Commit d3e0ce39 authored by Wang Nan's avatar Wang Nan Committed by Arnaldo Carvalho de Melo
Browse files

perf bpf: Improve BPF related error messages 



A series of bpf loader related error codes were introduced to help error
reporting. Functions were improved to return these new error codes.

Functions which return pointers were adjusted to encode error codes into
return value using the ERR_PTR() interface.

bpf_loader_strerror() was improved to convert these error messages to
strings. It checks the error codes and calls libbpf_strerror() and
strerror_r() accordingly, so caller don't need to consider checking the
range of the error code.

In bpf__strerror_load(), print kernel version of running kernel and the
object's 'version' section to notify user how to fix his/her program.

v1 -> v2:
 Use macro for error code.

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

 Print version strings.

Before:

  # perf record -e ./test_kversion_nomatch_program.o sleep 1
  event syntax error: './test_kversion_nomatch_program.o'
                       \___ Failed to load program: Validate your program and check 'license'/'version' sections in your object
  SKIP

  After:

  # perf record -e ./test_kversion_nomatch_program.o ls
  event syntax error: './test_kversion_nomatch_program.o'
                       \___ 'version' (4.4.0) doesn't match running kernel (4.3.0)
  SKIP

Signed-off-by: default avatarWang Nan <wangnan0@huawei.com>
Tested-by: default avatarArnaldo 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/1446818289-87444-1-git-send-email-wangnan0@huawei.com


[ Add 'static inline' to bpf__strerror_prepare_load() when LIBBPF is disabled ]
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 07bc5c69

tools/perf/util/bpf-loader.c

+76 −12
Original line number Diff line number Diff line
@@ -53,7 +53,7 @@ struct bpf_object *bpf__prepare_load(const char *filename, bool source) 


		err = llvm__compile_bpf(filename, &obj_buf, &obj_buf_sz);

		if (err)

			return ERR_PTR(err);

			return ERR_PTR(-BPF_LOADER_ERRNO__COMPILE);

		obj = bpf_object__open_buffer(obj_buf, obj_buf_sz, filename);

		free(obj_buf);

	} else
@@ -113,14 +113,14 @@ config_bpf_program(struct bpf_program *prog) 
	if (err < 0) {

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

			 config_str);

		err = -EINVAL;

		err = -BPF_LOADER_ERRNO__CONFIG;

		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;

		err = -BPF_LOADER_ERRNO__GROUP;

		goto errout;

	} else if (!pev->group)

		pev->group = strdup(PERF_BPF_PROBE_GROUP);
@@ -132,9 +132,9 @@ config_bpf_program(struct bpf_program *prog) 
	}



	if (!pev->event) {

		pr_debug("bpf: '%s': event name is missing\n",

		pr_debug("bpf: '%s': event name is missing. Section name should be 'key=value'\n",

			 config_str);

		err = -EINVAL;

		err = -BPF_LOADER_ERRNO__EVENTNAME;

		goto errout;

	}

	pr_debug("bpf: config '%s' is ok\n", config_str);
@@ -285,7 +285,7 @@ int bpf__foreach_tev(struct bpf_object *obj, 
				(void **)&priv);

		if (err || !priv) {

			pr_debug("bpf: failed to get private field\n");

			return -EINVAL;

			return -BPF_LOADER_ERRNO__INTERNAL;

		}



		pev = &priv->pev;
@@ -308,6 +308,18 @@ int bpf__foreach_tev(struct bpf_object *obj, 
	return 0;

}



#define ERRNO_OFFSET(e)		((e) - __BPF_LOADER_ERRNO__START)

#define ERRCODE_OFFSET(c)	ERRNO_OFFSET(BPF_LOADER_ERRNO__##c)

#define NR_ERRNO	(__BPF_LOADER_ERRNO__END - __BPF_LOADER_ERRNO__START)



static const char *bpf_loader_strerror_table[NR_ERRNO] = {

	[ERRCODE_OFFSET(CONFIG)]	= "Invalid config string",

	[ERRCODE_OFFSET(GROUP)]		= "Invalid group name",

	[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",

};



static int

bpf_loader_strerror(int err, char *buf, size_t size)

{
@@ -322,12 +334,23 @@ bpf_loader_strerror(int err, char *buf, size_t size) 
	if (err >= __LIBBPF_ERRNO__START)

		return libbpf_strerror(err, buf, size);



	msg = strerror_r(err, sbuf, sizeof(sbuf));

	if (err >= __BPF_LOADER_ERRNO__START && err < __BPF_LOADER_ERRNO__END) {

		msg = bpf_loader_strerror_table[ERRNO_OFFSET(err)];

		snprintf(buf, size, "%s", msg);

		buf[size - 1] = '\0';

		return 0;

	}



	if (err >= __BPF_LOADER_ERRNO__END)

		snprintf(buf, size, "Unknown bpf loader error %d", err);

	else

		snprintf(buf, size, "%s",

			 strerror_r(err, sbuf, sizeof(sbuf)));



	buf[size - 1] = '\0';

	return -1;

