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| author | Hugh Dickins <hugh@veritas.com> | 2005-10-29 18:16:27 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@g5.osdl.org> | 2005-10-29 21:40:40 -0700 |
| commit | 705e87c0c3c38424f7f30556c85bc20e808d2f59 (patch) | |
| tree | 7a237e6266f4801385e1226cc497b47e3a2458bd /include/asm-um/pgtable.h | |
| parent | 8f4e2101fd7df9031a754eedb82e2060b51f8c45 (diff) | |
| download | lwn-705e87c0c3c38424f7f30556c85bc20e808d2f59.tar.gz lwn-705e87c0c3c38424f7f30556c85bc20e808d2f59.zip | |
[PATCH] mm: pte_offset_map_lock loops
Convert those common loops using page_table_lock on the outside and
pte_offset_map within to use just pte_offset_map_lock within instead.
These all hold mmap_sem (some exclusively, some not), so at no level can a
page table be whipped away from beneath them. But whereas pte_alloc loops
tested with the "atomic" pmd_present, these loops are testing with pmd_none,
which on i386 PAE tests both lower and upper halves.
That's now unsafe, so add a cast into pmd_none to test only the vital lower
half: we lose a little sensitivity to a corrupt middle directory, but not
enough to worry about. It appears that i386 and UML were the only
architectures vulnerable in this way, and pgd and pud no problem.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include/asm-um/pgtable.h')
| -rw-r--r-- | include/asm-um/pgtable.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/asm-um/pgtable.h b/include/asm-um/pgtable.h index 616d02b57ea9..ac64eb955868 100644 --- a/include/asm-um/pgtable.h +++ b/include/asm-um/pgtable.h @@ -138,7 +138,7 @@ extern unsigned long pg0[1024]; #define pte_clear(mm,addr,xp) pte_set_val(*(xp), (phys_t) 0, __pgprot(_PAGE_NEWPAGE)) -#define pmd_none(x) (!(pmd_val(x) & ~_PAGE_NEWPAGE)) +#define pmd_none(x) (!((unsigned long)pmd_val(x) & ~_PAGE_NEWPAGE)) #define pmd_bad(x) ((pmd_val(x) & (~PAGE_MASK & ~_PAGE_USER)) != _KERNPG_TABLE) #define pmd_present(x) (pmd_val(x) & _PAGE_PRESENT) #define pmd_clear(xp) do { pmd_val(*(xp)) = _PAGE_NEWPAGE; } while (0) |