Re: [PATCH v2 4/4] x86/static_call: Add inline static call implementation for x86-64

[Peter Zijlstra]

On Mon, Nov 26, 2018 at 11:56:24AM -0600, Josh Poimboeuf wrote:
> Peter suggested updating the text_poke_bp() interface to add a handler
> which is called from int3 context.  This seems to work.

> @@ -760,8 +761,10 @@ int poke_int3_handler(struct pt_regs *regs)
>  	if (user_mode(regs) || regs->ip != (unsigned long)bp_int3_addr)
>  		return 0;
>  
> -	/* set up the specified breakpoint handler */
> -	regs->ip = (unsigned long) bp_int3_handler;
> +	if (bp_int3_handler)
> +		bp_int3_handler(regs);
> +
> +	regs->ip = (unsigned long)bp_int3_resume;
>  
>  	return 1;
>  

Peter also suggested you write that like:

	if (bp_int3_handler)
		bp_int3_handler(regs, resume);
	else
		regs->ip = resume;

That allows 'abusing' @resume as 'data' pointer for @handler. Which
allows for more complicated handlers.