From ac354e54dcab1c15addf2c8a540b33b081a0abb4 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=utf8 Content-Transfer-Encoding: 8bit commit 599c44cd21f4967774e0acf58f734009be4aea9a upstream. 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 Signed-off-by: Greg Kroah-Hartman --- 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 fc8130f995c1e..6907c456ac8c0 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(); -- 2.47.3