Re: [PATCH v2] objtool,ftrace: Implement UNWIND_HINT_RET_OFFSET

[Steven Rostedt]

On Wed, 1 Apr 2020 19:09:10 +0200
Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:

> > > +	if (state->cfa.offset != initial_func_cfi.cfa.offset &&
> > > +	    !(ret_offset && state->cfa.offset == initial_func_cfi.cfa.offset + ret_offset))  
> > 
> > Isn't that the same thing as "state->cfa.offset !=
> > initial_func_cfi.cfa.offset + ret_offset" ?  
> 
> I'm confused on what cfa.offset is, sometimes it increase with
> stack_size, sometimes it doesn't.

I believe what Julien is saying is the above logic is equivalent:

	if (x != y &&
	    !(z && x == y + z))

is the same as:

	if (x != y + z)

-- Steve