diff options
| author | Dave Hansen <dave.hansen@linux.intel.com> | 2016-07-08 03:19:12 +0300 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-07-13 10:43:25 +0300 |
| commit | 97e3c602ccbdd7db54e92fe05675c664c052a466 (patch) | |
| tree | 545003282185d14130c86c6e8ec2dbe4516cc2db | |
| parent | 00839ee3b299303c6a5e26a0a2485427a3afcbbf (diff) | |
| download | linux-97e3c602ccbdd7db54e92fe05675c664c052a466.tar.xz | |
x86/mm: Ignore A/D bits in pte/pmd/pud_none()
The erratum we are fixing here can lead to stray setting of the
A and D bits. That means that a pte that we cleared might
suddenly have A/D set. So, stop considering those bits when
determining if a pte is pte_none(). The same goes for the
other pmd_none() and pud_none(). pgd_none() can be skipped
because it is not affected; we do not use PGD entries for
anything other than pagetables on affected configurations.
This adds a tiny amount of overhead to all pte_none() checks.
I doubt we'll be able to measure it anywhere.
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Luis R. Rodriguez <mcgrof@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: dave.hansen@intel.com
Cc: linux-mm@kvack.org
Cc: mhocko@suse.com
Link: http://lkml.kernel.org/r/20160708001912.5216F89C@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
| -rw-r--r-- | arch/x86/include/asm/pgtable.h | 13 | ||||
| -rw-r--r-- | arch/x86/include/asm/pgtable_types.h | 6 |
2 files changed, 16 insertions, 3 deletions
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h index 1a27396b6ea0..2815d268af8b 100644 --- a/arch/x86/include/asm/pgtable.h +++ b/arch/x86/include/asm/pgtable.h @@ -480,7 +480,7 @@ pte_t *populate_extra_pte(unsigned long vaddr); static inline int pte_none(pte_t pte) { - return !pte.pte; + return !(pte.pte & ~(_PAGE_KNL_ERRATUM_MASK)); } #define __HAVE_ARCH_PTE_SAME @@ -552,7 +552,8 @@ static inline int pmd_none(pmd_t pmd) { /* Only check low word on 32-bit platforms, since it might be out of sync with upper half. */ - return (unsigned long)native_pmd_val(pmd) == 0; + unsigned long val = native_pmd_val(pmd); + return (val & ~_PAGE_KNL_ERRATUM_MASK) == 0; } static inline unsigned long pmd_page_vaddr(pmd_t pmd) @@ -616,7 +617,7 @@ static inline unsigned long pages_to_mb(unsigned long npg) #if CONFIG_PGTABLE_LEVELS > 2 static inline int pud_none(pud_t pud) { - return native_pud_val(pud) == 0; + return (native_pud_val(pud) & ~(_PAGE_KNL_ERRATUM_MASK)) == 0; } static inline int pud_present(pud_t pud) @@ -694,6 +695,12 @@ static inline int pgd_bad(pgd_t pgd) static inline int pgd_none(pgd_t pgd) { + /* + * There is no need to do a workaround for the KNL stray + * A/D bit erratum here. PGDs only point to page tables + * except on 32-bit non-PAE which is not supported on + * KNL. + */ return !native_pgd_val(pgd); } #endif /* CONFIG_PGTABLE_LEVELS > 3 */ diff --git a/arch/x86/include/asm/pgtable_types.h b/arch/x86/include/asm/pgtable_types.h index 7b5efe264eff..d14d0a55322a 100644 --- a/arch/x86/include/asm/pgtable_types.h +++ b/arch/x86/include/asm/pgtable_types.h @@ -70,6 +70,12 @@ _PAGE_PKEY_BIT2 | \ _PAGE_PKEY_BIT3) +#if defined(CONFIG_X86_64) || defined(CONFIG_X86_PAE) +#define _PAGE_KNL_ERRATUM_MASK (_PAGE_DIRTY | _PAGE_ACCESSED) +#else +#define _PAGE_KNL_ERRATUM_MASK 0 +#endif + #ifdef CONFIG_KMEMCHECK #define _PAGE_HIDDEN (_AT(pteval_t, 1) << _PAGE_BIT_HIDDEN) #else |