From: Linus Walleij linus.walleij@linaro.org
[ Upstream commit e1de94380af588bdf6ad6f0cc1f75004c35bc096 ]
Recent work with KASan exposed the folling hard-coded bitmask in arch/arm/mm/proc-macros.S:
bic rd, sp, #8128 bic rd, rd, #63
This forms the bitmask 0x1FFF that is coinciding with (PAGE_SIZE << THREAD_SIZE_ORDER) - 1, this code was assuming that THREAD_SIZE is always 8K (8192).
As KASan was increasing THREAD_SIZE_ORDER to 2, I ran into this bug.
Fix it by this little oneline suggested by Ard:
bic rd, sp, #(THREAD_SIZE - 1) & ~63
Where THREAD_SIZE is defined using THREAD_SIZE_ORDER.
We have to also include <linux/const.h> since the THREAD_SIZE expands to use the _AC() macro.
Cc: Ard Biesheuvel ardb@kernel.org Cc: Florian Fainelli f.fainelli@gmail.com Suggested-by: Ard Biesheuvel ardb@kernel.org Signed-off-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Russell King rmk+kernel@armlinux.org.uk Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/mm/proc-macros.S | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S index e6bfdcc381f8..1da55d34f4d6 100644 --- a/arch/arm/mm/proc-macros.S +++ b/arch/arm/mm/proc-macros.S @@ -4,6 +4,7 @@ * VMA_VM_FLAGS * VM_EXEC */ +#include <linux/const.h> #include <asm/asm-offsets.h> #include <asm/thread_info.h>
@@ -30,7 +31,7 @@ * act_mm - get current->active_mm */ .macro act_mm, rd - bic \rd, sp, #8128 + bic \rd, sp, #(THREAD_SIZE - 1) & ~63 bic \rd, \rd, #63 ldr \rd, [\rd, #TI_TASK] ldr \rd, [\rd, #TSK_ACTIVE_MM]