From: Peter Zijlstra <peterz@infradead.org>
To: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: paulmck <paulmck@kernel.org>, x86 <x86@kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <mhiramat@kernel.org>,
bristot <bristot@redhat.com>, jbaron <jbaron@akamai.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Nadav Amit <namit@vmware.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Andy Lutomirski <luto@kernel.org>,
Ard Biesheuvel <ard.biesheuvel@linaro.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Jessica Yu <jeyu@kernel.org>,
Alexei Starovoitov <alexei.starovoitov@gmail.com>,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH -v5 12/17] x86/kprobes: Fix ordering
Date: Thu, 14 Nov 2019 16:58:26 +0100 [thread overview]
Message-ID: <20191114155826.GV5671@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20191114154255.GR4114@hirez.programming.kicks-ass.net>
On Thu, Nov 14, 2019 at 04:42:55PM +0100, Peter Zijlstra wrote:
> On Thu, Nov 14, 2019 at 10:30:01AM -0500, Mathieu Desnoyers wrote:
> > ----- On Nov 14, 2019, at 10:28 AM, Peter Zijlstra peterz@infradead.org wrote:
>
> > > I don't think that is needed. As per the patch under discussion, we
> > > unconditionally need that IPI-sync (even for !optimized) but we only
> > > need the synchonize_rcu_tasks() thing for optimized kprobes.
> > >
> > > Also, they really do two different things. Lets not tie them together.
> >
> > I'm fine with this approach, I just thought it would be good to consider
> > the alternative.
>
> Fair enough; I also just remembered we use synchronize_rcu_tasks() in
> scenarios where we don't need to IPI-sync, for instrance when freeing
> ftrace trampolines. There we just want to make sure nothing is still
> preempted inside the trampoline when we free it -- which would be BAD
> :-)
One more thing. I have a TODO item for making text_poke_sync() more
complicated.
Specifically we don't have to IPI CPUs that are in NOHZ_FULL userspace
context, provided we can make the kernel entry perform the
core-serialize thing.
It's not far up the TODO list though, but I figure I'd mention it just
in case other people fancy having a go.
next prev parent reply other threads:[~2019-11-14 15:58 UTC|newest]
Thread overview: 115+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-11 13:12 [PATCH -v5 00/17] Rewrite x86/ftrace to use text_poke (and more) Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 01/17] x86/alternatives: Teach text_poke_bp() to emulate instructions Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 02/17] x86/alternatives: Update int3_emulate_push() comment Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 03/17] x86/alternatives,jump_label: Provide better text_poke() batching interface Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] x86/alternatives, jump_label: " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 04/17] x86/alternatives: Add and use text_gen_insn() helper Peter Zijlstra
2019-11-12 17:10 ` Steven Rostedt
2019-11-12 22:25 ` Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 05/17] x86/ftrace: Use text_poke() Peter Zijlstra
2019-11-12 18:25 ` Steven Rostedt
2019-11-12 22:24 ` Peter Zijlstra
2019-11-12 22:48 ` Steven Rostedt
2019-11-13 9:01 ` Peter Zijlstra
2019-11-13 14:27 ` Steven Rostedt
2019-11-14 13:18 ` Peter Zijlstra
2019-11-14 13:56 ` Steven Rostedt
2019-11-14 14:05 ` Peter Zijlstra
2019-11-13 8:53 ` Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-11-16 20:46 ` Borislav Petkov
2019-11-18 17:35 ` [PATCH] x86/ftrace: Mark ftrace_modify_code_direct() __ref Borislav Petkov
2019-11-18 17:52 ` Steven Rostedt
2019-11-19 9:55 ` [tip: core/kprobes] " tip-bot2 for Borislav Petkov
2019-12-04 8:33 ` tip-bot2 for Borislav Petkov
