[PATCH 1/1 v2] perf annotate: Properly notify the user that vmlinux is missing

[Arnaldo Carvalho de Melo]

From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

Before this patch we would not find a vmlinux, then try to pass objdump "[kernel.kallsyms]"
as the filename, it would get confused and produce no output:

[root@doppio ~]# perf annotate n_tty_write

------------------------------------------------
 Percent |      Source code & Disassembly of [kernel.kallsyms]
------------------------------------------------

Now we check that and emit meaningful warning:

[root@doppio ~]# perf annotate n_tty_write
Can't annotate n_tty_write: No vmlinux file was found in the path:
[0] vmlinux
[1] /boot/vmlinux
[2] /boot/vmlinux-2.6.34-rc1-tip+
[3] /lib/modules/2.6.34-rc1-tip+/build/vmlinux
[4] /usr/lib/debug/lib/modules/2.6.34-rc1-tip+/vmlinux
[root@doppio ~]#

This bug was introduced when we added automatic search for vmlinux, before that
time the user had to specify a vmlinux file.

v2: Print the warning just for the first symbol found when no symbol
name is specified, otherwise it will spam the screen repeating the
warning for each symbol.

Reported-by: Ingo Molnar <mingo@xxxxxxx>
Cc: stable@xxxxxxxxxx
Cc: FrÃdÃric Weisbecker <fweisbec@xxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/builtin-annotate.c |   10 ++++++++++
 tools/perf/util/newt.c        |    2 +-
 tools/perf/util/symbol.h      |    1 +
 3 files changed, 12 insertions(+), 1 deletions(-)

diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
index 6ad7148..45d1466 100644
--- a/tools/perf/builtin-annotate.c
+++ b/tools/perf/builtin-annotate.c
@@ -452,6 +452,16 @@ static void annotate_sym(struct hist_entry *he)
 	if (!filename)
 		return;
 
+	if (dso->origin == DSO__ORIG_KERNEL) {
+		if (dso->annotate_warned)
+			return;
+		dso->annotate_warned = 1;
+		pr_err("Can't annotate %s: No vmlinux file was found in the "
+		       "path:\n", sym->name);
+		vmlinux_path__fprintf(stderr);
+		return;
+	}
+
 	pr_debug("%s: filename=%s, sym=%s, start=%#Lx, end=%#Lx\n", __func__,
 		 filename, sym->name, map->unmap_ip(map, sym->start),
 		 map->unmap_ip(map, sym->end));
diff --git a/tools/perf/util/newt.c b/tools/perf/util/newt.c
index 2836394..2d19e7a 100644
--- a/tools/perf/util/newt.c
+++ b/tools/perf/util/newt.c
@@ -63,7 +63,7 @@ static void hist_entry__annotate_browser(struct hist_entry *self)
 	if (self->sym == NULL)
 		return;
 
-	if (asprintf(&str, "perf annotate %s | expand", self->sym->name) < 0)
+	if (asprintf(&str, "perf annotate %s 2>&1 | expand", self->sym->name) < 0)
 		return;
 
 	fp = popen(str, "r");
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index d983bba..5bd91d1 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -106,6 +106,7 @@ struct dso {
 	u8		 has_build_id:1;
 	u8		 kernel:1;
 	u8		 hit:1;
+	u8		 annotate_warned:1;
 	unsigned char	 origin;
 	u8		 sorted_by_name;
 	u8		 loaded;
-- 
1.6.2.5

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