Build tracequery to scan for tracepoints

	* session.h (systemtap_session): add tracepoint_derived_probes
	* buildrun.cxx (make_tracequery): New - builds a kernel module that
	hijacks the tracepoint declarations, so we can query debuginfo.
	* buildrun.h: declare above
	* tapsets.cxx (tracepoint_builder): New builder for tracepoint
	probes.  For now it just handles the initialization to build the
	tracequery kernel module.

4 files changed, 155 insertions, 0 deletions

diff --git a/buildrun.cxx b/buildrun.cxx
index 973343cd..b81cba23 100644
--- a/buildrun.cxx
+++ b/buildrun.cxx
@@ -24,6 +24,7 @@ extern "C" {
 #include <unistd.h>
 #include <string.h>
 #include <errno.h>
+#include <glob.h>
 }
 
 
@@ -336,4 +337,73 @@ run_pass (systemtap_session& s)
   return rc;
 }
 
+
+// Build a tiny kernel module to query tracepoints
+int
+make_tracequery(systemtap_session& s, string& name)
+{
+  // create a subdirectory for the module
+  string dir(s.tmpdir + "/tracequery");
+  if (create_dir(dir.c_str()) != 0)
+    {
+      if (! s.suppress_warnings)
+        cerr << "Warning: failed to create directory for querying tracepoints." << endl;
+      return 1;
+    }
+
+  name = dir + "/tracequery.ko";
+
+  // create a simple Makefile
+  string makefile(dir + "/Makefile");
+  ofstream omf(makefile.c_str());
+  omf << "EXTRA_CFLAGS := -g" << endl; // force debuginfo generation
+  omf << "obj-m := tracequery.o" << endl;
+  omf.close();
+
+  // create our source file
+  string source(dir + "/tracequery.c");
+  ofstream osrc(source.c_str());
+  osrc << "#include <linux/module.h>" << endl;
+  osrc << "#ifdef CONFIG_TRACEPOINTS" << endl;
+  osrc << "#include <linux/tracepoint.h>" << endl;
+
+  // override DECLARE_TRACE to synthesize probe functions for us
+  osrc << "#undef DECLARE_TRACE" << endl;
+  osrc << "#define DECLARE_TRACE(name, proto, args) \\" << endl;
+  osrc << "  void stapprobe_##name(proto) {}" << endl;
+
+  // dynamically pull in all tracepoint headers from include/trace/
+  glob_t trace_glob;
+  string glob_str(s.kernel_build_tree + "/include/trace/*.h");
+  glob(glob_str.c_str(), 0, NULL, &trace_glob);
+  for (unsigned i = 0; i < trace_glob.gl_pathc; ++i)
+    {
+      string header(basename(trace_glob.gl_pathv[i]));
+
+      // filter out a few known "internal-only" headers
+      if (header == "trace_events.h")
+        continue;
+      if (header.find("_event_types.h") != string::npos)
+        continue;
+
+      osrc << "#include <trace/" << header << ">" << endl;
+    }
+  globfree(&trace_glob);
+
+  // finish up the module source
+  osrc << "#endif /* CONFIG_TRACEPOINTS */" << endl;
+  osrc << "int init_module(void) { return 0; }" << endl;
+  osrc << "void cleanup_module(void) {}" << endl;
+  osrc << "MODULE_DESCRIPTION(\"tracepoint query\");" << endl;
+  osrc << "MODULE_LICENSE(\"GPL\");" << endl;
+  osrc.close();
+
+  // make the module
+  string make_cmd = "make -C '" + s.kernel_build_tree + "'"
+    + " M='" + dir + "' modules";
+  if (s.verbose < 4)
+    make_cmd += " >/dev/null 2>&1";
+  return run_make_cmd(s, make_cmd);
+}
+
 /* vim: set sw=2 ts=8 cino=>4,n-2,{2,^-2,t0,(0,u0,w1,M1 : */
diff --git a/buildrun.h b/buildrun.h
index 98c81251..88127449 100644
--- a/buildrun.h
+++ b/buildrun.h
@@ -14,6 +14,7 @@
 int compile_pass (systemtap_session& s);
 int run_pass (systemtap_session& s);
 
+int make_tracequery(systemtap_session& s, std::string& name);
 
