asm/cache.h>
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#include <asm/cacheflush.h>
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#include <asm/cachectl.h>
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#include <asm/tlbflush.h>
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#define PG_dcache_clean PG_arch_1
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void flush_dcache_page(struct page *page)
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{
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struct address_space *mapping;
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if (page == ZERO_PAGE(0))
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return;
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mapping = page_mapping_file(page);
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if (mapping && !page_mapcount(page))
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clear_bit(PG_dcache_clean, &page->flags);
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else {
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dcache_wbinv_all();
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if (mapping)
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icache_inv_all();
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set_bit(PG_dcache_clean, &page->flags);
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}
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}
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EXPORT_SYMBOL(flush_dcache_page);
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void update_mmu_cache(struct vm_area_struct *vma, unsigned long addr,
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pte_t *ptep)
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{
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unsigned long pfn = pte_pfn(*ptep);
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struct page *page;
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flush_tlb_page(vma, addr);
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if (!pfn_valid(pfn))
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return;
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page = pfn_to_page(pfn);
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if (page == ZERO_PAGE(0))
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return;
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if (!test_and_set_bit(PG_dcache_clean, &page->flags))
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dcache_wbinv_all();
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if (page_mapping_file(page)) {
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if (vma->vm_flags & VM_EXEC)
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icache_inv_all();
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}
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}
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void flush_cache_range(struct vm_area_struct *vma, unsigned long start,
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unsigned long end)
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{
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dcache_wbinv_all();
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if (vma->vm_flags & VM_EXEC)
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icache_inv_all();
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}
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