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: Pierre-Loup A. Griffais <pgriffais@nvidia.com>
Reported-by: Mike Sartain <mikesart@valvesoftware.com>
Tested-by: Mike 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: Arnaldo Carvalho de Melo <acme@redhat.com>
This commit is contained in:
Pierre-Loup A. Griffais 2012-06-22 11:38:13 -07:00 committed by Arnaldo Carvalho de Melo
parent da3789628f
commit 209bd9e3e1
2 changed files with 65 additions and 1 deletions

View File

@ -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] ||

View File

@ -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,