On Wed, Nov 18, 2020 at 07:31:50PM +0100, Florian Weimer 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. Like I said (but you cut off, didn't realise it matters I guess): > > In a function declaration that is not part of a definition it means no > > information about the arguments is specified, a quite different thing. Since the caller does not know if the callee will need a save area, it has to assume it does. Similar is true for many ABIs. > 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.) If you have no prototype for a function, you have to assume worst case, yes. Calling things "a () function" can mean two things (a declaration that is or isn't a definition, two very different things), so it helps to be explicit about it. Just use (void) and do not worry :-) Segher
