From: rostedt@goodmis.org (Steven Rostedt)
Subject: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions
Date: Fri, 3 May 2019 15:24:05 -0400 [thread overview]
Message-ID: <20190503152405.2d741af8@gandalf.local.home> (raw)
Message-ID: <20190503192405.ArDOE90_ZbnlvS8aoXpxcn7P9GR5qSNeYZcDDgKvmac@z> (raw)
In-Reply-To: <CAHk-=wh8bi5c_GkyjPtDAiaXaZRqtmhWs30usUvs4qK_F+c9tg@mail.gmail.com>
On Thu, 2 May 2019 13:49:29 -0700
Linus Torvalds <torvalds@linux-foundation.org> wrote:
> On Thu, May 2, 2019@1:22 PM Peter Zijlstra <peterz@infradead.org> wrote:
> >
> > Something like so; it boots; but I could've made some horrible mistake
> > (again).
>
> This actually looks much better to me.
>
> Maybe it's more lines (I didn't check), but it's a lot simpler in that
> now the magic of the int3 stack doesn't get exposed to anything else.
>
> We *could* also make this kernel-mode-only do_int3() be a special
> function, and do something like
>
> # args: pt_regs pointer (no error code for int3)
> movl %esp,%eax
> # allocate a bit of extra room on the stack, so that
> 'kernel_int3' can move the pt_regs
> subl $8,%esp
> call kernel_int3
> movl %eax,%esp
>
> and not do any stack switching magic in the asm code AT ALL. We'd do
>
> struct pt_regs *kernel_int3(struct pt_regs *regs)
> {
> ..
> return regs;
> }
>
> and now you the rule for call emulation ends up being that you need to
> "memmove()" the ptregs up and down properly, and return the new
> pt_regs pointer.
>
> Hmm? That would simplify the asm code further, but some people might
> find it objectionable?
>
The problem with this approach is that it would require doing the same
for x86_64, as the int3 C code is the same for both. And that may be a
bit more difficult on the x86_64 side because it's all done with a
simple flag in the idtentry macro to add the gap.
-- Steve
next prev parent reply other threads:[~2019-05-03 19:24 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
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 [this message]
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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