Commit f685a533 authored by Huang Pei's avatar Huang Pei Committed by Linus Torvalds
Browse files

MIPS: make userspace mapping young by default 

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: default avatarHuang Pei <huangpei@loongson.cn>
Reviewed-by: default avatarNicholas Piggin <npiggin@gmail.com>
Acked-by: default avatar <huangpei@loongson.cn>
Acked-by: default avatarThomas 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent dd23e809

arch/mips/mm/cache.c

+16 −14
Original line number Diff line number Diff line
@@ -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)

include/linux/pgtable.h

+0 −8
Original line number Diff line number Diff line
@@ -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

mm/memory.c

+0 −4
Original line number Diff line number Diff line
@@ -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);