[PATCH] powerpc: Fix check for copy/paste instructions in alignment handler

Commit 07d2a628bc00 ("powerpc/64s: Avoid cpabort in context switch
when possible", 2017-06-09) changed the definition of PPC_INST_COPY
and in so doing inadvertently broke the check for copy/paste
instructions in the alignment fault handler.  The check currently
matches no instructions.

This fixes it by ANDing both sides of the comparison with the mask.

Fixes: 07d2a628bc00 ("powerpc/64s: Avoid cpabort in context switch
when possible")
Reported-by: Markus Trippelsdorf <redacted>
Signed-off-by: Paul Mackerras <redacted>
---
Should go to 4.13 stable as well, and will probably apply there
with fuzz.

 arch/powerpc/kernel/align.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/powerpc/kernel/align.c b/arch/powerpc/kernel/align.c
index 43ef251..3e6c074 100644
--- a/arch/powerpc/kernel/align.c
+++ b/arch/powerpc/kernel/align.c

@@ -332,7 +332,7 @@ int fix_alignment(struct pt_regs *regs)
 	 * when pasting to a co-processor. Furthermore, paste_last is the
 	 * synchronisation point for preceding copy/paste sequences.
 	 */
-	if ((instr & 0xfc0006fe) == PPC_INST_COPY)
+	if ((instr & 0xfc0006fe) == (PPC_INST_COPY & 0xfc0006fe))
 		return -EIO;
 
 	r = analyse_instr(&op, regs, instr);

-- 
2.7.4

On Wed, 2017-10-25 at 07:16:53 UTC, Paul Mackerras wrote:

Commit 07d2a628bc00 ("powerpc/64s: Avoid cpabort in context switch
when possible", 2017-06-09) changed the definition of PPC_INST_COPY
and in so doing inadvertently broke the check for copy/paste
instructions in the alignment fault handler.  The check currently
matches no instructions.

This fixes it by ANDing both sides of the comparison with the mask.

Fixes: 07d2a628bc00 ("powerpc/64s: Avoid cpabort in context switch
when possible")
Reported-by: Markus Trippelsdorf <redacted>
Signed-off-by: Paul Mackerras <redacted>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/158f19698b594eb8a1bdf7d7937617

cheers