Messages in this thread |  | | | Date | Wed, 13 Jun 2012 17:25:40 +0900 | | From | Masami Hiramatsu <> | | Subject | Re: [RFC][PATCH 00/13 v2] kprobes/ftrace: Making ftrace usable for kprobes |
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(2012/06/13 7:43), Steven Rostedt wrote: > If an arch supports passing of ftrace ops, it must also pass regs. > But it does not need to support passing regs. By default > an arch can just pass NULL. If it supports regs, then > it can allow tools like kprobes to ask for regs. Otherwise the > regs parameter should just be NULL.
Hmm, by default, will the ftrace_ops be also NULL? or NULL only if the arch doesn't support passing ftrace ops? I mean, should the generic handler always check if ftrace_ops isn't NULL before using it?
> The second set is Masami's patches ported on top of these changes. > > This is v2, and I've cleaned the patches up a bit and added a lot more > comments. This is a more serious RFC as this is the current way I plan > on pushing it to mainline. But I'm posting first in case someone spots > something that I missed. I'll also be doing more testing on it and if > someting comes up I'll obviously will fix it before pushing. > > Some change since v1: > > Added fix for undefined ftrace_location() when compiling with !DYNAMIC_FTRACE. > > Added missing regs passed for x86_64 (segment regs, and r11). > > Saved flags for when regs are being saved. The cmp in the mcount trampoline > that checks if function tracing is disabled will save flags before > the compare, and restore flags before returning back to the function.
Nice! :) this is what I hope in previous thread.
> Decided that passing partial regs is a bad idea. Either the arch should > pass all regs or NULL. Even though partial regs are saved for calling the > function, it does't make sense to give that to the callback. By making > regs be full pt_regs or NULL, then the callbacks can simply check if > regs is NULL and if it isn't it can do more functionality, but if it > is NULL then it just does limited work. Having 'partial regs' would just > complicate that for no good reason. If in the future we want partial regs, > we can add another flag to request it.
Agreed.
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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