From: Zheng Yejian <zhengyejian1@huawei.com>
To: <joe@perches.com>
Cc: <linux-kernel@vger.kernel.org>, <mingo@redhat.com>,
<rostedt@goodmis.org>, <zhengyejian1@huawei.com>
Subject: Re: [PATCH] ftrace: Fix char print issue in print_ip_ins()
Date: Tue, 11 Oct 2022 11:22:32 +0000 [thread overview]
Message-ID: <20221011112232.1859993-1-zhengyejian1@huawei.com> (raw)
In-Reply-To: <0a9453d94419991aa38d64b7a446eeba1f9c5a80.camel@perches.com>
On Mon, 10 Oct 2022 19:35:38 -0700, Joe Perches <joe@perches.com> wrote:
> 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 <zhengyejian1@huawei.com>
> > ---
> > 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);
It works, thanks for your suggestion. I'll send a new version patch.
-- Zheng Yejian
prev parent reply other threads:[~2022-10-11 3:23 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-10 19:15 [PATCH] ftrace: Fix char print issue in print_ip_ins() Zheng Yejian
2022-10-11 2:35 ` Joe Perches
2022-10-11 11:22 ` Zheng Yejian [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20221011112232.1859993-1-zhengyejian1@huawei.com \
--to=zhengyejian1@huawei.com \
--cc=joe@perches.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=rostedt@goodmis.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).