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From: Ingo Molnar <mingo@kernel.org>
To: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, linux-kernel@vger.kernel.org,
	live-patching@vger.kernel.org, Michal Marek <mmarek@suse.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Andi Kleen <andi@firstfloor.org>, Pedro Alves <palves@redhat.com>,
	Namhyung Kim <namhyung@gmail.com>,
	Bernd Petrovitsch <bernd@petrovitsch.priv.at>,
	Chris J Arges <chris.j.arges@canonical.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Jiri Slaby <jslaby@suse.cz>,
	Arnaldo Carvalho de Melo <acme@kernel.org>,
	Alexei Starovoitov <ast@kernel.org>,
	netdev@vger.kernel.org, daniel@iogearbox.net
Subject: Re: [PATCH 23/33] x86/asm/bpf: Create stack frames in bpf_jit.S
Date: Fri, 22 Jan 2016 08:36:38 +0100	[thread overview]
Message-ID: <20160122073638.GA28042@gmail.com> (raw)
In-Reply-To: <20160122041845.GA7175@ast-mbp.thefacebook.com>


* Alexei Starovoitov <alexei.starovoitov@gmail.com> wrote:

> > > I could be missing something. I think either this patch is not need or you 
> > > need to teach the tool to ignore all JITed stuff. I don't think it's 
> > > practical to annotate everything. Different JITs do their own magic. s390 
> > > JIT is even more fancy.
> > 
> > Well, but the point of these patches isn't to make the tool happy.  It's 
> > really to make sure that runtime stack traces can be made reliable. Maybe I'm 
> > missing something but I don't see why JIT code can't honor 
> > CONFIG_FRAME_POINTER just like any other code.
> 
> It can if there is no performance cost added. I can speak for x64 JIT, but the 
> rest needs to be analyzed as well. My point was that may be it's easier to 
> ignore all JITed code and just say that such call stacks may be unreliable? 
> live-patching is not applicable to JITed code anyway or you want to livepatch 
> the callees of it?

So the rule is that if frame pointers are enabled all kernel code should have 
correct stack frames - in case an IRQ (or NMI) hits it or it crashes.

Thanks,

	Ingo

  reply	other threads:[~2016-01-22  7:36 UTC|newest]

Thread overview: 38+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-21 22:49 [PATCH 00/33] Compile-time stack metadata validation Josh Poimboeuf
2016-01-21 22:49 ` [PATCH 22/33] x86/asm/bpf: Annotate callable functions Josh Poimboeuf
2016-01-21 22:49 ` [PATCH 23/33] x86/asm/bpf: Create stack frames in bpf_jit.S Josh Poimboeuf
2016-01-22  2:44   ` Alexei Starovoitov
2016-01-22  3:55     ` Josh Poimboeuf
2016-01-22  4:18       ` Alexei Starovoitov
2016-01-22  7:36         ` Ingo Molnar [this message]
2016-01-22 15:58         ` Josh Poimboeuf
2016-01-22 17:18           ` Alexei Starovoitov
2016-01-22 17:36             ` Josh Poimboeuf
2016-01-22 17:40               ` Alexei Starovoitov
2016-01-21 22:49 ` [PATCH 31/33] bpf: Add __bpf_prog_run() to stacktool whitelist Josh Poimboeuf
2016-01-21 22:57   ` Daniel Borkmann
2016-01-22  2:55   ` Alexei Starovoitov
2016-01-22  4:13     ` Josh Poimboeuf
2016-01-22 17:19       ` Alexei Starovoitov
2016-01-22 17:43 ` [PATCH 00/33] Compile-time stack metadata validation Chris J Arges
     [not found]   ` <20160122174348.GB29221-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>
2016-01-22 19:14     ` Josh Poimboeuf
     [not found]       ` <20160122191447.GH20502-8wJ5/zUtDR0XGNroddHbYwC/G2K4zDHf@public.gmane.org>
2016-01-22 20:40         ` Chris J Arges
     [not found]           ` <20160122204034.GA5826-Z7WLFzj8eWMS+FvcfC7Uqw@public.gmane.org>
2016-01-22 20:47             ` Josh Poimboeuf
2016-02-12 10:36 ` Jiri Slaby
2016-02-12 10:41   ` Jiri Slaby
2016-02-12 14:45   ` Josh Poimboeuf
2016-02-12 17:10     ` Peter Zijlstra
2016-02-12 18:32       ` Josh Poimboeuf
     [not found]         ` <20160212183206.GB29004-8wJ5/zUtDR0XGNroddHbYwC/G2K4zDHf@public.gmane.org>
2016-02-12 18:34           ` Josh Poimboeuf
2016-02-12 20:10           ` Peter Zijlstra
2016-02-15 16:31             ` Josh Poimboeuf
     [not found]               ` <20160215163134.GA20585-8wJ5/zUtDR0XGNroddHbYwC/G2K4zDHf@public.gmane.org>
2016-02-15 16:49                 ` Peter Zijlstra
     [not found]               ` <CA+55aFzoPCd_LcSx1FUuEhSBYk2KrfzXGj-Vcn39W5bz=KuZhA@mail.gmail.com>
2016-02-15 20:01                 ` Josh Poimboeuf
     [not found]                 ` <CA+55aFzoPCd_LcSx1FUuEhSBYk2KrfzXGj-Vcn39W5bz=KuZhA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-02-15 20:02                   ` Andi Kleen
2016-02-23  8:14 ` Ingo Molnar
     [not found]   ` <20160223081406.GA606-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-02-23 14:27     ` Arnaldo Carvalho de Melo
2016-02-23 15:07       ` Josh Poimboeuf
2016-02-23 15:28         ` Arnaldo Carvalho de Melo
2016-02-23 15:01   ` Josh Poimboeuf
2016-02-24  7:40     ` Ingo Molnar
     [not found]       ` <20160224074054.GA13199-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
2016-02-24 16:32         ` Josh Poimboeuf

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