6.12-stable review patch. If anyone has any objections, please let me know.
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From: Thomas Weißschuh thomas.weissschuh@linutronix.de
[ Upstream commit 9f15e0f9ef514b8e1a80707931f6d07362e8ebc4 ]
The _rval register variable is meant to be an output operand of the asm statement but is instead used as input operand. clang 20.1 notices this and triggers -Wuninitialized warnings:
tools/testing/selftests/timers/auxclock.c:154:10: error: variable '_rval' is uninitialized when used here [-Werror,-Wuninitialized] 154 | return VDSO_CALL(self->vdso_clock_gettime64, 2, clockid, ts); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ tools/testing/selftests/timers/../vDSO/vdso_call.h:59:10: note: expanded from macro 'VDSO_CALL' 59 | : "r" (_rval) \ | ^~~~~ tools/testing/selftests/timers/auxclock.c:154:10: note: variable '_rval' is declared here tools/testing/selftests/timers/../vDSO/vdso_call.h:47:2: note: expanded from macro 'VDSO_CALL' 47 | register long _rval asm ("r3"); \ | ^
It seems the list of input and output operands have been switched around. However as the argument registers are not always initialized they can not be marked as pure inputs as that would trigger -Wuninitialized warnings. Adding _rval as another input and output operand does also not work as it would collide with the existing _r3 variable.
Instead reuse _r3 for both the argument and the return value.
Fixes: 6eda706a535c ("selftests: vDSO: fix the way vDSO functions are called for powerpc") Reported-by: kernel test robot lkp@intel.com Signed-off-by: Thomas Weißschuh thomas.weissschuh@linutronix.de Signed-off-by: Thomas Gleixner tglx@linutronix.de Reviewed-by: Christophe Leroy christophe.leroy@csgroup.eu Link: https://lore.kernel.org/all/20250812-vdso-tests-fixes-v2-1-90f499dd35f8@linu... Closes: https://lore.kernel.org/oe-kbuild-all/202506180223.BOOk5jDK-lkp@intel.com/ Signed-off-by: Sasha Levin sashal@kernel.org --- tools/testing/selftests/vDSO/vdso_call.h | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/tools/testing/selftests/vDSO/vdso_call.h b/tools/testing/selftests/vDSO/vdso_call.h index bb237d771051b..e7205584cbdca 100644 --- a/tools/testing/selftests/vDSO/vdso_call.h +++ b/tools/testing/selftests/vDSO/vdso_call.h @@ -44,7 +44,6 @@ register long _r6 asm ("r6"); \ register long _r7 asm ("r7"); \ register long _r8 asm ("r8"); \ - register long _rval asm ("r3"); \ \ LOADARGS_##nr(fn, args); \ \ @@ -54,13 +53,13 @@ " bns+ 1f\n" \ " neg 3, 3\n" \ "1:" \ - : "+r" (_r0), "=r" (_r3), "+r" (_r4), "+r" (_r5), \ + : "+r" (_r0), "+r" (_r3), "+r" (_r4), "+r" (_r5), \ "+r" (_r6), "+r" (_r7), "+r" (_r8) \ - : "r" (_rval) \ + : \ : "r9", "r10", "r11", "r12", "cr0", "cr1", "cr5", \ "cr6", "cr7", "xer", "lr", "ctr", "memory" \ ); \ - _rval; \ + _r3; \ })
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