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Commit d19f8564 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

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: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 03d30971

tools/perf/util/Build

+1 −0
Original line number Diff line number Diff line
@@ -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

tools/perf/util/bpf_map.c

0 → 100644
+72 −0
Original line number Diff line number Diff line 
// 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;

}

tools/perf/util/bpf_map.h

0 → 100644
+22 −0
Original line number Diff line number Diff line 
// 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