Add .library("lib").mark("mark") and use it for .mark semaphores.

tapset-utrace.cxx (TOK_LIBRARY): New.
 (utrace_derived_probe::utrace_derived_probe): Add library and has_library.
 (utrace_builder::build): Handle library.
 (utrace_derived_probe_group::emit_probe_decl): Add sdt_sem_offset to
  emitted stap_utrace_probes.  Add stap_task_finder_target
  mmap_callback for handling shared library.  Handle sdt_sem_offset in
  emitted_stp_utrace_probe_cb.  Add stap_utrace_mmap_found.
 (register_tapset_utrace): Handle .library
tapset-utrace.cxx (TOK_LIBRARY): New.
 (base_query::base_query):  Add path and has_library.
 (dwarf_derived_probe::dwarf_derived_probe) Likewise.
 (dwarf_derived_probe::register_patterns):  Handle .library
 (sdt_query::convert_location): Likewise.
 (dwarf_builder::build):  Likewise.
 (uprobe_derived_probe_group::emit_module_decls): Emit
  sdt_sem_address.  Add sdt_sem_offset to emitted stap_uprobe_spec.
  Add offset and vm_flags to signature of stap_uprobe_change_plus, and
  handle sdt_sem_offset.  Allow writeable segments in emitted
  stap_uprobe_mmap_found.
sdt_misc.exp:  Test .library
util.cxx (find_executable):  Add env_path to sig and use it in getenv.
util.h (find_executable): Likewise.  Make "PATH" the default.
dtrace.in (provider): Turn on semaphores.
sdt.h: Likewise.

1 files changed, 88 insertions, 14 deletions

diff --git a/tapset-utrace.cxx b/tapset-utrace.cxx
index 795d88b7..bd668a2b 100644
--- a/tapset-utrace.cxx
+++ b/tapset-utrace.cxx
@@ -29,6 +29,7 @@ static const string TOK_END("end");
 static const string TOK_THREAD("thread");
 static const string TOK_SYSCALL("syscall");
 static const string TOK_RETURN("return");
+static const string TOK_LIBRARY("library");
 
 
 // ------------------------------------------------------------------------
@@ -52,13 +53,15 @@ struct utrace_derived_probe: public derived_probe
 {
   bool has_path;
   string path;
+  bool has_library;
+  string library;
   int64_t pid;
   enum utrace_derived_probe_flags flags;
   bool target_symbol_seen;
 
   utrace_derived_probe (systemtap_session &s, probe* p, probe_point* l,
-                        bool hp, string &pn, int64_t pd,
-			enum utrace_derived_probe_flags f);
+                        bool hp, string &pn, bool hl, string &ln, 
+			int64_t pd, enum utrace_derived_probe_flags f);
   void join_group (systemtap_session& s);
 
   void emit_unprivileged_assertion (translator_output*);
@@ -115,10 +118,10 @@ struct utrace_var_expanding_visitor: public var_expanding_visitor
 
 utrace_derived_probe::utrace_derived_probe (systemtap_session &s,
                                             probe* p, probe_point* l,
-                                            bool hp, string &pn, int64_t pd,
-					    enum utrace_derived_probe_flags f):
+                                            bool hp, string &pn, bool hl, string &ln,
+					    int64_t pd, enum utrace_derived_probe_flags f):
   derived_probe (p, new probe_point (*l) /* .components soon rewritten */ ),
-  has_path(hp), path(pn), pid(pd), flags(f),
+  has_path(hp), path(pn), has_library(hl), library(ln), pid(pd), flags(f),
   target_symbol_seen(false)
 {
   if (s.kernel_config["CONFIG_UTRACE"] != string("y"))
@@ -599,9 +602,11 @@ struct utrace_builder: public derived_probe_builder
 		     vector<derived_probe *> & finished_results)
   {
     string path;
+    string lib;
     int64_t pid;
 
     bool has_path = get_param (parameters, TOK_PROCESS, path);
+    bool has_lib = get_param (parameters, TOK_LIBRARY, lib);
     bool has_pid = get_param (parameters, TOK_PROCESS, pid);
     enum utrace_derived_probe_flags flags = UDPF_NONE;
 
@@ -647,9 +652,11 @@ struct utrace_builder: public derived_probe_builder
 
         // XXX: could we use /proc/$pid/exe in unwindsym_modules and elsewhere?
       }
+    if (has_lib)
+      lib = find_executable (lib, "LD_LIBRARY_PATH");
 
     finished_results.push_back(new utrace_derived_probe(sess, base, location,
-                                                        has_path, path, pid,
+                                                        has_path, path, has_lib, lib, pid,
 							flags));
   }
 
