linux/tools
Thomas Weißschuh 9f15e0f9ef selftests: vDSO: Fix -Wunitialized in powerpc VDSO_CALL() wrapper
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: 6eda706a53 ("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@linutronix.de
Closes: https://lore.kernel.org/oe-kbuild-all/202506180223.BOOk5jDK-lkp@intel.com/
2025-09-09 10:57:38 +02:00
..
accounting tools/getdelays: add backward compatibility for taskstats version 2025-08-02 12:01:41 -07:00
arch ARM: 2025-08-29 13:54:26 -07:00
bootconfig bootconfig: Fix negative seeks on 32-bit with LFS enabled 2025-08-21 08:16:31 +09:00
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include perf-tools fixes for v6.17-rc4 2025-08-27 19:18:51 -07:00
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lib libbpf: Add the ability to suppress perf event enablement 2025-08-07 09:01:41 -07:00
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objtool objtool/LoongArch: Get table size correctly if LTO is enabled 2025-08-20 22:23:15 +08:00
pcmcia
perf perf symbol: Add blocking argument to filename__read_build_id 2025-08-25 15:07:18 -07:00
power cpupower: Allow control of boost feature on non-x86 based systems with boost support. 2025-08-15 10:49:14 -06:00
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scripts tools headers: Sync syscall tables with the kernel source 2025-08-18 13:49:25 -07:00
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testing selftests: vDSO: Fix -Wunitialized in powerpc VDSO_CALL() wrapper 2025-09-09 10:57:38 +02:00
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