Re: [tip: x86/asm] x86/asm: Make ASM_CALL_CONSTRAINT conditional on frame pointers

From: Josh Poimboeuf
Date: Fri Mar 07 2025 - 18:22:08 EST


On Sat, Mar 08, 2025 at 12:05:29AM +0100, Ingo Molnar wrote:
>
> * H. Peter Anvin <hpa@xxxxxxxxx> wrote:
>
> > > #endif /* __ASSEMBLY__ */
> >
> > So we are going to be using this version despite the gcc maintainers
> > telling us it is not supported?
>
> No, neither patches are in the x86 tree at the moment.

FWIW, the existing ASM_CALL_CONSTRAINT is also not supported, so this
patch wouldn't have changed anything in that respect.

Regardless I plan to post a new patch set soon with a bunch of cleanups.

It will keep the existing ASM_CALL_CONSTRAINT in place for GCC, and will
use the new __builtin_frame_address(0) input constraint for Clang only.

There will be a new asm_call() interface to hide the mess.

--
Josh