perf symbols: Use both runtime and debug images

We keep both a 'runtime' elf image as well as a 'debug' elf image around
and generate symbols by looking at both of these.

This eliminates the need for the want_symtab/goto restart mechanism
combined with iterating over and reopening the elf images a second time.

Also give dso__synthsize_plt_symbols() the runtime image (which has
dynsyms) instead of the symbol image (which may only have a symtab and
no dynsyms).

Previously if a debug image was found all runtime images were ignored.

This fixes 2 issues:

 - Symbol resolution to failure on PowerPC systems with debug symbols
   installed, as the debug images lack a '.opd' section which contains
   function descriptors.

 - On all archs, plt synthesis failed when a debug image was loaded and
   that debug image lacks a dynsym section while a runtime image has a
   dynsym section.

Assumptions:

 - If a .opd section exists, it is contained in the highest priority
   image with a dynsym section.

 - This generally implies that the debug image lacks a dynsym section
   (ie: it is marked as NO_BITS).

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Hansen <dave@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Matt Hellsley <matthltc@us.ibm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1344637382-22789-17-git-send-email-cody@linux.vnet.ibm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/symbol-elf.c b/tools/perf/util/symbol-elf.c
index 36e4a458e7a1d6b0a6f3a9a5356b340f92841801..5b37e13f08fb81b747ea2cbc813eac57b3b491c7 100644 (file)
--- a/tools/perf/util/symbol-elf.c
+++ b/tools/perf/util/symbol-elf.c
@@ -525,6 +525,11 @@ static int dso__swap_init(struct dso *dso, unsigned char eidata)
        return 0;
 }
 
+bool symsrc__possibly_runtime(struct symsrc *ss)
+{
+       return ss->dynsym || ss->opdsec;
+}
+
 bool symsrc__has_symtab(struct symsrc *ss)
 {
        return ss->symtab != NULL;

diff --git a/tools/perf/util/symbol-minimal.c b/tools/perf/util/symbol-minimal.c
index 7747ea6d7e970c9d8f6a5c31006e548b5245323d..6738ea128c90fa1753825eaec5a73361bafbd183 100644 (file)
--- a/tools/perf/util/symbol-minimal.c
+++ b/tools/perf/util/symbol-minimal.c
@@ -260,6 +260,12 @@ out_close:
        return -1;
 }
 
+bool symsrc__possibly_runtime(struct symsrc *ss __used)
+{
+       /* Assume all sym sources could be a runtime image. */
+       return true;
+}
+
 bool symsrc__has_symtab(struct symsrc *ss __used)
 {
        return false;

diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 739e5a32366abb24ac1344721140929a1b3ace32..2293a4a5af96a93def8117c4af0c1ffe34781ba0 100644 (file)
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -1026,11 +1026,12 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
 {
        char *name;
        int ret = -1;
-       struct symsrc ss;
        u_int i;
        struct machine *machine;
        char *root_dir = (char *) "";
-       int want_symtab;
+       int ss_pos = 0;
+       struct symsrc ss_[2];
+       struct symsrc *syms_ss = NULL, *runtime_ss = NULL;
 
        dso__set_loaded(dso, map->type);
 
@@ -1072,12 +1073,12 @@ int dso__load(struct dso *dso, struct map *map, symbol_filter_t filter)
                root_dir = machine->root_dir;
 
        /* Iterate over candidate debug images.
-        * On the first pass, only load images if they have a full symtab.
-        * Failing that, do a second pass where we accept .dynsym also
+        * Keep track of "interesting" ones (those which have a symtab, dynsym,
+        * and/or opd section) for processing.
         */
-       want_symtab = 1;
-restart:
        for (i = 0; i < DSO_BINARY_TYPE__SYMTAB_CNT; i++) {
+               struct symsrc *ss = &ss_[ss_pos];
+               bool next_slot = false;
 
                enum dso_binary_type symtab_type = binary_type_symtab[i];
 
@@ -1086,45 +1087,55 @@ restart:
                        continue;
 
                /* Name is now the name of the next image to try */
-               if (symsrc__init(&ss, dso, name, symtab_type) < 0)
+               if (symsrc__init(ss, dso, name, symtab_type) < 0)
                        continue;
 
-               if (want_symtab && !symsrc__has_symtab(&ss)) {
-                       symsrc__destroy(&ss);
-                       continue;
+               if (!syms_ss && symsrc__has_symtab(ss)) {
+                       syms_ss = ss;
+                       next_slot = true;
                }
 
-               ret = dso__load_sym(dso, map, &ss, &ss, filter, 0);
-
-               /*
-                * Some people seem to have debuginfo files _WITHOUT_ debug
-                * info!?!?
-                */
-               if (!ret) {
-                       symsrc__destroy(&ss);
-                       continue;
+               if (!runtime_ss && symsrc__possibly_runtime(ss)) {
+                       runtime_ss = ss;
+                       next_slot = true;
                }
 
-               if (ret > 0) {
-                       int nr_plt;
+               if (next_slot) {
+                       ss_pos++;
 
-                       nr_plt = dso__synthesize_plt_symbols(dso, &ss, map, filter);
-                       if (nr_plt > 0)
-                               ret += nr_plt;
-                       symsrc__destroy(&ss);
-                       break;
+                       if (syms_ss && runtime_ss)
+                               break;
                }
+
        }
 
-       /*
-        * If we wanted a full symtab but no image had one,
-        * relax our requirements and repeat the search.
-        */
-       if (ret <= 0 && want_symtab) {
-               want_symtab = 0;
-               goto restart;
+       if (!runtime_ss && !syms_ss)
+               goto out_free;
+
+       if (runtime_ss && !syms_ss) {
+               syms_ss = runtime_ss;
+       }
+
+       /* We'll have to hope for the best */
+       if (!runtime_ss && syms_ss)
+               runtime_ss = syms_ss;
+
+       if (syms_ss)
+               ret = dso__load_sym(dso, map, syms_ss, runtime_ss, filter, 0);
+       else
+               ret = -1;
+
+       if (ret > 0 && runtime_ss->dynsym) {
+               int nr_plt;
+
+               nr_plt = dso__synthesize_plt_symbols(dso, runtime_ss, map, filter);
+               if (nr_plt > 0)
+                       ret += nr_plt;
        }
 
+       for (; ss_pos > 0; ss_pos--)
+               symsrc__destroy(&ss_[ss_pos - 1]);
+out_free:
        free(name);
        if (ret < 0 && strstr(dso->name, " (deleted)") != NULL)
                return 0;

diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index 1f3eed21f35d96eded82e29ac43e2a28dbd5c66d..fc4b1e630fd9cc941e0367eea2fa829ec85e0b12 100644 (file)
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -253,6 +253,7 @@ void symsrc__destroy(struct symsrc *ss);
 int symsrc__init(struct symsrc *ss, struct dso *dso, const char *name,
                 enum dso_binary_type type);
 bool symsrc__has_symtab(struct symsrc *ss);
+bool symsrc__possibly_runtime(struct symsrc *ss);
 
 #define DSO__SWAP(dso, type, val)                      \
 ({                                                     \