On Mon, 6 Nov 2023 22:06:17 -0500
Steven Rostedt [off-list ref] wrote:

On Tue, 7 Nov 2023 09:42:58 +0900
Masami Hiramatsu (Google) [off-list ref] wrote:

quoted

Got it. So does ftrace_regs need a placeholder for direct trampoline?
(Or, can we use a register to pass it?)
I think we don't need to clear it for return_to_handler() but if
`ftrace_regs` spec requires it, it is better to do so.

It's per arch defined. I think I wrote somewhere that it just needs to pass
back something that can tell if the handler is to return to a direct
trampoline or not. It could be a unused register, or something else.

Oh, I meant the flag (address) for "return" trampoline. If we have
direct "return" trampoline we may use it, but currently not.

It's only needed if an architecture supports direct trampolines.

I see, and x86_64 needs it.
OK, maybe better to keep it clear on x86-64 even on the
return handler.

Thank you,

-- Steve

-- 
Masami Hiramatsu (Google) [off-list ref]