From: luto@amacapital.net (Andy Lutomirski)
Subject: [PATCH 1/4] x86/thread_info: introduce ->ftrace_int3_stack member
Date: Sun, 28 Apr 2019 16:27:21 -0700 [thread overview]
Message-ID: <C55DED25-C60D-4731-9A6B-92BDA8771766@amacapital.net> (raw)
Message-ID: <20190428232721.W4tNtE5lAHJT7mVyfqifvLPkFQVoZ3z-whuOp8UHTAs@z> (raw)
In-Reply-To: <87k1fdygcx.fsf@suse.de>
> On Apr 28, 2019,@2:22 PM, Nicolai Stange <nstange@suse.de> wrote:
>
> Steven Rostedt <rostedt at goodmis.org> writes:
>
>> On Sun, 28 Apr 2019 10:41:10 -0700
>> Andy Lutomirski <luto@amacapital.net> wrote:
>>
>>
>>>> Note that at any given point
>>>> in time, there can be at most four such call insn emulations pending:
>>>> namely at most one per "process", "irq", "softirq" and "nmi" context.
>>>>
>>>
>>> That’s quite an assumption. I think your list should also contain
>>> exception, exceptions nested inside that exception, and machine
>>> check, at the very least. I’m also wondering why irq and softirq are
>>> treated separately.
>
> You're right, I missed the machine check case.
>
>
>> 4 has usually been the context count we choose. But I guess in theory,
>> if we get exceptions then I could potentially be more.
>
> After having seen the static_call discussion, I'm in no way defending
> this limited approach here, but out of curiosity: can the code between
> the push onto the stack from ftrace_int3_handler() and the subsequent
> pop from the stub actually trigger an (non-#MC) exception? There's an
> iret inbetween, but that can fault only when returning to user space,
> correct?
IRET doesn’t do any fancy masking, so #DB, NMI and regular IRQs should all be possible.
>
>
>> As for irq vs softirq, an interrupt can preempt a softirq. Interrupts
>> are enabled while softirqs are running. When sofirqs run, softirqs are
>> disabled to prevent nested softirqs. But interrupts are enabled again,
>> and another interrupt may come in while a softirq is executing.
>>
>
> Thanks,
>
> Nicolai
>
>
> --
> SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton,
> HRB 21284 (AG Nürnberg)
next prev parent reply other threads:[~2019-04-28 23:27 UTC|newest]
Thread overview: 128+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-27 10:06 [PATCH 0/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation nstange
2019-04-27 10:06 ` Nicolai Stange
2019-04-27 10:06 ` [PATCH 1/4] x86/thread_info: introduce ->ftrace_int3_stack member nstange
2019-04-27 10:06 ` Nicolai Stange
2019-04-28 17:41 ` luto
2019-04-28 17:41 ` Andy Lutomirski
2019-04-28 17:51 ` rostedt
2019-04-28 17:51 ` Steven Rostedt
2019-04-28 18:08 ` luto
2019-04-28 18:08 ` Andy Lutomirski
2019-04-28 19:43 ` rostedt
2019-04-28 19:43 ` Steven Rostedt
2019-04-28 20:56 ` luto
2019-04-28 20:56 ` Andy Lutomirski
2019-04-28 21:22 ` nstange
2019-04-28 21:22 ` Nicolai Stange
2019-04-28 23:27 ` luto [this message]
2019-04-28 23:27 ` Andy Lutomirski
2019-04-27 10:06 ` [PATCH 2/4] ftrace: drop 'static' qualifier from ftrace_ops_list_func() nstange
2019-04-27 10:06 ` Nicolai Stange
2019-04-27 10:06 ` [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation nstange
2019-04-27 10:06 ` Nicolai Stange
2019-04-27 10:26 ` peterz
2019-04-27 10:26 ` Peter Zijlstra
2019-04-28 17:38 ` rostedt
2019-04-28 17:38 ` Steven Rostedt
2019-04-29 18:06 ` torvalds
2019-04-29 18:06 ` Linus Torvalds
2019-04-29 18:22 ` torvalds
2019-04-29 18:22 ` Linus Torvalds
2019-04-29 18:42 ` luto
2019-04-29 18:42 ` Andy Lutomirski
[not found] ` <CAHk-=whtt4K2f0KPtG-4Pykh3FK8UBOjD8jhXCUKB5nWDj_YRA@mail.gmail.com>
