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[PATCH v11 31/39] perf tools: Parse probe points of eBPF programs during preparation

From Wang Nan <wangnan0@huawei.com>
Newsgroups linux.kernel
Subject [PATCH v11 31/39] perf tools: Parse probe points of eBPF programs during preparation
Date 2015-07-08 15:30 +0200
Message-ID <pJXAe-3fG-25@gated-at.bofh.it> (permalink)
References <pJXqx-3bZ-3@gated-at.bofh.it>
Organization linux.* mail to news gateway

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This patch parses section name of each program, and creates
corresponding 'struct perf_probe_event' structure.

parse_perf_probe_command() is used to do the main parsing works.
Parsing result is stored into a global array. This is because
add_perf_probe_events() is non-reentrantable. In following patch,
add_perf_probe_events will be introduced to insert kprobes. It accepts
an array of 'struct perf_probe_event' and do all works in one call.

Define PERF_BPF_PROBE_GROUP as "perf_bpf_probe", which will be used
as group name of all eBPF probing points.

This patch utilizes bpf_program__set_private(), bind perf_probe_event
with bpf program by private field.

Signed-off-by: Wang Nan <wangnan0@huawei.com>
---
 tools/perf/util/bpf-loader.c | 126 ++++++++++++++++++++++++++++++++++++++++++-
 tools/perf/util/bpf-loader.h |   2 +
 2 files changed, 126 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index 61d3adf..e810d05 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -10,6 +10,8 @@
 #include "debug.h"
 #include "bpf-loader.h"
 #include "llvm-utils.h"
+#include "probe-event.h"
+#include "probe-finder.h"
 
 #define DEFINE_PRINT_FN(name, level) \
 static int libbpf_##name(const char *fmt, ...)	\
@@ -29,9 +31,122 @@ DEFINE_PRINT_FN(debug, 1)
 
 static bool libbpf_initialized;
 
+static struct perf_probe_event probe_event_array[MAX_PROBES];
+static size_t nr_probe_events;
+
+static struct perf_probe_event *
+alloc_perf_probe_event(void)
+{
+	struct perf_probe_event *pev;
+	int n = nr_probe_events;
+
+	if (n >= MAX_PROBES) {
+		pr_err("bpf: too many events, increase MAX_PROBES\n");
+		return NULL;
+	}
+
+	nr_probe_events = n + 1;
+	pev = &probe_event_array[n];
+	bzero(pev, sizeof(*pev));
+	return pev;
+}
+
+struct bpf_prog_priv {
+	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;
+
+	if (priv->pev)
+		clear_perf_probe_event(priv->pev);
+	free(priv);
+}
+
+static int
+config_bpf_program(struct bpf_program *prog)
+{
+	struct perf_probe_event *pev = alloc_perf_probe_event();
+	struct bpf_prog_priv *priv = NULL;
+	const char *config_str;
+	int err;
+
+	/* pr_err has been done by alloc_perf_probe_event */
+	if (!pev)
+		return -ENOMEM;
+
+	err = bpf_program__get_title(prog, &config_str, false);
+	if (err || !config_str) {
+		pr_err("bpf: unable to get title for program\n");
+		return -EINVAL;
+	}
+
+	pr_debug("bpf: config program '%s'\n", config_str);
+	err = parse_perf_probe_command(config_str, pev);
+	if (err < 0) {
+		pr_err("bpf: '%s' is not a valid config string\n",
+		       config_str);
+		/* parse failed, don't need clear pev. */
+		return -EINVAL;
+	}
+
+	if (pev->group && strcmp(pev->group, PERF_BPF_PROBE_GROUP)) {
+		pr_err("bpf: '%s': group for event is set and not '%s'.\n",
+		       config_str, PERF_BPF_PROBE_GROUP);
+		err = -EINVAL;
+		goto errout;
+	} else if (!pev->group)
+		pev->group = strdup(PERF_BPF_PROBE_GROUP);
+
+	if (!pev->group) {
+		pr_err("bpf: strdup failed\n");
+		err = -ENOMEM;
+		goto errout;
+	}
+
+	if (!pev->event) {
+		pr_err("bpf: '%s': event name is missing\n",
+		       config_str);
+		err = -EINVAL;
+		goto errout;
+	}
+
+	pr_debug("bpf: config '%s' is ok\n", config_str);
+
+	priv = calloc(1, sizeof(*priv));
+	if (!priv) {
+		pr_err("bpf: failed to alloc memory\n");
+		err = -ENOMEM;
+		goto errout;
+	}
+
+	priv->pev = pev;
+
+	err = bpf_program__set_private(prog, priv,
+				       bpf_prog_priv__clear);
+	if (err) {
+		pr_err("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;
+}
+
 int bpf__prepare_load(const char *filename, bool source)
 {
 	struct bpf_object *obj;
+	struct bpf_program *prog;
+	int err = 0;
 
