Re: [PATCH V4 04/50] x86/xen: Add xenpv_restore_regs_and_return_to_usermode()

[Borislav Petkov]

On Tue, Nov 02, 2021 at 12:22:50PM +0100, H. Peter Anvin wrote:
> It would be interesting to have an "override function with jmp"
> alternatives macro. It doesn't require any changes to the alternatives
> mechanism proper (but possibly to objtool): it would just insert an
> alternatives entry without adding any code including nops to the main
> path. It would of course only be applicable to a jmp, so a syntax like
> OVERRIDE_JMP feature, target rather than open-coding the instruction
> would probably be a good idea.

I think you wanna say ALTERNATIVE_JMP here seeing how we have
ALTERNATIVE_CALL already :)

As to marking it properly, we can finally add that struct
alt_instr.flags thing we have been trying to add for years now.

/me adds it to his evergrowing todo.

If anyone beats /me to it, /me will gladly have a look at it.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette