perf bpf: Add bpf_map dumper

At some point I'll suggest moving this to libbpf, for now I'll
experiment with ways to dump BPF maps set by events in 'perf trace',
starting with a very basic dumper for the current very limited needs
of the augmented_raw_syscalls code: dumping booleans.

Having functions that apply to the map keys and values and do table
lookup in things like syscall id to string tables should come next.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Yonghong Song <yhs@fb.com>
Link: https://lkml.kernel.org/n/tip-lz14w0esqyt1333aon05jpwc@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Arnaldo Carvalho de Melo 2019-02-19 16:11:56 -03:00
parent 03d309711d
commit d19f856479
3 changed files with 95 additions and 0 deletions

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@ -115,6 +115,7 @@ perf-y += branch.o
perf-y += mem2node.o
perf-$(CONFIG_LIBBPF) += bpf-loader.o
perf-$(CONFIG_LIBBPF) += bpf_map.o
perf-$(CONFIG_BPF_PROLOGUE) += bpf-prologue.o
perf-$(CONFIG_LIBELF) += symbol-elf.o
perf-$(CONFIG_LIBELF) += probe-file.o

72
tools/perf/util/bpf_map.c Normal file
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@ -0,0 +1,72 @@
// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
#include "util/bpf_map.h"
#include <bpf/bpf.h>
#include <bpf/libbpf.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <stdbool.h>
#include <stdlib.h>
#include <unistd.h>
static bool bpf_map_def__is_per_cpu(const struct bpf_map_def *def)
{
return def->type == BPF_MAP_TYPE_PERCPU_HASH ||
def->type == BPF_MAP_TYPE_PERCPU_ARRAY ||
def->type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
def->type == BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE;
}
static void *bpf_map_def__alloc_value(const struct bpf_map_def *def)
{
if (bpf_map_def__is_per_cpu(def))
return malloc(round_up(def->value_size, 8) * sysconf(_SC_NPROCESSORS_CONF));
return malloc(def->value_size);
}
int bpf_map__fprintf(struct bpf_map *map, FILE *fp)
{
const struct bpf_map_def *def = bpf_map__def(map);
void *prev_key = NULL, *key, *value;
int fd = bpf_map__fd(map), err;
int printed = 0;
if (fd < 0)
return fd;
if (IS_ERR(def))
return PTR_ERR(def);
err = -ENOMEM;
key = malloc(def->key_size);
if (key == NULL)
goto out;
value = bpf_map_def__alloc_value(def);
if (value == NULL)
goto out_free_key;
while ((err = bpf_map_get_next_key(fd, prev_key, key) == 0)) {
int intkey = *(int *)key;
if (!bpf_map_lookup_elem(fd, key, value)) {
bool boolval = *(bool *)value;
if (boolval)
printed += fprintf(fp, "[%d] = %d,\n", intkey, boolval);
} else {
printed += fprintf(fp, "[%d] = ERROR,\n", intkey);
}
prev_key = key;
}
if (err == ENOENT)
err = printed;
free(value);
out_free_key:
free(key);
out:
return err;
}

22
tools/perf/util/bpf_map.h Normal file
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@ -0,0 +1,22 @@
// SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
#ifndef __PERF_BPF_MAP_H
#define __PERF_BPF_MAP_H 1
#include <stdio.h>
#include <linux/compiler.h>
struct bpf_map;
#ifdef HAVE_LIBBPF_SUPPORT
int bpf_map__fprintf(struct bpf_map *map, FILE *fp);
#else
static inline int bpf_map__fprintf(struct bpf_map *map __maybe_unused, FILE *fp __maybe_unused)
{
return 0;
}
#endif // HAVE_LIBBPF_SUPPORT
#endif // __PERF_BPF_MAP_H