2019-12-04 8:33 ` [tip: core/kprobes] x86/ftrace: Use text_poke() tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 06/17] x86/mm: Remove set_kernel_text_r[ow]() Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:12 ` [PATCH -v5 07/17] x86/alternative: Add text_opcode_size() Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 08/17] x86/ftrace: Use text_gen_insn() Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 09/17] x86/alternative: Remove text_poke_loc::len Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 10/17] x86/alternative: Shrink text_poke_loc Peter Zijlstra
2019-11-15 9:43 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 11/17] x86/kprobes: Convert to text-patching.h Peter Zijlstra
2019-11-19 16:56 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 12/17] x86/kprobes: Fix ordering Peter Zijlstra
2019-11-13 14:31 ` Paul E. McKenney
2019-11-13 15:42 ` Mathieu Desnoyers
2019-11-14 13:53 ` Peter Zijlstra
2019-11-14 15:06 ` Mathieu Desnoyers
2019-11-14 15:13 ` Paul E. McKenney
2019-11-14 15:22 ` Mathieu Desnoyers
2019-11-14 15:28 ` Peter Zijlstra
2019-11-14 15:30 ` Mathieu Desnoyers
2019-11-14 15:42 ` Peter Zijlstra
2019-11-14 15:58 ` Peter Zijlstra [this message]
2019-11-19 16:56 ` [tip: core/kprobes] x86/kprobes: Fix ordering while text-patching tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 13/17] arm/ftrace: Use __patch_text_real() Peter Zijlstra
2019-11-11 16:47 ` Will Deacon
2019-11-11 17:19 ` Peter Zijlstra
2019-11-11 17:25 ` Peter Zijlstra
2019-11-12 11:29 ` Will Deacon
2019-11-13 9:26 ` [PATCH -v5mkII 13/17] arm/ftrace: Use __patch_text() Peter Zijlstra
2019-11-19 16:56 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2020-01-22 21:26 ` Dmitry Osipenko
2020-01-22 21:26 ` Dmitry Osipenko
2020-01-22 21:26 ` Dmitry Osipenko
2020-02-07 10:17 ` Peter Zijlstra
2020-02-07 10:17 ` Peter Zijlstra
2020-02-07 10:17 ` Peter Zijlstra
2020-02-07 10:26 ` Peter Zijlstra
2020-02-07 10:26 ` Peter Zijlstra
2020-02-07 10:26 ` Peter Zijlstra
2020-02-07 11:27 ` Peter Zijlstra
2020-02-07 11:27 ` Peter Zijlstra
[not found] ` <20200207112720.GF14914-Nxj+rRp3nVydTX5a5knrm8zTDFooKrT+cvkQGrU6aU0@public.gmane.org>
2020-02-07 16:47 ` Dmitry Osipenko
2020-02-07 16:47 ` Dmitry Osipenko
2020-02-07 16:47 ` Dmitry Osipenko
2020-01-08 12:22 ` [PATCH -v5mkII 13/17] " Arnd Bergmann
2020-01-08 14:16 ` Steven Rostedt
2020-01-08 14:22 ` Arnd Bergmann
2019-11-11 13:13 ` [PATCH -v5 14/17] module: Remove set_all_modules_text_*() Peter Zijlstra
2019-11-19 16:56 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 15/17] ftrace: Rework event_create_dir() Peter Zijlstra
2019-11-14 14:07 ` Steven Rostedt
2019-11-19 16:56 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 16/17] x86/kprobe: Add comments to arch_{,un}optimize_kprobes() Peter Zijlstra
2019-11-19 16:56 ` [tip: core/kprobes] " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 13:13 ` [PATCH -v5 17/17] x86/alternative: Use INT3_INSN_SIZE Peter Zijlstra
2019-11-19 16:56 ` [tip: core/kprobes] x86/alternatives: " tip-bot2 for Peter Zijlstra
2019-12-04 8:33 ` tip-bot2 for Peter Zijlstra
2019-11-11 19:47 ` [PATCH -v5 00/17] Rewrite x86/ftrace to use text_poke (and more) Alexei Starovoitov
2019-11-11 20:39 ` Peter Zijlstra
2019-11-11 20:42 ` Peter Zijlstra
2019-11-11 20:56 ` Alexei Starovoitov
2019-11-12 18:26 ` Steven Rostedt
2019-11-25 3:55 ` Masami Hiramatsu
2019-11-25 6:47 ` Masami Hiramatsu
2019-11-25 17:32 ` Steven Rostedt
2019-11-26 0:11 ` Masami Hiramatsu
2019-11-26 8:58 ` Masami Hiramatsu
2019-11-26 9:58 ` Masami Hiramatsu
2019-11-26 23:48 ` Masami Hiramatsu
[not found] ` <CAADnVQK4twuXzFhD-qLHmCVK0n1h-GDENQLu+4PVV3Hp++R6kQ@mail.gmail.com>
2019-11-27 4:32 ` Alexei Starovoitov
2019-11-27 5:01 ` Alexei Starovoitov
2019-11-27 6:41 ` Masami Hiramatsu
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