[tip:perf/core] perf tools: Compile scriptlets to BPF objects when passing '.c' to --event

From: tip-bot for Wang Nan
Date: Fri Oct 30 2015 - 05:15:39 EST

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Commit-ID: d509db0473e40134286271b1d1adadccf42ac467
Gitweb: http://git.kernel.org/tip/d509db0473e40134286271b1d1adadccf42ac467
Author: Wang Nan <wangnan0@xxxxxxxxxx>
AuthorDate: Wed, 14 Oct 2015 12:41:20 +0000
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Thu, 29 Oct 2015 17:16:23 -0300

perf tools: Compile scriptlets to BPF objects when passing '.c' to --event

This patch provides infrastructure for passing source files to --event
directly using:

# perf record --event bpf-file.c command

This patch does following works:

1) Allow passing '.c' file to '--event'. parse_events_load_bpf() is
expanded to allow caller tell it whether the passed file is source
file or object.

2) llvm__compile_bpf() is called to compile the '.c' file, the result
is saved into memory. Use bpf_object__open_buffer() to load the
in-memory object.

Introduces a bpf-script-example.c so we can manually test it:

# perf record --clang-opt "-DLINUX_VERSION_CODE=0x40200" --event ./bpf-script-example.c sleep 1

Note that '--clang-opt' must put before '--event'.

Futher patches will merge it into a testcase so can be tested automatically.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Acked-by: 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: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Link: http://lkml.kernel.org/r/1444826502-49291-10-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: He Kuang <hekuang@xxxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/tests/bpf-script-example.c | 44 +++++++++++++++++++++++++++++++++++
tools/perf/util/bpf-loader.c | 17 ++++++++++++--
tools/perf/util/bpf-loader.h | 5 ++--
tools/perf/util/parse-events.c | 5 ++--
tools/perf/util/parse-events.h | 3 ++-
tools/perf/util/parse-events.l | 3 +++
tools/perf/util/parse-events.y | 15 ++++++++++--
7 files changed, 83 insertions(+), 9 deletions(-)

diff --git a/tools/perf/tests/bpf-script-example.c b/tools/perf/tests/bpf-script-example.c
new file mode 100644
index 0000000..410a70b
--- /dev/null
+++ b/tools/perf/tests/bpf-script-example.c
@@ -0,0 +1,44 @@
+#ifndef LINUX_VERSION_CODE
+# error Need LINUX_VERSION_CODE
+# error Example: for 4.2 kernel, put 'clang-opt="-DLINUX_VERSION_CODE=0x40200" into llvm section of ~/.perfconfig'
+#endif
+#define BPF_ANY 0
+#define BPF_MAP_TYPE_ARRAY 2
+#define BPF_FUNC_map_lookup_elem 1
+#define BPF_FUNC_map_update_elem 2
+
+static void *(*bpf_map_lookup_elem)(void *map, void *key) =
+ (void *) BPF_FUNC_map_lookup_elem;
+static void *(*bpf_map_update_elem)(void *map, void *key, void *value, int flags) =
+ (void *) BPF_FUNC_map_update_elem;
+
+struct bpf_map_def {
+ unsigned int type;
+ unsigned int key_size;
+ unsigned int value_size;
+ unsigned int max_entries;
+};
+
+#define SEC(NAME) __attribute__((section(NAME), used))
+struct bpf_map_def SEC("maps") flip_table = {
+ .type = BPF_MAP_TYPE_ARRAY,
+ .key_size = sizeof(int),
+ .value_size = sizeof(int),
+ .max_entries = 1,
+};
+
+SEC("func=sys_epoll_pwait")
+int bpf_func__sys_epoll_pwait(void *ctx)
+{
+ int ind =0;
+ int *flag = bpf_map_lookup_elem(&flip_table, &ind);
+ int new_flag;
+ if (!flag)
+ return 0;
+ /* flip flag and store back */
+ new_flag = !*flag;
+ bpf_map_update_elem(&flip_table, &ind, &new_flag, BPF_ANY);
+ return new_flag;
+}
+char _license[] SEC("license") = "GPL";
+int _version SEC("version") = LINUX_VERSION_CODE;
diff --git a/tools/perf/util/bpf-loader.c b/tools/perf/util/bpf-loader.c
index aa784a4..ba6f752 100644
--- a/tools/perf/util/bpf-loader.c
+++ b/tools/perf/util/bpf-loader.c
@@ -12,6 +12,7 @@
#include "bpf-loader.h"
#include "probe-event.h"
#include "probe-finder.h" // for MAX_PROBES
+#include "llvm-utils.h"

#define DEFINE_PRINT_FN(name, level) \
static int libbpf_##name(const char *fmt, ...) \
@@ -33,7 +34,7 @@ struct bpf_prog_priv {
struct perf_probe_event pev;
};

-struct bpf_object *bpf__prepare_load(const char *filename)
+struct bpf_object *bpf__prepare_load(const char *filename, bool source)
{
struct bpf_object *obj;
static bool libbpf_initialized;
@@ -45,7 +46,19 @@ struct bpf_object *bpf__prepare_load(const char *filename)
libbpf_initialized = true;
}

- obj = bpf_object__open(filename);
+ if (source) {
+ int err;
+ void *obj_buf;
+ size_t obj_buf_sz;
+
+ err = llvm__compile_bpf(filename, &obj_buf, &obj_buf_sz);
+ if (err)
+ return ERR_PTR(err);
+ obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, filename);
+ free(obj_buf);
+ } else
+ obj = bpf_object__open(filename);
+
if (!obj) {
pr_debug("bpf: failed to load %s\n", filename);
return ERR_PTR(-EINVAL);
diff --git a/tools/perf/util/bpf-loader.h b/tools/perf/util/bpf-loader.h
index a8f25ee..ccd8d7f 100644
--- a/tools/perf/util/bpf-loader.h
+++ b/tools/perf/util/bpf-loader.h
@@ -18,7 +18,7 @@ typedef int (*bpf_prog_iter_callback_t)(struct probe_trace_event *tev,
int fd, void *arg);

