1 files changed, 16 insertions, 1 deletions

diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index d401d908c463..964cd717506b 100644
--- a/arch/arm/kernel/entry-armv.S
+++ b/arch/arm/kernel/entry-armv.S
@@ -333,10 +333,14 @@ __pabt_svc:
                                         @ from the exception stack
 
 #if __LINUX_ARM_ARCH__ < 6 && !defined(CONFIG_NEEDS_SYSCALL_FOR_CMPXCHG)
+#ifndef CONFIG_MMU
+#warning "NPTL on non MMU needs fixing"
+#else
         @ make sure our user space atomic helper is aborted
         cmp     r2, #TASK_SIZE
         bichs   r3, r3, #PSR_Z_BIT
 #endif
+#endif
 
         @
         @ We are now ready to fill in the remaining blanks on the stack:
@@ -705,7 +709,12 @@ __kuser_memory_barrier:				@ 0xffff0fa0
  * The C flag is also set if *ptr was changed to allow for assembly
  * optimization in the calling code.
  *
- * Note: this routine already includes memory barriers as needed.
+ * Notes:
+ *
+ *    - This routine already includes memory barriers as needed.
+ *
+ *    - A failure might be transient, i.e. it is possible, although unlikely,
+ *      that "failure" be returned even if *ptr == oldval.
  *
  * For example, a user space atomic_add implementation could look like this:
  *
@@ -756,12 +765,18 @@ __kuser_cmpxchg:				@ 0xffff0fc0
          * exception happening just after the str instruction which would
          * clear the Z flag although the exchange was done.
          */
+#ifdef CONFIG_MMU
         teq     ip, ip                  @ set Z flag
         ldr     ip, [r2]                @ load current val
         add     r3, r2, #1              @ prepare store ptr
         teqeq   ip, r0                  @ compare with oldval if still allowed
         streq   r1, [r3, #-1]!          @ store newval if still allowed
         subs    r0, r2, r3              @ if r2 == r3 the str occured
+#else
+#warning "NPTL on non MMU needs fixing"
+        mov     r0, #-1
+        adds    r0, r0, #0
+#endif
         mov     pc, lr
 
 #else