All of lore.kernel.org
 help / color / mirror / Atom feed
From: Ingo Molnar <mingo@kernel.org>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Marco Elver <elver@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Ingo Molnar <mingo@redhat.com>, Jiri Olsa <jolsa@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Alexander Potapenko <glider@google.com>,
	Al Viro <viro@zeniv.linux.org.uk>, Arnd Bergmann <arnd@arndb.de>,
	Christian Brauner <christian@brauner.io>,
	Jann Horn <jannh@google.com>, Jens Axboe <axboe@kernel.dk>,
	Matt Morehouse <mascasa@google.com>,
	Peter Collingbourne <pcc@google.com>,
	Ian Rogers <irogers@google.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	linux-arch <linux-arch@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	"open list:KERNEL SELFTEST FRAMEWORK" 
	<linux-kselftest@vger.kernel.org>
Subject: Re: [PATCH v3 07/11] perf: Add breakpoint information to siginfo on SIGTRAP
Date: Thu, 25 Mar 2021 15:18:20 +0100	[thread overview]
Message-ID: <20210325141820.GA1456211@gmail.com> (raw)
In-Reply-To: <CACT4Y+aKmdsXhRZi2f3LsX3m=krdY4kPsEUcieSugO2wY=xA-Q@mail.gmail.com>


* Dmitry Vyukov <dvyukov@google.com> wrote:

> On Wed, Mar 24, 2021 at 3:05 PM Marco Elver <elver@google.com> wrote:
> >
> > On Wed, 24 Mar 2021 at 15:01, Peter Zijlstra <peterz@infradead.org> wrote:
> > >
> > > One last try, I'll leave it alone now, I promise :-)
> >
> > This looks like it does what you suggested, thanks! :-)
> >
> > I'll still need to think about it, because of the potential problem
> > with modify-signal-races and what the user's synchronization story
> > would look like then.
> 
> I agree that this looks inherently racy. The attr can't be allocated
> on stack, user synchronization may be tricky and expensive. The API
> may provoke bugs and some users may not even realize the race problem.

Yeah, so why cannot we allocate enough space from the signal handler 
user-space stack and put the attr there, and point to it from 
sig_info?

The idea would be to create a stable, per-signal snapshot of whatever 
the perf_attr state is at the moment the event happens and the signal 
is generated - which is roughly what user-space wants, right?

Thanks,

	Ingo

  parent reply	other threads:[~2021-03-25 14:19 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-24 11:24 [PATCH v3 00/11] Add support for synchronous signals on perf events Marco Elver
2021-03-24 11:24 ` [PATCH v3 01/11] perf: Rework perf_event_exit_event() Marco Elver
2021-03-25 10:17   ` Marco Elver
2021-03-25 16:17     ` Marco Elver
2021-03-25 19:10       ` Marco Elver
2021-03-29 11:50         ` Peter Zijlstra
2021-03-24 11:24 ` [PATCH v3 02/11] perf: Apply PERF_EVENT_IOC_MODIFY_ATTRIBUTES to children Marco Elver
2021-03-24 11:24 ` [PATCH v3 03/11] perf: Support only inheriting events if cloned with CLONE_THREAD Marco Elver
2021-03-24 11:24 ` [PATCH v3 04/11] perf: Add support for event removal on exec Marco Elver
2021-03-24 11:24 ` [PATCH v3 05/11] signal: Introduce TRAP_PERF si_code and si_perf to siginfo Marco Elver
2021-03-24 11:24 ` [PATCH v3 06/11] perf: Add support for SIGTRAP on perf events Marco Elver
2021-03-25  8:14   ` Marco Elver
2021-03-29 12:07     ` Peter Zijlstra
2021-03-29 14:27       ` Oleg Nesterov
2021-03-29 14:32         ` Marco Elver
2021-03-30  7:04           ` Peter Zijlstra
2021-03-29 18:22         ` Marco Elver
2021-03-29 18:33           ` Oleg Nesterov
2021-03-31 12:32       ` Marco Elver
2021-03-31 14:51         ` Peter Zijlstra
2021-03-31 16:50           ` Marco Elver
2021-03-24 11:24 ` [PATCH v3 07/11] perf: Add breakpoint information to siginfo on SIGTRAP Marco Elver
2021-03-24 12:53   ` Peter Zijlstra
2021-03-24 13:01     ` Peter Zijlstra
2021-03-24 13:21       ` Peter Zijlstra
2021-03-24 13:43         ` Peter Zijlstra
2021-03-24 14:00           ` Peter Zijlstra
2021-03-24 14:05             ` Marco Elver
2021-03-24 14:12               ` Dmitry Vyukov
2021-03-24 14:15                 ` Dmitry Vyukov
2021-03-25  7:00                   ` Marco Elver
2021-03-25 14:18                 ` Ingo Molnar [this message]
2021-03-25 15:17                   ` Marco Elver
2021-03-25 15:35                     ` Ingo Molnar
2021-03-24 13:47         ` Marco Elver
2021-03-24 11:25 ` [PATCH v3 08/11] selftests/perf_events: Add kselftest for process-wide sigtrap handling Marco Elver
2021-03-24 11:25 ` [PATCH v3 09/11] selftests/perf_events: Add kselftest for remove_on_exec Marco Elver
2021-03-24 11:25 ` [PATCH v3 10/11] tools headers uapi: Sync tools/include/uapi/linux/perf_event.h Marco Elver
2021-03-24 11:25 ` [PATCH v3 11/11] perf test: Add basic stress test for sigtrap handling Marco Elver

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=20210325141820.GA1456211@gmail.com \
    --to=mingo@kernel.org \
    --cc=acme@kernel.org \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=arnd@arndb.de \
    --cc=axboe@kernel.dk \
    --cc=christian@brauner.io \
    --cc=dvyukov@google.com \
    --cc=elver@google.com \
    --cc=glider@google.com \
    --cc=irogers@google.com \
    --cc=jannh@google.com \
    --cc=jolsa@redhat.com \
    --cc=kasan-dev@googlegroups.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=mark.rutland@arm.com \
    --cc=mascasa@google.com \
    --cc=mingo@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=pcc@google.com \
    --cc=peterz@infradead.org \
    --cc=tglx@linutronix.de \
    --cc=viro@zeniv.linux.org.uk \
    --cc=x86@kernel.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.