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: <20250414194346.060f96c6@gandalf.local.home>
Date: Mon, 14 Apr 2025 19:43:46 -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 16:37:19 -0700
Dave Hansen <dave.hansen@...el.com> wrote:

> On 4/14/25 16:22, Junxuan Liao wrote:
> > On 4/14/25 6:14 PM, Junxuan Liao wrote:  
> >> Do people find separate user/kernel tracepoints useful? For me, I can
> >> check regs in eBPF tracing code instead.  
> > I think it might be good to add a field to the tracepoints to indicate
> > whether it's in user space or not.  
> 
> Sounds sane to me.  Doing something like this:
> 
>         TP_STRUCT__entry(
>                 __field(                unsigned long, address  )
>                 __field(                unsigned long, ip       )
> +               __field(                bool	     , user_mode)
>                 __field(                unsigned long, error_code )
>         ),
> 
>         TP_fast_assign(
>                  __entry->address = address;
>                  __entry->ip         = regs->ip;
> +                __entry->user_mode  = user_mode(regs);
>                  __entry->error_code = error_code;
>         ),
> 
> seems highly superior to having two sets of tracepoints and static keys.

I agree.

Acked-by: Steven Rostedt (Google) <rostedt@...dmis.org>

-- Steve