perf script: Add the offset field specifier

Add the offset field specifier 'symoff' to show the offset from
the symbols in the output of perf-script. We can get the more
detailed address information.

Output sample:
ffffffff81467612 irq_return+0x0 => 301ec016b0 _start+0x0
ffffffff81467612 irq_return+0x0 => 301ec016b0 _start+0x0
      301ec016b3 _start+0x3     => 301ec04b70 _dl_start+0x0
ffffffff81467612 irq_return+0x0 => 301ec04b70 _dl_start+0x0
ffffffff81467612 irq_return+0x0 => 301ec04b96 _dl_start+0x26
ffffffff81467612 irq_return+0x0 => 301ec04b9d _dl_start+0x2d
      301ec04beb _dl_start+0x7b => 301ec04c0d _dl_start+0x9d
      301ec04c11 _dl_start+0xa1 => 301ec04bf0 _dl_start+0x80
[snip]

Cc: David Ahern <dsahern@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20120130044314.2384.67094.stgit@linux3
Signed-off-by: Akihiro Nagai <akihiro.nagai.hw@hitachi.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index b580fa8..fc6e12f 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -263,16 +263,26 @@
 		       sym->name);
 }
 
+size_t symbol__fprintf_symname_offs(const struct symbol *sym,
+				    const struct addr_location *al, FILE *fp)
+{
+	unsigned long offset;
+	size_t length;
+
+	if (sym && sym->name) {
+		length = fprintf(fp, "%s", sym->name);
+		if (al) {
+			offset = al->addr - sym->start;
+			length += fprintf(fp, "+0x%lx", offset);
+		}
+		return length;
+	} else
+		return fprintf(fp, "[unknown]");
+}
+
 size_t symbol__fprintf_symname(const struct symbol *sym, FILE *fp)
 {
-	const char *symname;
-
-	if (sym && sym->name)
-		symname = sym->name;
-	else
-		symname = "[unknown]";
-
-	return fprintf(fp, "%s", symname);
+	return symbol__fprintf_symname_offs(sym, NULL, fp);
 }
 
 void dso__set_long_name(struct dso *dso, char *name)