Re: [tip:perf/core] kprobes/x86: Call out into INT3 handler directlyinstead of using notifier

[H. Peter Anvin]

On 07/23/2013 08:55 PM, tip-bot for Jiri Kosina wrote:
> Commit-ID:  17f41571bb2c4a398785452ac2718a6c5d77180e
> Gitweb:     http://git.kernel.org/tip/17f41571bb2c4a398785452ac2718a6c5d77180e
> Author:     Jiri Kosina <jkosina@xxxxxxx>
> AuthorDate: Tue, 23 Jul 2013 10:09:28 +0200
> Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
> CommitDate: Tue, 23 Jul 2013 10:12:57 +0200
> 
> kprobes/x86: Call out into INT3 handler directly instead of using notifier
> 
> In fd4363fff3d96 ("x86: Introduce int3 (breakpoint)-based
> instruction patching"), the mechanism that was introduced for
> notifying alternatives code from int3 exception handler that and
> exception occured was die_notifier.
> 
> This is however problematic, as early code might be using jump
> labels even before the notifier registration has been performed,
> which will then lead to an oops due to unhandled exception. One
> of such occurences has been encountered by Fengguang:
> 

Please note that putting this patch in perf/core means x86/jumplabel is
completely nonfunctional by itself.

	-hpa


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