}



#define bpf__strerror_head(err, buf, size) \

	char sbuf[STRERR_BUFSIZE], *emsg;\

	if (!size)\
@@ -351,21 +374,62 @@ bpf_loader_strerror(int err, char *buf, size_t size) 
	}\

	buf[size - 1] = '\0';



int bpf__strerror_prepare_load(const char *filename, bool source,

			       int err, char *buf, size_t size)

{

	size_t n;

	int ret;



	n = snprintf(buf, size, "Failed to load %s%s: ",

			 filename, source ? " from source" : "");

	if (n >= size) {

		buf[size - 1] = '\0';

		return 0;

	}

	buf += n;

	size -= n;



	ret = bpf_loader_strerror(err, buf, size);

	buf[size - 1] = '\0';

	return ret;

}



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_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");

	bpf__strerror_entry(ENOENT, "You need to check probing points in BPF file");

	bpf__strerror_end(buf, size);

	return 0;

}



int bpf__strerror_load(struct bpf_object *obj __maybe_unused,

int bpf__strerror_load(struct bpf_object *obj,

		       int err, char *buf, size_t size)

{

	bpf__strerror_head(err, buf, size);

	case LIBBPF_ERRNO__KVER: {

		unsigned int obj_kver = bpf_object__get_kversion(obj);

		unsigned int real_kver;



		if (fetch_kernel_version(&real_kver, NULL, 0)) {

			scnprintf(buf, size, "Unable to fetch kernel version");

			break;

		}



		if (obj_kver != real_kver) {

			scnprintf(buf, size,

				  "'version' ("KVER_FMT") doesn't match running kernel ("KVER_FMT")",

				  KVER_PARAM(obj_kver),

				  KVER_PARAM(real_kver));

			break;

		}



		scnprintf(buf, size, "Failed to load program for unknown reason");

		break;

	}

	bpf__strerror_end(buf, size);

	return 0;

}

tools/perf/util/bpf-loader.h

+23 −0
Original line number Diff line number Diff line
@@ -8,9 +8,21 @@ 
#include <linux/compiler.h>

#include <linux/err.h>

#include <string.h>

#include <bpf/libbpf.h>

#include "probe-event.h"

#include "debug.h"



enum bpf_loader_errno {

	__BPF_LOADER_ERRNO__START = __LIBBPF_ERRNO__START - 100,

	/* Invalid config string */

	BPF_LOADER_ERRNO__CONFIG = __BPF_LOADER_ERRNO__START,

	BPF_LOADER_ERRNO__GROUP,	/* Invalid group name */

	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__END,

};



struct bpf_object;

#define PERF_BPF_PROBE_GROUP "perf_bpf_probe"
@@ -19,6 +31,8 @@ typedef int (*bpf_prog_iter_callback_t)(struct probe_trace_event *tev, 


#ifdef HAVE_LIBBPF_SUPPORT

struct bpf_object *bpf__prepare_load(const char *filename, bool source);

int bpf__strerror_prepare_load(const char *filename, bool source,

			       int err, char *buf, size_t size);



void bpf__clear(void);
@@ -67,6 +81,15 @@ __bpf_strerror(char *buf, size_t size) 
	return 0;

}



static inline

int bpf__strerror_prepare_load(const char *filename __maybe_unused,

			       bool source __maybe_unused,

			       int err __maybe_unused,

			       char *buf, size_t size)

{

	return __bpf_strerror(buf, size);

}



static inline int

bpf__strerror_probe(struct bpf_object *obj __maybe_unused,

		    int err __maybe_unused,

tools/perf/util/parse-events.c

+4 −3
Original line number Diff line number Diff line
@@ -642,9 +642,10 @@ int parse_events_load_bpf(struct parse_events_evlist *data, 
			snprintf(errbuf, sizeof(errbuf),

				 "BPF support is not compiled");

		else

			snprintf(errbuf, sizeof(errbuf),

				 "BPF object file '%s' is invalid",

				 bpf_file_name);

			bpf__strerror_prepare_load(bpf_file_name,

						   source,

						   -err, errbuf,

						   sizeof(errbuf));



		data->error->help = strdup("(add -v to see detail)");

		data->error->str = strdup(errbuf);

tools/perf/util/util.h

+5 −0
Original line number Diff line number Diff line
@@ -352,5 +352,10 @@ int get_stack_size(const char *str, unsigned long *_size); 


int fetch_kernel_version(unsigned int *puint,

			 char *str, size_t str_sz);

#define KVER_VERSION(x)		(((x) >> 16) & 0xff)

#define KVER_PATCHLEVEL(x)	(((x) >> 8) & 0xff)

#define KVER_SUBLEVEL(x)	((x) & 0xff)

#define KVER_FMT	"%d.%d.%d"

#define KVER_PARAM(x)	KVER_VERSION(x), KVER_PATCHLEVEL(x), KVER_SUBLEVEL(x)



#endif /* GIT_COMPAT_UTIL_H */

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