[RFC 6/6] perf probe: Make it possible to add a C++ uprobe

[Holger Freyther]

From: Holger Hans Peter Freyther <holgar+ker...@google.com>

If the linkage name looks like a common C++ ABI name use it instead of
the original function name. This makes adding a uprobe for a C++ symbol
possible.

./perf probe -x ./cxx-example  "std::vector<int, std::allocator<int> >::at"
Added new event:
  probe_foo:_ZNSt6vectorIiSaIiEE2atEm (on _ZN... in /cxx-example)

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

        perf record -e probe_foo:_ZNSt6vectorIiSaIiEE2atEm -aR sleep 1

Signed-off-by: Holger Hans Peter Freyther <holgar+ker...@google.com>
---
 tools/perf/util/probe-finder.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/tools/perf/util/probe-finder.c b/tools/perf/util/probe-finder.c
index 4ba4b18..4cfa3de 100644
--- a/tools/perf/util/probe-finder.c
+++ b/tools/perf/util/probe-finder.c
@@ -1317,6 +1317,7 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, 
struct probe_finder *pf)
        struct perf_probe_point *pp = &pf->pev->point;
        struct probe_trace_event *tev;
        struct perf_probe_arg *args = NULL;
+       const char *linkage_name;
        int ret, i;
 
        /* Check number of tevs */
@@ -1333,6 +1334,16 @@ static int add_probe_trace_event(Dwarf_Die *sc_die, 
struct probe_finder *pf)
        if (ret < 0)
                goto end;
 
+       /*
+        * Adding a C++ name like std::vector<int, std::allocator<int> >::at
+        * will fail. Check if we want to use the linkage name instead.
+        */
+       linkage_name = die_get_linkage_name(&pf->sp_die);
+       if (linkage_name && strncmp(linkage_name, "_Z", 2) == 0) {
+               free(pp->function);
+               pp->function = strdup(linkage_name);
+       }
+
        tev->point.realname = strdup(dwarf_diename(sc_die));
        if (!tev->point.realname) {
                ret = -ENOMEM;
-- 
2.7.4