linux/tools/perf/util/bpf-loader.c
Wang Nan 6371ca3b54 bpf tools: Improve libbpf error reporting
In this patch, a series of libbpf specific error numbers and
libbpf_strerror() are introduced to help reporting errors.

Functions are updated to pass correct the error number through the
CHECK_ERR() macro.

All users of bpf_object__open{_buffer}() and bpf_program__title() in
perf are modified accordingly. In addition, due to the error codes
changing, bpf__strerror_load() is also modified to use them.

bpf__strerror_head() is also changed accordingly so it can parse libbpf
errors. bpf_loader_strerror() is introduced for that purpose, and will
be improved by the following patch.

load_program() is improved not to dump log buffer if it is empty. log
buffer is also used to deduce whether the error was caused by an invalid
program or other problem.

v1 -> v2:

 - Using macro for error code.

 - Fetch error message based on array index, eliminate for-loop.

 - Use log buffer to detect the reason of failure. 3 new error code
   are introduced to replace LIBBPF_ERRNO__LOAD.

In v1:

  # perf record -e ./test_ill_program.o ls
  event syntax error: './test_ill_program.o'
                       \___ Failed to load program: Validate your program and check 'license'/'version' sections in your object
  SKIP

  # perf record -e ./test_kversion_nomatch_program.o ls
  event syntax error: './test_kversion_nomatch_program.o'
                       \___ Failed to load program: Validate your program and check 'license'/'version' sections in your object
  SKIP

  # perf record -e ./test_big_program.o ls
  event syntax error: './test_big_program.o'
                       \___ Failed to load program: Validate your program and check 'license'/'version' sections in your object
  SKIP

  In v2:

  # perf record -e ./test_ill_program.o ls
  event syntax error: './test_ill_program.o'
                       \___ Kernel verifier blocks program loading
  SKIP

  # perf record -e ./test_kversion_nomatch_program.o
  event syntax error: './test_kversion_nomatch_program.o'
                       \___ Incorrect kernel version
  SKIP
  (Will be further improved by following patches)

  # perf record -e ./test_big_program.o
  event syntax error: './test_big_program.o'
                       \___ Program too big
  SKIP

Signed-off-by: Wang Nan <wangnan0@huawei.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1446817783-86722-2-git-send-email-wangnan0@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2015-11-06 15:52:41 -03:00

