linux-kernel - Re: x86-32: Early microcode loading stumbles over disabled DYNAMIC

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Date:	Fri, 30 Aug 2013 09:35:18 -0700
From:	"H. Peter Anvin" <hpa@...or.com>
To:	Steven Rostedt <rostedt@...dmis.org>
CC:	Jan Kiszka <jan.kiszka@...mens.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	x86 <x86@...nel.org>, Ingo Molnar <mingo@...e.hu>,
	Thomas Gleixner <tglx@...utronix.de>
Subject: Re: x86-32: Early microcode loading stumbles over disabled DYNAMIC_FTRACE

On 08/30/2013 08:51 AM, Steven Rostedt wrote:
> 
> It does when dynamic tracing is enabled. But this issue is with static
> tracing, there's no code modification, thus all functions call
> mcount/__fentry__ and we need to look at a variable to determine if we
> should trace or not.
> 

And of course global variables are a no-no without special handling in
pre-paging mode.  Sigh.

You *could* bail out of the calling address is < PAGE_OFFSET.

	-hpa

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