From patchwork Tue Feb 22 13:02:26 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 83964 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [199.232.76.165]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id E0B21B7082 for ; Wed, 23 Feb 2011 00:03:54 +1100 (EST) Received: from localhost ([127.0.0.1]:60295 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PrruC-0000Gn-2Y for incoming@patchwork.ozlabs.org; Tue, 22 Feb 2011 08:03:52 -0500 Received: from [140.186.70.92] (port=44154 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Prrsy-0008Kk-BA for qemu-devel@nongnu.org; Tue, 22 Feb 2011 08:02:37 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Prrsx-0003Sc-7r for qemu-devel@nongnu.org; Tue, 22 Feb 2011 08:02:36 -0500 Received: from mnementh.archaic.org.uk ([81.2.115.146]:48387) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Prrsx-0003Ro-0k for qemu-devel@nongnu.org; Tue, 22 Feb 2011 08:02:35 -0500 Received: from pm215 by mnementh.archaic.org.uk with local (Exim 4.72) (envelope-from ) id 1Prrso-0004oZ-7X; Tue, 22 Feb 2011 13:02:26 +0000 From: Peter Maydell To: qemu-devel@nongnu.org Date: Tue, 22 Feb 2011 13:02:26 +0000 Message-Id: <1298379746-18484-1-git-send-email-peter.maydell@linaro.org> X-Mailer: git-send-email 1.7.2.3 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 2) X-Received-From: 81.2.115.146 Cc: Eoghan Sherry , patches@linaro.org Subject: [Qemu-devel] [PATCH] linux-user: Fix large seeks by 32 bit guest on 64 bit host X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org When emulating a 32 bit Linux user-mode program on a 64 bit target we implement the llseek syscall in terms of lseek. Correct a bug which meant we were silently casting the result of host lseek() to a 32 bit integer as it passed through get_errno() and thus throwing away the top half. We also don't try to store the result back to userspace unless the seek succeeded; this matches the kernel behaviour. Thanks to Eoghan Sherry for identifying the problem and suggesting a solution. Signed-off-by: Peter Maydell --- linux-user/syscall.c | 16 ++++++++++------ 1 files changed, 10 insertions(+), 6 deletions(-) diff --git a/linux-user/syscall.c b/linux-user/syscall.c index cf8a4c3..23d7a63 100644 --- a/linux-user/syscall.c +++ b/linux-user/syscall.c @@ -6127,16 +6127,20 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1, #ifdef TARGET_NR__llseek /* Not on alpha */ case TARGET_NR__llseek: { + int64_t res; #if !defined(__NR_llseek) - ret = get_errno(lseek(arg1, ((uint64_t )arg2 << 32) | arg3, arg5)); - if (put_user_s64(ret, arg4)) - goto efault; + res = lseek(arg1, ((uint64_t)arg2 << 32) | arg3, arg5); + if (res == -1) { + ret = get_errno(res); + } else { + ret = 0; + } #else - int64_t res; ret = get_errno(_llseek(arg1, arg2, arg3, &res, arg5)); - if (put_user_s64(res, arg4)) - goto efault; #endif + if ((ret == 0) && put_user_s64(res, arg4)) { + goto efault; + } } break; #endif