Hi Jan,
On 19/08/2022 08:49, Jan Beulich wrote:
While Arm64 does so uniformly, for Arm32 only strchr() currently handles
this properly. Add the necessary conversion also to strrchr(), memchr(),
and memset().
As to the placement in memset(): Putting the new insn at the beginning
of the function could perhaps be deemed more "obvious", but the code
reachable without ever making it to the "1" label only ever does byte
stores.
So the assumption here is the rest of the code will always use byte
stores. Given that this issue has been present for a long time, I think
it would be wiser to do the conversion at the start of the function.
The changes in memchr() and strrchr() looks fine to me.
Signed-off-by: Jan Beulich <jbeul...@suse.com>
--- a/xen/arch/arm/arm32/lib/memchr.S
+++ b/xen/arch/arm/arm32/lib/memchr.S
@@ -14,6 +14,7 @@
.text
.align 5
ENTRY(memchr)
+ and r1, r1, #0xff
1: subs r2, r2, #1
bmi 2f
ldrb r3, [r0], #1
--- a/xen/arch/arm/arm32/lib/memset.S
+++ b/xen/arch/arm/arm32/lib/memset.S
@@ -21,7 +21,8 @@ ENTRY(memset)
* we know that the pointer in ip is aligned to a word boundary.
*/
-1: orr r1, r1, r1, lsl #8
+1: and r1, r1, #0xff
+ orr r1, r1, r1, lsl #8
orr r1, r1, r1, lsl #16
mov r3, r1
cmp r2, #16
--- a/xen/arch/arm/arm32/lib/strrchr.S
+++ b/xen/arch/arm/arm32/lib/strrchr.S
@@ -14,6 +14,7 @@
.text
.align 5
ENTRY(strrchr)
+ and r1, r1, #0xff
mov r3, #0
1: ldrb r2, [r0], #1
teq r2, r1
Cheers,
--
Julien Grall
