| Message ID | 1393328334-27285-3-git-send-email-steve.capper@linaro.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Feb 25, 2014 at 11:38:53AM +0000, Steve Capper wrote: > Page table entries on ARM64 are 64 bits, and some pte functions such as > pte_dirty return a bitwise-and of a flag with the pte value. If the > flag to be tested resides in the upper 32 bits of the pte, then we run > into the danger of the result being dropped if downcast. > > For example: > gather_stats(page, md, pte_dirty(*pte), 1); > where pte_dirty(*pte) is downcast to an int. > > This patch adds a double logical invert to all the pte_ accessors to > ensure predictable downcasting. > > Signed-off-by: Steve Capper <steve.capper@linaro.org> Applied and added cc stable as well. Thanks.
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index b524dcd..aa3917c 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -136,11 +136,11 @@ extern struct page *empty_zero_page; /* * The following only work if pte_present(). Undefined behaviour otherwise. */ -#define pte_present(pte) (pte_val(pte) & (PTE_VALID | PTE_PROT_NONE)) -#define pte_dirty(pte) (pte_val(pte) & PTE_DIRTY) -#define pte_young(pte) (pte_val(pte) & PTE_AF) -#define pte_special(pte) (pte_val(pte) & PTE_SPECIAL) -#define pte_write(pte) (pte_val(pte) & PTE_WRITE) +#define pte_present(pte) (!!(pte_val(pte) & (PTE_VALID | PTE_PROT_NONE))) +#define pte_dirty(pte) (!!(pte_val(pte) & PTE_DIRTY)) +#define pte_young(pte) (!!(pte_val(pte) & PTE_AF)) +#define pte_special(pte) (!!(pte_val(pte) & PTE_SPECIAL)) +#define pte_write(pte) (!!(pte_val(pte) & PTE_WRITE)) #define pte_exec(pte) (!(pte_val(pte) & PTE_UXN)) #define pte_valid_user(pte) \
Page table entries on ARM64 are 64 bits, and some pte functions such as pte_dirty return a bitwise-and of a flag with the pte value. If the flag to be tested resides in the upper 32 bits of the pte, then we run into the danger of the result being dropped if downcast. For example: gather_stats(page, md, pte_dirty(*pte), 1); where pte_dirty(*pte) is downcast to an int. This patch adds a double logical invert to all the pte_ accessors to ensure predictable downcasting. Signed-off-by: Steve Capper <steve.capper@linaro.org> --- Changes in V2: drop the pte_isset macro, just add the !! --- arch/arm64/include/asm/pgtable.h | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-)