[PATCH] perf tools: Allow BPF program attach to modules

[Wang Nan]

By extending the syntax of BPF object section names, this patch allows
user to attach BPF programs to symbol in modules. For example:

 SEC("module=i915\n"
     "parse_cmds=i915_parse_cmds")
 int parse_cmds(void *ctx)
 {
     return 1;
 }

Implementation is very simple: like what 'perf probe' does, for module,
fill 'uprobe' field in 'struct perf_probe_event'. Other parts would be
done automatically.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxxxx>
Cc: Brendan Gregg <brendan.d.gregg@xxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kaixu Xia <xiakaixu@xxxxxxxxxx>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@xxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Link: http://lkml.kernel.org/n/ebpf-x1mxko3tby054o573zd575qp@xxxxxxxxxxxxxx
---

This patch is based on commit ad14ba45236a496a7ce25f4ea947d245b1406e40
in my git tree[1], and will be appear in the next pull request of this
perf eBPF support patchset.

[1] https://git.kernel.org/cgit/linux/kernel/git/pi3orama/linux.git

---
 tools/perf/util/bpf-loader.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index b14aff4..a85caae 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -120,10 +120,17 @@ do_config(const char *key, const char *value,
 		pev->target = strdup(value);
 		return 0;
 	}
+	if (strcmp(key, "module") == 0) {
+		pev->uprobes = false;
+		pev->target = strdup(value);
+		return 0;
+	}
 
 	pr_warning("BPF: WARNING: invalid config option in object: %s=%s\n",
 		   key, value);
-	pr_warning("\tHint: Currently only valid option is 'exec=<full patch of file>'\n");
+	pr_warning("\tHint: Currently valid options are:\n");
+	pr_warning("\t          'exec=<full patch of file>'\n");
+	pr_warning("\t          'module=<module name>'\n");
 	return 0;
 }
 
-- 
1.8.3.4

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