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Commit 361f2b1d authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
Browse files

perf bpf: Allow BPF program attach to uprobe events 



This patch adds a new syntax to the BPF object section name to support
probing at uprobe event. Now we can use BPF program like this:

  SEC(
  "exec=/lib64/libc.so.6;"
  "libcwrite=__write"
  )
  int libcwrite(void *ctx)
  {
      return 1;
  }

Where, in section name of a program, before the main config string, we
can use 'key=value' style options. Now the only option key is "exec",
for uprobes.

Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Zefan Li <lizefan@huawei.com>
Cc: pi3orama@163.com
Link: http://lkml.kernel.org/r/1447675815-166222-4-git-send-email-wangnan0@huawei.com


[ Changed the separator from \n to ; ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 30433a3a

tools/perf/util/bpf-loader.c

+114 −6
Original line number Diff line number Diff line
@@ -109,6 +109,113 @@ bpf_prog_priv__clear(struct bpf_program *prog __maybe_unused, 
	free(priv);

}



static int

config__exec(const char *value, struct perf_probe_event *pev)

{

	pev->uprobes = true;

	pev->target = strdup(value);

	if (!pev->target)

		return -ENOMEM;

	return 0;

}



static struct {

	const char *key;

	const char *usage;

	const char *desc;

	int (*func)(const char *, struct perf_probe_event *);

} bpf_config_terms[] = {

	{

		.key	= "exec",

		.usage	= "exec=<full path of file>",

		.desc	= "Set uprobe target",

		.func	= config__exec,

	},

};



static int

do_config(const char *key, const char *value,

	  struct perf_probe_event *pev)

{

	unsigned int i;



	pr_debug("config bpf program: %s=%s\n", key, value);

	for (i = 0; i < ARRAY_SIZE(bpf_config_terms); i++)

		if (strcmp(key, bpf_config_terms[i].key) == 0)

			return bpf_config_terms[i].func(value, pev);



	pr_debug("BPF: ERROR: invalid config option in object: %s=%s\n",

		 key, value);



	pr_debug("\nHint: Currently valid options are:\n");

	for (i = 0; i < ARRAY_SIZE(bpf_config_terms); i++)

		pr_debug("\t%s:\t%s\n", bpf_config_terms[i].usage,

			 bpf_config_terms[i].desc);

	pr_debug("\n");



	return -BPF_LOADER_ERRNO__CONFIG_TERM;

}



static const char *

parse_config_kvpair(const char *config_str, struct perf_probe_event *pev)

{

	char *text = strdup(config_str);

	char *sep, *line;

	const char *main_str = NULL;

	int err = 0;



	if (!text) {

		pr_debug("No enough memory: dup config_str failed\n");

		return ERR_PTR(-ENOMEM);

	}



	line = text;

	while ((sep = strchr(line, ';'))) {

		char *equ;



		*sep = '\0';

		equ = strchr(line, '=');

		if (!equ) {

			pr_warning("WARNING: invalid config in BPF object: %s\n",

				   line);

			pr_warning("\tShould be 'key=value'.\n");

			goto nextline;

		}

		*equ = '\0';



		err = do_config(line, equ + 1, pev);

		if (err)

			break;

nextline:

		line = sep + 1;

	}



	if (!err)

		main_str = config_str + (line - text);

	free(text);



	return err ? ERR_PTR(err) : main_str;

}



static int

parse_config(const char *config_str, struct perf_probe_event *pev)

{

	int err;

	const char *main_str = parse_config_kvpair(config_str, pev);



	if (IS_ERR(main_str))

		return PTR_ERR(main_str);



	err = parse_perf_probe_command(main_str, pev);

	if (err < 0) {

		pr_debug("bpf: '%s' is not a valid config string\n",

			 config_str);

		/* parse failed, don't need clear pev. */

		return -BPF_LOADER_ERRNO__CONFIG;

	}

	return 0;

}



static int

config_bpf_program(struct bpf_program *prog)

{
@@ -131,13 +238,9 @@ config_bpf_program(struct bpf_program *prog) 
	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 = -BPF_LOADER_ERRNO__CONFIG;

	err = parse_config(config_str, pev);

	if (err)

		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",
@@ -340,6 +443,7 @@ static const char *bpf_loader_strerror_table[NR_ERRNO] = { 
	[ERRCODE_OFFSET(EVENTNAME)]	= "No event name found in config string",

	[ERRCODE_OFFSET(INTERNAL)]	= "BPF loader internal error",

	[ERRCODE_OFFSET(COMPILE)]	= "Error when compiling BPF scriptlet",

	[ERRCODE_OFFSET(CONFIG_TERM)]	= "Invalid config term in config string",

};



static int
@@ -420,6 +524,10 @@ int bpf__strerror_probe(struct bpf_object *obj __maybe_unused, 
			int err, char *buf, size_t size)

{

	bpf__strerror_head(err, buf, size);

	case BPF_LOADER_ERRNO__CONFIG_TERM: {

		scnprintf(buf, size, "%s (add -v to see detail)", emsg);

		break;

	}

	bpf__strerror_entry(EEXIST, "Probe point exist. Try use 'perf probe -d \"*\"'");

	bpf__strerror_entry(EACCES, "You need to be root");

	bpf__strerror_entry(EPERM, "You need to be root, and /proc/sys/kernel/kptr_restrict should be 0");

tools/perf/util/bpf-loader.h

+1 −0
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ enum bpf_loader_errno { 
	BPF_LOADER_ERRNO__EVENTNAME,	/* Event name is missing */

	BPF_LOADER_ERRNO__INTERNAL,	/* BPF loader internal error */

	BPF_LOADER_ERRNO__COMPILE,	/* Error when compiling BPF scriptlet */

	BPF_LOADER_ERRNO__CONFIG_TERM,	/* Invalid config term in config term */

	__BPF_LOADER_ERRNO__END,

};