From b80388950303fe7711554614bd94b6231e937653 Mon Sep 17 00:00:00 2001 From: David Mosberger Date: Thu, 27 May 2004 10:38:21 -0700 Subject: [PATCH] [PATCH] ia64: use new ptep_set_access_flags ia64: Implement race-free ptep_set_access_flags() Signed-off-by: davidm@hpl.hp.com Signed-off-by: Linus Torvalds --- include/asm-ia64/pgtable.h | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) diff --git a/include/asm-ia64/pgtable.h b/include/asm-ia64/pgtable.h index e061bb305fd46..590432c084076 100644 --- a/include/asm-ia64/pgtable.h +++ b/include/asm-ia64/pgtable.h @@ -8,7 +8,7 @@ * This hopefully works with any (fixed) IA-64 page-size, as defined * in (currently 8192). * - * Copyright (C) 1998-2003 Hewlett-Packard Co + * Copyright (C) 1998-2004 Hewlett-Packard Co * David Mosberger-Tang */ @@ -476,6 +476,42 @@ extern void hugetlb_free_pgtables(struct mmu_gather *tlb, */ extern void update_mmu_cache (struct vm_area_struct *vma, unsigned long vaddr, pte_t pte); +#define __HAVE_ARCH_PTEP_SET_ACCESS_FLAGS +/* + * Update PTEP with ENTRY, which is guaranteed to be a less + * restrictive PTE. That is, ENTRY may have the ACCESSED, DIRTY, and + * WRITABLE bits turned on, when the value at PTEP did not. The + * WRITABLE bit may only be turned if SAFELY_WRITABLE is TRUE. + * + * SAFELY_WRITABLE is TRUE if we can update the value at PTEP without + * having to worry about races. On SMP machines, there are only two + * cases where this is true: + * + * (1) *PTEP has the PRESENT bit turned OFF + * (2) ENTRY has the DIRTY bit turned ON + * + * On ia64, we could implement this routine with a cmpxchg()-loop + * which ORs in the _PAGE_A/_PAGE_D bit if they're set in ENTRY. + * However, like on x86, we can get a more streamlined version by + * observing that it is OK to drop ACCESSED bit updates when + * SAFELY_WRITABLE is FALSE. Besides being rare, all that would do is + * result in an extra Access-bit fault, which would then turn on the + * ACCESSED bit in the low-level fault handler (iaccess_bit or + * daccess_bit in ivt.S). + */ +#ifdef CONFIG_SMP +# define ptep_set_access_flags(__vma, __addr, __ptep, __entry, __safely_writable) \ +do { \ + if (__safely_writable) { \ + set_pte(__ptep, __entry); \ + flush_tlb_page(__vma, __addr); \ + } \ +} while (0) +#else +# define ptep_set_access_flags(__vma, __addr, __ptep, __entry, __safely_writable) \ + ptep_establish(__vma, __addr, __ptep, __entry) +#endif + # ifdef CONFIG_VIRTUAL_MEM_MAP /* arch mem_map init routine is needed due to holes in a virtual mem_map */ # define __HAVE_ARCH_MEMMAP_INIT -- 2.53.0