[tip:perf/urgent] perf bpf: Save bpf_prog_info information as headers to perf.data

From: tip-bot for Song Liu
Date: Fri Mar 22 2019 - 18:40:00 EST

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Commit-ID: 606f972b1361f477cbd4e6e8ac00742fde4b39db
Gitweb: https://git.kernel.org/tip/606f972b1361f477cbd4e6e8ac00742fde4b39db
Author: Song Liu <songliubraving@xxxxxx>
AuthorDate: Mon, 11 Mar 2019 22:30:43 -0700
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Tue, 19 Mar 2019 16:52:06 -0300

perf bpf: Save bpf_prog_info information as headers to perf.data

This patch enables perf-record to save bpf_prog_info information as
headers to perf.data. A new header type HEADER_BPF_PROG_INFO is
introduced for this data.

Committer testing:

As root, being on the kernel sources top level directory, run:

# perf trace -e tools/perf/examples/bpf/augmented_raw_syscalls.c -e *msg

Just to compile and load a BPF program that attaches to the
raw_syscalls:sys_{enter,exit} tracepoints to trace the syscalls ending
in "msg" (recvmsg, sendmsg, recvmmsg, sendmmsg, etc).

Then do a systemwide perf record session for a few seconds:

# perf record -a sleep 2s

Then look at:

# perf report --header-only | grep -i bpf
# bpf_prog_info of id 13
# bpf_prog_info of id 14
# bpf_prog_info of id 15
# bpf_prog_info of id 16
# bpf_prog_info of id 17
# bpf_prog_info of id 18
# bpf_prog_info of id 21
# bpf_prog_info of id 22
# bpf_prog_info of id 208
# bpf_prog_info of id 209
#

We need to show more info about these programs, like bpftool does for
the ones running on the system, i.e. 'perf record/perf report' become a
way of saving the BPF state in a machine to then analyse on another,
together with all the other information that is already saved in the
perf.data header:

# perf report --header-only
# ========
# captured on : Tue Mar 12 11:42:13 2019
# header version : 1
# data offset : 296
# data size : 16294184
# feat offset : 16294480
# hostname : quaco
# os release : 5.0.0+
# perf version : 5.0.gd783c8
# arch : x86_64
# nrcpus online : 8
# nrcpus avail : 8
# cpudesc : Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz
# cpuid : GenuineIntel,6,142,10
# total memory : 24555720 kB
# cmdline : /home/acme/bin/perf (deleted) record -a
# event : name = cycles:ppp, , id = { 3190123, 3190124, 3190125, 3190126, 3190127, 3190128, 3190129, 3190130 }, size = 112, { sample_period, sample_freq } = 4000, sample_type = IP|TID|TIME|CPU|PERIOD, read_format = ID, disabled = 1, inherit = 1, mmap = 1, comm = 1, freq = 1, task = 1, precise_ip = 3, sample_id_all = 1, exclude_guest = 1, mmap2 = 1, comm_exec = 1
# CPU_TOPOLOGY info available, use -I to display
# NUMA_TOPOLOGY info available, use -I to display
# pmu mappings: intel_pt = 8, software = 1, power = 11, uprobe = 7, uncore_imc = 12, cpu = 4, cstate_core = 18, uncore_cbox_2 = 15, breakpoint = 5, uncore_cbox_0 = 13, tracepoint = 2, cstate_pkg = 19, uncore_arb = 17, kprobe = 6, i915 = 10, msr = 9, uncore_cbox_3 = 16, uncore_cbox_1 = 14
# CACHE info available, use -I to display
# time of first sample : 116392.441701
# time of last sample : 116400.932584
# sample duration : 8490.883 ms
# MEM_TOPOLOGY info available, use -I to display
# bpf_prog_info of id 13
# bpf_prog_info of id 14
# bpf_prog_info of id 15
# bpf_prog_info of id 16
# bpf_prog_info of id 17
# bpf_prog_info of id 18
# bpf_prog_info of id 21
# bpf_prog_info of id 22
# bpf_prog_info of id 208
# bpf_prog_info of id 209
# missing features: TRACING_DATA BRANCH_STACK GROUP_DESC AUXTRACE STAT CLOCKID DIR_FORMAT
# ========
#

Committer notes:

We can't use the libbpf unconditionally, as the build may have been with
NO_LIBBPF, when we end up with linking errors, so provide dummy
{process,write}_bpf_prog_info() wrapped by HAVE_LIBBPF_SUPPORT for that
case.

