On Wed, Aug 9, 2023 at 4:43 PM Masami Hiramatsu <mhiramat@xxxxxxxxxx> wrote: > > > I think there are two things that can be meant with "rethook uses ftrace_regs": > > > > - rethook callbacks receive a ftrace_regs (that's what you do further down) > > - rethook can hook to a traced function using a ftrace_regs (that's > > what you use in fprobe now) > > > > But I think the second proposition shouldn't imply that rethook_hook > > can _only_ hook to ftrace_regs. For the kprobe use case, I think there > > should also be a rethook_hook_pt_regs() that operates on a pt_regs. We > > could have a default implementation of rethook_hook that calls into > > the other (or vice versa) on HAVE_FTRACE_REGS_COMPATIBLE_WITH_PT_REGS > > but I think it's good to separate these two APIs > > Yeah, so for simplying the 2nd case, I added this dependency. > > diff --git a/arch/Kconfig b/arch/Kconfig > index aff2746c8af2..e321bdb8b22b 100644 > --- a/arch/Kconfig > +++ b/arch/Kconfig > @@ -201,6 +201,7 @@ config KRETPROBE_ON_RETHOOK > def_bool y > depends on HAVE_RETHOOK > depends on KRETPROBES > + depends on HAVE_PT_REGS_COMPAT_FTRACE_REGS || !HAVE_DYNAMIC_FTRACE_WITH_ARGS > select RETHOOK > > This is the point why I said that "do not remove kretprobe trampoline". > If there is arch dependent kretprobe trampoline, kretprobe does not use > the rethook for hooking return. And eventually I would like to remove > kretprobe itself (replace it with fprobe + rethook). If so, I don't want > to pay more efforts on this part, and keep kretprobe on rethook as it is. What are your thoughts on kprobe + rethook though ? If that's something you think is worth having, then in this case, it seems that having a rethook_hook_pt_regs() API would help users. If that's a frankenstein use case you don't want to support then I agree we can live without this API and get away with the cast protected by the depends on HAVE_PT_REGS_COMPAT_FTRACE_REGS...
