Re: [PATCH v8 8/8] livepatch: Detect offset for the ftrace location during build

From: Torsten Duwe
Date: Tue Feb 16 2016 - 03:23:10 EST


On Tue, Feb 16, 2016 at 11:17:02AM +0530, Kamalesh Babulal wrote:
> * Petr Mladek <pmladek@xxxxxxxx> [2016-02-12 17:45:17]:
> > int test(int a)
> > {
> > + printk("%d\n", a);
> > return ++a;
> > }
>
> Thanks. This workaround, helped to load sample livepatch module.

N.b.: if you try to livepatch/trace such a leaf function without
global dependencies, it will crash if that function got called with
a different TOC value. Hence this whole testing.

You may alternatively try my gcc patch ;-)

Another caveat is functions with stack arguments (>8 args, varargs).
My code needs special precautions then because of the return helper.

Torsten