On Mon, 6 Nov 2023 22:06:17 -0500 Steven Rostedt <rost...@goodmis.org> wrote:
> On Tue, 7 Nov 2023 09:42:58 +0900 > Masami Hiramatsu (Google) <mhira...@kernel.org> wrote: > > > 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) <mhira...@kernel.org>
