linux-kernel - Re: [PATCH 0/3] support '%pd' and '%pD' for print file name

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Fri, 19 Jan 2024 10:52:43 -0500
From: Steven Rostedt <rostedt@...dmis.org>
To: "Masami Hiramatsu (Google)" <mhiramat@...nel.org>
Cc: Ye Bin <yebin10@...wei.com>, <mathieu.desnoyers@...icios.com>,
 <linux-trace-kernel@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] support '%pd' and '%pD' for print file name

On Fri, 19 Jan 2024 23:43:56 +0900
Masami Hiramatsu (Google) <mhiramat@...nel.org> wrote:

> Thanks for your proposal!
> 
> Generically, I think this type of hack is not good for the tracing
> because there are already some ways to do that. e.g.
>  - Use perf probe to specify dentry->name:string or file->name:string 
>  - Use BTF to specify in the same way (but only for function entry)
> And those are more obvious what it does.
> 
> However, if this is implemented in more generic syntax, it will be
> acceptable.
> For example, type specifying with "arg1:printfmt(%pD)" will be
> more generic because it is apparently one of the printfmt and output
> string. Or, maybe we can just allow to use ":%pD" as a fetch type
> (start with '%' means the printfmt)

Yes, I like this idea a lot. Please add the '%' keyword/token to change how
to display this in the print format.

We may need to add more than one token though. Is that supported?

  $arg1:u32:%08x

or that could also be:

  $arg1:%08x:u32

That is, the order should not be important.

Thoughts?

-- Steve


> 
> Also, could you update readme_msg[] in kernel/trace/trace.c if
> you add a type, and add a testcase of selftests/ftrace, for this
> feature? Documentation should also be updated with more syntax
> information.