Re: x86-32: Early microcode loading stumbles over disabledDYNAMIC_FTRACE

[Steven Rostedt]

On Fri, 30 Aug 2013 09:35:18 -0700
"H. Peter Anvin" <hpa@xxxxxxxxx> 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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/