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88d6160737
Enhance bpftool to display comprehensive information about exposed
perf_event links, covering uprobe, kprobe, tracepoint, and generic perf
event. The resulting output will include the following details:
$ tools/bpf/bpftool/bpftool link show
3: perf_event prog 14
event software:cpu-clock
bpf_cookie 0
pids perf_event(19483)
4: perf_event prog 14
event hw-cache:LLC-load-misses
bpf_cookie 0
pids perf_event(19483)
5: perf_event prog 14
event hardware:cpu-cycles
bpf_cookie 0
pids perf_event(19483)
6: perf_event prog 19
tracepoint sched_switch
bpf_cookie 0
pids tracepoint(20947)
7: perf_event prog 26
uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
bpf_cookie 0
pids uprobe(21973)
8: perf_event prog 27
uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
bpf_cookie 0
pids uprobe(21973)
10: perf_event prog 43
kprobe ffffffffb70a9660 kernel_clone
bpf_cookie 0
pids kprobe(35275)
11: perf_event prog 41
kretprobe ffffffffb70a9660 kernel_clone
bpf_cookie 0
pids kprobe(35275)
$ tools/bpf/bpftool/bpftool link show -j
[{"id":3,"type":"perf_event","prog_id":14,"event_type":"software","event_config":"cpu-clock","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":4,"type":"perf_event","prog_id":14,"event_type":"hw-cache","event_config":"LLC-load-misses","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":5,"type":"perf_event","prog_id":14,"event_type":"hardware","event_config":"cpu-cycles","bpf_cookie":0,"pids":[{"pid":19483,"comm":"perf_event"}]},{"id":6,"type":"perf_event","prog_id":19,"tracepoint":"sched_switch","bpf_cookie":0,"pids":[{"pid":20947,"comm":"tracepoint"}]},{"id":7,"type":"perf_event","prog_id":26,"retprobe":false,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":21973,"comm":"uprobe"}]},{"id":8,"type":"perf_event","prog_id":27,"retprobe":true,"file":"/home/dev/waken/bpf/uprobe/a.out","offset":4920,"bpf_cookie":0,"pids":[{"pid":21973,"comm":"uprobe"}]},{"id":10,"type":"perf_event","prog_id":43,"retprobe":false,"addr":18446744072485508704,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":35275,"comm":"kprobe"}]},{"id":11,"type":"perf_event","prog_id":41,"retprobe":true,"addr":18446744072485508704,"func":"kernel_clone","offset":0,"bpf_cookie":0,"pids":[{"pid":35275,"comm":"kprobe"}]}]
For generic perf events, the displayed information in bpftool is limited to
the type and configuration, while other attributes such as sample_period,
sample_freq, etc., are not included.
The kernel function address won't be exposed if it is not permitted by
kptr_restrict. The result as follows when kptr_restrict is 2.
$ tools/bpf/bpftool/bpftool link show
3: perf_event prog 14
event software:cpu-clock
4: perf_event prog 14
event hw-cache:LLC-load-misses
5: perf_event prog 14
event hardware:cpu-cycles
6: perf_event prog 19
tracepoint sched_switch
7: perf_event prog 26
uprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
8: perf_event prog 27
uretprobe /home/dev/waken/bpf/uprobe/a.out+0x1338
10: perf_event prog 43
kprobe kernel_clone
11: perf_event prog 41
kretprobe kernel_clone
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Quentin Monnet <quentin@isovalent.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: https://lore.kernel.org/r/20230709025630.3735-11-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.