Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1333080
| From | Peter Zijlstra <peterz@infradead.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 00/33] Compile-time stack metadata validation |
| Date | 2016-02-12 21:20 +0100 |
| Message-ID | <r1sm5-3kI-5@gated-at.bofh.it> (permalink) |
| References | <qTwmS-3nT-7@gated-at.bofh.it> <r1jiO-5IA-19@gated-at.bofh.it> <r1ncL-8iz-17@gated-at.bofh.it> <r1pxW-1vA-49@gated-at.bofh.it> <r1qNl-2ew-27@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Fri, Feb 12, 2016 at 12:32:06PM -0600, Josh Poimboeuf wrote:
> What I actually see in the listing is:
>
> decl __percpu_prefix:__preempt_count
> je 1f:
> ....
> 1:
> call ___preempt_schedule
>
> So it puts the "call ___preempt_schedule" in the slow path.
Ah yes indeed. Same difference though.
> I also don't see how that would be related to the use of the asm
> statement in the __preempt_schedule() macro. Doesn't the use of
> unlikely() in preempt_enable() put the call in the slow path?
Sadly no, unlikely() and asm_goto don't work well together. But the slow
path or not isn't the reason we do the asm call thing.
> #define preempt_enable() \
> do { \
> barrier(); \
> if (unlikely(preempt_count_dec_and_test())) \
> preempt_schedule(); \
> } while (0)
>
> Also, why is the thunk needed? Any reason why preempt_enable() can't be
> called directly from C?
That would make the call-site save registers and increase the size of
every preempt_enable(). By using the thunk we can do callee saved
registers and avoid blowing up the call site.
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
Re: [PATCH 00/33] Compile-time stack metadata validation Jiri Slaby <jslaby@suse.cz> - 2016-02-12 11:40 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Jiri Slaby <jslaby@suse.cz> - 2016-02-12 11:50 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-12 15:50 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Peter Zijlstra <peterz@infradead.org> - 2016-02-12 18:20 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-12 19:40 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-12 19:40 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Peter Zijlstra <peterz@infradead.org> - 2016-02-12 21:20 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-15 17:40 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Peter Zijlstra <peterz@infradead.org> - 2016-02-15 18:00 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Andi Kleen <andi@firstfloor.org> - 2016-02-15 21:10 +0100
Re: [PATCH 00/33] Compile-time stack metadata validation Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-15 21:10 +0100
[PATCH] sched/x86: Add stack frame dependency to __preempt_schedule[_notrace] Josh Poimboeuf <jpoimboe@redhat.com> - 2016-02-18 18:50 +0100
Re: [PATCH] sched/x86: Add stack frame dependency to __preempt_schedule[_notrace] Jiri Slaby <jslaby@suse.cz> - 2016-02-19 13:10 +0100
csiph-web