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MIPS: make userspace mapping young by default

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MIPS page fault path(except huge page) takes 3 exceptions (1 TLB Miss + 2
TLB Invalid), butthe second TLB Invalid exception is just triggered by
__update_tlb from do_page_fault writing tlb without _PAGE_VALID set.  With
this patch, user space mapping prot is made young by default (with both
_PAGE_VALID and _PAGE_YOUNG set), and it only take 1 TLB Miss + 1 TLB
Invalid exception

Remove pte_sw_mkyoung without polluting MM code and make page fault delay
of MIPS on par with other architecture

Link: https://lkml.kernel.org/r/20210204013942.8398-1-huangpei@loongson.cn
Signed-off-by: Huang Pei <huangpei@loongson.cn>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Acked-by: <huangpei@loongson.cn>
Acked-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: <ambrosehua@gmail.com>
Cc: Bibo Mao <maobibo@loongson.cn>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Paul Burton <paulburton@kernel.org>
Cc: Li Xuefeng <lixuefeng@loongson.cn>
Cc: Yang Tiezhu <yangtiezhu@loongson.cn>
Cc: Gao Juxin <gaojuxin@loongson.cn>
Cc: Fuxin Zhang <zhangfx@lemote.com>
Cc: Huacai Chen <chenhc@lemote.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Huang Pei 2021-02-25 17:22:49 -08:00 committed by Linus Torvalds
parent dd23e8098f
commit f685a533a7
3 changed files with 16 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

30
arch/mips/mm/cache.c
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@ -157,29 +157,31 @@ unsigned long _page_cachable_default;
EXPORT_SYMBOL(_page_cachable_default);
#define PM(p) __pgprot(_page_cachable_default | (p))
#define PVA(p) PM(_PAGE_VALID | _PAGE_ACCESSED | (p))
static inline void setup_protection_map(void)
{
protection_map[0] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
protection_map[1] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC);
protection_map[2] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
protection_map[3] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC);
protection_map[4] = PM(_PAGE_PRESENT);
protection_map[5] = PM(_PAGE_PRESENT);
protection_map[6] = PM(_PAGE_PRESENT);
protection_map[7] = PM(_PAGE_PRESENT);
protection_map[1] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC);
protection_map[2] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
protection_map[3] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC);
protection_map[4] = PVA(_PAGE_PRESENT);
protection_map[5] = PVA(_PAGE_PRESENT);
protection_map[6] = PVA(_PAGE_PRESENT);
protection_map[7] = PVA(_PAGE_PRESENT);
protection_map[8] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ);
protection_map[9] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC);
protection_map[10] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE |
protection_map[9] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC);
protection_map[10] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE |
_PAGE_NO_READ);
protection_map[11] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE);
protection_map[12] = PM(_PAGE_PRESENT);
protection_map[13] = PM(_PAGE_PRESENT);
protection_map[14] = PM(_PAGE_PRESENT | _PAGE_WRITE);
protection_map[15] = PM(_PAGE_PRESENT | _PAGE_WRITE);
protection_map[11] = PVA(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE);
protection_map[12] = PVA(_PAGE_PRESENT);
protection_map[13] = PVA(_PAGE_PRESENT);
protection_map[14] = PVA(_PAGE_PRESENT);
protection_map[15] = PVA(_PAGE_PRESENT);
}
#undef _PVA
#undef PM
void cpu_cache_init(void)

8
include/linux/pgtable.h
View File

@ -432,14 +432,6 @@ static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addres
* To be differentiate with macro pte_mkyoung, this macro is used on platforms
* where software maintains page access bit.
*/
#ifndef pte_sw_mkyoung
static inline pte_t pte_sw_mkyoung(pte_t pte)
{
return pte;
}
#define pte_sw_mkyoung pte_sw_mkyoung
#endif
#ifndef pte_savedwrite
#define pte_savedwrite pte_write
#endif

4
mm/memory.c
View File

@ -2902,7 +2902,6 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
}
flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
entry = mk_pte(new_page, vma->vm_page_prot);
entry = pte_sw_mkyoung(entry);
entry = maybe_mkwrite(pte_mkdirty(entry), vma);
/*
@ -3560,7 +3559,6 @@ static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
__SetPageUptodate(page);
entry = mk_pte(page, vma->vm_page_prot);
entry = pte_sw_mkyoung(entry);
if (vma->vm_flags & VM_WRITE)
entry = pte_mkwrite(pte_mkdirty(entry));
@ -3745,8 +3743,6 @@ void do_set_pte(struct vm_fault *vmf, struct page *page, unsigned long addr)
if (prefault && arch_wants_old_prefaulted_pte())
entry = pte_mkold(entry);
else
entry = pte_sw_mkyoung(entry);
if (write)
entry = maybe_mkwrite(pte_mkdirty(entry), vma);