From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EFE2EC433DB for ; Wed, 24 Mar 2021 14:32:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BF3C6619FB for ; Wed, 24 Mar 2021 14:32:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236340AbhCXOcY (ORCPT ); Wed, 24 Mar 2021 10:32:24 -0400 Received: from smtprelay0227.hostedemail.com ([216.40.44.227]:47958 "EHLO smtprelay.hostedemail.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S236330AbhCXOcC (ORCPT ); Wed, 24 Mar 2021 10:32:02 -0400 Received: from filter.hostedemail.com (clb03-v110.bra.tucows.net [216.40.38.60]) by smtprelay06.hostedemail.com (Postfix) with ESMTP id 32F09182244EB; Wed, 24 Mar 2021 14:32:01 +0000 (UTC) X-Session-Marker: 6A6F6540706572636865732E636F6D X-HE-Tag: hill42_1e033b52777b X-Filterd-Recvd-Size: 4973 Received: from [192.168.1.159] (unknown [47.151.137.21]) (Authenticated sender: joe@perches.com) by omf11.hostedemail.com (Postfix) with ESMTPA; Wed, 24 Mar 2021 14:31:59 +0000 (UTC) Message-ID: <382fd12d804ac8e2693f92cf649c4f038f9c022e.camel@perches.com> Subject: Re: [PATCH] amdgpu: fix gcc -Wrestrict warning From: Joe Perches To: Arnd Bergmann , Alex Deucher , Christian =?ISO-8859-1?Q?K=F6nig?= , David Airlie , Daniel Vetter Cc: Arnd Bergmann , Huang Rui , Jinzhou Su , amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Date: Wed, 24 Mar 2021 07:31:58 -0700 In-Reply-To: <20210323130430.2250052-1-arnd@kernel.org> References: <20210323130430.2250052-1-arnd@kernel.org> Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.38.1-1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2021-03-23 at 14:04 +0100, Arnd Bergmann wrote: > From: Arnd Bergmann > > gcc warns about an sprintf() that uses the same buffer as source > and destination, which is undefined behavior in C99: > > drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c: In function 'amdgpu_securedisplay_debugfs_write': > drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c:141:6: error: 'sprintf' argument 3 overlaps destination object 'i2c_output' [-Werror=restrict] >   141 | sprintf(i2c_output, "%s 0x%X", i2c_output, >       | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >   142 | securedisplay_cmd->securedisplay_out_message.send_roi_crc.i2c_buf[i]); >       | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c:97:7: note: destination object referenced by 'restrict'-qualified argument 1 was declared here >    97 | char i2c_output[256]; >       | ^~~~~~~~~~ > > Rewrite it to remember the current offset into the buffer instead. > > Signed-off-by: Arnd Bergmann > --- >  drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c | 3 ++- >  1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c > index 834440ab9ff7..69d7f6bff5d4 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c > @@ -136,9 +136,10 @@ static ssize_t amdgpu_securedisplay_debugfs_write(struct file *f, const char __u >   ret = psp_securedisplay_invoke(psp, TA_SECUREDISPLAY_COMMAND__SEND_ROI_CRC); >   if (!ret) { >   if (securedisplay_cmd->status == TA_SECUREDISPLAY_STATUS__SUCCESS) { > + int pos = 0; >   memset(i2c_output, 0, sizeof(i2c_output)); >   for (i = 0; i < TA_SECUREDISPLAY_I2C_BUFFER_SIZE; i++) > - sprintf(i2c_output, "%s 0x%X", i2c_output, > + pos += sprintf(i2c_output + pos, " 0x%X", >   securedisplay_cmd->securedisplay_out_message.send_roi_crc.i2c_buf[i]); >   dev_info(adev->dev, "SECUREDISPLAY: I2C buffer out put is :%s\n", i2c_output); Perhaps use a hex output like: --- drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c | 11 ++++------- 1 file changed, 4 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c index 9cf856c94f94..25bb34c72d20 100644 --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_securedisplay.c @@ -97,13 +97,12 @@ static ssize_t amdgpu_securedisplay_debugfs_write(struct file *f, const char __u uint32_t op; int i; char str[64]; - char i2c_output[256]; int ret; if (*pos || size > sizeof(str) - 1) return -EINVAL; - memset(str, 0, sizeof(str)); + memset(str, 0, sizeof(str)); ret = copy_from_user(str, buf, size); if (ret) return -EFAULT; @@ -139,11 +138,9 @@ static ssize_t amdgpu_securedisplay_debugfs_write(struct file *f, const char __u ret = psp_securedisplay_invoke(psp, TA_SECUREDISPLAY_COMMAND__SEND_ROI_CRC); if (!ret) { if (securedisplay_cmd->status == TA_SECUREDISPLAY_STATUS__SUCCESS) { - memset(i2c_output, 0, sizeof(i2c_output)); - for (i = 0; i < TA_SECUREDISPLAY_I2C_BUFFER_SIZE; i++) - sprintf(i2c_output, "%s 0x%X", i2c_output, - securedisplay_cmd->securedisplay_out_message.send_roi_crc.i2c_buf[i]); - dev_info(adev->dev, "SECUREDISPLAY: I2C buffer out put is :%s\n", i2c_output); + dev_info(adev->dev, "SECUREDISPLAY: I2C buffer output is: %*ph\n", + (int)TA_SECUREDISPLAY_I2C_BUFFER_SIZE, + securedisplay_cmd->securedisplay_out_message.send_roi_crc.i2c_buf); } else { psp_securedisplay_parse_resp_status(psp, securedisplay_cmd->status); }