From patchwork Fri Jun 15 14:24:55 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peter Maydell X-Patchwork-Id: 930006 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=nongnu.org (client-ip=2001:4830:134:3::11; helo=lists.gnu.org; envelope-from=qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=linaro.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 416k374cdLz9s19 for ; Sat, 16 Jun 2018 00:51:47 +1000 (AEST) Received: from localhost ([::1]:47307 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fTq4n-0006cd-7s for incoming@patchwork.ozlabs.org; Fri, 15 Jun 2018 10:51:45 -0400 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60787) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fTpfV-0001d2-Ny for qemu-devel@nongnu.org; Fri, 15 Jun 2018 10:25:39 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fTpfU-0006EF-Au for qemu-devel@nongnu.org; Fri, 15 Jun 2018 10:25:37 -0400 Received: from orth.archaic.org.uk ([2001:8b0:1d0::2]:42766) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fTpfU-0006Bk-1G for qemu-devel@nongnu.org; Fri, 15 Jun 2018 10:25:36 -0400 Received: from pm215 by orth.archaic.org.uk with local (Exim 4.89) (envelope-from ) id 1fTpfS-0003hA-ST for qemu-devel@nongnu.org; Fri, 15 Jun 2018 15:25:34 +0100 From: Peter Maydell To: qemu-devel@nongnu.org Date: Fri, 15 Jun 2018 15:24:55 +0100 Message-Id: <20180615142521.19143-18-peter.maydell@linaro.org> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20180615142521.19143-1-peter.maydell@linaro.org> References: <20180615142521.19143-1-peter.maydell@linaro.org> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2001:8b0:1d0::2 Subject: [Qemu-devel] [PULL 17/43] exec.c: Don't accidentally sign-extend 4-byte loads in subpage_read() X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: "Qemu-devel" In subpage_read() we perform a load of the data into a local buffer which we then access using ldub_p(), lduw_p(), ldl_p() or ldq_p() depending on its size, storing the result into the uint64_t *data. Since ldl_p() returns an 'int', this means that for the 4-byte case we will sign-extend the data, whereas for 1 and 2 byte reads we zero-extend it. This ought not to matter since the caller will likely ignore values in the high bytes of the data, but add a cast so that we're consistent. Signed-off-by: Peter Maydell Reviewed-by: Richard Henderson Message-id: 20180611171007.4165-3-peter.maydell@linaro.org --- exec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/exec.c b/exec.c index 9cbba6adcd3..90b47cde7b1 100644 --- a/exec.c +++ b/exec.c @@ -2747,7 +2747,7 @@ static MemTxResult subpage_read(void *opaque, hwaddr addr, uint64_t *data, *data = lduw_p(buf); return MEMTX_OK; case 4: - *data = ldl_p(buf); + *data = (uint32_t)ldl_p(buf); return MEMTX_OK; case 8: *data = ldq_p(buf);