 	if (!libbpf_initialized)
 		libbpf_set_print(libbpf_warning,
@@ -41,7 +156,6 @@ int bpf__prepare_load(const char *filename, bool source)
 	if (source) {
 		void *obj_buf;
 		size_t obj_buf_sz;
-		int err;
 
 		err = llvm__compile_bpf(filename, &obj_buf, &obj_buf_sz);
 		if (err)
@@ -56,12 +170,20 @@ int bpf__prepare_load(const char *filename, bool source)
 		return -EINVAL;
 	}
 
+	bpf_object__for_each_program(prog, obj) {
+		err = config_bpf_program(prog);
+		if (err)
+			goto errout;
+	}
+
 	/*
 	 * Throw object pointer away: it will be retrived using
 	 * bpf_objects iterater.
 	 */
-
 	return 0;
+errout:
+	bpf_object__close(obj);
+	return err;
 }
 
 void bpf__clear(void)
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index 5566be0..5a3c954 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -8,6 +8,8 @@
 #include <linux/compiler.h>
 #include "debug.h"
 
+#define PERF_BPF_PROBE_GROUP "perf_bpf_probe"
+
 #ifdef HAVE_LIBBPF_SUPPORT
 int bpf__prepare_load(const char *filename, bool source);
 
-- 
1.8.3.4

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Thread

[PATCH v11 00/39] perf tools: filtering events using eBPF programs - part1 Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 03/39] bpf tools: Introduce 'bpf' library and add bpf feature check Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 35/39] perf tools: Add bpf_fd field to evsel and config it Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 28/39] perf tools: Make perf depend on libbpf Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 34/39] perf record: Load all eBPF object into kernel Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 13/39] bpf tools: Collect relocation sections from SHT_REL sections Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 22/39] bpf tools: Link all bpf objects onto a list Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 02/39] tracing, perf: Implement BPF programs attached to uprobes Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 07/39] bpf tools: Check endianness and make libbpf fail early Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 38/39] perf record: Add clang options for compiling BPF scripts Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 33/39] perf record: Probe at kprobe points Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 32/39] perf probe: Attach trace_probe_event with perf_probe_event Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 36/39] perf tools: Attach eBPF program to perf event Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 23/39] perf tools: Introduce llvm config options Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 11/39] bpf tools: Collect symbol table from SHT_SYMTAB section Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 10/39] bpf tools: Collect map definitions from 'maps' section Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:20 +0200
  [PATCH v11 19/39] bpf tools: Load eBPF programs in object files into kernel Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 18/39] bpf tools: Introduce bpf_load_program() to bpf.c Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 15/39] bpf tools: Add bpf.c/h for common bpf operations Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 29/39] perf record: Enable passing bpf object file to --event Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 05/39] bpf tools: Open eBPF object file and do basic validation Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 27/39] perf tests: Add LLVM test for eBPF on-the-fly compiling Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 09/39] bpf tools: Collect version and license from ELF sections Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 31/39] perf tools: Parse probe points of eBPF programs during preparation Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 17/39] bpf tools: Relocate eBPF programs Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 16/39] bpf tools: Create eBPF maps defined in an object file Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 14/39] bpf tools: Record map accessing instructions for each program Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 25/39] perf tools: Auto detecting kernel build directory Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 39/39] bpf tools: Load a program with different instance using preprocessor Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 04/39] bpf tools: Allow caller to set printing function Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 21/39] bpf tools: Introduce accessors for struct bpf_object Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 06/39] bpf tools: Read eBPF object from buffer Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 24/39] perf tools: Call clang to compile C source to object code Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 20/39] bpf tools: Introduce accessors for struct bpf_program Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 37/39] perf tools: Suppress probing messages when probing by BPF loading Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  [PATCH v11 26/39] perf tools: Auto detecting kernel include options Wang Nan <wangnan0@huawei.com> - 2015-07-08 15:30 +0200
  Re: [PATCH v11 00/39] perf tools: filtering events using eBPF  programs - part1 Arnaldo Carvalho de Melo <acme@kernel.org> - 2015-07-08 16:10 +0200

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