Messages in this thread |  | | Date | Tue, 05 Nov 2013 10:45:12 +0900 | From | Masami Hiramatsu <> | Subject | Re: Re: [PATCH -tip v2 1/3] kprobes: Introduce nokprobe annotation for non-probe-able functions |
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(2013/11/01 22:55), Steven Rostedt wrote: > On Fri, 01 Nov 2013 11:25:32 +0000 > Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> wrote: > >> Instead of __kprobes annotation, introduce 'nokprobe' new annotation >> to annotate that the function is not probed by kprobes. >> >> Previously the '__kprobes' is used just for avoiding probes on >> kprobes-related functions which will be used from kprobes. However >> nowadays we use it for prohibiting probing the functions implicitly >> invoked from kprobes int3 handler, since that causes infinit-loop >> lockup or sudden reboot. In this case, the annotated functions are >> not limited in the kprobes-related functions, and __kprobes looks >> very confusing. (Moreover, actually, most of control-side kprobes >> functions like as register_kprobes() are safely probed by kprobes) >> >> Thus, we decide to introduce 'nokprobe' new annotation. We leave >> "__kprobes" just for compatibility but it should be replaced or >> removed eventually. >> >> New commits must use 'nokprobe' for this purpose. >> >> Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> >> Cc: Ingo Molnar <mingo@kernel.org> >> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> >> Cc: "David S. Miller" <davem@davemloft.net> >> --- >> include/linux/compiler.h | 6 ++++-- >> 1 file changed, 4 insertions(+), 2 deletions(-) >> >> diff --git a/include/linux/compiler.h b/include/linux/compiler.h >> index 92669cd..173c64e 100644 >> --- a/include/linux/compiler.h >> +++ b/include/linux/compiler.h >> @@ -353,8 +353,10 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); >> >> /* Ignore/forbid kprobes attach on very low level functions marked by this attribute: */ >> #ifdef CONFIG_KPROBES >> -# define __kprobes __attribute__((__section__(".kprobes.text"))) >> +# define nokprobe __attribute__((__section__(".kprobes.text"))) > > I wonder if we should have both a __kprobes and nokprobe annotation, > such that we have: > > # define __kprobes __attribute__((__section__(".kprobes.text"))) > # define nokprobe __attribute__((__section__(".nokprobes.text"))) > > Then use __kprobes for the actual kprobes code, and nokprobe for all > the places that must not be traced by kprobes.
No, actually, we don't need __kprobes anymore. That has started historically by misunderstanding the problem. kprobes is using the .kprobes.text only for blacklisting the non probe-able functions. Thus, eventually it should be renamed .nokprobe.text, not be added.
> It just seems strange to me grouping kprobes code with non kprobes code.
Yeah, so I'd like to cleanup all the __kprobes finally (and classify which is not needed).
Thank you,
-- Masami HIRAMATSU IT Management Research Dept. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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