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SubjectRe: perf tools: interface for improved PEBS ABI can accept wrong parameter

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;
> }
> --
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--
Thanks,

Ingo


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