Re: [PATCH] x86/entry/64: Context-track syscalls before enabling interrupts

From	Ingo Molnar <mingo@kernel.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] x86/entry/64: Context-track syscalls before enabling interrupts
Date	2015-08-21 10:00 +0200
Message-ID	<pZPoZ-5LS-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <pYXoC-3m5-15@gated-at.bofh.it> <pYXHX-3Pc-3@gated-at.bofh.it> <pYYaZ-4D3-9@gated-at.bofh.it> <pYYb0-4D3-13@gated-at.bofh.it> <pZfbQ-3Xo-21@gated-at.bofh.it>
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* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> > I want to have a real hook to call that says "switch to IRQ context from 
> > CONTEXT_USER" or "switch to IRQ context from CONTEXT_KERNEL" (aka noop), but 
> > that doesn't currently exist.
> 
> You're not answering _why_ you want that.

So we'd have a comprehensive, 100% coverage, self-sufficient set of callbacks that 
track the kernel's current context state at the points where the context switches 
actually occur - not just something cobbled together heterogenously. The low level 
x86 asm code was rather messy in this area, better organization would be welcome, 
I don't think we can overdo it.

( I'm assuming here that it can all be done for zero or negative cost, and that
  the result will be correct and won't hurt existing users in any fashion. )

Thanks,

	Ingo
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Re: [PATCH] x86/entry/64: Context-track syscalls before enabling  interrupts Ingo Molnar <mingo@kernel.org> - 2015-08-21 10:00 +0200
  Re: [PATCH] x86/entry/64: Context-track syscalls before enabling  interrupts Frederic Weisbecker <fweisbec@gmail.com> - 2015-08-21 15:20 +0200

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