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authorLinus Walleij <linus.walleij@linaro.org>2020-05-19 14:59:12 +0300
committerRussell King <rmk+kernel@armlinux.org.uk>2020-05-26 14:02:39 +0300
commite1de94380af588bdf6ad6f0cc1f75004c35bc096 (patch)
treecfee95f272b0fa026757140f1f9078b88c4564e8
parentfce2bc254adbfe0449ab6bfb51bffba9d3c42689 (diff)
downloadlinux-e1de94380af588bdf6ad6f0cc1f75004c35bc096.tar.xz
ARM: 8978/1: mm: make act_mm() respect THREAD_SIZE
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>
-rw-r--r--arch/arm/mm/proc-macros.S3
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/arm/mm/proc-macros.S b/arch/arm/mm/proc-macros.S
index 5461d589a1e2..60ac7c5999a9 100644
--- a/arch/arm/mm/proc-macros.S
+++ b/arch/arm/mm/proc-macros.S
@@ -5,6 +5,7 @@
* 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]
.if (TSK_ACTIVE_MM > IMM12_MASK)