From: luto at amacapital.net (Andy Lutomirski)
Subject: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions
Date: Fri, 3 May 2019 16:32:15 -0700 [thread overview]
Message-ID: <93546F2D-0DF6-4E6A-98B0-BA49491C00CC@amacapital.net> (raw)
In-Reply-To: <CAHk-=wjZDhwStWvioV7totCnZfp74bqH0y1UJxkmFfdLg48wDA@mail.gmail.com>
> On May 3, 2019, at 4:16 PM, Linus Torvalds <torvalds at linux-foundation.org> wrote:
>
>> On Fri, May 3, 2019 at 3:55 PM Andy Lutomirski <luto at amacapital.net> wrote:
>>
>> But I think this will end up worse than the version where the entry code fixes it up. This is because, if the C code moves pt_regs, then we need some way to pass the new pointer back to the asm.
>
> What? I already posted that code. Let me quote it again:
>
> Message-ID: <CAHk-=wh8bi5c_GkyjPtDAiaXaZRqtmhWs30usUvs4qK_F+c9tg at mail.gmail.com>
>
> # 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
>
> It's that easy (this is with the assumption that we've already applied
> the "standalone simple int3" case, but I think the above might work
> even with the current code model, just the "call do_int3" needs to
> have the kernel/not-kernel distinction and do the above for the kernel
> case)
>
> That's *MUCH* easier than your code to move entries around on the
> stack just as you return, and has the advantage of not changing any
> C-visible layout.
>
> The C interface looks like this
>
> /* Note: on x86-32, we can move 'regs' around for push/pop emulation */
> struct pt_regs *kernel_int3(struct pt_regs *regs)
> {
> ..
> .. need to pass regs to emulation functions
> .. and call emulation needs to return it
> ..
> return regs;
> }
>
> and I just posted as a response to Stephen the *trivial* do_int3()
> wrapper (so that x86-64 doesn't need to care), and the *trivial* code
> to actually emulate a call instruction.
>
> And when I say "trivial", I obviously mean "totally untested and
> probably buggy", but it sure seems *simple*.,
>
> Notice? Simple and minimal changes to entry code that only affect
> int3, and nothing else.
>
>
I can get on board with this.
WARNING: multiple messages have this Message-ID (diff)
From: luto@amacapital.net (Andy Lutomirski)
Subject: [RFC][PATCH 1/2] x86: Allow breakpoints to emulate call functions
Date: Fri, 3 May 2019 16:32:15 -0700 [thread overview]
Message-ID: <93546F2D-0DF6-4E6A-98B0-BA49491C00CC@amacapital.net> (raw)
Message-ID: <20190503233215.-1QrYJ3AR72RymM1-uK66fH3vs703cOizFhTAZYyDwM@z> (raw)
In-Reply-To: <CAHk-=wjZDhwStWvioV7totCnZfp74bqH0y1UJxkmFfdLg48wDA@mail.gmail.com>
> On May 3, 2019,@4:16 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
>> On Fri, May 3, 2019@3:55 PM Andy Lutomirski <luto@amacapital.net> wrote:
>>
>> But I think this will end up worse than the version where the entry code fixes it up. This is because, if the C code moves pt_regs, then we need some way to pass the new pointer back to the asm.
>
> What? I already posted that code. Let me quote it again:
>
> Message-ID: <CAHk-=wh8bi5c_GkyjPtDAiaXaZRqtmhWs30usUvs4qK_F+c9tg at mail.gmail.com>
>
> # 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
>
> It's that easy (this is with the assumption that we've already applied
> the "standalone simple int3" case, but I think the above might work
> even with the current code model, just the "call do_int3" needs to
> have the kernel/not-kernel distinction and do the above for the kernel
> case)
>
> That's *MUCH* easier than your code to move entries around on the
> stack just as you return, and has the advantage of not changing any
> C-visible layout.
>
> The C interface looks like this
>
> /* Note: on x86-32, we can move 'regs' around for push/pop emulation */
> struct pt_regs *kernel_int3(struct pt_regs *regs)
> {
> ..
> .. need to pass regs to emulation functions
> .. and call emulation needs to return it
> ..
> return regs;
> }
>
> and I just posted as a response to Stephen the *trivial* do_int3()
> wrapper (so that x86-64 doesn't need to care), and the *trivial* code
> to actually emulate a call instruction.
>
> And when I say "trivial", I obviously mean "totally untested and
> probably buggy", but it sure seems *simple*.,
>
> Notice? Simple and minimal changes to entry code that only affect
> int3, and nothing else.
>
>
I can get on board with this.
next prev parent reply other threads:[~2019-05-03 23:32 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
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 [this message]
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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