2019-04-29 18:56 ` luto
2019-04-29 18:56 ` Andy Lutomirski
[not found] ` <CAHk-=wgewK4eFhF3=0RNtk1KQjMANFH6oDE=8m=84RExn2gxhw@mail.gmail.com>
[not found] ` <CAHk-=whay7eN6+2gZjY-ybRbkbcqAmgrLwwszzHx8ws3c=S-MA@mail.gmail.com>
2019-04-29 19:24 ` luto
2019-04-29 19:24 ` Andy Lutomirski
2019-04-29 20:07 ` torvalds
2019-04-29 20:07 ` Linus Torvalds
2019-04-30 13:56 ` peterz
2019-04-30 13:56 ` Peter Zijlstra
2019-04-30 16:06 ` torvalds
2019-04-30 16:06 ` Linus Torvalds
2019-04-30 16:33 ` luto
2019-04-30 16:33 ` Andy Lutomirski
2019-04-30 17:03 ` rostedt
2019-04-30 17:03 ` Steven Rostedt
2019-04-30 17:20 ` rostedt
2019-04-30 17:20 ` Steven Rostedt
2019-04-30 17:49 ` [RFC][PATCH] ftrace/x86: Emulate call function while updating in breakpoint handler rostedt
2019-04-30 17:49 ` Steven Rostedt
2019-04-30 18:33 ` torvalds
2019-04-30 18:33 ` Linus Torvalds
2019-04-30 19:00 ` rostedt
2019-04-30 19:00 ` Steven Rostedt
2019-04-30 21:08 ` rostedt
2019-04-30 21:08 ` Steven Rostedt
2019-05-01 13:11 ` peterz
2019-05-01 13:11 ` Peter Zijlstra
2019-05-01 18:58 ` rostedt
2019-05-01 18:58 ` Steven Rostedt
2019-05-01 19:03 ` peterz
2019-05-01 19:03 ` Peter Zijlstra
2019-05-01 19:03 ` torvalds
2019-05-01 19:03 ` Linus Torvalds
2019-05-01 19:13 ` peterz
2019-05-01 19:13 ` Peter Zijlstra
2019-05-01 19:13 ` rostedt
2019-05-01 19:13 ` Steven Rostedt
2019-05-01 19:33 ` jikos
2019-05-01 19:33 ` Jiri Kosina
2019-05-01 19:41 ` peterz
2019-05-01 19:41 ` Peter Zijlstra
2019-04-30 21:53 ` [RFC][PATCH v2] " rostedt
2019-04-30 21:53 ` Steven Rostedt
2019-05-01 1:35 ` rostedt
2019-05-01 1:35 ` Steven Rostedt
2019-05-01 1:58 ` torvalds
2019-05-01 1:58 ` Linus Torvalds
2019-05-01 8:26 ` nstange
2019-05-01 8:26 ` Nicolai Stange
2019-05-01 13:22 ` rostedt
2019-05-01 13:22 ` Steven Rostedt
2019-04-29 20:16 ` [PATCH 3/4] x86/ftrace: make ftrace_int3_handler() not to skip fops invocation torvalds
2019-04-29 20:16 ` Linus Torvalds
2019-04-29 22:08 ` sean.j.christopherson
2019-04-29 22:08 ` Sean Christopherson
2019-04-29 22:22 ` torvalds
2019-04-29 22:22 ` Linus Torvalds
2019-04-30 0:08 ` sean.j.christopherson
2019-04-30 0:08 ` Sean Christopherson
2019-04-30 0:45 ` sean.j.christopherson
2019-04-30 0:45 ` Sean Christopherson
2019-04-30 2:26 ` torvalds
2019-04-30 2:26 ` Linus Torvalds
2019-04-30 10:40 ` peterz
2019-04-30 10:40 ` Peter Zijlstra
2019-04-30 11:17 ` jikos
2019-04-30 11:17 ` Jiri Kosina
2019-04-29 22:06 ` torvalds
2019-04-29 22:06 ` Linus Torvalds
2019-04-30 11:18 ` peterz
2019-04-30 11:18 ` Peter Zijlstra
2019-04-29 18:52 ` rostedt
2019-04-29 18:52 ` Steven Rostedt
[not found] ` <CAHk-=wjm93jLtVxTX4HZs6K4k1Wqh3ujjmapqaYtcibVk_YnzQ@mail.gmail.com>
2019-04-29 19:07 ` rostedt
2019-04-29 19:07 ` Steven Rostedt
2019-04-29 20:06 ` torvalds
2019-04-29 20:06 ` Linus Torvalds
2019-04-29 20:20 ` torvalds
2019-04-29 20:20 ` Linus Torvalds
2019-04-29 20:30 ` rostedt
2019-04-29 20:30 ` Steven Rostedt
2019-04-29 21:38 ` torvalds
2019-04-29 21:38 ` Linus Torvalds
2019-04-29 22:07 ` rostedt
2019-04-29 22:07 ` Steven Rostedt
2019-04-30 9:24 ` nstange
2019-04-30 9:24 ` Nicolai Stange
2019-04-30 10:46 ` peterz
2019-04-30 10:46 ` Peter Zijlstra
2019-04-30 13:44 ` rostedt
2019-04-30 13:44 ` Steven Rostedt
2019-04-30 14:20 ` peterz
2019-04-30 14:20 ` Peter Zijlstra
2019-04-30 14:36 ` rostedt
2019-04-30 14:36 ` Steven Rostedt
2019-04-27 10:06 ` [PATCH 4/4] selftests/livepatch: add "ftrace a live patched function" test nstange
2019-04-27 10:06 ` Nicolai Stange
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