From 1fc00e145172068ddeb56275c3db1fbd6ae4dddf Mon Sep 17 00:00:00 2001 From: Sasha Levin Date: Wed, 2 Jul 2025 18:01:44 -0400 Subject: [PATCH] riscv/atomic: Do proper sign extension also for unsigned in arch_cmpxchg [ Upstream commit 1898300abf3508bca152e65b36cce5bf93d7e63e ] Sign extend also an unsigned compare value to match what lr.w is doing. Otherwise try_cmpxchg may spuriously return true when used on a u32 value that has the sign bit set, as it happens often in inode_set_ctime_current. Do this in three conversion steps. The first conversion to long is needed to avoid a -Wpointer-to-int-cast warning when arch_cmpxchg is used with a pointer type. Then convert to int and back to long to always sign extend the 32-bit value to 64-bit. Fixes: 6c58f25e6938 ("riscv/atomic: Fix sign extension for RV64I") Signed-off-by: Andreas Schwab Reviewed-by: Alexandre Ghiti Reviewed-by: Andrew Jones Tested-by: Xi Ruoyao Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/mvmed0k4prh.fsf@suse.de Signed-off-by: Palmer Dabbelt Signed-off-by: Sasha Levin --- arch/riscv/include/asm/cmpxchg.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/include/asm/cmpxchg.h b/arch/riscv/include/asm/cmpxchg.h index ebbce134917c..6efa95ad033a 100644 --- a/arch/riscv/include/asm/cmpxchg.h +++ b/arch/riscv/include/asm/cmpxchg.h @@ -169,7 +169,7 @@ break; \ case 4: \ __arch_cmpxchg(".w", ".w" sc_sfx, prepend, append, \ - __ret, __ptr, (long), __old, __new); \ + __ret, __ptr, (long)(int)(long), __old, __new); \ break; \ case 8: \ __arch_cmpxchg(".d", ".d" sc_sfx, prepend, append, \