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Date: Thu, 9 Feb 2017 11:27:03 +0100
From: Peter Zijlstra <>
To: Kees Cook <>
Cc: Mark Rutland <>,
	"Reshetova, Elena" <>,
	Greg KH <>, Arnd Bergmann <>,
	Thomas Gleixner <>,
	Ingo Molnar <>,
	"H. Peter Anvin" <>,
	Will Deacon <>,
	David Windsor <>,
	Hans Liljestrand <>,
	David Howells <>,
	LKML <>,
	"" <>
Subject: Re: Re: [PATCH 4/4] refcount: Report failures

On Wed, Feb 08, 2017 at 01:20:26PM -0800, Kees Cook wrote:

> Ooooh, that is intense. And the trampolines (EX_REG_HANDLERs) are all
> just there to catch whatever register gcc decides to stuff the value
> into? *cover face* Sure, okay. :)

Right, they shouldn't be big functions, but barring whole program LTO
there's just no knowing which are unused.

> I wonder how many existing WARN callsites could be repurposed to use this?

At the very least all WARN/BUG instances with trivial @format argument
that are inlined I think. For example, things like:

static inline some_function()
	/* ... */
	WARN(cond, "blah blah blah\n");
	/* ... */

where the format has no arguments. Here we can out-of-line the printk()
stuff, which, as is the purpose here, shrinks the size of the inline.

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