From: Ard Biesheuvel
maillist inclusion
commit a58cdcfbee11974669a651e3ce049ef729e81411
category: feature
feature: ARM kaslr support
issue: #I3ZXZF
CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/ardb/linux.git/commit/?h=arm-kaslr-latest&id=a58cdcfbee11974669a651e3ce049ef729e81411
-------------------------------------------------
When randomizing the kernel load address, there may be a large
distance in memory between the decompressor binary and its payload
and the destination area in memory. Ensure that the decompressor
itself is mapped cacheable in this case, by tweaking the existing
routine that takes care of this for XIP decompressors.
Cc: Russell King
Acked-by: Nicolas Pitre
Signed-off-by: Ard Biesheuvel
Signed-off-by: Cui GaoSheng
Reviewed-by: Xiu Jianfeng
Signed-off-by: Chen Jun
Signed-off-by: Yu Changchun
---
arch/arm/boot/compressed/head.S | 16 ++++++++++------
1 file changed, 10 insertions(+), 6 deletions(-)
diff --git a/arch/arm/boot/compressed/head.S b/arch/arm/boot/compressed/head.S
index 538c2b08b7e5..1b92d8a66036 100644
--- a/arch/arm/boot/compressed/head.S
+++ b/arch/arm/boot/compressed/head.S
@@ -790,20 +790,24 @@ __setup_mmu: sub r3, r4, #16384 @ Page directory size
teq r0, r2
bne 1b
/*
- * If ever we are running from Flash, then we surely want the cache
- * to be enabled also for our execution instance... We map 2MB of it
- * so there is no map overlap problem for up to 1 MB compressed kernel.
- * If the execution is in RAM then we would only be duplicating the above.
+ * Make sure our entire executable image (including payload) is mapped
+ * cacheable, in case it is located outside the region we covered above.
+ * (This may be the case if running from flash or with randomization enabled)
+ * If the regions happen to overlap, we just duplicate some of the above.
*/
orr r1, r6, #0x04 @ ensure B is set for this
orr r1, r1, #3 << 10
mov r2, pc
+ adr_l r9, _end
mov r2, r2, lsr #20
+ mov r9, r9, lsr #20
orr r1, r1, r2, lsl #20
add r0, r3, r2, lsl #2
- str r1, [r0], #4
+ add r9, r3, r9, lsl #2
+0: str r1, [r0], #4
add r1, r1, #1048576
- str r1, [r0]
+ cmp r0, r9
+ bls 0b
mov pc, lr
ENDPROC(__setup_mmu)
--
2.22.0
