Commit 18425f13 authored by Arnaldo Carvalho de Melo's avatar Arnaldo Carvalho de Melo
Browse files

perf symbols: Save DSO loading errno to better report errors 



Before, when some problem happened while trying to load the kernel
symtab, 'perf top' would show:

      ┌─Warning:───────────────────────────┐
      │The vmlinux file can't be used.     │
      │Kernel samples will not be resolved.│
      │                                    │
      │                                    │
      │Press any key...                    │
      └────────────────────────────────────┘

Now, it reports:

  # perf top --vmlinux /dev/null

      ┌─Warning:───────────────────────────────────────────┐
      │The /tmp/passwd file can't be used: Invalid ELF file│
      │Kernel samples will not be resolved.                │
      │                                                    │
      │                                                    │
      │Press any key...                                    │
      └────────────────────────────────────────────────────┘

This is possible because we now register the reason for not being able
to load the symtab in the dso->load_errno member, and provide a
dso__strerror_load() routine to format this error into a strerror like
string with a short reason for the error while loading.

That can be just forwarding the dso__strerror_load() call to
strerror_r(), or, for a separate errno range providing a custom message.

Reported-by: default avatarIngo Molnar <mingo@kernel.org>
Acked-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Borislav Petkov <bp@suse.de>
Cc: David Ahern <dsahern@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-u5rb5uq63xqhkfb8uv2lxd5u@git.kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 17e44dc4

tools/perf/builtin-top.c

+4 −2
Original line number Diff line number Diff line
@@ -757,8 +757,10 @@ static void perf_event__process_sample(struct perf_tool *tool, 
		    al.map == machine->vmlinux_maps[MAP__FUNCTION] &&

		    RB_EMPTY_ROOT(&al.map->dso->symbols[MAP__FUNCTION])) {

			if (symbol_conf.vmlinux_name) {

				ui__warning("The %s file can't be used.\n%s",

					    symbol_conf.vmlinux_name, msg);

				char serr[256];

				dso__strerror_load(al.map->dso, serr, sizeof(serr));

				ui__warning("The %s file can't be used: %s\n%s",

					    symbol_conf.vmlinux_name, serr, msg);

			} else {

				ui__warning("A vmlinux file was not found.\n%s",

					    msg);

tools/perf/util/dso.c

+33 −0
Original line number Diff line number Diff line
@@ -1137,3 +1137,36 @@ enum dso_type dso__type(struct dso *dso, struct machine *machine) 


	return dso__type_fd(fd);

}



int dso__strerror_load(struct dso *dso, char *buf, size_t buflen)

{

	int idx, errnum = dso->load_errno;

	/*

	 * This must have a same ordering as the enum dso_load_errno.

	 */

	static const char *dso_load__error_str[] = {

	"Internal tools/perf/ library error",

	"Invalid ELF file",

	"Can not read build id",

	"Mismatching build id",

	"Decompression failure",

	};



	BUG_ON(buflen == 0);



	if (errnum >= 0) {

		const char *err = strerror_r(errnum, buf, buflen);



		if (err != buf)

			scnprintf(buf, buflen, "%s", err);



		return 0;

	}



	if (errnum <  __DSO_LOAD_ERRNO__START || errnum >= __DSO_LOAD_ERRNO__END)

		return -1;



	idx = errnum - __DSO_LOAD_ERRNO__START;

	scnprintf(buf, buflen, "%s", dso_load__error_str[idx]);

	return 0;

}

tools/perf/util/dso.h

+28 −0
Original line number Diff line number Diff line
@@ -60,6 +60,31 @@ enum dso_type { 
	DSO__TYPE_X32BIT,

};



enum dso_load_errno {

	DSO_LOAD_ERRNO__SUCCESS		= 0,



	/*

	 * Choose an arbitrary negative big number not to clash with standard

	 * errno since SUS requires the errno has distinct positive values.

	 * See 'Issue 6' in the link below.

