Messages in this thread | | | Subject | Re: [RFC][PATCH 05/13 v2] ftrace/x86: Add separate function to save regs | From | Steven Rostedt <> | Date | Fri, 15 Jun 2012 07:33:31 -0400 |
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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?
-- Steve
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