From: Andy Lutomirski <luto@amacapital.net>
To: Jiri Kosina <jikos@kernel.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>,
Ingo Molnar <mingo@redhat.com>, X86 ML <x86@kernel.org>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
"linux-s390@vger.kernel.org" <linux-s390@vger.kernel.org>,
live-patching@vger.kernel.org,
Michael Ellerman <mpe@ellerman.id.au>,
Chris J Arges <chris.j.arges@canonical.com>,
linuxppc-dev@lists.ozlabs.org, Jessica Yu <jeyu@redhat.com>,
Petr Mladek <pmladek@suse.com>, Jiri Slaby <jslaby@suse.cz>,
Vojtech Pavlik <vojtech@suse.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Miroslav Benes <mbenes@suse.cz>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [RFC PATCH v2 05/18] sched: add task flag for preempt IRQ tracking
Date: Mon, 2 May 2016 17:39:52 -0700 [thread overview]
Message-ID: <CALCETrUV0sbmjHAFwFwJQuOUhrsXPW_egOaQ2k38tSm6ni=3qg@mail.gmail.com> (raw)
In-Reply-To: <alpine.LNX.2.00.1605022159230.27942@cbobk.fhfr.pm>
On Mon, May 2, 2016 at 1:00 PM, Jiri Kosina <jikos@kernel.org> wrote:
> On Mon, 2 May 2016, Jiri Kosina wrote:
>
>> > FWIW, I just tried this:
>> >
>> > static bool is_entry_text(unsigned long addr)
>> > {
>> > return addr >= (unsigned long)__entry_text_start &&
>> > addr < (unsigned long)__entry_text_end;
>> > }
>> >
>> > it works. So the entry code is already annotated reasonably well :)
>> >
>> > I just hacked it up here:
>> >
>> > https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/commit/?h=stack&id=085eacfe0edfc18768e48340084415dba9a6bd21
>> >
>> > and it seems to work, at least for page faults. A better
>> > implementation would print out the entire contents of pt_regs so that
>> > people reading the stack trace will know the registers at the time of
>> > the exception, which might be helpful.
>>
>> Sorry for being dense, but how do you distinguish here between a "real"
>> kernel entry, that pushes pt_regs, and any "non-entry" function call that
>> passes pt_regs around?
>
> Umm, actually, the more tricky part is the other way around -- how do you
> make sure that whenever you are calling out from a code between
> __entry_text_start and __entry_text_end, pt_regs will be at the place
> you're looking for it? How's that guaranteed?
It's not guaranteed in my code. I think we'd want to add a little
table of call sites and their pt_regs offsets. This was just meant to
test that the general idea works (and it does indeed generate better
traces than the stock kernel, which gets it unconditionally wrong).
--Andy
>
> Thanks,
>
> --
> Jiri Kosina
> SUSE Labs
>
--
Andy Lutomirski
AMA Capital Management, LLC
next prev parent reply other threads:[~2016-05-03 0:40 UTC|newest]
Thread overview: 118+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-28 20:44 [RFC PATCH v2 00/18] livepatch: hybrid consistency model Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 01/18] x86/asm/head: clean up initial stack variable Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 02/18] x86/asm/head: use a common function for starting CPUs Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 03/18] x86/asm/head: standardize the bottom of the stack for idle tasks Josh Poimboeuf
2016-04-29 18:46 ` Brian Gerst
2016-04-29 20:28 ` Josh Poimboeuf
2016-04-29 19:39 ` Andy Lutomirski
2016-04-29 20:50 ` Josh Poimboeuf
2016-04-29 21:38 ` Andy Lutomirski
2016-04-29 23:27 ` Josh Poimboeuf
2016-04-30 0:10 ` Andy Lutomirski
2016-04-28 20:44 ` [RFC PATCH v2 04/18] x86: move _stext marker before head code Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 05/18] sched: add task flag for preempt IRQ tracking Josh Poimboeuf
2016-04-29 18:06 ` Andy Lutomirski
2016-04-29 20:11 ` Josh Poimboeuf
2016-04-29 20:19 ` Andy Lutomirski
2016-04-29 20:27 ` Josh Poimboeuf
2016-04-29 20:32 ` Andy Lutomirski
2016-04-29 21:25 ` Josh Poimboeuf
2016-04-29 21:37 ` Andy Lutomirski
2016-04-29 22:11 ` Jiri Kosina
2016-04-29 22:57 ` Josh Poimboeuf
2016-04-30 0:09 ` Andy Lutomirski
2016-04-29 22:41 ` Josh Poimboeuf
2016-04-30 0:08 ` Andy Lutomirski
2016-05-02 13:52 ` Josh Poimboeuf
