linux-kernel - Re: [PATCH v2 3/9] rcu,tracing: Create trace_rcu

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: <20200218113503.1170c188@gandalf.local.home>
Date:   Tue, 18 Feb 2020 11:35:03 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Joel Fernandes <joel@...lfernandes.org>,
        Peter Zijlstra <peterz@...radead.org>,
        linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        mingo@...nel.org, gregkh@...uxfoundation.org,
        gustavo@...eddedor.com, tglx@...utronix.de, josh@...htriplett.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com
Subject: Re: [PATCH v2 3/9] rcu,tracing: Create trace_rcu_{enter,exit}()

On Tue, 18 Feb 2020 08:12:31 -0800
"Paul E. McKenney" <paulmck@...nel.org> wrote:

> Would it work to describe the general problem, then give x86 details
> as a specific example, as follows?
> 
> /*
>  * On some architectures, certain exceptions prohibit use of kprobes until
>  * the exception code path reaches a certain point.  For example, on x86 all
>  * functions called by do_int3() must be marked NOKPROBE.  However, once
>  * kprobe_int3_handler() is called, kprobing is permitted.  Specifically,
>  * ist_enter() is called in do_int3() before kprobe_int3_handle().
>  * Furthermore, ist_enter() calls rcu_nmi_enter(), which means that
>  * rcu_nmi_enter() must be marked NOKRPOBE.
>  */
> 
> That way, I don't feel like I need to update the commment each time
> a new architecture adds this capability.  ;-)

I don't think this is going to be an issue for other archs, as they
don't have an IST.

-- Steve