3.18-stable review patch. If anyone has any objections, please let me know.
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From: Michael Ellerman mpe@ellerman.id.au
[ 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@ellerman.id.au Acked-by: Michael Neuling mikey@neuling.org Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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 @@ -45,12 +45,12 @@ 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;"