Printing are not affected by this, so can continue as is.

Signed-off-by: Song Liu <songliubraving@xxxxxx>
Reviewed-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Tested-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Alexei Starovoitov <ast@xxxxxxxxxx>
Cc: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stanislav Fomichev <sdf@xxxxxxxxxx>
Cc: kernel-team@xxxxxx
Link: http://lkml.kernel.org/r/20190312053051.2690567-8-songliubraving@xxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/header.c | 153 ++++++++++++++++++++++++++++++++++++++++++++++-
tools/perf/util/header.h | 1 +
2 files changed, 153 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index b0683bf4d9f3..e6a81af516f6 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -18,6 +18,7 @@
#include <sys/utsname.h>
#include <linux/time64.h>
#include <dirent.h>
+#include <bpf/libbpf.h>

#include "evlist.h"
#include "evsel.h"
@@ -40,6 +41,7 @@
#include "time-utils.h"
#include "units.h"
#include "cputopo.h"
+#include "bpf-event.h"

#include "sane_ctype.h"

@@ -876,6 +878,56 @@ static int write_dir_format(struct feat_fd *ff,
return do_write(ff, &data->dir.version, sizeof(data->dir.version));
}

+#ifdef HAVE_LIBBPF_SUPPORT
+static int write_bpf_prog_info(struct feat_fd *ff,
+ struct perf_evlist *evlist __maybe_unused)
+{
+ struct perf_env *env = &ff->ph->env;
+ struct rb_root *root;
+ struct rb_node *next;
+ int ret;
+
+ down_read(&env->bpf_progs.lock);
+
+ ret = do_write(ff, &env->bpf_progs.infos_cnt,
+ sizeof(env->bpf_progs.infos_cnt));
+ if (ret < 0)
+ goto out;
+
+ root = &env->bpf_progs.infos;
+ next = rb_first(root);
+ while (next) {
+ struct bpf_prog_info_node *node;
+ size_t len;
+
+ node = rb_entry(next, struct bpf_prog_info_node, rb_node);
+ next = rb_next(&node->rb_node);
+ len = sizeof(struct bpf_prog_info_linear) +
+ node->info_linear->data_len;
+
+ /* before writing to file, translate address to offset */
+ bpf_program__bpil_addr_to_offs(node->info_linear);
+ ret = do_write(ff, node->info_linear, len);
+ /*
+ * translate back to address even when do_write() fails,
+ * so that this function never changes the data.
+ */
+ bpf_program__bpil_offs_to_addr(node->info_linear);
+ if (ret < 0)
+ goto out;
+ }
+out:
+ up_read(&env->bpf_progs.lock);
+ return ret;
+}
+#else // HAVE_LIBBPF_SUPPORT
+static int write_bpf_prog_info(struct feat_fd *ff __maybe_unused,
+ struct perf_evlist *evlist __maybe_unused)
+{
+ return 0;
+}
+#endif // HAVE_LIBBPF_SUPPORT
+
static int cpu_cache_level__sort(const void *a, const void *b)
{
struct cpu_cache_level *cache_a = (struct cpu_cache_level *)a;
@@ -1367,6 +1419,29 @@ static void print_dir_format(struct feat_fd *ff, FILE *fp)
fprintf(fp, "# directory data version : %"PRIu64"\n", data->dir.version);
}

+static void print_bpf_prog_info(struct feat_fd *ff, FILE *fp)
+{
+ struct perf_env *env = &ff->ph->env;
+ struct rb_root *root;
+ struct rb_node *next;
+
+ down_read(&env->bpf_progs.lock);
+
+ root = &env->bpf_progs.infos;
+ next = rb_first(root);
+
+ while (next) {
+ struct bpf_prog_info_node *node;
+
+ node = rb_entry(next, struct bpf_prog_info_node, rb_node);
+ next = rb_next(&node->rb_node);
+ fprintf(fp, "# bpf_prog_info of id %u\n",
+ node->info_linear->info.id);
+ }
+
+ up_read(&env->bpf_progs.lock);
+}
+
static void free_event_desc(struct perf_evsel *events)
{
struct perf_evsel *evsel;
@@ -2414,6 +2489,81 @@ static int process_dir_format(struct feat_fd *ff,
return do_read_u64(ff, &data->dir.version);
}

