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From: Ingo Molnar <mingo@kernel.org>
To: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andy Lutomirski <luto@amacapital.net>,
	Andy Lutomirski <luto@kernel.org>, X86 ML <x86@kernel.org>,
	Sasha Levin <sasha.levin@oracle.com>,
	Brian Gerst <brgerst@gmail.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Oleg Nesterov <oleg@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH] x86/entry/64: Context-track syscalls before enabling interrupts
Date: Fri, 21 Aug 2015 09:50:35 +0200	[thread overview]
Message-ID: <20150821075035.GB9511@gmail.com> (raw)
In-Reply-To: <20150819171007.GA21717@lerouge>


* 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

  reply	other threads:[~2015-08-21  7:50 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-08-18 19:11 [PATCH] x86/entry/64: Context-track syscalls before enabling interrupts Andy Lutomirski
2015-08-18 22:16 ` Frederic Weisbecker
2015-08-18 22:35   ` Andy Lutomirski
2015-08-18 23:02     ` Frederic Weisbecker
2015-08-18 23:07       ` Andy Lutomirski
2015-08-19 17:10         ` Frederic Weisbecker
2015-08-21  7:50           ` Ingo Molnar [this message]
2015-08-21 13:14             ` Frederic Weisbecker
2015-08-19  0:30 ` Andy Lutomirski
2015-08-19 15:54   ` Andy Lutomirski

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