From: jikos at kernel.org (Jiri Kosina)
Subject: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions
Date: Thu, 2 May 2019 21:28:53 +0200 (CEST) [thread overview]
Message-ID: <nycvar.YFH.7.76.1905022101060.10635@cbobk.fhfr.pm> (raw)
In-Reply-To: <CAHk-=wi6A9tgw=kkPh5Ywqt687VvsVEjYXVkAnq0jpt0u0tk6g@mail.gmail.com>
On Thu, 2 May 2019, Linus Torvalds wrote:
> I forget: is #BP _only_ for the "int3" instruction?
Hmm, according to 17.3.2 in vol 3 of SDM (and table 6-1 there), that
indeed seems to be the case, so we should be fine.
> But if "int3 from kernel space" _only_ happens on actual "int3"
> instructions, then we really could just special-case that case. We'd
> know that %cr3 has been switched, we'd know that we don't need to do
> fsgs switching, we'd know we already have a good stack and percpu data
> etc set up.
That should indeed be doable, under the asumption that noone is doing any
int3 games before we've switched away from entry trampoline.
I've briefly looked, and seems like we have proper notrace anotations for
stackleak_erase(), which seems to be the only C (ftrace-able) code that's
running on a trampoline (off-topic: where does PTI code make sure that we
actually map this symbol into user pagetables in case we're not doing
global mapping?).
--
Jiri Kosina
SUSE Labs
WARNING: multiple messages have this Message-ID (diff)
From: jikos@kernel.org (Jiri Kosina)
Subject: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions
Date: Thu, 2 May 2019 21:28:53 +0200 (CEST) [thread overview]
Message-ID: <nycvar.YFH.7.76.1905022101060.10635@cbobk.fhfr.pm> (raw)
Message-ID: <20190502192853.Jpao92lvZPUFcGkhOgPJqJu_GWjRyX5P_OfO1MN55_o@z> (raw)
In-Reply-To: <CAHk-=wi6A9tgw=kkPh5Ywqt687VvsVEjYXVkAnq0jpt0u0tk6g@mail.gmail.com>
On Thu, 2 May 2019, Linus Torvalds wrote:
> I forget: is #BP _only_ for the "int3" instruction?
Hmm, according to 17.3.2 in vol 3 of SDM (and table 6-1 there), that
indeed seems to be the case, so we should be fine.
> But if "int3 from kernel space" _only_ happens on actual "int3"
> instructions, then we really could just special-case that case. We'd
> know that %cr3 has been switched, we'd know that we don't need to do
> fsgs switching, we'd know we already have a good stack and percpu data
> etc set up.
That should indeed be doable, under the asumption that noone is doing any
int3 games before we've switched away from entry trampoline.
I've briefly looked, and seems like we have proper notrace anotations for
stackleak_erase(), which seems to be the only C (ftrace-able) code that's
running on a trampoline (off-topic: where does PTI code make sure that we
actually map this symbol into user pagetables in case we're not doing
global mapping?).
--
Jiri Kosina
SUSE Labs
next prev parent reply other threads:[~2019-05-02 19:28 UTC|newest]
Thread overview: 204+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20190501202830.347656894@goodmis.org>
2019-05-01 20:28 ` [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions rostedt
2019-05-01 20:28 ` Steven Rostedt
2019-05-02 3:24 ` rostedt
2019-05-02 3:24 ` Steven Rostedt
2019-05-02 16:21 ` peterz
2019-05-02 16:21 ` Peter Zijlstra
2019-05-02 16:29 ` peterz