+#ifdef HAVE_LIBBPF_SUPPORT
+static int process_bpf_prog_info(struct feat_fd *ff, void *data __maybe_unused)
+{
+ struct bpf_prog_info_linear *info_linear;
+ struct bpf_prog_info_node *info_node;
+ struct perf_env *env = &ff->ph->env;
+ u32 count, i;
+ int err = -1;
+
+ if (ff->ph->needs_swap) {
+ pr_warning("interpreting bpf_prog_info from systems with endianity is not yet supported\n");
+ return 0;
+ }
+
+ if (do_read_u32(ff, &count))
+ return -1;
+
+ down_write(&env->bpf_progs.lock);
+
+ for (i = 0; i < count; ++i) {
+ u32 info_len, data_len;
+
+ info_linear = NULL;
+ info_node = NULL;
+ if (do_read_u32(ff, &info_len))
+ goto out;
+ if (do_read_u32(ff, &data_len))
+ goto out;
+
+ if (info_len > sizeof(struct bpf_prog_info)) {
+ pr_warning("detected invalid bpf_prog_info\n");
+ goto out;
+ }
+
+ info_linear = malloc(sizeof(struct bpf_prog_info_linear) +
+ data_len);
+ if (!info_linear)
+ goto out;
+ info_linear->info_len = sizeof(struct bpf_prog_info);
+ info_linear->data_len = data_len;
+ if (do_read_u64(ff, (u64 *)(&info_linear->arrays)))
+ goto out;
+ if (__do_read(ff, &info_linear->info, info_len))
+ goto out;
+ if (info_len < sizeof(struct bpf_prog_info))
+ memset(((void *)(&info_linear->info)) + info_len, 0,
+ sizeof(struct bpf_prog_info) - info_len);
+
+ if (__do_read(ff, info_linear->data, data_len))
+ goto out;
+
+ info_node = malloc(sizeof(struct bpf_prog_info_node));
+ if (!info_node)
+ goto out;
+
+ /* after reading from file, translate offset to address */
+ bpf_program__bpil_offs_to_addr(info_linear);
+ info_node->info_linear = info_linear;
+ perf_env__insert_bpf_prog_info(env, info_node);
+ }
+
+ return 0;
+out:
+ free(info_linear);
+ free(info_node);
+ up_write(&env->bpf_progs.lock);
+ return err;
+}
+#else // HAVE_LIBBPF_SUPPORT
+static int process_bpf_prog_info(struct feat_fd *ff __maybe_unused, void *data __maybe_unused)
+{
+ return 0;
+}
+#endif // HAVE_LIBBPF_SUPPORT
+
struct feature_ops {
int (*write)(struct feat_fd *ff, struct perf_evlist *evlist);
void (*print)(struct feat_fd *ff, FILE *fp);
@@ -2474,7 +2624,8 @@ static const struct feature_ops feat_ops[HEADER_LAST_FEATURE] = {
FEAT_OPR(SAMPLE_TIME, sample_time, false),
FEAT_OPR(MEM_TOPOLOGY, mem_topology, true),
FEAT_OPR(CLOCKID, clockid, false),
- FEAT_OPN(DIR_FORMAT, dir_format, false)
+ FEAT_OPN(DIR_FORMAT, dir_format, false),
+ FEAT_OPR(BPF_PROG_INFO, bpf_prog_info, false)
};

struct header_print_data {
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index 6a231340238d..1dc85f0f895d 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -40,6 +40,7 @@ enum {
HEADER_MEM_TOPOLOGY,
HEADER_CLOCKID,
HEADER_DIR_FORMAT,
+ HEADER_BPF_PROG_INFO,
HEADER_LAST_FEATURE,
HEADER_FEAT_BITS = 256,
};

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