2016-05-02 15:52 ` Andy Lutomirski
2016-05-02 17:31 ` Josh Poimboeuf
2016-05-02 18:12 ` Andy Lutomirski
2016-05-02 18:34 ` Ingo Molnar
2016-05-02 19:44 ` Josh Poimboeuf
2016-05-02 19:54 ` Jiri Kosina
2016-05-02 20:00 ` Jiri Kosina
2016-05-03 0:39 ` Andy Lutomirski [this message]
2016-05-04 15:16 ` David Laight
2016-05-19 23:15 ` Josh Poimboeuf
2016-05-19 23:39 ` Andy Lutomirski
2016-05-20 14:05 ` Josh Poimboeuf
2016-05-20 15:41 ` Andy Lutomirski
2016-05-20 16:41 ` Josh Poimboeuf
2016-05-20 16:59 ` Andy Lutomirski
2016-05-20 17:49 ` Josh Poimboeuf
2016-05-23 23:02 ` Jiri Kosina
2016-05-24 1:42 ` Andy Lutomirski
2016-05-23 21:34 ` Andy Lutomirski
2016-05-24 2:28 ` Josh Poimboeuf
2016-05-24 3:52 ` Andy Lutomirski
2016-06-22 16:30 ` Josh Poimboeuf
2016-06-22 17:59 ` Andy Lutomirski
2016-06-22 18:22 ` Josh Poimboeuf
2016-06-22 18:26 ` Andy Lutomirski
2016-06-22 18:40 ` Josh Poimboeuf
2016-06-22 19:17 ` Andy Lutomirski
2016-06-23 16:19 ` Josh Poimboeuf
2016-06-23 16:35 ` Andy Lutomirski
2016-06-23 18:31 ` Josh Poimboeuf
2016-06-23 20:40 ` Josh Poimboeuf
2016-06-23 22:00 ` Andy Lutomirski
2016-06-23 0:09 ` Andy Lutomirski
2016-06-23 15:55 ` Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 06/18] x86: dump_trace() error handling Josh Poimboeuf
2016-04-29 13:45 ` Minfei Huang
2016-04-29 14:00 ` Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 07/18] stacktrace/x86: function for detecting reliable stack traces Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 08/18] livepatch: temporary stubs for klp_patch_pending() and klp_patch_task() Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 09/18] livepatch/x86: add TIF_PATCH_PENDING thread flag Josh Poimboeuf
2016-04-29 18:08 ` Andy Lutomirski
2016-04-29 20:18 ` Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 10/18] livepatch/powerpc: " Josh Poimboeuf
2016-05-03 9:07 ` Petr Mladek
2016-05-03 12:06 ` Miroslav Benes
2016-04-28 20:44 ` [RFC PATCH v2 11/18] livepatch/s390: reorganize TIF thread flag bits Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 12/18] livepatch/s390: add TIF_PATCH_PENDING thread flag Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 13/18] livepatch: separate enabled and patched states Josh Poimboeuf
2016-05-03 9:30 ` Petr Mladek
2016-05-03 13:48 ` Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 14/18] livepatch: remove unnecessary object loaded check Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 15/18] livepatch: move patching functions into patch.c Josh Poimboeuf
2016-05-03 9:39 ` Petr Mladek
2016-04-28 20:44 ` [RFC PATCH v2 16/18] livepatch: store function sizes Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 17/18] livepatch: change to a per-task consistency model Josh Poimboeuf
2016-05-04 8:42 ` Petr Mladek
2016-05-04 15:51 ` Josh Poimboeuf
2016-05-05 9:41 ` Miroslav Benes
2016-05-05 13:06 ` Petr Mladek
2016-05-04 12:39 ` barriers: was: " Petr Mladek
2016-05-04 13:53 ` Peter Zijlstra
2016-05-04 16:51 ` Josh Poimboeuf
2016-05-04 14:12 ` Petr Mladek
2016-05-04 17:25 ` Josh Poimboeuf
2016-05-05 11:21 ` Petr Mladek
2016-05-09 15:42 ` Miroslav Benes
2016-05-04 17:02 ` Josh Poimboeuf
2016-05-05 10:21 ` Petr Mladek
2016-05-04 14:48 ` klp_task_patch: " Petr Mladek
2016-05-04 14:56 ` Jiri Kosina
2016-05-04 17:57 ` Josh Poimboeuf
2016-05-05 11:57 ` Petr Mladek
2016-05-06 12:38 ` Josh Poimboeuf
2016-05-09 12:23 ` Petr Mladek
2016-05-16 18:12 ` Josh Poimboeuf
2016-05-18 13:12 ` Petr Mladek
2016-05-06 11:33 ` Petr Mladek
2016-05-06 12:44 ` Josh Poimboeuf
2016-05-09 9:41 ` Miroslav Benes
2016-05-16 17:27 ` Josh Poimboeuf
2016-05-10 11:39 ` Miroslav Benes
2016-05-17 22:53 ` Jessica Yu
2016-05-18 8:16 ` Jiri Kosina
2016-05-18 16:51 ` Josh Poimboeuf
2016-05-18 20:22 ` Jiri Kosina
2016-05-23 9:42 ` David Laight
2016-05-23 18:44 ` Jiri Kosina
2016-05-24 15:06 ` David Laight
2016-05-24 22:45 ` Jiri Kosina
2016-06-06 13:54 ` [RFC PATCH v2 17/18] " Petr Mladek
2016-06-06 14:29 ` Josh Poimboeuf
2016-04-28 20:44 ` [RFC PATCH v2 18/18] livepatch: add /proc/<pid>/patch_state Josh Poimboeuf
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