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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 <irogers@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: https://lore.kernel.org/r/20221103045437.163510-5-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
|
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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 <stdio.h>
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 <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: https://lkml.kernel.org/n/tip-4tiaqlx5crf0fwpe7a6j84x7@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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