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Message-ID: <1441523623-152703-7-git-send-email-wangnan0@huawei.com>
Date: Sun, 6 Sep 2015 07:13:22 +0000
From: Wang Nan <wangnan0@...wei.com>
To: <acme@...hat.com>, <ast@...mgrid.com>,
<masami.hiramatsu.pt@...achi.com>, <namhyung@...nel.org>
CC: <a.p.zijlstra@...llo.nl>, <brendan.d.gregg@...il.com>,
<daniel@...earbox.net>, <dsahern@...il.com>, <hekuang@...wei.com>,
<jolsa@...nel.org>, <lizefan@...wei.com>, <paulus@...ba.org>,
<wangnan0@...wei.com>, <xiakaixu@...wei.com>, <pi3orama@....com>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH 06/27] perf bpf: Collect 'struct perf_probe_event' for bpf_program
This patch utilizes bpf_program__set_private(), binding perf_probe_event
with bpf program by private field.
Saving those information so 'perf record' knows which kprobe point a program
should be attached.
Since data in 'struct perf_probe_event' is build by 2 stages, pev_ready
is used to mark whether the information (especially tevs) in 'struct
perf_probe_event' is valid or not. It is false at first, and set to true
by sync_bpf_program_pev(), which copies all pointers in original pev into
a program specific memory region. sync_bpf_program_pev() is called after
apply_perf_probe_events() to make sure ready of data.
Remove code which cleans 'struct perf_probe_event' after bpf__probe()
because pointers in pevs are copied to program's private field, calling
cleanup_perf_probe_events() becomes unsafe.
Signed-off-by: Wang Nan <wangnan0@...wei.com>
Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Alexei Starovoitov <ast@...mgrid.com>
Cc: Brendan Gregg <brendan.d.gregg@...il.com>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: David Ahern <dsahern@...il.com>
Cc: He Kuang <hekuang@...wei.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Kaixu Xia <xiakaixu@...wei.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Paul Mackerras <paulus@...ba.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: Zefan Li <lizefan@...wei.com>
Cc: pi3orama@....com
Link: http://lkml.kernel.org/n/1436445342-1402-21-git-send-email-wangnan0@huawei.com
[Splitted from a larger patch
wangnan: Utilize new perf probe API {convert,apply,cleanup}_perf_probe_events()
]
---
tools/perf/util/bpf-loader.c | 110 +++++++++++++++++++++++++++++++++++++++++--
1 file changed, 106 insertions(+), 4 deletions(-)
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 10505cb..ce95db8 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -30,9 +30,47 @@ DEFINE_PRINT_FN(debug, 1)
static bool libbpf_initialized;
+struct bpf_prog_priv {
+ /*
+ * If pev_ready is false, ppev pointes to a local memory which
+ * is only valid inside bpf__probe().
+ * pev is valid only when pev_ready.
+ */
+ bool pev_ready;
+ union {
+ struct perf_probe_event *ppev;
+ struct perf_probe_event pev;
+ };
+};
+
+static void
+bpf_prog_priv__clear(struct bpf_program *prog __maybe_unused,
+ void *_priv)
+{
+ struct bpf_prog_priv *priv = _priv;
+
+ /* check if pev is initialized */
+ if (priv && priv->pev_ready) {
+ int i;
+
+ /*
+ * Similar code with cleanup_perf_probe_events, but without
+ * exit_symbol_maps().
+ */
+ for (i = 0; i < priv->pev.ntevs; i++)
+ clear_probe_trace_event(&priv->pev.tevs[i]);
+ zfree(&priv->pev.tevs);
+ priv->pev.ntevs = 0;
+
+ clear_perf_probe_event(&priv->pev);
+ }
+ free(priv);
+}
+
static int
config_bpf_program(struct bpf_program *prog, struct perf_probe_event *pev)
{
+ struct bpf_prog_priv *priv = NULL;
const char *config_str;
int err;
@@ -74,14 +112,58 @@ config_bpf_program(struct bpf_program *prog, struct perf_probe_event *pev)
pr_debug("bpf: config '%s' is ok\n", config_str);
+ priv = calloc(1, sizeof(*priv));
+ if (!priv) {
+ pr_debug("bpf: failed to alloc memory\n");
+ err = -ENOMEM;
+ goto errout;
+ }
+
+ /*
+ * At this very early stage, tevs inside pev are not ready.
+ * It becomes usable after add_perf_probe_events() is called.
+ * set pev_ready to false so further access read priv->ppev
+ * only.
+ */
+ priv->pev_ready = false;
+ priv->ppev = pev;
+
+ err = bpf_program__set_private(prog, priv,
+ bpf_prog_priv__clear);
+ if (err) {
+ pr_debug("bpf: set program private failed\n");
+ err = -ENOMEM;
+ goto errout;
+ }
return 0;
errout:
if (pev)
clear_perf_probe_event(pev);
+ if (priv)
+ free(priv);
return err;
}
+static int
+sync_bpf_program_pev(struct bpf_program *prog)
+{
+ int err;
+ struct bpf_prog_priv *priv;
+ struct perf_probe_event *ppev;
+
+ err = bpf_program__get_private(prog, (void **)&priv);
+ if (err || !priv || priv->pev_ready) {
+ pr_debug("Internal error: sync_bpf_program_pev\n");
+ return -EINVAL;
+ }
+
+ ppev = priv->ppev;
+ memcpy(&priv->pev, ppev, sizeof(*ppev));
+ priv->pev_ready = true;
+ return 0;
+}
+
int bpf__prepare_load(const char *filename)
{
struct bpf_object *obj;
@@ -186,15 +268,35 @@ int bpf__probe(void)
}
err = apply_perf_probe_events(pevs, nr_events);
- if (err < 0)
+ if (err < 0) {
pr_debug("bpf probe: failed to probe events\n");
- else
+ goto out_cleanup;
+ } else
is_probed = true;
-out_cleanup:
- cleanup_perf_probe_events(pevs, nr_events);
+
+ /*
+ * After add_perf_probe_events, 'struct perf_probe_event' is ready.
+ * Until now copying program's priv->pev field and freeing
+ * the big array allocated before become safe.
+ */
+ bpf_object__for_each_safe(obj, tmp) {
+ bpf_object__for_each_program(prog, obj) {
+ err = sync_bpf_program_pev(prog);
+ if (err)
+ goto out;
+ }
+ }
out:
+ /*
+ * Don't call cleanup_perf_probe_events() for entries of pevs:
+ * they are used by prog's private field.
+ */
free(pevs);
return err < 0 ? err : 0;
+
+out_cleanup:
+ cleanup_perf_probe_events(pevs, nr_events);
+ goto out;
}
#define bpf__strerror_head(err, buf, size) \
--
2.1.0
--
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