Re: violating function pointer signature

Steven Rostedt
2020-11-18T18:58:51Z

On Wed, 18 Nov 2020 19:31:50 +0100
Florian Weimer <fw@deneb.enyo.de> wrote:

> * Segher Boessenkool:
>
> > On Wed, Nov 18, 2020 at 12:17:30PM -0500, Steven Rostedt wrote:
> >> I could change the stub from (void) to () if that would be better.
> >
> > Don't? In a function definition they mean exactly the same thing (and
> > the kernel uses (void) everywhere else, which many people find clearer).
>
> And I think () functions expected a caller-provided parameter save
> area on powerpc64le, while (void) functions do not. It does not
> matter for an empty function, but GCC prefers to use the parameter
> save area instead of setting up a stack frame if it is present. So
> you get stack corruption if you call a () function as a (void)
> function. (The other way round is fine.)

I wonder if we should define on all architectures a void void_stub(void),
in assembly, that just does a return, an not worry about gcc messing up the
creation of the stub function.

On x86_64:

GLOBAL(void_stub)
retq

And so on.

-- Steve