2019-05-02 16:29 ` Peter Zijlstra
2019-05-02 18:02 ` torvalds
2019-05-02 18:02 ` Linus Torvalds
2019-05-02 18:18 ` peterz
2019-05-02 18:18 ` Peter Zijlstra
2019-05-02 18:30 ` peterz
2019-05-02 18:30 ` Peter Zijlstra
2019-05-02 18:43 ` torvalds
2019-05-02 18:43 ` Linus Torvalds
2019-05-02 19:28 ` jikos [this message]
2019-05-02 19:28 ` Jiri Kosina
2019-05-02 20:25 ` luto
2019-05-02 20:25 ` Andy Lutomirski
2019-05-02 20:21 ` peterz
2019-05-02 20:21 ` Peter Zijlstra
2019-05-02 20:49 ` torvalds
2019-05-02 20:49 ` Linus Torvalds
2019-05-02 21:32 ` peterz
2019-05-02 21:32 ` Peter Zijlstra
2019-05-03 19:24 ` rostedt
2019-05-03 19:24 ` Steven Rostedt
2019-05-03 21:46 ` torvalds
2019-05-03 21:46 ` Linus Torvalds
2019-05-03 22:49 ` rostedt
2019-05-03 22:49 ` Steven Rostedt
2019-05-03 23:07 ` torvalds
2019-05-03 23:07 ` Linus Torvalds
2019-05-04 4:17 ` rostedt
2019-05-04 4:17 ` Steven Rostedt
[not found] ` <CAHk-=wiuSFbv_rELND-BLWcP0GSZ0yF=xOAEcf61GE3bU9d=yg@mail.gmail.com>
2019-05-04 18:59 ` torvalds
2019-05-04 18:59 ` Linus Torvalds
2019-05-04 20:12 ` luto
2019-05-04 20:12 ` Andy Lutomirski
2019-05-04 20:28 ` torvalds
2019-05-04 20:28 ` Linus Torvalds
2019-05-04 20:36 ` torvalds
2019-05-04 20:36 ` Linus Torvalds
2019-05-03 22:55 ` luto
2019-05-03 22:55 ` Andy Lutomirski
2019-05-03 23:16 ` torvalds
2019-05-03 23:16 ` Linus Torvalds
2019-05-03 23:32 ` luto
2019-05-03 23:32 ` Andy Lutomirski
2019-05-02 22:52 ` rostedt
2019-05-02 22:52 ` Steven Rostedt
2019-05-02 23:31 ` rostedt
2019-05-02 23:31 ` Steven Rostedt
2019-05-02 23:50 ` rostedt
2019-05-02 23:50 ` Steven Rostedt
2019-05-03 1:51 ` [RFC][PATCH 1/2 v2] " rostedt
2019-05-03 1:51 ` Steven Rostedt
2019-05-03 9:29 ` [RFC][PATCH 1/2] " peterz
2019-05-03 9:29 ` Peter Zijlstra
2019-05-03 13:22 ` rostedt
2019-05-03 13:22 ` Steven Rostedt
2019-05-03 16:20 ` luto
2019-05-03 16:20 ` Andy Lutomirski
2019-05-03 16:31 ` rostedt
2019-05-03 16:31 ` Steven Rostedt
2019-05-03 16:35 ` peterz
2019-05-03 16:35 ` Peter Zijlstra
2019-05-03 16:44 ` luto
2019-05-03 16:44 ` Andy Lutomirski
2019-05-03 16:49 ` rostedt
2019-05-03 16:49 ` Steven Rostedt
2019-05-03 16:32 ` peterz
2019-05-03 16:32 ` Peter Zijlstra
2019-05-03 18:57 ` torvalds
2019-05-03 18:57 ` Linus Torvalds
2019-05-06 8:19 ` peterz
2019-05-06 8:19 ` Peter Zijlstra
2019-05-06 13:56 ` rostedt
2019-05-06 13:56 ` Steven Rostedt
2019-05-06 16:17 ` torvalds
2019-05-06 16:17 ` Linus Torvalds
2019-05-06 16:19 ` torvalds
2019-05-06 16:19 ` Linus Torvalds
2019-05-06 17:06 ` rostedt
2019-05-06 17:06 ` Steven Rostedt
2019-05-06 18:06 ` torvalds
2019-05-06 18:06 ` Linus Torvalds
2019-05-06 18:57 ` rostedt
2019-05-06 18:57 ` Steven Rostedt
2019-05-06 19:46 ` torvalds
2019-05-06 19:46 ` Linus Torvalds
2019-05-06 20:29 ` rostedt
2019-05-06 20:29 ` Steven Rostedt
2019-05-06 20:42 ` torvalds
2019-05-06 20:42 ` Linus Torvalds
2019-05-06 20:44 ` torvalds
2019-05-06 20:44 ` Linus Torvalds
2019-05-06 21:45 ` rostedt
2019-05-06 21:45 ` Steven Rostedt
2019-05-06 22:06 ` torvalds
2019-05-06 22:06 ` Linus Torvalds
2019-05-06 22:31 ` torvalds
2019-05-06 22:31 ` Linus Torvalds
2019-05-07 0:10 ` rostedt
2019-05-07 0:10 ` Steven Rostedt
2019-05-07 1:06 ` torvalds