#ifdef HAVE_LIBBPF_SUPPORT
-struct bpf_object *bpf__prepare_load(const char *filename);
+struct bpf_object *bpf__prepare_load(const char *filename, bool source);

void bpf__clear(void);

@@ -34,7 +34,8 @@ int bpf__foreach_tev(struct bpf_object *obj,
bpf_prog_iter_callback_t func, void *arg);
#else
static inline struct bpf_object *
-bpf__prepare_load(const char *filename __maybe_unused)
+bpf__prepare_load(const char *filename __maybe_unused,
+ bool source __maybe_unused)
{
pr_debug("ERROR: eBPF object loading is disabled during compiling.\n");
return ERR_PTR(-ENOTSUP);
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index cee8c61..bee6058 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -626,11 +626,12 @@ errout:

int parse_events_load_bpf(struct parse_events_evlist *data,
struct list_head *list,
- char *bpf_file_name)
+ char *bpf_file_name,
+ bool source)
{
struct bpf_object *obj;

- obj = bpf__prepare_load(bpf_file_name);
+ obj = bpf__prepare_load(bpf_file_name, source);
if (IS_ERR(obj) || !obj) {
char errbuf[BUFSIZ];
int err;
diff --git a/tools/perf/util/parse-events.h b/tools/perf/util/parse-events.h
index 765018a..f1a6db1 100644
--- a/tools/perf/util/parse-events.h
+++ b/tools/perf/util/parse-events.h
@@ -125,7 +125,8 @@ int parse_events_add_tracepoint(struct list_head *list, int *idx,
struct list_head *head_config);
int parse_events_load_bpf(struct parse_events_evlist *data,
struct list_head *list,
- char *bpf_file_name);
+ char *bpf_file_name,
+ bool source);
/* Provide this function for perf test */
struct bpf_object;
int parse_events_load_bpf_obj(struct parse_events_evlist *data,
diff --git a/tools/perf/util/parse-events.l b/tools/perf/util/parse-events.l
index cf330eb..58c5831 100644
--- a/tools/perf/util/parse-events.l
+++ b/tools/perf/util/parse-events.l
@@ -116,6 +116,7 @@ group [^,{}/]*[{][^}]*[}][^,{}/]*
event_pmu [^,{}/]+[/][^/]*[/][^,{}/]*
event [^,{}/]+
bpf_object .*\.(o|bpf)
+bpf_source .*\.c

num_dec [0-9]+
num_hex 0x[a-fA-F0-9]+
@@ -161,6 +162,7 @@ modifier_bp [rwx]{1,3}

{event_pmu} |
{bpf_object} |
+{bpf_source} |
{event} {
BEGIN(INITIAL);
REWIND(1);
@@ -269,6 +271,7 @@ r{num_raw_hex} { return raw(yyscanner); }

{modifier_event} { return str(yyscanner, PE_MODIFIER_EVENT); }
{bpf_object} { return str(yyscanner, PE_BPF_OBJECT); }
+{bpf_source} { return str(yyscanner, PE_BPF_SOURCE); }
{name} { return pmu_str_check(yyscanner); }
"/" { BEGIN(config); return '/'; }
- { return '-'; }
diff --git a/tools/perf/util/parse-events.y b/tools/perf/util/parse-events.y
index 497f19b..ad37996 100644
--- a/tools/perf/util/parse-events.y
+++ b/tools/perf/util/parse-events.y
@@ -42,7 +42,7 @@ static inc_group_count(struct list_head *list,
%token PE_VALUE PE_VALUE_SYM_HW PE_VALUE_SYM_SW PE_RAW PE_TERM
%token PE_EVENT_NAME
%token PE_NAME
-%token PE_BPF_OBJECT
+%token PE_BPF_OBJECT PE_BPF_SOURCE
%token PE_MODIFIER_EVENT PE_MODIFIER_BP
%token PE_NAME_CACHE_TYPE PE_NAME_CACHE_OP_RESULT
%token PE_PREFIX_MEM PE_PREFIX_RAW PE_PREFIX_GROUP
@@ -55,6 +55,7 @@ static inc_group_count(struct list_head *list,
%type <num> PE_TERM
%type <str> PE_NAME
%type <str> PE_BPF_OBJECT
+%type <str> PE_BPF_SOURCE
%type <str> PE_NAME_CACHE_TYPE
%type <str> PE_NAME_CACHE_OP_RESULT
%type <str> PE_MODIFIER_EVENT
@@ -461,7 +462,17 @@ PE_BPF_OBJECT
struct list_head *list;

ALLOC_LIST(list);
- ABORT_ON(parse_events_load_bpf(data, list, $1));
+ ABORT_ON(parse_events_load_bpf(data, list, $1, false));
+ $$ = list;
+}
+|
+PE_BPF_SOURCE
+{
+ struct parse_events_evlist *data = _data;
+ struct list_head *list;
+
+ ALLOC_LIST(list);
+ ABORT_ON(parse_events_load_bpf(data, list, $1, true));
$$ = list;
}

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Next message: tip-bot for Rabin Vincent: "[tip:perf/core] perf unwind: Pass symbol source to libunwind"
Previous message: tip-bot for Wang Nan: "[tip:perf/core] perf record: Add clang options for compiling BPF scripts"
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