 #endif // BUILDRUN_H
 
diff --git a/session.h b/session.h
index e6d8eb82..8fa491fd 100644
--- a/session.h
+++ b/session.h
@@ -37,6 +37,7 @@ struct task_finder_derived_probe_group;
 struct timer_derived_probe_group;
 struct profile_derived_probe_group;
 struct mark_derived_probe_group;
+struct tracepoint_derived_probe_group;
 struct hrtimer_derived_probe_group;
 struct perfmon_derived_probe_group;
 struct procfs_derived_probe_group;
@@ -162,6 +163,7 @@ struct systemtap_session
   timer_derived_probe_group* timer_derived_probes;
   profile_derived_probe_group* profile_derived_probes;
   mark_derived_probe_group* mark_derived_probes;
+  tracepoint_derived_probe_group* tracepoint_derived_probes;
   hrtimer_derived_probe_group* hrtimer_derived_probes;
   perfmon_derived_probe_group* perfmon_derived_probes;
   procfs_derived_probe_group* procfs_derived_probes;
diff --git a/tapsets.cxx b/tapsets.cxx
index 834aa06a..6693e9c3 100644
--- a/tapsets.cxx
+++ b/tapsets.cxx
@@ -15,6 +15,7 @@
 #include "translate.h"
 #include "session.h"
 #include "util.h"
+#include "buildrun.h"
 #include "dwarf_wrappers.h"
 #include "auto_free.h"
 
@@ -465,6 +466,7 @@ static string TOK_STATEMENT("statement");
 static string TOK_ABSOLUTE("absolute");
 static string TOK_PROCESS("process");
 static string TOK_MARK("mark");
+static string TOK_TRACE("trace");
 static string TOK_LABEL("label");
 
 // Can we handle this query with just symbol-table info?
@@ -9201,6 +9203,81 @@ mark_builder::build(systemtap_session & sess,
 
 
 // ------------------------------------------------------------------------
+// statically inserted kernel-tracepoint derived probes
+// ------------------------------------------------------------------------
+
+
+struct tracepoint_derived_probe: public derived_probe
+{
+  // TODO
+};
+
+
+struct tracepoint_derived_probe_group: public generic_dpg<tracepoint_derived_probe>
+{
+  // TODO
+};
+
+
+struct tracepoint_builder: public derived_probe_builder
+{
+private:
+  dwflpp *dw;
+  bool init_dw(systemtap_session& s);
+
+public:
+  tracepoint_builder(): dw(0) {}
+  ~tracepoint_builder() { delete dw; }
+
+  void build_no_more (systemtap_session& s)
+  {
+    if (dw && s.verbose > 3)
+      clog << "tracepoint_builder releasing dwflpp" << endl;
+    delete dw;
+    dw = NULL;
+  }
+
+  void build(systemtap_session& s,
+             probe *base, probe_point *location,
+             literal_map_t const& parameters,
+             vector<derived_probe*>& finished_results);
+};
+
+
+bool
+tracepoint_builder::init_dw(systemtap_session& s)
+{
+  if (dw != NULL)
+    return true;
+
+  string tracequery_ko;
+  int rc = make_tracequery(s, tracequery_ko);
+  if (rc != 0)
+    return false;
+
+  // TODO cache tracequery.ko
+
+  dw = new dwflpp(s);
+  dw->setup_user(tracequery_ko);
+  return true;
+}
+
+
+void
+tracepoint_builder::build(systemtap_session& s,
+                          probe *base, probe_point *location,
+                          literal_map_t const& parameters,
+                          vector<derived_probe*>& finished_results)
+{
+  if (!init_dw(s))
+    return;
+
+  // TODO run a query to match tracepoint locations
+}
+
+
+
+// ------------------------------------------------------------------------
 // hrtimer derived probes
 // ------------------------------------------------------------------------
 // This is a new timer interface that provides more flexibility in specifying
@@ -10002,6 +10079,10 @@ register_standard_tapsets(systemtap_session & s)
   s.pattern_root->bind(TOK_KERNEL)->bind_str(TOK_MARK)->bind_str(TOK_FORMAT)
     ->bind(new mark_builder());
 
+  // kernel tracepoint probes
+  s.pattern_root->bind(TOK_KERNEL)->bind_str(TOK_TRACE)
+    ->bind(new tracepoint_builder());
+
   // procfs parts
   s.pattern_root->bind(TOK_PROCFS)->bind(TOK_READ)->bind(new procfs_builder());
   s.pattern_root->bind_str(TOK_PROCFS)->bind(TOK_READ)
@@ -10030,6 +10111,7 @@ all_session_groups(systemtap_session& s)
   DOONE(timer);
   DOONE(profile);
   DOONE(mark);
+  DOONE(tracepoint);
   DOONE(hrtimer);
   DOONE(perfmon);
   DOONE(procfs);