[PATCH] selftests/powerpc: Fix earlyclobber in tm-vmxcopy

In some cases, compiler can allocate the same register for operand 'res'
and 'vecoutptr', resulting in segfault at 'stxvd2x 40,0,%[vecoutptr]'
because base register will contain 1, yielding a false-positive.

This is because output 'res' must be marked as an earlyclobber operand so
it may not overlap an input operand ('vecoutptr').

Signed-off-by: Gustavo Romero <redacted>
---
 tools/testing/selftests/powerpc/tm/tm-vmxcopy.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/powerpc/tm/tm-vmxcopy.c b/tools/testing/selftests/powerpc/tm/tm-vmxcopy.c
index 147c6dc..c1e788a 100644
--- a/tools/testing/selftests/powerpc/tm/tm-vmxcopy.c
+++ b/tools/testing/selftests/powerpc/tm/tm-vmxcopy.c

@@ -79,7 +79,7 @@ int test_vmxcopy()
 
 		"5:;"
 		"stxvd2x 40,0,%[vecoutptr];"
-		: [res]"=r"(aborted)
+		: [res]"=&r"(aborted)
 		: [vecinptr]"r"(&vecin),
 		  [vecoutptr]"r"(&vecout),
 		  [map]"r"(a)

-- 
2.7.4

On Mon, Jun 17, 2019 at 05:24:58PM -0400, Gustavo Romero wrote:

In some cases, compiler can allocate the same register for operand 'res'
and 'vecoutptr', resulting in segfault at 'stxvd2x 40,0,%[vecoutptr]'
because base register will contain 1, yielding a false-positive.

This is because output 'res' must be marked as an earlyclobber operand so
it may not overlap an input operand ('vecoutptr').

Signed-off-by: Gustavo Romero <redacted>

Reviewed-by: Segher Boessenkool <redacted>


Segher

On Mon, 2019-06-17 at 21:24:58 UTC, Gustavo Romero wrote:

In some cases, compiler can allocate the same register for operand 'res'
and 'vecoutptr', resulting in segfault at 'stxvd2x 40,0,%[vecoutptr]'
because base register will contain 1, yielding a false-positive.

This is because output 'res' must be marked as an earlyclobber operand so
it may not overlap an input operand ('vecoutptr').

Signed-off-by: Gustavo Romero <redacted>
Reviewed-by: Segher Boessenkool <redacted>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/8d0f1e05ab16c4bd628ddaefd20b94ffb36d799c

cheers