Re: [PATCH 0/5] perf bpf: Improve error code delivering and output

From: Arnaldo Carvalho de Melo
Date: Tue Nov 03 2015 - 10:43:22 EST


Em Tue, Nov 03, 2015 at 10:44:41AM +0000, Wang Nan escreveu:
> This patchset is based on tip/core.
>
> Arnaldo found some confusing error reports when reviewing BPF related
> patches. This patch set makes some changes:

Thanks for working on this!

I applied the first two and made comments about the conversion to using
err.h, please check,

- Arnaldo

> - perf test only print ok, failed or skip. Extra messages can be seen
> by '-v'.
>
> - libbpf not output anything when called from perf without '-v'.
>
> - Create libbpf and bpf-loader specific error number group to deliver
> precise error. New strerror framework makes adding new error code
> easier.
>
> - Improve error messages.
>
> After applying this patch:
>
> When target object not exist:
>
> $ ls ./foo.o
> ls: cannot access ./foo.o: No such file or directory
> $ ./perf record --event foo.o sleep
> event syntax error: 'foo.o'
> \___ Failed to load foo.o: No such file or directory
>
> (add -v to see detail)
> Run 'perf list' for a list of valid events
>
> Usage: perf record [<options>] [<command>]
> or: perf record [<options>] -- <command> [<options>]
>
> -e, --event <event> event selector. use 'perf list' to list available events
>
> When target object format invalid:
>
> $ cp /etc/passwd ./badbpf.o
> $ ./perf record --event ./badbpf.o sleep
> event syntax error: './badbpf.o'
> \___ Failed to load ./badbpf.o: BPF object format invalid
> (... skip ...)
>
> When run by normal user and /proc/sys/kernel/kptr_restrict is 1:
>
> $ cat /proc/sys/kernel/kptr_restrict
> 1
> $ ./perf record --event ./bpf-script-example.o sleep
> Failed to init vmlinux path.
> event syntax error: './bpf-script-example.o'
> \___ You need to be root, and /proc/sys/kernel/kptr_restrict should be 0
> (... skip ...)
>
> After fixing /proc/sys/kernel/kptr_restrict:
>
> $ sudo -s
> # echo 0 > /proc/sys/kernel/kptr_restrict
> # exit
> $ ./perf record --event ./bpf-script-example.o sleep
> Failed to open kprobe_events: Permission denied
> event syntax error: './bpf-script-example.o'
> \___ You need to be root
> (... skip ...)
>
> Load an object with no 'version' section:
>
> # ./perf record --event ./bpf-script-example.o sleep
> event syntax error: './bpf-script-example.o'
> \___ Failed to load ./bpf-script-example.o: 'version' section incorrect or lost
> (... skip ...)
>
> Load an object with incorrect 'version' section:
> # ./perf record --event ./bpf-script-example.o sleep
> event syntax error: './bpf-script-example.o'
> \___ Failed to load program: Validate your program and check 'license'/'version' sections in your object
> (... skip ...)
>
> When event name not set:
>
> # ./perf record --event ./bpf-script-example.o sleep
> event syntax error: './bpf-script-example.o'
> \___ No event name found in config string
> (... skip ...)
>
> Wang Nan (5):
> perf test: Keep test result clean if '-v' not set
> perf tools: Mute libbpf when '-v' not set
> perf tools: Parsing libbpf return value using err.h
> bpf tools: Improve libbpf error reporting
> perf tools: Improve BPF related error messages output
>
> tools/lib/bpf/libbpf.c | 149 +++++++++++++++++++++++++------------
> tools/lib/bpf/libbpf.h | 12 +++
> tools/perf/tests/attr.c | 3 +-
> tools/perf/tests/code-reading.c | 8 +-
> tools/perf/tests/keep-tracking.c | 4 +-
> tools/perf/tests/llvm.c | 13 ++--
> tools/perf/tests/switch-tracking.c | 4 +-
> tools/perf/util/bpf-loader.c | 110 +++++++++++++++++++++++----
> tools/perf/util/bpf-loader.h | 18 +++++
> tools/perf/util/parse-events.c | 7 +-
> 10 files changed, 243 insertions(+), 85 deletions(-)
>
> --
> 1.8.3.4
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