Messages in this thread | | | Date | Mon, 18 Jun 2012 18:14:57 +0900 | From | Masami Hiramatsu <> | Subject | Re: [RFC][PATCH 05/13 v2] ftrace/x86: Add separate function to save regs |
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(2012/06/15 20:33), Steven Rostedt wrote: > On Fri, 2012-06-15 at 17:15 +0900, Masami Hiramatsu wrote: > >>> It is OK for an arch to pass NULL regs. All function trace users that >>> require regs passing must add the flag FTRACE_OPS_FL_SAVE_REGS when >>> registering the ftrace_ops and either check if regs is not NULL or >>> check if ARCH_SUPPORTS_FTRACE_SAVE_REGS. If the arch supports passing >>> regs it will set this macro and pass regs for ops that request them. >>> All other archs will just pass NULL. >> >> Hmm, so would you mean that user is responsible for checking >> whether the arch supports save_regs or not? >> I would rather like ftrace to check it as my patch has done. >> I think ARCH_SUPPORTS_FTRACE_SAVE_REGS macro checking in all >> handler code is something like odd... > > I was thinking of routines that may or may not use regs. Actually, I was > thinking about perf in general, that could use regs if supported, or get > its own set. > > But I agree that it may not be the best for those that must have regs. > > Perhaps we could add another flag: > > FTRACE_OPS_FL_SAVE_REGS_IF_SUPPORTED > > Where it wont error out if you have this set. But if you just pass in > FTRACE_OPS_FL_SAVE_REGS (as kprobes does) it will fail. > > How's that sound?
Yeah, that's good for me. :)
Thank you,
-- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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