From: Zachary Amsden Date: Sat, 3 Sep 2005 22:55:06 +0000 (-0700) Subject: [PATCH] x86_64: avoid some atomic operations during address space destruction X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=61e06037e764337da39dff307cbcdbe9cf288349;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git [PATCH] x86_64: avoid some atomic operations during address space destruction Any architecture that has hardware updated A/D bits that require synchronization against other processors during PTE operations can benefit from doing non-atomic PTE updates during address space destruction. Originally done on i386, now ported to x86_64. Doing a read/write pair instead of an xchg() operation saves the implicit lock, which turns out to be a big win on 32-bit (esp w PAE). Signed-off-by: Zachary Amsden Cc: Andi Kleen Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- diff --git a/include/asm-x86_64/pgtable.h b/include/asm-x86_64/pgtable.h index a1ada852f00..5e0f2fdab0d 100644 --- a/include/asm-x86_64/pgtable.h +++ b/include/asm-x86_64/pgtable.h @@ -104,6 +104,19 @@ extern inline void pgd_clear (pgd_t * pgd) ((unsigned long) __va(pud_val(pud) & PHYSICAL_PAGE_MASK)) #define ptep_get_and_clear(mm,addr,xp) __pte(xchg(&(xp)->pte, 0)) + +static inline pte_t ptep_get_and_clear_full(struct mm_struct *mm, unsigned long addr, pte_t *ptep, int full) +{ + pte_t pte; + if (full) { + pte = *ptep; + *ptep = __pte(0); + } else { + pte = ptep_get_and_clear(mm, addr, ptep); + } + return pte; +} + #define pte_same(a, b) ((a).pte == (b).pte) #define PMD_SIZE (1UL << PMD_SHIFT) @@ -434,6 +447,7 @@ extern int kern_addr_valid(unsigned long addr); #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_YOUNG #define __HAVE_ARCH_PTEP_TEST_AND_CLEAR_DIRTY #define __HAVE_ARCH_PTEP_GET_AND_CLEAR +#define __HAVE_ARCH_PTEP_GET_AND_CLEAR_FULL #define __HAVE_ARCH_PTEP_SET_WRPROTECT #define __HAVE_ARCH_PTE_SAME #include