372 lines
7.6 KiB
C

/*
* bpf-loader.c
*
* Copyright (C) 2015 Wang Nan <wangnan0@huawei.com>
* Copyright (C) 2015 Huawei Inc.
*/
#include <bpf/libbpf.h>
#include <linux/err.h>
#include "perf.h"
#include "debug.h"
#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, ...) \
{ \
va_list args; \
int ret; \
\
va_start(args, fmt); \
ret = veprintf(level, verbose, pr_fmt(fmt), args);\
va_end(args); \
return ret; \
}
DEFINE_PRINT_FN(warning, 1)
DEFINE_PRINT_FN(info, 1)
DEFINE_PRINT_FN(debug, 1)
struct bpf_prog_priv {
struct perf_probe_event pev;
};
struct bpf_object *bpf__prepare_load(const char *filename, bool source)
{
struct bpf_object *obj;
static bool libbpf_initialized;
if (!libbpf_initialized) {
libbpf_set_print(libbpf_warning,
libbpf_info,
libbpf_debug);
libbpf_initialized = true;
}
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 (IS_ERR(obj)) {
pr_debug("bpf: failed to load %s\n", filename);
return obj;
}
return obj;
}
void bpf__clear(void)
{
struct bpf_object *obj, *tmp;
bpf_object__for_each_safe(obj, tmp) {
bpf__unprobe(obj);
bpf_object__close(obj);
}
}
static void
bpf_prog_priv__clear(struct bpf_program *prog __maybe_unused,
void *_priv)
{
struct bpf_prog_priv *priv = _priv;
cleanup_perf_probe_events(&priv->pev, 1);
free(priv);
}
static int
config_bpf_program(struct bpf_program *prog)
{
struct perf_probe_event *pev = NULL;
struct bpf_prog_priv *priv = NULL;
const char *config_str;
int err;
config_str = bpf_program__title(prog, false);
if (IS_ERR(config_str)) {
pr_debug("bpf: unable to get title for program\n");
return PTR_ERR(config_str);
}
priv = calloc(sizeof(*priv), 1);
if (!priv) {
pr_debug("bpf: failed to alloc priv\n");
return -ENOMEM;
}
pev = &priv->pev;
pr_debug("bpf: config program '%s'\n", config_str);
err = parse_perf_probe_command(config_str, pev);
if (err < 0) {
pr_debug("bpf: '%s' is not a valid config string\n",
config_str);
err = -EINVAL;
goto errout;
}
if (pev->group && strcmp(pev->group, PERF_BPF_PROBE_GROUP)) {
pr_debug("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_debug("bpf: strdup failed\n");
err = -ENOMEM;
goto errout;
}
if (!pev->event) {
pr_debug("bpf: '%s': event name is missing\n",
config_str);
err = -EINVAL;
goto errout;
}
pr_debug("bpf: config '%s' is ok\n", config_str);
err = bpf_program__set_private(prog, priv, bpf_prog_priv__clear);
if (err) {
pr_debug("Failed to set priv for program '%s'\n", config_str);
goto errout;
}
return 0;
errout:
if (pev)
clear_perf_probe_event(pev);
free(priv);
return err;
}
static int bpf__prepare_probe(void)
{
static int err = 0;
static bool initialized = false;
/*
* Make err static, so if init failed the first, bpf__prepare_probe()
* fails each time without calling init_probe_symbol_maps multiple
* times.
*/
if (initialized)
return err;
initialized = true;
err = init_probe_symbol_maps(false);
if (err < 0)
pr_debug("Failed to init_probe_symbol_maps\n");
probe_conf.max_probes = MAX_PROBES;
return err;
}
int bpf__probe(struct bpf_object *obj)
{
int err = 0;
struct bpf_program *prog;
struct bpf_prog_priv *priv;
struct perf_probe_event *pev;
err = bpf__prepare_probe();
if (err) {
pr_debug("bpf__prepare_probe failed\n");
return err;
}
bpf_object__for_each_program(prog, obj) {
err = config_bpf_program(prog);
if (err)
goto out;
err = bpf_program__get_private(prog, (void **)&priv);
if (err || !priv)
goto out;
pev = &priv->pev;
err = convert_perf_probe_events(pev, 1);
if (err < 0) {
pr_debug("bpf_probe: failed to convert perf probe events");
goto out;
}
err = apply_perf_probe_events(pev, 1);
if (err < 0) {
pr_debug("bpf_probe: failed to apply perf probe events");
goto out;
}
}
out:
return err < 0 ? err : 0;
}
#define EVENTS_WRITE_BUFSIZE 4096
int bpf__unprobe(struct bpf_object *obj)
{
int err, ret = 0;
struct bpf_program *prog;
struct bpf_prog_priv *priv;
bpf_object__for_each_program(prog, obj) {
int i;
err = bpf_program__get_private(prog, (void **)&priv);
if (err || !priv)
continue;
for (i = 0; i < priv->pev.ntevs; i++) {
struct probe_trace_event *tev = &priv->pev.tevs[i];
char name_buf[EVENTS_WRITE_BUFSIZE];
struct strfilter *delfilter;
snprintf(name_buf, EVENTS_WRITE_BUFSIZE,
"%s:%s", tev->group, tev->event);
name_buf[EVENTS_WRITE_BUFSIZE - 1] = '\0';
delfilter = strfilter__new(name_buf, NULL);
if (!delfilter) {
pr_debug("Failed to create filter for unprobing\n");
ret = -ENOMEM;
continue;
}
err = del_perf_probe_events(delfilter);
strfilter__delete(delfilter);
if (err) {
pr_debug("Failed to delete %s\n", name_buf);
ret = err;
continue;
}
}
}
return ret;
}
int bpf__load(struct bpf_object *obj)
{
int err;
err = bpf_object__load(obj);
if (err) {
pr_debug("bpf: load objects failed\n");
return err;
}
return 0;
}
int bpf__foreach_tev(struct bpf_object *obj,
bpf_prog_iter_callback_t func,
void *arg)
{
struct bpf_program *prog;
int err;
bpf_object__for_each_program(prog, obj) {
struct probe_trace_event *tev;
struct perf_probe_event *pev;
struct bpf_prog_priv *priv;
int i, fd;
err = bpf_program__get_private(prog,
(void **)&priv);
if (err || !priv) {
pr_debug("bpf: failed to get private field\n");
return -EINVAL;
}
pev = &priv->pev;
for (i = 0; i < pev->ntevs; i++) {
tev = &pev->tevs[i];
fd = bpf_program__fd(prog);
if (fd < 0) {
pr_debug("bpf: failed to get file descriptor\n");
return fd;
}
err = (*func)(tev, fd, arg);
if (err) {
pr_debug("bpf: call back failed, stop iterate\n");
return err;
}
}
}
return 0;
}
static int
bpf_loader_strerror(int err, char *buf, size_t size)
{
char sbuf[STRERR_BUFSIZE];
const char *msg;
if (!buf || !size)
return -1;
err = err > 0 ? err : -err;
if (err >= __LIBBPF_ERRNO__START)
return libbpf_strerror(err, buf, size);
msg = strerror_r(err, sbuf, sizeof(sbuf));
snprintf(buf, size, "%s", msg);
buf[size - 1] = '\0';
return 0;
}
#define bpf__strerror_head(err, buf, size) \
char sbuf[STRERR_BUFSIZE], *emsg;\
if (!size)\
return 0;\
if (err < 0)\
err = -err;\
bpf_loader_strerror(err, sbuf, sizeof(sbuf));\
emsg = sbuf;\
switch (err) {\
default:\
scnprintf(buf, size, "%s", emsg);\
break;
#define bpf__strerror_entry(val, fmt...)\
case val: {\
scnprintf(buf, size, fmt);\
break;\
}
#define bpf__strerror_end(buf, size)\
}\
buf[size - 1] = '\0';
int bpf__strerror_probe(struct bpf_object *obj __maybe_unused,
int err, char *buf, size_t size)
{
bpf__strerror_head(err, buf, size);
bpf__strerror_entry(EEXIST, "Probe point exist. Try use 'perf probe -d \"*\"'");
bpf__strerror_entry(EPERM, "You need to be root, and /proc/sys/kernel/kptr_restrict should be 0\n");
bpf__strerror_entry(ENOENT, "You need to check probing points in BPF file\n");
bpf__strerror_end(buf, size);
return 0;
}
int bpf__strerror_load(struct bpf_object *obj __maybe_unused,
int err, char *buf, size_t size)
{
bpf__strerror_head(err, buf, size);
bpf__strerror_end(buf, size);
return 0;
}