[BUGFIX PATCH V2 4/6] perf/probe: Fix to list probe event with correct line number

From: Masami Hiramatsu
Date: Sat Oct 26 2019 - 05:01:01 EST


Since debuginfo__find_probe_point() uses dwarf_entrypc() for
finding the entry address of the function on which a probe is,
it will fail when the function DIE has only ranges attribute.

To fix this issue, use die_entrypc() instead of dwarf_entrypc().

Without this fix, perf probe -l shows incorrect offset.

# perf probe --force -a clear_tasks_mm_cpumask:0 clear_tasks_mm_cpumask:21
Added new events:
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask)
probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:21)

You can now use it in all perf tools, such as:

perf record -e probe:clear_tasks_mm_cpumask_1 -aR sleep 1

# perf probe -l
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask+18446744071579478000@xxxxxxxxxxx/kernel/cpu.c)
probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask+18446744071579478067@xxxxxxxxxxx/kernel/cpu.c)

With this,
# perf probe -l
probe:clear_tasks_mm_cpumask (on clear_tasks_mm_cpumask@xxxxxxxxxxx/kernel/cpu.c)
probe:clear_tasks_mm_cpumask_1 (on clear_tasks_mm_cpumask:21@xxxxxxxxxxx/kernel/cpu.c)

Fixes: 1d46ea2a6a40 ("perf probe: Fix listing incorrect line number with inline function")
Signed-off-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
---
tools/perf/util/probe-finder.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 2fa932bcf960..88e17a4f5ac3 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1566,7 +1566,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
/* Get function entry information */
func = basefunc = dwarf_diename(&spdie);
if (!func ||
- dwarf_entrypc(&spdie, &baseaddr) != 0 ||
+ die_entrypc(&spdie, &baseaddr) != 0 ||
dwarf_decl_line(&spdie, &baseline) != 0) {
lineno = 0;
goto post;
@@ -1583,7 +1583,7 @@ int debuginfo__find_probe_point(struct debuginfo *dbg, unsigned long addr,
while (die_find_top_inlinefunc(&spdie, (Dwarf_Addr)addr,
&indie)) {
/* There is an inline function */
- if (dwarf_entrypc(&indie, &_addr) == 0 &&
+ if (die_entrypc(&indie, &_addr) == 0 &&
_addr == addr) {
/*
* addr is at an inline function entry.