On Fri, 2017-05-19 at 11:37 +1000, Michael Ellerman wrote:
> 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 <m...@ellerman.id.au>
Thanks.
Acked-by: Michael Neuling <mi...@neuling.org>
> ---
> tools/testing/selftests/powerpc/tm/tm-resched-dscr.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/powerpc/tm/tm-resched-dscr.c
> b/tools/testing/selftests/powerpc/tm/tm-resched-dscr.c
> index d9c49f41515e..e79ccd6aada1 100644
> --- 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;"
