[PATCH] tools/nolibc: mark arg1 operand in __nolibc_syscall0() as write-only

[Thomas Weißschuh]

__nolibc_syscall0() does not set the arg1 variable before passing it to
the asm block. This uninitialized variable read is undefined behavior.
Clang can miscompile this.

Mark the asm operand as write-only to fix this.

Fixes: 8e1930296f92 ("tools/nolibc: Add support for SPARC")
Signed-off-by: Thomas Weißschuh <linux@xxxxxxxxxxxxxx>
---
 tools/include/nolibc/arch-sparc.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/include/nolibc/arch-sparc.h b/tools/include/nolibc/arch-sparc.h
index ddae9bc10dfe..23fab40accfa 100644
--- a/tools/include/nolibc/arch-sparc.h
+++ b/tools/include/nolibc/arch-sparc.h
@@ -45,7 +45,7 @@
 									      \
 	__asm__ volatile (                                                    \
 		_NOLIBC_SYSCALL                                               \
-		: "+r"(_arg1)                                                 \
+		: "=r"(_arg1)                                                 \
 		: "r"(_num)                                                   \
 		: "memory", "cc"                                              \
 	);                                                                    \

---
base-commit: d92642aeb2b9b0c670194d5768c3a6b227002d0d
change-id: 20260703-nolibc-sparc-asm-3544ec0f1edc

Best regards,
--  
Thomas Weißschuh <linux@xxxxxxxxxxxxxx>