[PATCH] MIPS: make userspace mapping young by default

* [PATCH] MIPS: make userspace mapping young by default
@ 2021-02-04  1:39 Huang Pei
  2021-02-04  3:29 ` Nicholas Piggin
  2021-02-04 15:22 ` Thomas Bogendoerfer
  0 siblings, 2 replies; 15+ messages in thread
From: Huang Pei @ 2021-02-04  1:39 UTC (permalink / raw)
  To: Thomas Bogendoerfer, ambrosehua
  Cc: Bibo Mao, Andrew Morton, linux-mips, linux-arch, linux-mm,
	Jiaxun Yang, Paul Burton, Li Xuefeng, Yang Tiezhu, Gao Juxin,
	Fuxin Zhang, Huacai Chen

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

Signed-off-by: Huang Pei <huangpei@loongson.cn>
---
 arch/mips/mm/cache.c    | 30 ++++++++++++++++--------------
 include/linux/pgtable.h |  8 --------
 mm/memory.c             |  3 ---
 3 files changed, 16 insertions(+), 25 deletions(-)

diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c
index 23b16bfd97b2..e19cf424bb39 100644
--- a/arch/mips/mm/cache.c
+++ b/arch/mips/mm/cache.c
@@ -156,29 +156,31 @@ 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)
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 8fcdfa52eb4b..8c042627399a 100644
--- a/include/linux/pgtable.h
+++ b/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
diff --git a/mm/memory.c b/mm/memory.c
index feff48e1465a..95718a623884 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2890,7 +2890,6 @@ 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);
 
 		/*
@@ -3548,7 +3547,6 @@ 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));
 
@@ -3824,7 +3822,6 @@ vm_fault_t alloc_set_pte(struct vm_fault *vmf, struct page *page)
 
 	flush_icache_page(vma, page);
 	entry = mk_pte(page, vma->vm_page_prot);
-	entry = pte_sw_mkyoung(entry);
 	if (write)
 		entry = maybe_mkwrite(pte_mkdirty(entry), vma);
 	/* copy-on-write page */
-- 
2.17.1


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