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| author | John David Anglin <dave.anglin@bell.net> | 2017-09-30 17:24:23 -0400 |
|---|---|---|
| committer | Helge Deller <deller@gmx.de> | 2017-10-19 08:48:44 +0200 |
| commit | 374b3bf8e8b519f61eb9775888074c6e46b3bf0c (patch) | |
| tree | f3bf23769e2de1a8e6c8e3b9486a7221e6fc56cf /arch/parisc/kernel/syscall.S | |
| parent | 73d3393ada4f70fa3df5639c8d438f2f034c0ecb (diff) | |
| download | linux-374b3bf8e8b519f61eb9775888074c6e46b3bf0c.tar.bz2 | |
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>
Diffstat (limited to 'arch/parisc/kernel/syscall.S')
| -rw-r--r-- | arch/parisc/kernel/syscall.S | 6 |
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 #else - /* 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 #else /* 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 */ |