From 3d3ca416d9b0784cfcf244eeeba1bcaf421bc64d Mon Sep 17 00:00:00 2001 From: Toshi Kani Date: Tue, 26 May 2015 10:28:07 +0200 Subject: x86/mm/mtrr: Use symbolic define as a retval for disabled MTRRs mtrr_type_lookup() returns verbatim 0xFF when MTRRs are disabled. This patch defines MTRR_TYPE_INVALID to clarify the meaning of this value, and documents its usage. Document the return values of the kernel virtual address mapping helpers pud_set_huge(), pmd_set_huge, pud_clear_huge() and pmd_clear_huge(). There is no functional change in this patch. Signed-off-by: Toshi Kani Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: Elliott@hp.com Cc: H. Peter Anvin Cc: Linus Torvalds Cc: Luis R. Rodriguez Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: dave.hansen@intel.com Cc: linux-mm Cc: pebolle@tiscali.nl Link: http://lkml.kernel.org/r/1431714237-880-5-git-send-email-toshi.kani@hp.com Link: http://lkml.kernel.org/r/1432628901-18044-5-git-send-email-bp@alien8.de Signed-off-by: Ingo Molnar --- arch/x86/mm/pgtable.c | 42 ++++++++++++++++++++++++++++++++---------- 1 file changed, 32 insertions(+), 10 deletions(-) (limited to 'arch/x86/mm/pgtable.c') diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 0b97d2c75df3..c30f9819786b 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -563,16 +563,22 @@ void native_set_fixmap(enum fixed_addresses idx, phys_addr_t phys, } #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP +/** + * pud_set_huge - setup kernel PUD mapping + * + * MTRR can override PAT memory types with 4KiB granularity. Therefore, + * this function does not set up a huge page when the range is covered + * by a non-WB type of MTRR. MTRR_TYPE_INVALID indicates that MTRR are + * disabled. + * + * Returns 1 on success and 0 on failure. + */ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot) { u8 mtrr; - /* - * Do not use a huge page when the range is covered by non-WB type - * of MTRRs. - */ mtrr = mtrr_type_lookup(addr, addr + PUD_SIZE); - if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != 0xFF)) + if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != MTRR_TYPE_INVALID)) return 0; prot = pgprot_4k_2_large(prot); @@ -584,16 +590,22 @@ int pud_set_huge(pud_t *pud, phys_addr_t addr, pgprot_t prot) return 1; } +/** + * pmd_set_huge - setup kernel PMD mapping + * + * MTRR can override PAT memory types with 4KiB granularity. Therefore, + * this function does not set up a huge page when the range is covered + * by a non-WB type of MTRR. MTRR_TYPE_INVALID indicates that MTRR are + * disabled. + * + * Returns 1 on success and 0 on failure. + */ int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot) { u8 mtrr; - /* - * Do not use a huge page when the range is covered by non-WB type - * of MTRRs. - */ mtrr = mtrr_type_lookup(addr, addr + PMD_SIZE); - if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != 0xFF)) + if ((mtrr != MTRR_TYPE_WRBACK) && (mtrr != MTRR_TYPE_INVALID)) return 0; prot = pgprot_4k_2_large(prot); @@ -605,6 +617,11 @@ int pmd_set_huge(pmd_t *pmd, phys_addr_t addr, pgprot_t prot) return 1; } +/** + * pud_clear_huge - clear kernel PUD mapping when it is set + * + * Returns 1 on success and 0 on failure (no PUD map is found). + */ int pud_clear_huge(pud_t *pud) { if (pud_large(*pud)) { @@ -615,6 +632,11 @@ int pud_clear_huge(pud_t *pud) return 0; } +/** + * pmd_clear_huge - clear kernel PMD mapping when it is set + * + * Returns 1 on success and 0 on failure (no PMD map is found). + */ int pmd_clear_huge(pmd_t *pmd) { if (pmd_large(*pmd)) { -- cgit v1.2.3