From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8EEEA8481 for ; Fri, 10 Mar 2023 14:06:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 12B22C433EF; Fri, 10 Mar 2023 14:06:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1678457183; bh=NvTI4qf5sKzalATCqRQ8nzW4CH2chdRl2A4V7MhqBQo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=McNVAsxL/Hbr2gX9ZBNHOww+M0YZg5U2V0KEcDzdispX84iGW6E1gRkdUi8Z1GCB+ Qd+l1yurZ+Qh0uxChV0HnQJZtRzBhGPStULeMywN9ZSD+G9bWezFc7Xs6GuUYSJsSd LqE6L4nPbG2vaXWN+kKHxgUDw0NWspfCYAi5YW3I= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ammar Faizi , Richard Weinberger , Sasha Levin Subject: [PATCH 6.1 048/200] x86: um: vdso: Add %rcx and %r11 to the syscall clobber list Date: Fri, 10 Mar 2023 14:37:35 +0100 Message-Id: <20230310133718.575836293@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230310133717.050159289@linuxfoundation.org> References: <20230310133717.050159289@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Ammar Faizi [ Upstream commit 5541992e512de8c9133110809f767bd1b54ee10d ] The 'syscall' instruction clobbers '%rcx' and '%r11', but they are not listed in the inline Assembly that performs the syscall instruction. No real bug is found. It wasn't buggy by luck because '%rcx' and '%r11' are caller-saved registers, and not used in the functions, and the functions are never inlined. Add them to the clobber list for code correctness. Fixes: f1c2bb8b9964ed31de988910f8b1cfb586d30091 ("um: implement a x86_64 vDSO") Signed-off-by: Ammar Faizi Signed-off-by: Richard Weinberger Signed-off-by: Sasha Levin --- arch/x86/um/vdso/um_vdso.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/arch/x86/um/vdso/um_vdso.c b/arch/x86/um/vdso/um_vdso.c index 2112b8d146688..ff0f3b4b6c45e 100644 --- a/arch/x86/um/vdso/um_vdso.c +++ b/arch/x86/um/vdso/um_vdso.c @@ -17,8 +17,10 @@ int __vdso_clock_gettime(clockid_t clock, struct __kernel_old_timespec *ts) { long ret; - asm("syscall" : "=a" (ret) : - "0" (__NR_clock_gettime), "D" (clock), "S" (ts) : "memory"); + asm("syscall" + : "=a" (ret) + : "0" (__NR_clock_gettime), "D" (clock), "S" (ts) + : "rcx", "r11", "memory"); return ret; } @@ -29,8 +31,10 @@ int __vdso_gettimeofday(struct __kernel_old_timeval *tv, struct timezone *tz) { long ret; - asm("syscall" : "=a" (ret) : - "0" (__NR_gettimeofday), "D" (tv), "S" (tz) : "memory"); + asm("syscall" + : "=a" (ret) + : "0" (__NR_gettimeofday), "D" (tv), "S" (tz) + : "rcx", "r11", "memory"); return ret; } -- 2.39.2