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Subject[tip:perf/core] perf probe: Show appropriate symbol for ref_reloc_sym based kprobes
Commit-ID:  8f33f7deac485a61f38aa690b85489322a4d958e
Gitweb: http://git.kernel.org/tip/8f33f7deac485a61f38aa690b85489322a4d958e
Author: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
AuthorDate: Thu, 6 Feb 2014 05:32:20 +0000
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Tue, 18 Feb 2014 09:34:51 -0300

perf probe: Show appropriate symbol for ref_reloc_sym based kprobes

Show appropriate symbol for ref_reloc_sym based kprobes instead of
refpoint+offset when perf-probe -l runs without debuginfo.

Without this change:
# ./perf probe -l
probe:t_show (on _stext+889880 with m v)
probe:t_show_1 (on _stext+928568 with m v t)
probe:t_show_2 (on _stext+969512 with m v fmt)
probe:t_show_3 (on _stext+1001416 with m v file)

With this change:
# ./perf probe -l
probe:t_show (on t_show with m v)
probe:t_show_1 (on t_show with m v t)
probe:t_show_2 (on t_show with m v fmt)
probe:t_show_3 (on t_show with m v file)

Changes from v2:
- Check ref_reloc_sym to find correct unrelocated address.

Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: "David A. Long" <dave.long@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: yrl.pp-manager.tt@hitachi.com
Link: http://lkml.kernel.org/r/20140206053220.29635.81819.stgit@kbuild-fedora.yrl.intra.hitachi.co.jp
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/util/probe-event.c | 83 ++++++++++++++++++++++++++++---------------
1 file changed, 55 insertions(+), 28 deletions(-)

diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index 8e34c8d..f86820c 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -121,6 +121,42 @@ static struct symbol *__find_kernel_function_by_name(const char *name,
NULL);
}

+static struct symbol *__find_kernel_function(u64 addr, struct map **mapp)
+{
+ return machine__find_kernel_function(host_machine, addr, mapp, NULL);
+}
+
+static struct ref_reloc_sym *kernel_get_ref_reloc_sym(void)
+{
+ /* kmap->ref_reloc_sym should be set if host_machine is initialized */
+ struct kmap *kmap;
+
+ if (map__load(host_machine->vmlinux_maps[MAP__FUNCTION], NULL) < 0)
+ return NULL;
+
+ kmap = map__kmap(host_machine->vmlinux_maps[MAP__FUNCTION]);
+ return kmap->ref_reloc_sym;
+}
+
+static u64 kernel_get_symbol_address_by_name(const char *name, bool reloc)
+{
+ struct ref_reloc_sym *reloc_sym;
+ struct symbol *sym;
+ struct map *map;
+
+ /* ref_reloc_sym is just a label. Need a special fix*/
+ reloc_sym = kernel_get_ref_reloc_sym();
+ if (reloc_sym && strcmp(name, reloc_sym->name) == 0)
+ return (reloc) ? reloc_sym->addr : reloc_sym->unrelocated_addr;
+ else {
+ sym = __find_kernel_function_by_name(name, &map);
+ if (sym)
+ return map->unmap_ip(map, sym->start) -
+ (reloc) ? 0 : map->reloc;
+ }
+ return 0;
+}
+
static struct map *kernel_get_module_map(const char *module)
{
struct rb_node *nd;
@@ -216,12 +252,26 @@ out:
static int convert_to_perf_probe_point(struct probe_trace_point *tp,
struct perf_probe_point *pp)
{
- pp->function = strdup(tp->symbol);
+ struct symbol *sym;
+ struct map *map;
+ u64 addr = kernel_get_symbol_address_by_name(tp->symbol, true);
+
+ if (addr) {
+ addr += tp->offset;
+ sym = __find_kernel_function(addr, &map);
+ if (!sym)
+ goto failed;
+ pp->function = strdup(sym->name);
+ pp->offset = addr - map->unmap_ip(map, sym->start);
+ } else {
+failed:
+ pp->function = strdup(tp->symbol);
+ pp->offset = tp->offset;
+ }

if (pp->function == NULL)
return -ENOMEM;

- pp->offset = tp->offset;
pp->retprobe = tp->retprobe;

return 0;
@@ -248,18 +298,6 @@ static struct debuginfo *open_debuginfo(const char *module)
return debuginfo__new(path);
}

-static struct ref_reloc_sym *__kernel_get_ref_reloc_sym(void)
-{
- /* kmap->ref_reloc_sym should be set if host_machine is initialized */
- struct kmap *kmap;
-
- if (map__load(host_machine->vmlinux_maps[MAP__FUNCTION], NULL) < 0)
- return NULL;
-
- kmap = map__kmap(host_machine->vmlinux_maps[MAP__FUNCTION]);
- return kmap->ref_reloc_sym;
-}
-
/*
* Convert trace point to probe point with debuginfo
* Currently only handles kprobes.
@@ -267,24 +305,13 @@ static struct ref_reloc_sym *__kernel_get_ref_reloc_sym(void)
static int kprobe_convert_to_perf_probe(struct probe_trace_point *tp,
struct perf_probe_point *pp)
{
- struct symbol *sym;
- struct ref_reloc_sym *reloc_sym;
- struct map *map;
u64 addr = 0;
int ret = -ENOENT;
struct debuginfo *dinfo;

- /* ref_reloc_sym is just a label. Need a special fix*/
- reloc_sym = __kernel_get_ref_reloc_sym();
- if (reloc_sym && strcmp(tp->symbol, reloc_sym->name) == 0)
- addr = reloc_sym->unrelocated_addr + tp->offset;
- else {
- sym = __find_kernel_function_by_name(tp->symbol, &map);
- if (sym)
- addr = map->unmap_ip(map, sym->start + tp->offset) -
- map->reloc;
- }
+ addr = kernel_get_symbol_address_by_name(tp->symbol, false);
if (addr) {
+ addr += tp->offset;
pr_debug("try to find %s+%ld@%" PRIx64 "\n", tp->symbol,
tp->offset, addr);

@@ -420,7 +447,7 @@ static int post_process_probe_trace_events(struct probe_trace_event *tevs,
if (module)
return add_module_to_probe_trace_events(tevs, ntevs, module);

- reloc_sym = __kernel_get_ref_reloc_sym();
+ reloc_sym = kernel_get_ref_reloc_sym();
if (!reloc_sym) {
pr_warning("Relocated base symbol is not found!\n");
return -EINVAL;

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