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x86/mm: Use pte_none() to test for empty PTE

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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@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/20160708001915.813703D9@viggo.jf.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Dave Hansen 2016-07-07 17:19:15 -07:00 committed by Ingo Molnar
parent e4a84be6f0
commit dcb32d9913
3 changed files with 8 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
arch/x86/mm/init_64.c
View File

@ -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;
}

2
arch/x86/mm/pageattr.c
View File

@ -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) {

2
arch/x86/mm/pgtable_32.c
View File

@ -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);