linux-stable.git/tools/perf/examples/bpf/hello.c, branch master

perf bpf examples: With no BPF events remove examples

2023-08-15T19:41:48+00:00

The examples were used to give demonstrations of BPF events but such
functionality is now subsumed by using --filter with 'perf record' or
the direct use of BPF skeletons.

Signed-off-by: Ian Rogers 
Acked-by: Jiri Olsa 
Cc: Adrian Hunter 
Cc: Alexander Shishkin 
Cc: Andi Kleen 
Cc: Andrii Nakryiko 
Cc: Anshuman Khandual 
Cc: Athira Rajeev 
Cc: Brendan Gregg 
Cc: Carsten Haitzler 
Cc: Eduard Zingerman 
Cc: Fangrui Song 
Cc: He Kuang 
Cc: Ingo Molnar 
Cc: James Clark 
Cc: Kan Liang 
Cc: Leo Yan 
Cc: Madhavan Srinivasan 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Nathan Chancellor 
Cc: Naveen N. Rao 
Cc: Nick Desaulniers 
Cc: Peter Zijlstra 
Cc: Ravi Bangoria 
Cc: Rob Herring 
Cc: Tiezhu Yang 
Cc: Tom Rix 
Cc: Wang Nan 
Cc: Wang ShaoBo 
Cc: Yang Jihong 
Cc: Yonghong Song 
Cc: YueHaibing 
Cc: bpf@vger.kernel.org
Cc: llvm@lists.linux.dev
Link: https://lore.kernel.org/r/20230810184853.2860737-4-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf trace: hello fix libbpf 1.0+ compatibility

2022-11-04T14:36:23+00:00

Don't use deprecated and now broken map style. Avoid use of
tools/perf/include/bpf/bpf.h and use the more regular BPF headers.

Switch to raw_syscalls:sys_enter to avoid the evlist being empty and
fixing generating output.

Committer testing:

  # perf trace -e ~acme/git/perf/tools/perf/examples/bpf/hello.c --call-graph=dwarf --max-events 5
     0.000 perf/206852 __bpf_stdout__(Hello, world)
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64_after_hwframe ([kernel.kallsyms])
                                       __GI___sched_setaffinity_new (/usr/lib64/libc.so.6)
     8.561 pipewire/2290 __bpf_stdout__(Hello, world)
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64_after_hwframe ([kernel.kallsyms])
                                       __libc_read (/usr/lib64/libc.so.6)
     8.571 pipewire/2290 __bpf_stdout__(Hello, world)
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64_after_hwframe ([kernel.kallsyms])
                                       __GI___ioctl (/usr/lib64/libc.so.6)
     8.586 pipewire/2290 __bpf_stdout__(Hello, world)
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64_after_hwframe ([kernel.kallsyms])
                                       __GI___write (/usr/lib64/libc.so.6)
     8.592 pipewire/2290 __bpf_stdout__(Hello, world)
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       syscall_trace_enter.constprop.0 ([kernel.kallsyms])
                                       do_syscall_64 ([kernel.kallsyms])
                                       entry_SYSCALL_64_after_hwframe ([kernel.kallsyms])
                                       __timerfd_settime (/usr/lib64/libc.so.6)
  #

Signed-off-by: Ian Rogers 
Tested-by: Arnaldo Carvalho de Melo 
Cc: Alexander Shishkin 
Cc: Ingo Molnar 
Cc: Jiri Olsa 
Cc: Leo Yan 
Cc: Mark Rutland 
Cc: Namhyung Kim 
Cc: Peter Zijlstra 
Cc: Stephane Eranian 
Link: https://lore.kernel.org/r/20221103045437.163510-5-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo

perf bpf: Add bpf/stdio.h wrapper to bpf_perf_event_output function

2018-08-08T18:55:55+00:00

That, together with the map __bpf_output__ that is already handled by
'perf trace' to print that event's contents as strings provides a
debugging facility, to show it in use, print a simple string everytime
the syscalls:sys_enter_openat() syscall tracepoint is hit:

  # cat tools/perf/examples/bpf/hello.c
  #include 

  int syscall_enter(openat)(void *args)
  {
	  puts("Hello, world\n");
	  return 0;
  }

  license(GPL);
  #
  # perf trace -e openat,tools/perf/examples/bpf/hello.c cat /etc/passwd > /dev/null
     0.016 (         ): __bpf_stdout__:Hello, world
     0.018 ( 0.010 ms): cat/9079 openat(dfd: CWD, filename: /etc/ld.so.cache, flags: CLOEXEC) = 3
     0.057 (         ): __bpf_stdout__:Hello, world
     0.059 ( 0.011 ms): cat/9079 openat(dfd: CWD, filename: /lib64/libc.so.6, flags: CLOEXEC) = 3
     0.417 (         ): __bpf_stdout__:Hello, world
     0.419 ( 0.009 ms): cat/9079 openat(dfd: CWD, filename: /etc/passwd) = 3
  #

This is part of an ongoing experimentation on making eBPF scripts as
consumed by perf to be as concise as possible and using familiar
concepts such as stdio.h functions, that end up just wrapping the
existing BPF functions, trying to hide as much boilerplate as possible
while using just conventions and C preprocessor tricks.

Cc: Adrian Hunter 
Cc: David Ahern 
Cc: Jiri Olsa 
Cc: Namhyung Kim 
Cc: Wang Nan 
Link: https://lkml.kernel.org/n/tip-4tiaqlx5crf0fwpe7a6j84x7@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo