Commit-ID: dcb32d9913b7ed527b135a7e221f8d14b67bb952
Gitweb: http://git.kernel.org/tip/dcb32d9913b7ed527b135a7e221f8d14b67bb952
Author: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
AuthorDate: Thu, 7 Jul 2016 17:19:15 -0700
Committer: Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Wed, 13 Jul 2016 09:43:25 +0200
x86/mm: Use pte_none() to test for empty PTE
The page table manipulation code seems to have grown a couple of
sites that are looking for empty PTEs. Just in case one of these
entries got a stray bit set, use pte_none() instead of checking
for a zero pte_val().
The use pte_same() makes me a bit nervous. If we were doing a
pte_same() check against two cleared entries and one of them had
a stray bit set, it might fail the pte_same() check. But, I
don't think we ever _do_ pte_same() for cleared entries. It is
almost entirely used for checking for races in fault-in paths.
Signed-off-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Brian Gerst <brgerst@xxxxxxxxx>
Cc: Dave Hansen <dave@xxxxxxxx>
Cc: Denys Vlasenko <dvlasenk@xxxxxxxxxx>
Cc: H. Peter Anvin <hpa@xxxxxxxxx>
Cc: Josh Poimboeuf <jpoimboe@xxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Luis R. Rodriguez <mcgrof@xxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxx>
Cc: dave.hansen@xxxxxxxxx
Cc: linux-mm@xxxxxxxxx
Cc: mhocko@xxxxxxxx
Link: http://lkml.kernel.org/r/20160708001915.813703D9@xxxxxxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
arch/x86/mm/init_64.c | 12 ++++++------
arch/x86/mm/pageattr.c | 2 +-
arch/x86/mm/pgtable_32.c | 2 +-
3 files changed, 8 insertions(+), 8 deletions(-)
diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c
index bce2e5d..bb88fbc 100644
--- a/arch/x86/mm/init_64.c
+++ b/arch/x86/mm/init_64.c
@@ -354,7 +354,7 @@ phys_pte_init(pte_t *pte_page, unsigned long addr, unsigned long end,
* pagetable pages as RO. So assume someone who pre-setup
* these mappings are more intelligent.
*/
- if (pte_val(*pte)) {
+ if (!pte_none(*pte)) {
if (!after_bootmem)
pages++;
continue;
@@ -396,7 +396,7 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long address, unsigned long end,
continue;
}
- if (pmd_val(*pmd)) {
+ if (!pmd_none(*pmd)) {
if (!pmd_large(*pmd)) {
spin_lock(&init_mm.page_table_lock);
pte = (pte_t *)pmd_page_vaddr(*pmd);
@@ -470,7 +470,7 @@ phys_pud_init(pud_t *pud_page, unsigned long addr, unsigned long end,
continue;
}
- if (pud_val(*pud)) {
+ if (!pud_none(*pud)) {
if (!pud_large(*pud)) {
pmd = pmd_offset(pud, 0);
last_map_addr = phys_pmd_init(pmd, addr, end,
@@ -673,7 +673,7 @@ static void __meminit free_pte_table(pte_t *pte_start, pmd_t *pmd)
for (i = 0; i < PTRS_PER_PTE; i++) {
pte = pte_start + i;
- if (pte_val(*pte))
+ if (!pte_none(*pte))
return;
}
@@ -691,7 +691,7 @@ static void __meminit free_pmd_table(pmd_t *pmd_start, pud_t *pud)
for (i = 0; i < PTRS_PER_PMD; i++) {
pmd = pmd_start + i;
- if (pmd_val(*pmd))
+ if (!pmd_none(*pmd))
return;
}
@@ -710,7 +710,7 @@ static bool __meminit free_pud_table(pud_t *pud_start, pgd_t *pgd)
for (i = 0; i < PTRS_PER_PUD; i++) {
pud = pud_start + i;
- if (pud_val(*pud))
+ if (!pud_none(*pud))
return false;
}
diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
index 7a1f7bb..7514215 100644
--- a/arch/x86/mm/pageattr.c
+++ b/arch/x86/mm/pageattr.c
@@ -1185,7 +1185,7 @@ repeat:
return __cpa_process_fault(cpa, address, primary);
old_pte = *kpte;
- if (!pte_val(old_pte))
+ if (pte_none(old_pte))
return __cpa_process_fault(cpa, address, primary);
if (level == PG_LEVEL_4K) {
diff --git a/arch/x86/mm/pgtable_32.c b/arch/x86/mm/pgtable_32.c
index 75cc097..e67ae0e6 100644
--- a/arch/x86/mm/pgtable_32.c
+++ b/arch/x86/mm/pgtable_32.c
@@ -47,7 +47,7 @@ void set_pte_vaddr(unsigned long vaddr, pte_t pteval)
return;
}
pte = pte_offset_kernel(pmd, vaddr);
- if (pte_val(pteval))
+ if (!pte_none(pteval))
set_pte_at(&init_mm, vaddr, pte, pteval);
else
pte_clear(&init_mm, vaddr, pte);
--
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