From: Toshi Kani Date: Tue, 7 Apr 2015 23:57:07 +0000 (+1000) Subject: mm, x86: document return values of mapping funcs X-Git-Tag: KARO-TXA5-2015-06-26~17^2~8 X-Git-Url: https://git.karo-electronics.de/?p=karo-tx-linux.git;a=commitdiff_plain;h=a1c8262949dd125ca5da8ad8dfe407efa0e2661c mm, x86: document return values of mapping funcs This patchset enhances MTRR checks for the kernel huge I/O mapping, which was enabled by the patchset below: https://lkml.org/lkml/2015/3/3/589 The following functional changes are made in patch 7/7. - Allow pud_set_huge() and pmd_set_huge() to create a huge page mapping to a range covered by a single MTRR entry of any memory type. - Log a pr_warn() message when a specified PMD map range spans more than a single MTRR entry. Drivers should make a mapping request aligned to a single MTRR entry when the range is covered by MTRRs. This patch (of 7): Document the return values of KVA mapping functions, pud_set_huge(), pmd_set_huge, pud_clear_huge() and pmd_clear_huge(). Simplify the conditions to select HAVE_ARCH_HUGE_VMAP in the Kconfig, since X86_PAE depends on X86_32. There is no functional change in this patch. Signed-off-by: Toshi Kani Cc: Dave Hansen Cc: Robert Elliott Cc: Paul Bolle Cc: "H. Peter Anvin" Cc: Thomas Gleixner Cc: Ingo Molnar Signed-off-by: Andrew Morton --- diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index bd5ecb4de842..780cbe3834bc 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -100,7 +100,7 @@ config X86 select IRQ_FORCED_THREADING select HAVE_BPF_JIT if X86_64 select HAVE_ARCH_TRANSPARENT_HUGEPAGE - select HAVE_ARCH_HUGE_VMAP if X86_64 || (X86_32 && X86_PAE) + select HAVE_ARCH_HUGE_VMAP if X86_64 || X86_PAE select ARCH_HAS_SG_CHAIN select CLKEVT_I8253 select ARCH_HAVE_NMI_SAFE_CMPXCHG diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 0b97d2c75df3..4891fa10e616 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -563,14 +563,19 @@ 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 4KB granularity. Therefore, + * it does not set up a huge page when the range is covered by a non-WB + * type of MTRR. 0xFF indicates that MTRR are disabled. + * + * Return 1 on success, and 0 when no PUD was set. + */ 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)) return 0; @@ -584,14 +589,19 @@ 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 4KB granularity. Therefore, + * it does not set up a huge page when the range is covered by a non-WB + * type of MTRR. 0xFF indicates that MTRR are disabled. + * + * Return 1 on success, and 0 when no PMD was set. + */ 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)) return 0; @@ -605,6 +615,11 @@ 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 + * + * Return 1 on success, and 0 when no PUD map was found. + */ int pud_clear_huge(pud_t *pud) { if (pud_large(*pud)) { @@ -615,6 +630,11 @@ int pud_clear_huge(pud_t *pud) return 0; } +/** + * pmd_clear_huge - clear kernel PMD mapping when it is set + * + * Return 1 on success, and 0 when no PMD map was found. + */ int pmd_clear_huge(pmd_t *pmd) { if (pmd_large(*pmd)) {