linux-kernel - Re: [PATCH] x86/tracing: introduce enter/exit tracepoint pairs for page faults

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-ID: <20250414165736.77415836@gandalf.local.home>
Date: Mon, 14 Apr 2025 16:57:36 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Dave Hansen <dave.hansen@...el.com>
Cc: Junxuan Liao <ljx@...wisc.edu>, linux-trace-kernel@...r.kernel.org,
 linux-kernel@...r.kernel.org, x86@...nel.org, Thomas Gleixner
 <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, Borislav Petkov
 <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, "H. Peter Anvin"
 <hpa@...or.com>, Masami Hiramatsu <mhiramat@...nel.org>, Mathieu Desnoyers
 <mathieu.desnoyers@...icios.com>, "Paul E. McKenney" <paulmck@...nel.org>
Subject: Re: [PATCH] x86/tracing: introduce enter/exit tracepoint pairs for
 page faults

On Mon, 14 Apr 2025 13:42:23 -0700
Dave Hansen <dave.hansen@...el.com> wrote:

> On 4/14/25 13:35, Junxuan Liao wrote:
> > Rename page_fault_{user,kernel} to page_fault_{user,kernel}_enter, and
> > add the exit counterparts. This might be useful for measuring page fault
> > handling latencies.  
> 
> Is there a reason kprobes don't work for this?

Kprobes is not always easy to add, and it does add more overhead.

I use to have measurements by using function graph tracing of all timings
into the kernel, but when the noinstr was added, that broke. I still do
timings but that's by manually adding hacks into the kernel. I haven't done
timings on a vanilla kernel for some time. It would be nice to be able to
do that again.

-- Steve