| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 080/310] selftests/powerpc: Fix TM resched DSCR test with some compilers | Date | Wed, 11 Apr 2018 20:33:39 +0200 |
| |
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
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 @@ -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;"
|