lkml.org 
[lkml]   [2021]   [Feb]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [GIT PULL] x86/urgent for v5.11-rc7
On Tue, 9 Feb 2021, Steven Rostedt wrote:

> On Tue, 9 Feb 2021 09:32:34 +0100 (CET)
> Miroslav Benes <mbenes@suse.cz> wrote:
>
> > powerpc has this
> >
> > static inline unsigned long klp_get_ftrace_location(unsigned long faddr)
> > {
> > /*
> > * Live patch works only with -mprofile-kernel on PPC. In this case,
> > * the ftrace location is always within the first 16 bytes.
> > */
> > return ftrace_location_range(faddr, faddr + 16);
> > }
> >
> > > > I suppose the trivial fix is to see if it points to endbr64 and if so,
> > > > increment the addr by the length of that.
> > >
> > > I thought of that too. But one thing that may be possible, is to use
> > > kallsym. I believe you can get the range of a function (start and end of
> > > the function) from kallsyms. Then ask ftrace for the addr in that range
> > > (there should only be one).
> >
> > And we can do this if a hard-coded value live above is not welcome. If I
> > remember correctly, we used to have exactly this in the old versions of
> > kGraft. We walked through all ftrace records, called
> > kallsyms_lookup_size_offset() on every record's ip and if the offset+ip
> > matched faddr (in this case), we returned the ip.
>
> Either way is fine. Question is, should we just wait till CET is
> implemented for the kernel before making any of these changes? Just knowing
> that we have a solution to handle it may be good enough for now.

I'd prefer it to be a part of CET enablement patch set.

Miroslav

\
 
 \ /
  Last update: 2021-02-09 16:18    [W:0.096 / U:2.160 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site