lkml.org 
[lkml]   [2013]   [Aug]   [30]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: x86-32: Early microcode loading stumbles over disabled DYNAMIC_FTRACE
On 08/23/2013 09:40 AM, Jan Kiszka wrote:
> Hi all,
>
> 32-bit kernels currently crash/reboot in early microcode loading when
> non-dynamic function tracing is enabled. Several functions in that path
> get instrumented with mcount, but its non-dynamic implementation does
> not work before paging is enabled (it accesses global variables at wrong
> addresses).
>
> Below some hunks to get it working again - at least in the absence of
> any microcode in the initrd. Marking all involved functions as __init is
> another option (as __init implies notrace). But I bet there is more
> hidden. I see e.g. a pr_warn() in find_cpio_init that should trigger the
> issue as well if we hit the error it reports (btw. printing at this
> point of the boot should not work anyway, should it?).
>
> Better ideas?
>
> Jan
>

A better idea would be for the mcount/__fentry__ function to simply
return until the function tracing stuff is actually ready.

-hpa




\
 
 \ /
  Last update: 2013-08-30 18:01    [W:0.081 / U:0.100 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site