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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 49349C433F5 for ; Tue, 11 Oct 2022 02:35:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229791AbiJKCfr convert rfc822-to-8bit (ORCPT ); Mon, 10 Oct 2022 22:35:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47510 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229461AbiJKCfo (ORCPT ); Mon, 10 Oct 2022 22:35:44 -0400 Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DA47D83F1A for ; Mon, 10 Oct 2022 19:35:41 -0700 (PDT) Received: from omf09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id DD855AB72D; Tue, 11 Oct 2022 02:35:40 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: joe@perches.com) by omf09.hostedemail.com (Postfix) with ESMTPA id 2948720025; Tue, 11 Oct 2022 02:35:03 +0000 (UTC) Message-ID: <0a9453d94419991aa38d64b7a446eeba1f9c5a80.camel@perches.com> Subject: Re: [PATCH] ftrace: Fix char print issue in print_ip_ins() From: Joe Perches To: Zheng Yejian , rostedt@goodmis.org, mingo@redhat.com, linux-kernel@vger.kernel.org Date: Mon, 10 Oct 2022 19:35:38 -0700 In-Reply-To: <20221010191524.1626867-1-zhengyejian1@huawei.com> References: <20221010191524.1626867-1-zhengyejian1@huawei.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 8BIT User-Agent: Evolution 3.44.4 (3.44.4-2.fc36) MIME-Version: 1.0 X-Rspamd-Server: rspamout07 X-Rspamd-Queue-Id: 2948720025 X-Stat-Signature: gpg9p3o1nsk1c5qs4gcrtj9fydhrnitm X-Session-Marker: 6A6F6540706572636865732E636F6D X-Session-ID: U2FsdGVkX18CSZ+g118vqqIdgHlGRsJ9urPIdQuasbg= X-HE-Tag: 1665455703-670618 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2022-10-10 at 19:15 +0000, Zheng Yejian wrote: > When ftrace bug happened, following log shows every byte data in > problem ip address: > actual: ffffffe8:6b:ffffffd9:01:21 > > However that seems a little confusing, and it is because format > '%x' being used to print signed chars in print_ip_ins(). > > After this patch, the log is like: > actual: e8:6b:d9:01:21 > > Fixes: 6c14133d2d3f ("ftrace: Do not blindly read the ip address in ftrace_bug()") > Signed-off-by: Zheng Yejian > --- > kernel/trace/ftrace.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c [] > @@ -2015,7 +2015,7 @@ static int ftrace_hash_ipmodify_update(struct ftrace_ops *ops, > > static void print_ip_ins(const char *fmt, const unsigned char *p) > { > - char ins[MCOUNT_INSN_SIZE]; > + unsigned char ins[MCOUNT_INSN_SIZE]; > int i; > > if (copy_from_kernel_nofault(ins, p, MCOUNT_INSN_SIZE)) { Perhaps nicer would be to change the for loop below this from for (i = 0; i < MCOUNT_INSN_SIZE; i++) printk(KERN_CONT "%s%02x", i ? ":" : "", ins[i]); to pr_cont("%*phC", MCOUNT_INSN_SIZE, ins);