fix arm __a_barrier_oldkuser when built as thumb

as noted in commit 05870abeaac0588fb9115cfd11f96880a0af2108, mov lr,pc
is not a valid method for saving the return address in code that might
be built as thumb.

this one is unlikely to matter, since any ISA level that has thumb2
should also have native implementations of atomics that don't involve
kuser_helper, and the affected code is only used on very old kernels
to begin with.

diff --git a/src/thread/arm/atomics.s b/src/thread/arm/atomics.s
index 101ad391e838021bc86eddb0627e6f85bafc587f..da50508d8d45ceb659fdd2ea4883a0b60f979925 100644 (file)
--- a/src/thread/arm/atomics.s
+++ b/src/thread/arm/atomics.s
@@ -15,10 +15,10 @@ __a_barrier_oldkuser:
        mov r1,r0
        mov r2,sp
        ldr ip,=0xffff0fc0
-       mov lr,pc
-       mov pc,ip
+       bl 1f
        pop {r0,r1,r2,r3,ip,lr}
        bx lr
+1:     bx ip
 
 .global __a_barrier_v6
 .hidden __a_barrier_v6