From: Toshi Kani <toshi.k...@hp.com> 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 <toshi.k...@hp.com> Cc: dave.han...@intel.com Cc: elli...@hp.com Cc: pebo...@tiscali.nl Cc: Luis R. Rodriguez <mcg...@suse.com> Cc: Andrew Morton <a...@linux-foundation.org> Cc: H. Peter Anvin <h...@zytor.com> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Ingo Molnar <mi...@kernel.org> Cc: linux-mm <linux...@kvack.org> Cc: x86-ml <x...@kernel.org> Cc: lkml <linux-kernel@vger.kernel.org> Link: http://lkml.kernel.org/r/1431714237-880-5-git-send-email-toshi.k...@hp.com Signed-off-by: Borislav Petkov <b...@suse.de> --- arch/x86/include/asm/mtrr.h | 2 +- arch/x86/include/uapi/asm/mtrr.h | 8 +++++++- arch/x86/kernel/cpu/mtrr/generic.c | 14 ++++++------- arch/x86/mm/pgtable.c | 42 +++++++++++++++++++++++++++++--------- 4 files changed, 47 insertions(+), 19 deletions(-) diff --git a/arch/x86/include/asm/mtrr.h b/arch/x86/include/asm/mtrr.h index ef927948657c..bb03a547c1ab 100644 --- a/arch/x86/include/asm/mtrr.h +++ b/arch/x86/include/asm/mtrr.h @@ -55,7 +55,7 @@ static inline u8 mtrr_type_lookup(u64 addr, u64 end) /* * Return no-MTRRs: */ - return 0xff; + return MTRR_TYPE_INVALID; } #define mtrr_save_fixed_ranges(arg) do {} while (0) #define mtrr_save_state() do {} while (0) diff --git a/arch/x86/include/uapi/asm/mtrr.h b/arch/x86/include/uapi/asm/mtrr.h index d0acb658c8f4..7528dcf59691 100644 --- a/arch/x86/include/uapi/asm/mtrr.h +++ b/arch/x86/include/uapi/asm/mtrr.h @@ -103,7 +103,7 @@ struct mtrr_state_type { #define MTRRIOC_GET_PAGE_ENTRY _IOWR(MTRR_IOCTL_BASE, 8, struct mtrr_gentry) #define MTRRIOC_KILL_PAGE_ENTRY _IOW(MTRR_IOCTL_BASE, 9, struct mtrr_sentry) -/* These are the region types */ +/* MTRR memory types, which are defined in SDM */ #define MTRR_TYPE_UNCACHABLE 0 #define MTRR_TYPE_WRCOMB 1 /*#define MTRR_TYPE_ 2*/ @@ -113,5 +113,11 @@ struct mtrr_state_type { #define MTRR_TYPE_WRBACK 6 #define MTRR_NUM_TYPES 7 +/* + * Invalid MTRR memory type. mtrr_type_lookup() returns this value when + * MTRRs are disabled. Note, this value is allocated from the reserved + * values (0x7-0xff) of the MTRR memory types. + */ +#define MTRR_TYPE_INVALID 0xff #endif /* _UAPI_ASM_X86_MTRR_H */ diff --git a/arch/x86/kernel/cpu/mtrr/generic.c b/arch/x86/kernel/cpu/mtrr/generic.c index b0599dbb899a..7b1491c6232d 100644 --- a/arch/x86/kernel/cpu/mtrr/generic.c +++ b/arch/x86/kernel/cpu/mtrr/generic.c @@ -104,7 +104,7 @@ static int check_type_overlap(u8 *prev, u8 *curr) /* * Error/Semi-error returns: - * 0xFF - when MTRR is not enabled + * MTRR_TYPE_INVALID - when MTRR is not enabled * *repeat == 1 implies [start:end] spanned across MTRR range and type returned * corresponds only to [start:*partial_end]. * Caller has to lookup again for [*partial_end:end]. @@ -117,10 +117,10 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) *repeat = 0; if (!mtrr_state_set) - return 0xFF; + return MTRR_TYPE_INVALID; if (!(mtrr_state.enabled & MTRR_STATE_MTRR_ENABLED)) - return 0xFF; + return MTRR_TYPE_INVALID; /* Make end inclusive end, instead of exclusive */ end--; @@ -151,7 +151,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) * Look of multiple ranges matching this address and pick type * as per MTRR precedence */ - prev_match = 0xFF; + prev_match = MTRR_TYPE_INVALID; for (i = 0; i < num_var_ranges; ++i) { unsigned short start_state, end_state, inclusive; @@ -206,7 +206,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) continue; curr_match = mtrr_state.var_ranges[i].base_lo & 0xff; - if (prev_match == 0xFF) { + if (prev_match == MTRR_TYPE_INVALID) { prev_match = curr_match; continue; } @@ -220,7 +220,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) return MTRR_TYPE_WRBACK; } - if (prev_match != 0xFF) + if (prev_match != MTRR_TYPE_INVALID) return prev_match; return mtrr_state.def_type; @@ -229,7 +229,7 @@ static u8 __mtrr_type_lookup(u64 start, u64 end, u64 *partial_end, int *repeat) /* * Returns the effective MTRR type for the region * Error return: - * 0xFF - when MTRR is not enabled + * MTRR_TYPE_INVALID - when MTRR is not enabled */ u8 mtrr_type_lookup(u64 start, u64 end) { 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)) { -- 1.9.0.258.g00eda23 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
