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authorArnaldo Carvalho de Melo <acme@redhat.com>2018-05-04 21:59:16 +0300
committerArnaldo Carvalho de Melo <acme@redhat.com>2018-05-15 20:31:24 +0300
commitd8fc764d0b39c912de510b50102b60a64882223e (patch)
tree8ffbda5a7322abf331f4aae229a980be5283c909 /tools/perf/examples
parent1f477305ab462e2fd1fa8a4c4fa425ad752b3175 (diff)
downloadlinux-d8fc764d0b39c912de510b50102b60a64882223e.tar.xz
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 <bpf.h> 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 <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-1v9r8f6ds5av0w9pcwpeknyl@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/examples')
-rw-r--r--tools/perf/examples/bpf/5sec.c10
1 files changed, 8 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 <bpf.h>
-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;
}