perf trace: Add interface to access perf data from Perl handlers

The Perl scripting support for perf trace allows most of a trace
event's data to be accessed directly as handler arguments, but
not all of it e.g. the less common fields aren't passed in.  To
give scripts access to the other fields and/or any other data or
metadata in the main perf executable that might be useful, a way
to access the C data in perf from Perl is needed; this patch
uses the Perl XS facility to do it for the common_xxx event
fields not passed to handler functions.

Context.pm exports three functions to Perl scripts that access
fields for the current event by calling back into perf:
common_pc(), common_flags() and common_lock_depth().  Support
for common_flags() field values was added to Core.pm and a
script used to sanity check these and other basic scripting
features, check-perf-trace.pl, was also added.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: fweisbec@gmail.com
Cc: rostedt@goodmis.org
Cc: anton@samba.org
Cc: hch@infradead.org
LKML-Reference: <1259133352-23685-6-git-send-email-tzanussi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

4 files changed, 60 insertions, 4 deletions

diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c
index 1f16495e5597..0302405aa2ca 100644
--- a/tools/perf/util/trace-event-parse.c
+++ b/tools/perf/util/trace-event-parse.c
@@ -1982,7 +1982,7 @@ int trace_parse_common_pid(void *data)
                               "common_pid");
 }
 
-static int parse_common_pc(void *data)
+int parse_common_pc(void *data)
 {
         static int pc_offset;
         static int pc_size;
@@ -1991,7 +1991,7 @@ static int parse_common_pc(void *data)
                               "common_preempt_count");
 }
 
-static int parse_common_flags(void *data)
+int parse_common_flags(void *data)
 {
         static int flags_offset;
         static int flags_size;
@@ -2000,7 +2000,7 @@ static int parse_common_flags(void *data)
                               "common_flags");
 }
 
-static int parse_common_lock_depth(void *data)
+int parse_common_lock_depth(void *data)
 {
         static int ld_offset;
         static int ld_size;
diff --git a/tools/perf/util/trace-event-perl.c b/tools/perf/util/trace-event-perl.c
index c56b08d704da..d179adebc547 100644
--- a/tools/perf/util/trace-event-perl.c
+++ b/tools/perf/util/trace-event-perl.c
@@ -30,6 +30,21 @@
 #include "trace-event.h"
 #include "trace-event-perl.h"
 
+void xs_init(pTHX);
+
+void boot_Perf__Trace__Context(pTHX_ CV *cv);
+void boot_DynaLoader(pTHX_ CV *cv);
+
+void xs_init(pTHX)
+{
+        const char *file = __FILE__;
+        dXSUB_SYS;
+
+        newXS("Perf::Trace::Context::bootstrap", boot_Perf__Trace__Context,
+              file);
+        newXS("DynaLoader::boot_DynaLoader", boot_DynaLoader, file);
+}
+
 INTERP my_perl;
 
 #define FTRACE_MAX_EVENT                                \
@@ -227,6 +242,33 @@ static inline struct event *find_cache_event(int type)
         return event;
 }
 
+int get_common_pc(struct scripting_context *context)
+{
+        int pc;
+
+        pc = parse_common_pc(context->event_data);
+
+        return pc;
+}
+
+int get_common_flags(struct scripting_context *context)
+{
+        int flags;
+
+        flags = parse_common_flags(context->event_data);
+
+        return flags;
+}
+
+int get_common_lock_depth(struct scripting_context *context)
+{
+        int lock_depth;
+
+        lock_depth = parse_common_lock_depth(context->event_data);
+
+        return lock_depth;
+}
+
 static void perl_process_event(int cpu, void *data,
                                int size __attribute((unused)),
                                unsigned long long nsecs, char *comm)
@@ -290,6 +332,7 @@ static void perl_process_event(int cpu, void *data,
         }
 
         PUTBACK;
+
         if (get_cv(handler, 0))
                 call_pv(handler, G_SCALAR);
         else if (get_cv("main::trace_unhandled", 0)) {
@@ -328,7 +371,8 @@ static int perl_start_script(const char *script)
         my_perl = perl_alloc();
         perl_construct(my_perl);
 
-        if (perl_parse(my_perl, NULL, 2, (char **)command_line, (char **)NULL))
+        if (perl_parse(my_perl, xs_init, 2, (char **)command_line,
+                       (char **)NULL))
                 return -1;
 
         perl_run(my_perl);
diff --git a/tools/perf/util/trace-event-perl.h b/tools/perf/util/trace-event-perl.h
index 6c94fa93013d..666a864f5dda 100644
--- a/tools/perf/util/trace-event-perl.h
+++ b/tools/perf/util/trace-event-perl.h
@@ -29,6 +29,11 @@ typedef int INTERP;
 #define perl_run(a)             (0)
 #define perl_destruct(a)        (0)
 #define perl_free(a)            (0)
+#define pTHX                    void
+#define CV                      void
+#define dXSUB_SYS
+#define pTHX_
+static inline void newXS(const char *a, void *b, const char *c) {}
 #else
 #include <EXTERN.h>
 #include <perl.h>
@@ -39,4 +44,8 @@ struct scripting_context {
         void *event_data;
 };
 
+int get_common_pc(struct scripting_context *context);
+int get_common_flags(struct scripting_context *context);
+int get_common_lock_depth(struct scripting_context *context);
+
 #endif /* __PERF_TRACE_EVENT_PERL_H */
diff --git a/tools/perf/util/trace-event.h b/tools/perf/util/trace-event.h
index b1e58d3d947d..81698d5e6503 100644
--- a/tools/perf/util/trace-event.h
+++ b/tools/perf/util/trace-event.h
@@ -246,6 +246,9 @@ extern int latency_format;
 int parse_header_page(char *buf, unsigned long size);
 int trace_parse_common_type(void *data);
 int trace_parse_common_pid(void *data);
+int parse_common_pc(void *data);
+int parse_common_flags(void *data);
+int parse_common_lock_depth(void *data);
 struct event *trace_find_event(int id);
 struct event *trace_find_next_event(struct event *event);
 unsigned long long read_size(void *ptr, int size);