Messages in this thread | | | Date | Tue, 18 Oct 2011 20:19:43 +0200 | From | Ingo Molnar <> | Subject | Re: perf tools: interface for improved PEBS ABI can accept wrong parameter |
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Added more Cc:s of maintainers.
thanks,
Ingo
* Xu, Anhua <anhua.xu@intel.com> wrote:
> For the commit: ab60834 perf, x86: Improve the PEBS ABI > The precise_ip is restricted to 2 bits. The values larger than 3 are truncated less or equal to 3. > This can effectively restricted value passing to syscall. But the user space interface can accept other wrong values which are larger than 3 and lowest 2 bits are 0 can meet the requirement. > > # Here is an example, Monitor "All branches" events on Sandybridge platform( Please refer to SDM 3B Table 30-21 to check Sandybridge specific events ) > > perf top -e r04c4:p # precise_ip = 1 , Correct > perf top -e r04c4:pp # precise_ip =2, Correct > perf top -e r04c4:ppp # not supported, Correct > perf top -e r04c4:pppppp # should not be supported, but after truncation , the number of 'p' treated as 2 which is accepted > > > diff --git a/include/linux/perf_event.h b/include/linux/perf_event.h > index c816075..07d3cf9 100644 > --- a/include/linux/perf_event.h > +++ b/include/linux/perf_event.h > @@ -216,6 +216,7 @@ struct perf_event_attr { > * > * See also PERF_RECORD_MISC_EXACT_IP > */ > +#define SAMPLE_IP_MAX 3 > precise_ip : 2, /* skid constraint */ > mmap_data : 1, /* non-exec mmap data */ > sample_id_all : 1, /* sample_type all events */ > diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c > index 928918b..a2068cc 100644 > --- a/tools/perf/util/parse-events.c > +++ b/tools/perf/util/parse-events.c > @@ -775,7 +775,10 @@ parse_event_modifier(const char **strp, struct perf_event_attr *attr) > attr->exclude_user = eu; > attr->exclude_kernel = ek; > attr->exclude_hv = eh; > - attr->precise_ip = precise; > + if ( precise < SAMPLE_IP_MAX ) > + attr->precise_ip = precise; > + else > + return -1; > > return 0; > } > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/
-- Thanks,
Ingo
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