From 6faa4c53b2f06fd271060761ce27f4f53289175c Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Wed, 30 Jan 2008 13:34:03 +0100 Subject: [PATCH] x86: 64-bit, add the new split_large_page() function Signed-off-by: Ingo Molnar Signed-off-by: Thomas Gleixner --- arch/x86/mm/pageattr_64.c | 95 +++++++++++++++++++++++++++++++++++------------ 1 file changed, 71 insertions(+), 24 deletions(-) diff --git a/arch/x86/mm/pageattr_64.c b/arch/x86/mm/pageattr_64.c index 190d4d3..1397950 100644 --- a/arch/x86/mm/pageattr_64.c +++ b/arch/x86/mm/pageattr_64.c @@ -45,34 +45,91 @@ pte_t *lookup_address(unsigned long address, int *level) return pte_offset_kernel(pmd, address); } -static struct page * -split_large_page(unsigned long address, pgprot_t ref_prot) +static void __set_pmd_pte(pte_t *kpte, unsigned long address, pte_t pte) { + /* change init_mm */ + set_pte_atomic(kpte, pte); +#ifdef CONFIG_X86_32 + if (SHARED_KERNEL_PMD) + return; + { + struct page *page; + + for (page = pgd_list; page; page = (struct page *)page->index) { + pgd_t *pgd; + pud_t *pud; + pmd_t *pmd; + + pgd = (pgd_t *)page_address(page) + pgd_index(address); + pud = pud_offset(pgd, address); + pmd = pmd_offset(pud, address); + set_pte_atomic((pte_t *)pmd, pte); + } + } +#endif +} + +static int split_large_page(pte_t *kpte, unsigned long address) +{ + pgprot_t ref_prot = pte_pgprot(pte_clrhuge(*kpte)); + gfp_t gfp_flags = GFP_KERNEL; + unsigned long flags; unsigned long addr; + pte_t *pbase, *tmp; struct page *base; - pte_t *pbase; - int i; + int i, level; + - base = alloc_pages(GFP_KERNEL, 0); +#ifdef CONFIG_DEBUG_PAGEALLOC + gfp_flags = GFP_ATOMIC; +#endif + base = alloc_pages(gfp_flags, 0); if (!base) - return NULL; + return -ENOMEM; + + spin_lock_irqsave(&pgd_lock, flags); + /* + * Check for races, another CPU might have split this page + * up for us already: + */ + tmp = lookup_address(address, &level); + if (tmp != kpte) { + WARN_ON_ONCE(1); + goto out_unlock; + } address = __pa(address); addr = address & LARGE_PAGE_MASK; pbase = (pte_t *)page_address(base); +#ifdef CONFIG_X86_32 + paravirt_alloc_pt(&init_mm, page_to_pfn(base)); +#endif + for (i = 0; i < PTRS_PER_PTE; i++, addr += PAGE_SIZE) - pbase[i] = pfn_pte(addr >> PAGE_SHIFT, ref_prot); + set_pte(&pbase[i], pfn_pte(addr >> PAGE_SHIFT, ref_prot)); + + /* + * Install the new, split up pagetable: + */ + __set_pmd_pte(kpte, address, mk_pte(base, ref_prot)); + base = NULL; + +out_unlock: + spin_unlock_irqrestore(&pgd_lock, flags); + + if (base) + __free_pages(base, 0); - return base; + return 0; } static int __change_page_attr(unsigned long address, struct page *page, pgprot_t prot) { + pgprot_t ref_prot2, oldprot; struct page *kpte_page; + int level, err = 0; pte_t *kpte; - pgprot_t ref_prot2, oldprot; - int level; repeat: kpte = lookup_address(address, &level); @@ -88,22 +145,12 @@ repeat: if (level == 4) { set_pte_atomic(kpte, mk_pte(page, prot)); } else { - /* - * split_large_page will take the reference for this - * change_page_attr on the split page. - */ - struct page *split; - - ref_prot2 = pte_pgprot(pte_clrhuge(*kpte)); - split = split_large_page(address, ref_prot2); - if (!split) - return -ENOMEM; - pgprot_val(ref_prot2) &= ~_PAGE_NX; - set_pte_atomic(kpte, mk_pte(split, ref_prot2)); - goto repeat; + err = split_large_page(kpte, address); + if (!err) + goto repeat; } - return 0; + return err; } /** -- 2.7.4