[PATCH AUTOSEL for 4.15 009/124] perf probe: Find versioned symbols from map

Sasha Levin
2018-03-19T22:41:57Z

From: Masami Hiramatsu <mhiramat@kernel.org>

[ Upstream commit 4b3a2716dd785fabb9f6ac80c1d53cb29a88169d ]

Commit d80406453ad4 ("perf symbols: Allow user probes on versioned
symbols") allows user to find default versioned symbols (with "@@") in
map. However, it did not enable normal versioned symbol (with "@") for
perf-probe. E.g.

=====
# ./perf probe -x /lib64/libc-2.25.so malloc_get_state
Failed to find symbol malloc_get_state in /usr/lib64/libc-2.25.so
Error: Failed to add events.
=====

This solves above issue by improving perf-probe symbol search function,
as below.

=====
# ./perf probe -x /lib64/libc-2.25.so malloc_get_state
Added new event:
probe_libc:malloc_get_state (on malloc_get_state in /usr/lib64/libc-2.25.so)

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

perf record -e probe_libc:malloc_get_state -aR sleep 1

# ./perf probe -l
probe_libc:malloc_get_state (on malloc_get_state@GLIBC_2.2.5 in /usr/lib64/libc-2.25.so)
=====

Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Thomas Richter <tmricht@linux.vnet.ibm.com>
Acked-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Clarke <pc@us.ibm.com>
Cc: bhargavb <bhargavaramudu@gmail.com>
Cc: linux-rt-users@vger.kernel.org
Link: http://lkml.kernel.org/r/151275049269.24652.1639103455496216255.stgit@devbox
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
tools/perf/arch/powerpc/util/sym-handling.c | 8 ++++++++
tools/perf/util/probe-event.c | 20 ++++++++++++++++++--
tools/perf/util/symbol.c | 5 +++++
tools/perf/util/symbol.h | 1 +
4 files changed, 32 insertions(+), 2 deletions(-)

diff --git a/tools/perf/arch/powerpc/util/sym-handling.c b/tools/perf/arch/powerpc/util/sym-handling.c
index 9c4e23d8c8ce..53d83d7e6a09 100644
--- a/tools/perf/arch/powerpc/util/sym-handling.c
+++ b/tools/perf/arch/powerpc/util/sym-handling.c
@@ -64,6 +64,14 @@ int arch__compare_symbol_names_n(const char *namea, const char *nameb,

return strncmp(namea, nameb, n);
}
+
+const char *arch__normalize_symbol_name(const char *name)
+{
+ /* Skip over initial dot */
+ if (name && *name == '.')
+ name++;
+ return name;
+}
#endif

#if defined(_CALL_ELF) && _CALL_ELF == 2
diff --git a/tools/perf/util/probe-event.c b/tools/perf/util/probe-event.c
index b7aaf9b2294d..c3cd3488fee7 100644
--- a/tools/perf/util/probe-event.c
+++ b/tools/perf/util/probe-event.c
@@ -2792,16 +2792,32 @@ static int find_probe_functions(struct map *map, char *name,
int found = 0;
struct symbol *sym;
struct rb_node *tmp;
+ const char *norm, *ver;
+ char *buf = NULL;

if (map__load(map) < 0)
return 0;

map__for_each_symbol(map, sym, tmp) {
- if (strglobmatch(sym->name, name)) {
+ norm = arch__normalize_symbol_name(sym->name);
+ if (!norm)
+ continue;
+
+ /* We don't care about default symbol or not */
+ ver = strchr(norm, '@');
+ if (ver) {
+ buf = strndup(norm, ver - norm);
+ if (!buf)
+ return -ENOMEM;
+ norm = buf;
+ }
+ if (strglobmatch(norm, name)) {
found++;
if (syms && found < probe_conf.max_probes)
syms[found - 1] = sym;
}
+ if (buf)
+ zfree(&buf);
}

return found;
@@ -2847,7 +2863,7 @@ static int find_probe_trace_events_from_map(struct perf_probe_event *pev,
* same name but different addresses, this lists all the symbols.
*/
num_matched_functions = find_probe_functions(map, pp->function, syms);
- if (num_matched_functions == 0) {
+ if (num_matched_functions <= 0) {
pr_err("Failed to find symbol %s in %s\n", pp->function,
pev->target ? : "kernel");
ret = -ENOENT;
diff --git a/tools/perf/util/symbol.c b/tools/perf/util/symbol.c
index 1b67a8639dfe..cc065d4bfafc 100644
--- a/tools/perf/util/symbol.c
+++ b/tools/perf/util/symbol.c
@@ -94,6 +94,11 @@ static int prefix_underscores_count(const char *str)
return tail - str;
}

+const char * __weak arch__normalize_symbol_name(const char *name)
+{
+ return name;
+}
+
int __weak arch__compare_symbol_names(const char *namea, const char *nameb)
{
return strcmp(namea, nameb);
diff --git a/tools/perf/util/symbol.h b/tools/perf/util/symbol.h
index a4f0075b4e5c..0563f33c1eb3 100644
--- a/tools/perf/util/symbol.h
+++ b/tools/perf/util/symbol.h
@@ -349,6 +349,7 @@ bool elf__needs_adjust_symbols(GElf_Ehdr ehdr);
void arch__sym_update(struct symbol *s, GElf_Sym *sym);
#endif

+const char *arch__normalize_symbol_name(const char *name);
#define SYMBOL_A 0
#define SYMBOL_B 1

--
2.14.1