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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2018-02-01 03:18:13 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2018-02-01 04:18:38 +0300
commit86fa949b050184ffc53688516a6a83ae5f98d08a (patch)
tree58d1c3e2704aa32706c528afd6030a70de60ae15 /arch/x86/include/asm/pgtable-3level.h
parenta8e654f01cb725d0bfd741ebca1bf4c9337969cc (diff)
downloadlinux-86fa949b050184ffc53688516a6a83ae5f98d08a.tar.xz
x86/mm: provide pmdp_establish() helper
We need an atomic way to setup pmd page table entry, avoiding races with CPU setting dirty/accessed bits. This is required to implement pmdp_invalidate() that doesn't lose these bits. On PAE we can avoid expensive cmpxchg8b for cases when new page table entry is not present. If it's present, fallback to cpmxchg loop. [akpm@linux-foundation.org: add missing `do' to do-while loop] Link: http://lkml.kernel.org/r/20171213105756.69879-10-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/x86/include/asm/pgtable-3level.h')
-rw-r--r--arch/x86/include/asm/pgtable-3level.h37
1 files changed, 36 insertions, 1 deletions
diff --git a/arch/x86/include/asm/pgtable-3level.h b/arch/x86/include/asm/pgtable-3level.h
index bc4af5453802..f24df59c40b2 100644
--- a/arch/x86/include/asm/pgtable-3level.h
+++ b/arch/x86/include/asm/pgtable-3level.h
@@ -158,7 +158,6 @@ static inline pte_t native_ptep_get_and_clear(pte_t *ptep)
#define native_ptep_get_and_clear(xp) native_local_ptep_get_and_clear(xp)
#endif
-#ifdef CONFIG_SMP
union split_pmd {
struct {
u32 pmd_low;
@@ -166,6 +165,8 @@ union split_pmd {
};
pmd_t pmd;
};
+
+#ifdef CONFIG_SMP
static inline pmd_t native_pmdp_get_and_clear(pmd_t *pmdp)
{
union split_pmd res, *orig = (union split_pmd *)pmdp;
@@ -181,6 +182,40 @@ static inline pmd_t native_pmdp_get_and_clear(pmd_t *pmdp)
#define native_pmdp_get_and_clear(xp) native_local_pmdp_get_and_clear(xp)
#endif
+#ifndef pmdp_establish
+#define pmdp_establish pmdp_establish
+static inline pmd_t pmdp_establish(struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmdp, pmd_t pmd)
+{
+ pmd_t old;
+
+ /*
+ * If pmd has present bit cleared we can get away without expensive
+ * cmpxchg64: we can update pmdp half-by-half without racing with
+ * anybody.
+ */
+ if (!(pmd_val(pmd) & _PAGE_PRESENT)) {
+ union split_pmd old, new, *ptr;
+
+ ptr = (union split_pmd *)pmdp;
+
+ new.pmd = pmd;
+
+ /* xchg acts as a barrier before setting of the high bits */
+ old.pmd_low = xchg(&ptr->pmd_low, new.pmd_low);
+ old.pmd_high = ptr->pmd_high;
+ ptr->pmd_high = new.pmd_high;
+ return old.pmd;
+ }
+
+ do {
+ old = *pmdp;
+ } while (cmpxchg64(&pmdp->pmd, old.pmd, pmd.pmd) != old.pmd);
+
+ return old;
+}
+#endif
+
#ifdef CONFIG_SMP
union split_pud {
struct {