Commit 209bd9e3 authored by Pierre-Loup A. Griffais's avatar Pierre-Loup A. Griffais Committed by Arnaldo Carvalho de Melo
Browse files

perf symbols: Follow .gnu_debuglink section to find separate symbols 

The .gnu_debuglink section is specified to contain the filename of the
debug info file, as well as a CRC that can be used to validate it.

This doesn't currently use the checksum and relies on the usual build-id
matching for validation.

This provides more context:
http://sourceware.org/gdb/onlinedocs/gdb/Separate-Debug-Files.html



Signed-off-by: default avatarPierre-Loup A. Griffais <pgriffais@nvidia.com>
Reported-by: default avatarMike Sartain <mikesart@valvesoftware.com>
Tested-by: default avatarMike Sartain <mikesart@valvesoftware.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Sartain <mikesart@valvesoftware.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4FE4BB95.3080309@nvidia.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent da378962

tools/perf/util/symbol.c

+64 −1
Original line number Diff line number Diff line
@@ -1590,11 +1590,62 @@ out: 
	return err;

}



static int filename__read_debuglink(const char *filename,

				    char *debuglink, size_t size)

{

	int fd, err = -1;

	Elf *elf;

	GElf_Ehdr ehdr;

	GElf_Shdr shdr;

	Elf_Data *data;

	Elf_Scn *sec;

	Elf_Kind ek;



	fd = open(filename, O_RDONLY);

	if (fd < 0)

		goto out;



	elf = elf_begin(fd, PERF_ELF_C_READ_MMAP, NULL);

	if (elf == NULL) {

		pr_debug2("%s: cannot read %s ELF file.\n", __func__, filename);

		goto out_close;

	}



	ek = elf_kind(elf);

	if (ek != ELF_K_ELF)

		goto out_close;



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

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

		goto out_close;

	}



	sec = elf_section_by_name(elf, &ehdr, &shdr,

				  ".gnu_debuglink", NULL);

	if (sec == NULL)

		goto out_close;



	data = elf_getdata(sec, NULL);

	if (data == NULL)

		goto out_close;



	/* the start of this section is a zero-terminated string */

	strncpy(debuglink, data->d_buf, size);



	elf_end(elf);



out_close:

	close(fd);

out:

	return err;

}



char dso__symtab_origin(const struct dso *dso)

{

	static const char origin[] = {

		[SYMTAB__KALLSYMS]	      = 'k',

		[SYMTAB__JAVA_JIT]	      = 'j',

		[SYMTAB__DEBUGLINK]           = 'l',

		[SYMTAB__BUILD_ID_CACHE]      = 'B',

		[SYMTAB__FEDORA_DEBUGINFO]    = 'f',

		[SYMTAB__UBUNTU_DEBUGINFO]    = 'u',
@@ -1662,10 +1713,22 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter) 
	 */

	want_symtab = 1;

restart:

	for (dso->symtab_type = SYMTAB__BUILD_ID_CACHE;

	for (dso->symtab_type = SYMTAB__DEBUGLINK;

	     dso->symtab_type != SYMTAB__NOT_FOUND;

	     dso->symtab_type++) {

		switch (dso->symtab_type) {

		case SYMTAB__DEBUGLINK: {

			char *debuglink;

			strncpy(name, dso->long_name, size);

			debuglink = name + dso->long_name_len;

			while (debuglink != name && *debuglink != '/')

				debuglink--;

			if (*debuglink == '/')

				debuglink++;

			filename__read_debuglink(dso->long_name, debuglink,

						 size - (debuglink - name));

			}

			break;

		case SYMTAB__BUILD_ID_CACHE:

			/* skip the locally configured cache if a symfs is given */

			if (symbol_conf.symfs[0] ||

tools/perf/util/symbol.h

+1 −0
Original line number Diff line number Diff line
@@ -257,6 +257,7 @@ enum symtab_type { 
	SYMTAB__KALLSYMS = 0,

	SYMTAB__GUEST_KALLSYMS,

	SYMTAB__JAVA_JIT,

	SYMTAB__DEBUGLINK,

	SYMTAB__BUILD_ID_CACHE,

	SYMTAB__FEDORA_DEBUGINFO,

	SYMTAB__UBUNTU_DEBUGINFO,

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