Messages in this thread Patch in this message | | | From | Andi Kleen <> | Subject | [PATCH] [3/7] Add set_memory_4k to pageattr.c | Date | Wed, 12 Mar 2008 03:53:29 +0100 (CET) |
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Add a new function to force split large pages into 4k pages. This is needed for some followup optimizations.
I had to add a new field to cpa_data to pass down the information that try_preserve_large_page should not run.
Right now no set_page_4k() because I didn't need it and all the specialized users I have in mind would be more comfortable with pure addresses. I also didn't export it because it's unlikely external code needs it.
Signed-off-by: Andi Kleen <ak@suse.de>
Index: linux/arch/x86/mm/pageattr.c =================================================================== --- linux.orig/arch/x86/mm/pageattr.c +++ linux/arch/x86/mm/pageattr.c @@ -28,6 +28,7 @@ struct cpa_data { int numpages; int flushtlb; unsigned long pfn; + unsigned force_split : 1; }; #ifdef CONFIG_X86_64 @@ -259,6 +260,9 @@ try_preserve_large_page(pte_t *kpte, uns int i, do_split = 1; unsigned int level; + if (cpa->force_split) + return 1; + spin_lock_irqsave(&pgd_lock, flags); /* * Check for races, another CPU might have split this page @@ -693,7 +697,8 @@ static inline int cache_attr(pgprot_t at } static int change_page_attr_set_clr(unsigned long addr, int numpages, - pgprot_t mask_set, pgprot_t mask_clr) + pgprot_t mask_set, pgprot_t mask_clr, + int force_split) { struct cpa_data cpa; int ret, cache, checkalias; @@ -704,7 +709,7 @@ static int change_page_attr_set_clr(unsi */ mask_set = canon_pgprot(mask_set); mask_clr = canon_pgprot(mask_clr); - if (!pgprot_val(mask_set) && !pgprot_val(mask_clr)) + if (!pgprot_val(mask_set) && !pgprot_val(mask_clr) && !force_split) return 0; /* Ensure we are PAGE_SIZE aligned */ @@ -721,6 +726,7 @@ static int change_page_attr_set_clr(unsi cpa.mask_set = mask_set; cpa.mask_clr = mask_clr; cpa.flushtlb = 0; + cpa.force_split = force_split; /* No alias checking for _NX bit modifications */ checkalias = (pgprot_val(mask_set) | pgprot_val(mask_clr)) != _PAGE_NX; @@ -759,13 +765,13 @@ out: static inline int change_page_attr_set(unsigned long addr, int numpages, pgprot_t mask) { - return change_page_attr_set_clr(addr, numpages, mask, __pgprot(0)); + return change_page_attr_set_clr(addr, numpages, mask, __pgprot(0), 0); } static inline int change_page_attr_clear(unsigned long addr, int numpages, pgprot_t mask) { - return change_page_attr_set_clr(addr, numpages, __pgprot(0), mask); + return change_page_attr_set_clr(addr, numpages, __pgprot(0), mask, 0); } int set_memory_uc(unsigned long addr, int numpages) @@ -809,6 +815,12 @@ int set_memory_np(unsigned long addr, in return change_page_attr_clear(addr, numpages, __pgprot(_PAGE_PRESENT)); } +int set_memory_4k(unsigned long addr, int numpages) +{ + return change_page_attr_set_clr(addr, numpages, __pgprot(0), + __pgprot(0), 1); +} + int set_pages_uc(struct page *page, int numpages) { unsigned long addr = (unsigned long)page_address(page); Index: linux/include/asm-x86/cacheflush.h =================================================================== --- linux.orig/include/asm-x86/cacheflush.h +++ linux/include/asm-x86/cacheflush.h @@ -41,6 +41,7 @@ int set_memory_nx(unsigned long addr, in int set_memory_ro(unsigned long addr, int numpages); int set_memory_rw(unsigned long addr, int numpages); int set_memory_np(unsigned long addr, int numpages); +int set_memory_4k(unsigned long addr, int numpages); void clflush_cache_range(void *addr, unsigned int size);
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