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.cnSigned-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>

arch/mips/mm/cache.c

@@ -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

@@ -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

@@ -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);