2019-05-07 1:06 ` Linus Torvalds
2019-05-07 1:04 ` rostedt
2019-05-07 1:04 ` Steven Rostedt
2019-05-07 1:34 ` rostedt
2019-05-07 1:34 ` Steven Rostedt
2019-05-07 1:34 ` torvalds
2019-05-07 1:34 ` Linus Torvalds
2019-05-07 1:53 ` rostedt
2019-05-07 1:53 ` Steven Rostedt
2019-05-07 2:22 ` torvalds
2019-05-07 2:22 ` Linus Torvalds
2019-05-07 2:58 ` rostedt
2019-05-07 2:58 ` Steven Rostedt
2019-05-07 3:05 ` torvalds
2019-05-07 3:05 ` Linus Torvalds
2019-05-07 3:21 ` rostedt
2019-05-07 3:21 ` Steven Rostedt
2019-05-07 3:28 ` torvalds
2019-05-07 3:28 ` Linus Torvalds
2019-05-07 14:54 ` torvalds
2019-05-07 14:54 ` Linus Torvalds
2019-05-07 15:12 ` rostedt
2019-05-07 15:12 ` Steven Rostedt
2019-05-07 15:25 ` rostedt
2019-05-07 15:25 ` Steven Rostedt
2019-05-07 16:25 ` rostedt
2019-05-07 16:25 ` Steven Rostedt
2019-05-07 15:31 ` torvalds
2019-05-07 15:31 ` Linus Torvalds
2019-05-07 15:45 ` rostedt
2019-05-07 15:45 ` Steven Rostedt
2019-05-07 16:34 ` peterz
2019-05-07 16:34 ` Peter Zijlstra
2019-05-07 17:08 ` torvalds
2019-05-07 17:08 ` Linus Torvalds
2019-05-07 17:21 ` jpoimboe
2019-05-07 17:21 ` Josh Poimboeuf
2019-05-07 21:24 ` rostedt
2019-05-07 21:24 ` Steven Rostedt
2019-05-08 4:50 ` torvalds
2019-05-08 4:50 ` Linus Torvalds
2019-05-08 16:37 ` rostedt
2019-05-08 16:37 ` Steven Rostedt
2019-05-07 17:38 ` peterz
2019-05-07 17:38 ` Peter Zijlstra
2019-05-07 9:51 ` peterz
2019-05-07 9:51 ` Peter Zijlstra
2019-05-07 14:48 ` luto
2019-05-07 14:48 ` Andy Lutomirski
2019-05-07 14:57 ` torvalds
2019-05-07 14:57 ` Linus Torvalds
2019-05-07 14:13 ` mhiramat
2019-05-07 14:13 ` Masami Hiramatsu
2019-05-07 17:15 ` mhiramat
2019-05-07 17:15 ` Masami Hiramatsu
2019-05-06 14:22 ` peterz
2019-05-06 14:22 ` Peter Zijlstra
2019-05-07 8:57 ` peterz
2019-05-07 8:57 ` Peter Zijlstra
2019-05-07 9:18 ` David.Laight
2019-05-07 9:18 ` David Laight
2019-05-07 11:30 ` peterz
2019-05-07 11:30 ` Peter Zijlstra
2019-05-07 12:57 ` David.Laight
2019-05-07 12:57 ` David Laight
2019-05-07 13:14 ` rostedt
2019-05-07 13:14 ` Steven Rostedt
2019-05-07 14:50 ` David.Laight
2019-05-07 14:50 ` David Laight
2019-05-07 14:57 ` rostedt
2019-05-07 14:57 ` Steven Rostedt
2019-05-07 15:46 ` David.Laight
2019-05-07 15:46 ` David Laight
2019-05-07 13:32 ` peterz
2019-05-07 13:32 ` Peter Zijlstra
2019-05-07 9:27 ` peterz
2019-05-07 9:27 ` Peter Zijlstra
2019-05-07 12:27 ` rostedt
2019-05-07 12:27 ` Steven Rostedt
2019-05-07 12:41 ` peterz
2019-05-07 12:41 ` Peter Zijlstra
2019-05-07 12:54 ` rostedt
2019-05-07 12:54 ` Steven Rostedt
2019-05-07 17:22 ` masami.hiramatsu
2019-05-07 17:22 ` Masami Hiramatsu
2019-05-07 14:28 ` peterz
2019-05-07 14:28 ` Peter Zijlstra
2019-05-02 20:48 ` rostedt
2019-05-02 20:48 ` Steven Rostedt
2019-05-06 15:14 ` jpoimboe
2019-05-06 15:14 ` Josh Poimboeuf
2019-05-01 20:28 ` [RFC][PATCH 2/2] ftrace/x86: Emulate call function while updating in breakpoint handler rostedt
2019-05-01 20:28 ` Steven Rostedt
2019-05-03 10:22 ` [RFC][PATCH 1.5/2] x86: Add int3_emulate_call() selftest peterz
2019-05-03 10:22 ` Peter Zijlstra
2019-05-03 18:46 ` rostedt
2019-05-03 18:46 ` Steven Rostedt
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