Commit 30d7a77d authored Jul 02, 2009 by Arnaldo Carvalho de Melo Committed by Ingo Molnar Jul 03, 2009

perf_counter tools: Adjust symbols in ET_EXEC files too



Ingo Molnar wrote:

> i just bisected a 'perf report' bug that would cause us to not
> resolve all user-space symbols in a 'git gc' run to:
>
> f5812a7a is first bad commit
> commit f5812a7a
> Author: Arnaldo Carvalho de Melo <acme@redhat.com>
> Date:   Tue Jun 30 11:43:17 2009 -0300
>
>     perf_counter tools: Adjust only prelinked symbol's addresses

Rename ->prelinked to ->adjust_symbols and making what was done
only for prelinked libraries also to ET_EXEC binaries, such as
/usr/bin/git:

[acme@doppio pahole]$ readelf -h /usr/bin/git | grep Type
  Type:                              EXEC (Executable file)
[acme@doppio pahole]$

And after installing the 'git-debuginfo' package, I get correct results:

[acme@doppio linux-2.6-tip]$ perf report --sort comm,dso,symbol -d /usr/bin/git | head -20

 #
 # (1139614 samples)
 #
 # Overhead           Command  Shared Object              Symbol
 # ........  ................  .........................  ......
 #
    34.98%               git  /usr/bin/git               [.] send_sideband
    33.39%               git  /usr/bin/git               [.] enter_repo
     6.81%               git  /usr/bin/git               [.] diff_opt_parse
     4.95%               git  /usr/bin/git               [.] is_repository_shallow
     3.24%               git  /usr/bin/git               [.] odb_mkstemp
     1.39%               git  /usr/bin/git               [.] output
     1.34%               git  /usr/bin/git               [.] xmmap
     1.25%               git  /usr/bin/git               [.] receive_pack_config
     1.16%               git  /usr/bin/git               [.] git_pathdup
     0.90%               git  /usr/bin/git               [.] read_object_with_reference
     0.86%               git  /usr/bin/git               [.] show_patch_diff
     0.85%               git  /usr/bin/git               0x00000000095e2e
     0.69%               git  /usr/bin/git               [.] display
[acme@doppio linux-2.6-tip]$

I'll check what are the last cases where we can't resolve symbols, like
this 0x00000000095e2e later.

And I guess this will fix the problems Mike were seeing too:

 [acme@doppio linux-2.6-tip]$ readelf -h ../build/perf/vmlinux | grep Type
   Type:                              EXEC (Executable file)
 [acme@doppio linux-2.6-tip]$

Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 24b57c69

tools/perf/util/symbol.c

+6 −5

Original line number	Diff line number	Diff line
		@@ -555,9 +555,10 @@ static int dso__load_sym(struct dso self, int fd, const char name,
		nr_syms = shdr.sh_size / shdr.sh_entsize;

		memset(&sym, 0, sizeof(sym));
		self->prelinked = elf_section_by_name(elf, &ehdr, &shdr,
		self->adjust_symbols = (ehdr.e_type == ET_EXEC \|\|
		elf_section_by_name(elf, &ehdr, &shdr,
		".gnu.prelink_undo",
		NULL) != NULL;
		NULL) != NULL);
		elf_symtab__for_each_symbol(syms, nr_syms, index, sym) {
		struct symbol *f;
		u64 obj_start;
		@@ -580,7 +581,7 @@ static int dso__load_sym(struct dso self, int fd, const char name,
		section_name = elf_sec__name(&shdr, secstrs);
		obj_start = sym.st_value;

		if (self->prelinked) {
		if (self->adjust_symbols) {
		if (verbose >= 2)
		printf("adjusting symbol: st_value: %Lx sh_addr: %Lx sh_offset: %Lx\n",
		(u64)sym.st_value, (u64)shdr.sh_addr, (u64)shdr.sh_offset);
		@@ -632,7 +633,7 @@ int dso__load(struct dso *self, symbol_filter_t filter, int verbose)
		if (!name)
		return -1;

		self->prelinked = 0;
		self->adjust_symbols = 0;

		if (strncmp(self->name, "/tmp/perf-", 10) == 0)
		return dso__load_perf_map(self, filter, verbose);

tools/perf/util/symbol.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -24,7 +24,7 @@ struct dso {
		struct rb_root syms;
		struct symbol (find_symbol)(struct dso *, u64 ip);
		unsigned int sym_priv_size;
		unsigned char prelinked;
		unsigned char adjust_symbols;
		char name[0];
		};