PR10655 part 1: uprobes: track sdt semaphores properly

commit 6846cfc8 introduced an unintended side-effect where semaphore tracking
was identified with stap_uprobe_specs[] elements, which are normally static/const.
This kernel patch <http://article.gmane.org/gmane.linux.kernel/854187> catches
and panics on this.  The cure is to move the variable over to the stap_uprobes[]
array.

* tapsets.cxx (uprobe emit_module_decls): Add sdt_sem_address to stap_uprobe{} struct,
  to contain per-process relocated semaphore address.
  (emit_module_decls,_init): Remove tsk field, restore constness of appropriate
  locals.  Activate uprobe semaphore right around uprobe activation time.  Remove
  semaphore clearing upon process exit, since by then it's gone.
  (emit_module_exit): Use remembered relocated semaphore address to clean up.
  Fix "-uprobe" DEBUG_UPROBES message.
* runtime.h: #include <linux/sched.h>.
* dtrace.in (*_semaphore): Make it an unsigned short - intended 16 bits on all
  common architectures/multilibs.

1 files changed, 4 insertions, 2 deletions

diff --git a/dtrace.in b/dtrace.in
index 98783604..c18f4efd 100755
--- a/dtrace.in
+++ b/dtrace.in
@@ -37,7 +37,8 @@ class provider:
                 typedefs += (type_name + type_name + "_v;\n")
         return typedefs
     def semaphore_def_append(self, this_probe):
-        self.semaphores_def += "__extension__ long %s_semaphore __attribute__ ((unused)) __attribute__ ((section (\".probes\")));\n" % (this_probe)
+        # NB: unsigned short is fixed in ABI
+        self.semaphores_def += "__extension__ unsigned short %s_semaphore __attribute__ ((unused)) __attribute__ ((section (\".probes\")));\n" % (this_probe)
     def semaphore_def_write(self, file):
         file.write(self.semaphores_def)
     def generate(self, provider, header, add_typedefs):
@@ -106,7 +107,8 @@ class provider:
                     i += 1
                 self.h.write ('/* %s (%s) */\n' % (this_probe_canon,args_string))
                 self.h.write ('#define %s_ENABLED() %s_semaphore\n' % (this_probe_canon,this_probe))
-                self.h.write ("__extension__ extern long %s_semaphore __attribute__ ((unused)) __attribute__ ((section (\".probes\")));\n" % (this_probe))
+                # NB: unsigned short is fixed in ABI
+                self.h.write ("__extension__ extern unsigned short %s_semaphore __attribute__ ((unused)) __attribute__ ((section (\".probes\")));\n" % (this_probe))
                 self.h.write (define_str + ") \\\n")
                 self.h.write (stap_str + ")\n\n")
             elif (line.find("}") != -1 and have_provider):