4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
[ Upstream commit fe06fe860250a4f01d0eaf70a2563b1997174a74 ]
The tm-resched-dscr test has started failing sometimes, depending on
what compiler it's built with, eg:
test: tm_resched_dscr
Check DSCR TM context switch: tm-resched-dscr: tm-resched-dscr.c:76: test_body: Assertion `rv' failed.
!! child died by signal 6
When it fails we see that the compiler doesn't initialise rv to 1 before
entering the inline asm block. Although that's counter intuitive, it
is allowed because we tell the compiler that the inline asm will write
to rv (using "=r"), meaning the original value is irrelevant.
Marking it as a read/write parameter would presumably work, but it seems
simpler to fix it by setting the initial value of rv in the inline asm.
Fixes: 96d016108640 ("powerpc: Correct DSCR during TM context switch")
Signed-off-by: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Acked-by: Michael Neuling <mikey@xxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
tools/testing/selftests/powerpc/tm/tm-resched-dscr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/tools/testing/selftests/powerpc/tm/tm-resched-dscr.c
+++ b/tools/testing/selftests/powerpc/tm/tm-resched-dscr.c
@@ -42,12 +42,12 @@ int test_body(void)
printf("Check DSCR TM context switch: ");
fflush(stdout);
for (;;) {
- rv = 1;
asm __volatile__ (
/* set a known value into the DSCR */
"ld 3, %[dscr1];"
"mtspr %[sprn_dscr], 3;"
+ "li %[rv], 1;"
/* start and suspend a transaction */
"tbegin.;"
"beq 1f;"