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SubjectRe: x86-32: Early microcode loading stumbles over disabled DYNAMIC_FTRACE
On Fri, 30 Aug 2013 09:35:18 -0700
"H. Peter Anvin" <hpa@zytor.com> wrote:

> 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.
>

We could do that too, as static tracing already gives us high overhead,
I'm not sure how much more overhead another check like this even
matters.

Who uses static tracing? I only use it to test that it still works ;-)

-- Steve


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