	 *

	 * http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/errno.h.html

	 */

	__DSO_LOAD_ERRNO__START		= -10000,



	DSO_LOAD_ERRNO__INTERNAL_ERROR	= __DSO_LOAD_ERRNO__START,



	/* for symsrc__init() */

	DSO_LOAD_ERRNO__INVALID_ELF,

	DSO_LOAD_ERRNO__CANNOT_READ_BUILDID,

	DSO_LOAD_ERRNO__MISMATCHING_BUILDID,



	/* for decompress_kmodule */

	DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE,



	__DSO_LOAD_ERRNO__END,

};



#define DSO__SWAP(dso, type, val)			\

({							\

	type ____r = val;				\
@@ -113,6 +138,7 @@ struct dso { 
	enum dso_swap_type	needs_swap;

	enum dso_binary_type	symtab_type;

	enum dso_binary_type	binary_type;

	enum dso_load_errno	load_errno;

	u8		 adjust_symbols:1;

	u8		 has_build_id:1;

	u8		 has_srcline:1;
@@ -294,4 +320,6 @@ void dso__free_a2l(struct dso *dso); 


enum dso_type dso__type(struct dso *dso, struct machine *machine);



int dso__strerror_load(struct dso *dso, char *buf, size_t buflen);



#endif /* __PERF_DSO */

tools/perf/util/symbol-elf.c

+27 −10
Original line number Diff line number Diff line
@@ -595,10 +595,13 @@ static int decompress_kmodule(struct dso *dso, const char *name, 
		return -1;



	fd = mkstemp(tmpbuf);

	if (fd < 0)

	if (fd < 0) {

		dso->load_errno = errno;

		goto out;

	}



	if (!decompress_to_file(m.ext, name, fd)) {

		dso->load_errno = DSO_LOAD_ERRNO__DECOMPRESSION_FAILURE;

		close(fd);

		fd = -1;

	}
@@ -635,38 +638,50 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, 
	Elf *elf;

	int fd;



	if (dso__needs_decompress(dso))

	if (dso__needs_decompress(dso)) {

		fd = decompress_kmodule(dso, name, type);

	else

		fd = open(name, O_RDONLY);



		if (fd < 0)

			return -1;

	} else {

		fd = open(name, O_RDONLY);

		if (fd < 0) {

			dso->load_errno = errno;

			return -1;

		}

	}



	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);

	if (elf == NULL) {

		pr_debug("%s: cannot read %s ELF file.\n", __func__, name);

		dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF;

		goto out_close;

	}



	if (gelf_getehdr(elf, &ehdr) == NULL) {

		dso->load_errno = DSO_LOAD_ERRNO__INVALID_ELF;

		pr_debug("%s: cannot get elf header.\n", __func__);

		goto out_elf_end;

	}



	if (dso__swap_init(dso, ehdr.e_ident[EI_DATA]))

	if (dso__swap_init(dso, ehdr.e_ident[EI_DATA])) {

		dso->load_errno = DSO_LOAD_ERRNO__INTERNAL_ERROR;

		goto out_elf_end;

	}



	/* Always reject images with a mismatched build-id: */

	if (dso->has_build_id) {

		u8 build_id[BUILD_ID_SIZE];



		if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0)

		if (elf_read_build_id(elf, build_id, BUILD_ID_SIZE) < 0) {

			dso->load_errno = DSO_LOAD_ERRNO__CANNOT_READ_BUILDID;

			goto out_elf_end;

		}



		if (!dso__build_id_equal(dso, build_id))

		if (!dso__build_id_equal(dso, build_id)) {

			dso->load_errno = DSO_LOAD_ERRNO__MISMATCHING_BUILDID;

			goto out_elf_end;

		}

	}



	ss->is_64_bit = (gelf_getclass(elf) == ELFCLASS64);
@@ -701,8 +716,10 @@ int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name, 
	}



	ss->name   = strdup(name);

	if (!ss->name)

	if (!ss->name) {

		dso->load_errno = errno;

		goto out_elf_end;

	}



	ss->elf    = elf;

	ss->fd     = fd;

tools/perf/util/symbol-minimal.c

+4 −3
Original line number Diff line number Diff line
@@ -246,13 +246,12 @@ out: 
	return ret;

}



int symsrc__init(struct symsrc *ss, struct dso *dso __maybe_unused,

		 const char *name,

int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,

	         enum dso_binary_type type)

{

	int fd = open(name, O_RDONLY);

	if (fd < 0)

		return -1;

		goto out_errno;



	ss->name = strdup(name);

	if (!ss->name)
@@ -264,6 +263,8 @@ int symsrc__init(struct symsrc *ss, struct dso *dso __maybe_unused, 
	return 0;

out_close:

	close(fd);

out_errno:

	dso->load_errno = errno;

	return -1;

}

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