From d8fc764d0b39c912de510b50102b60a64882223e Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Fri, 4 May 2018 15:59:16 -0300 Subject: [PATCH] perf bpf: Add probe() helper to reduce kprobes boilerplate So that kprobe definitions become: int probe(function, variables)(void *ctx, int err, var1, var2, ...) The existing 5sec.c, got converted and goes from: SEC("func=hrtimer_nanosleep rqtp->tv_sec") int func(void *ctx, int err, long sec) { } To: int probe(hrtimer_nanosleep, rqtp->tv_sec)(void *ctx, int err, long sec) { } If we decide to add tv_nsec as well, then it becomes: $ cat tools/perf/examples/bpf/5sec.c #include int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec) { return sec == 5; } license(GPL); $ And if we run it, system wide as before and run some 'sleep' with values for the tv_nsec field, we get: # perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c 0.000 perf_bpf_probe:hrtimer_nanosleep:(ffffffff9811b5f0) tv_sec=5 tv_nsec=100000000 9641.650 perf_bpf_probe:hrtimer_nanosleep:(ffffffff9811b5f0) tv_sec=5 tv_nsec=123450001 ^C# Cc: Adrian Hunter Cc: David Ahern Cc: Jiri Olsa Cc: Namhyung Kim Cc: Wang Nan Link: https://lkml.kernel.org/n/tip-1v9r8f6ds5av0w9pcwpeknyl@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/examples/bpf/5sec.c | 10 ++++++++-- tools/perf/include/bpf/bpf.h | 3 +++ 2 files changed, 11 insertions(+), 2 deletions(-) diff --git a/tools/perf/examples/bpf/5sec.c b/tools/perf/examples/bpf/5sec.c index 6fc3697ac749..b9c203219691 100644 --- a/tools/perf/examples/bpf/5sec.c +++ b/tools/perf/examples/bpf/5sec.c @@ -15,6 +15,13 @@ . While this is running, run something like "sleep 5s". + . If we decide to add tv_nsec as well, then it becomes: + + int probe(hrtimer_nanosleep, rqtp->tv_sec rqtp->tv_nsec)(void *ctx, int err, long sec, long nsec) + + I.e. add where it comes from (rqtp->tv_nsec) and where it will be + accessible in the function body (nsec) + # perf trace --no-syscalls -e tools/perf/examples/bpf/5sec.c/call-graph=dwarf/ 0.000 perf_bpf_probe:func:(ffffffff9811b5f0) tv_sec=5 hrtimer_nanosleep ([kernel.kallsyms]) @@ -34,8 +41,7 @@ #include -SEC("func=hrtimer_nanosleep rqtp->tv_sec") -int func(void *ctx, int err, long sec) +int probe(hrtimer_nanosleep, rqtp->tv_sec)(void *ctx, int err, long sec) { return sec == 5; } diff --git a/tools/perf/include/bpf/bpf.h b/tools/perf/include/bpf/bpf.h index cdfd18b9c318..dd764ad5efdf 100644 --- a/tools/perf/include/bpf/bpf.h +++ b/tools/perf/include/bpf/bpf.h @@ -3,6 +3,9 @@ #define _PERF_BPF_H #define SEC(NAME) __attribute__((section(NAME), used)) +#define probe(function, vars) \ + SEC(#function "=" #function " " #vars) function + #define license(name) \ char _license[] SEC("license") = #name; \ int _version SEC("version") = LINUX_VERSION_CODE;