[ARM] 3103/1: ARM EABI: stack pointer must be 64-bit aligned (part 2)

Patch from Nicolas Pitre

We must make sure that assembly code that modifies the stack pointer
before calling a C function does it so it remains 64-bit aligned.

Signed-off-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

1 files changed, 9 insertions, 8 deletions

diff --git a/arch/arm/kernel/semaphore.c b/arch/arm/kernel/semaphore.c
index 4c31f2923055..981fe5c6ccbe 100644
--- a/arch/arm/kernel/semaphore.c
+++ b/arch/arm/kernel/semaphore.c
@@ -177,41 +177,42 @@ int __down_trylock(struct semaphore * sem)
  * ip contains the semaphore pointer on entry. Save the C-clobbered
  * registers (r0 to r3 and lr), but not ip, as we use it as a return
  * value in some cases..
+ * To remain AAPCS compliant (64-bit stack align) we save r4 as well.
  */
 asm("   .section .sched.text,\"ax\",%progbits   \n\
         .align  5                               \n\
         .globl  __down_failed                   \n\
 __down_failed:                                  \n\
-        stmfd   sp!, {r0 - r3, lr}              \n\
+        stmfd   sp!, {r0 - r4, lr}              \n\
         mov     r0, ip                          \n\
         bl      __down                          \n\
-        ldmfd   sp!, {r0 - r3, pc}              \n\
+        ldmfd   sp!, {r0 - r4, pc}              \n\
                                                 \n\
         .align  5                               \n\
         .globl  __down_interruptible_failed     \n\
 __down_interruptible_failed:                    \n\
-        stmfd   sp!, {r0 - r3, lr}              \n\
+        stmfd   sp!, {r0 - r4, lr}              \n\
         mov     r0, ip                          \n\
         bl      __down_interruptible            \n\
         mov     ip, r0                          \n\
-        ldmfd   sp!, {r0 - r3, pc}              \n\
+        ldmfd   sp!, {r0 - r4, pc}              \n\
                                                 \n\
         .align  5                               \n\
         .globl  __down_trylock_failed           \n\
 __down_trylock_failed:                          \n\
-        stmfd   sp!, {r0 - r3, lr}              \n\
+        stmfd   sp!, {r0 - r4, lr}              \n\
         mov     r0, ip                          \n\
         bl      __down_trylock                  \n\
         mov     ip, r0                          \n\
-        ldmfd   sp!, {r0 - r3, pc}              \n\
+        ldmfd   sp!, {r0 - r4, pc}              \n\
                                                 \n\
         .align  5                               \n\
         .globl  __up_wakeup                     \n\
 __up_wakeup:                                    \n\
-        stmfd   sp!, {r0 - r3, lr}              \n\
+        stmfd   sp!, {r0 - r4, lr}              \n\
         mov     r0, ip                          \n\
         bl      __up                            \n\
-        ldmfd   sp!, {r0 - r3, pc}              \n\
+        ldmfd   sp!, {r0 - r4, pc}              \n\
         ");
 
 EXPORT_SYMBOL(__down_failed);