linux-kernel - Re: [RFC/PATCH] i386: handle all exceptions with interrupts off initially

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Date:	Wed, 10 Sep 2008 09:00:14 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	heukelum@...tmail.fm, linux-kernel@...r.kernel.org
Subject: Re: [RFC/PATCH] i386: handle all exceptions with interrupts off
	initially


* H. Peter Anvin <hpa@...or.com> wrote:

> Ingo Molnar wrote:
>>
>> the entry paths here are really short (we enable irqs almost 
>> immediately) so it's a non-issue in terms of worst-case latencies.
>>
>>> In other words, it's not something we want to do "just because", but 
>>> to the extent that it provides real benefit, it makes sense.
>>
>> this is historically pretty fragile code so bringing the 32-bit and 
>> 64-bit variants more in line sounds like a good reason to me. For 
>> example we had various long-living irq state annotation bugs (the 
>> combination of kprobes and lockdep, etc.) that remained unfixed 
>> partly due to this assymetry.
>
> Agreed completely.  I certainly didn't mean to come across sounding 
> negative.

great - i'll check which topic this fits in best. I suspect it will get 
its own topic - but there could be interactions as traps*.c is a central 
(and hence popular) file - here are the currently pending changes in 
-tip:

db4b0f1: kmemcheck: implement REP MOVS/STOS emulation
48e2bd5: x86: coding style fixes to arch/x86/kernel/traps_64.c
c9c3ddd: x86_64: remove empty lines from stack traces/oopses
4df9e51: x86: coding style fixes to arch/x86/kernel/traps_64.c
b359e8a: x86, xsave: context switch support using xsave/xrstor
dc1e35c: x86, xsave: enable xsave/xrstor on cpus with xsave support
862849a: x86: add hooks for kmemcheck on x86_64
787ecfa: x86: add hooks for kmemcheck
afdb702: x86: __show_registers() and __show_regs() API unification
0d84b78: x86 NMI-safe INT3 and Page Fault

we'll see.

	Ingo
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