diff options
authorJohn David Anglin <dave.anglin@bell.net>2017-09-30 17:24:23 -0400
committerHelge Deller <deller@gmx.de>2017-10-19 08:48:44 +0200
commit374b3bf8e8b519f61eb9775888074c6e46b3bf0c (patch)
parent73d3393ada4f70fa3df5639c8d438f2f034c0ecb (diff)
parisc: Fix double-word compare and exchange in LWS code on 32-bit kernels
As discussed on the debian-hppa list, double-wordcompare and exchange operations fail on 32-bit kernels. Looking at the code, I realized that the ",ma" completer does the wrong thing in the "ldw,ma 4(%r26), %r29" instruction. This increments %r26 and causes the following store to write to the wrong location. Note by Helge Deller: The patch applies cleanly to stable kernel series if this upstream commit is merged in advance: f4125cfdb300 ("parisc: Avoid trashing sr2 and sr3 in LWS code"). Signed-off-by: John David Anglin <dave.anglin@bell.net> Tested-by: Christoph Biedl <debian.axhn@manchmal.in-ulm.de> Fixes: 89206491201c ("parisc: Implement new LWS CAS supporting 64 bit operations.") Cc: stable@vger.kernel.org # 3.13+ Signed-off-by: Helge Deller <deller@gmx.de>
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S
index 23de307c3052..41e60a9c7db2 100644
--- a/arch/parisc/kernel/syscall.S
+++ b/arch/parisc/kernel/syscall.S
@@ -742,7 +742,7 @@ lws_compare_and_swap_2:
10: ldd 0(%r25), %r25
11: ldd 0(%r24), %r24
- /* Load new value into r22/r23 - high/low */
+ /* Load old value into r22/r23 - high/low */
10: ldw 0(%r25), %r22
11: ldw 4(%r25), %r23
/* Load new value into fr4 for atomic store later */
@@ -834,11 +834,11 @@ cas2_action:
copy %r0, %r28
/* Compare first word */
-19: ldw,ma 0(%r26), %r29
+19: ldw 0(%r26), %r29
sub,= %r29, %r22, %r0
b,n cas2_end
/* Compare second word */
-20: ldw,ma 4(%r26), %r29
+20: ldw 4(%r26), %r29
sub,= %r29, %r23, %r0
b,n cas2_end
/* Perform the store */