From 599c44cd21f4967774e0acf58f734009be4aea9a Mon Sep 17 00:00:00 2001 From: Andreas Schwab Date: Mon, 3 Feb 2025 11:06:00 +0100 Subject: [PATCH] riscv/futex: sign extend compare value in atomic cmpxchg MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Make sure the compare value in the lr/sc loop is sign extended to match what lr.w does. Fortunately, due to the compiler keeping the register contents sign extended anyway the lack of the explicit extension didn't result in wrong code so far, but this cannot be relied upon. Fixes: b90edb33010b ("RISC-V: Add futex support.") Signed-off-by: Andreas Schwab Reviewed-by: Alexandre Ghiti Reviewed-by: Björn Töpel Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/mvmfrkv2vhz.fsf@suse.de Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/futex.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/include/asm/futex.h b/arch/riscv/include/asm/futex.h index 72be100afa23..90c86b115e00 100644 --- a/arch/riscv/include/asm/futex.h +++ b/arch/riscv/include/asm/futex.h @@ -93,7 +93,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr, _ASM_EXTABLE_UACCESS_ERR(1b, 3b, %[r]) \ _ASM_EXTABLE_UACCESS_ERR(2b, 3b, %[r]) \ : [r] "+r" (ret), [v] "=&r" (val), [u] "+m" (*uaddr), [t] "=&r" (tmp) - : [ov] "Jr" (oldval), [nv] "Jr" (newval) + : [ov] "Jr" ((long)(int)oldval), [nv] "Jr" (newval) : "memory"); __disable_user_access();