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authorDave Hansen <dave.hansen@linux.intel.com>2016-07-07 17:19:12 -0700
committerIngo Molnar <mingo@kernel.org>2016-07-13 09:43:25 +0200
commit97e3c602ccbdd7db54e92fe05675c664c052a466 (patch)
tree545003282185d14130c86c6e8ec2dbe4516cc2db /arch/x86/include
parent00839ee3b299303c6a5e26a0a2485427a3afcbbf (diff)
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>
Diffstat (limited to 'arch/x86/include')
-rw-r--r--arch/x86/include/asm/pgtable.h13
-rw-r--r--arch/x86/include/asm/pgtable_types.h6
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