[PATCH 1/2] Arm32: correct string.h functions for "int" -> "unsigned char" conversion

[Jan Beulich <jbeulich@xxxxxxxx>]

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.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

--- 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