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-rw-r--r--arch/arm/kernel/entry-armv.S17
1 files changed, 16 insertions, 1 deletions
diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S
index d401d908c46..964cd717506 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