[patch added to the 3.12 stable tree] arm64: mm: Add double logical invert to pte accessors

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



From: Steve Capper <steve.capper@xxxxxxxxxx>

This patch has been added to the 3.12 stable tree. If you have any
objections, please let us know.

===============

commit 84fe6826c28f69d8708bd575faed7f75e6b6f57f upstream.

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@xxxxxxxxxx>
[steve.capper@xxxxxxxxxx: rebased patch to leave pte_write alone to
allow for merge with 3.13 stable]
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 arch/arm64/include/asm/pgtable.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 0b27b6574296..965c28ff7b3b 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -136,10 +136,10 @@ 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_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_RDONLY))
 #define pte_exec(pte)		(!(pte_val(pte) & PTE_UXN))
 
-- 
1.9.0

--
To unsubscribe from this list: send the line "unsubscribe stable" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html




[Index of Archives]     [Linux Kernel]     [Kernel Development Newbies]     [Linux USB Devel]     [Video for Linux]     [Linux Audio Users]     [Yosemite Hiking]     [Linux Kernel]     [Linux SCSI]