Re: [PATCH] Documentation/livepatch: remove the limitation for schedule() patching
From: Miroslav Benes
Date: Tue Jan 10 2017 - 05:32:32 EST
On Mon, 9 Jan 2017, Josh Poimboeuf wrote:
> On Mon, Jan 09, 2017 at 01:50:19PM +0100, Miroslav Benes wrote:
> > There is still one thing which I don't understand. Why __schedule()
> > (patched or the original) is not on the stack. The actual "sleep"
> > should happen in __switch_to_asm() which is C function now. And there is a
> > call to __switch_to_asm() in __schedule(). __schedule() thus should be on
> > the stack, shouldn't it? What am I missing? __switch_to_asm() pushes %rbp
> > on the stack...
>
> Ah, this is an unwinder bug. get_frame_pointer() needs to be fixed so
> that for an inactive task it returns a pointer to inactive_task_frame.bp
> rather than the value of inactive_task_frame.bp itself. Will fix it.
And it works with the fix. Thanks.
Miroslav