@@ -750,11 +757,25 @@ utrace_derived_probe_group::emit_probe_decl (systemtap_session& s,
   s.op->line() << " .engine_attached=0,";
 
   if (p->sdt_semaphore_addr != 0)
-    s.op->line() << " .sdt_sem_address=(unsigned long)0x"
+    s.op->line() << " .sdt_sem_offset=(unsigned long)0x"
                  << hex << p->sdt_semaphore_addr << dec << "ULL,";
-
+  s.op->line() << " .sdt_sem_address=0,";
   s.op->line() << " .tsk=0,";
   s.op->line() << " },";
+
+  if (p->has_library && p->sdt_semaphore_addr != 0)
+    {
+      s.op->newline() << "{";
+      s.op->line() << " .tgt={";
+      s.op->line() << " .procname=\"" << p->path << "\",";
+      s.op->line() << " .mmap_callback=&stap_utrace_mmap_found,";
+      s.op->line() << " },";
+      s.op->line() << " .pathname=\"" << p->library << "\",";
+      s.op->line() << " .sdt_sem_offset=(unsigned long)0x"
+		   << hex << p->sdt_semaphore_addr << dec << "ULL,";
+      s.op->line() << " .sdt_sem_address=0,";
+      s.op->line() << " },";
+    }
 }
 
 
@@ -789,7 +810,11 @@ utrace_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "struct utrace_engine_ops ops;";
   s.op->newline() << "unsigned long events;";
   s.op->newline() << "struct task_struct *tsk;";
+  s.op->newline() << "unsigned long sdt_sem_offset;";
+  // FIXME: if this probe is attached to more than 1 task, having 1
+  // address here won't work
   s.op->newline() << "unsigned long sdt_sem_address;";
+  s.op->newline(0) << "const char *pathname;";
   s.op->newline(-1) << "};";
 
 
@@ -913,15 +938,23 @@ utrace_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->indent(-1);
   s.op->newline(-1) << "}";
 
+  s.op->newline() << "if (p->sdt_sem_offset && p->sdt_sem_address == 0) {";
+  s.op->indent(1);
+  // If the probe is in the executable itself, the offset *is* the address.
+  s.op->newline() << "p->sdt_sem_address = p->sdt_sem_offset;";
+  s.op->newline(-1) << "}";
+
+  // Before writing to the semaphore, we need to check for VM_WRITE access.
   s.op->newline() << "if (p->sdt_sem_address != 0) {";
   s.op->newline(1) << "size_t sdt_semaphore;";
   // XXX p could get registered to more than one task!
   s.op->newline() << "p->tsk = tsk;";
-  s.op->newline() << "__access_process_vm (tsk, p->sdt_sem_address, &sdt_semaphore, sizeof (sdt_semaphore), 0);";
-  s.op->newline() << "sdt_semaphore += 1;";
+
+  s.op->newline() << "if (__access_process_vm (tsk, p->sdt_sem_address, &sdt_semaphore, sizeof (sdt_semaphore), 0) == sizeof (sdt_semaphore)) {";
+  s.op->newline(1) << "sdt_semaphore ++;";
   s.op->newline() << "__access_process_vm (tsk, p->sdt_sem_address, &sdt_semaphore, sizeof (sdt_semaphore), 1);";
   s.op->newline(-1) << "}";
-
+  s.op->newline(-1) << "}";
   s.op->newline(-1) << "}";
 
   // Since this engine could be attached to multiple threads, don't
@@ -985,6 +1018,44 @@ utrace_derived_probe_group::emit_module_decls (systemtap_session& s)
   s.op->newline() << "return rc;";
   s.op->newline(-1) << "}";
 
+  // The task_finder_mmap_callback
+  s.op->newline() << "static int stap_utrace_mmap_found (struct stap_task_finder_target *tgt, struct task_struct *tsk, char *path, unsigned long addr, unsigned long length, unsigned long offset, unsigned long vm_flags) {";
+  s.op->newline(1) << "struct stap_utrace_probe *p = container_of(tgt, struct stap_utrace_probe, tgt);";
+  s.op->newline() << "int rc = 0;";
+  // the shared library we're interested in
+  s.op->newline() << "if (path == NULL || strcmp (path, p->pathname)) return 0;";
+  s.op->newline() << "if (p->sdt_sem_address == 0) {";
+  s.op->indent(1);
+  // If the probe is in the executable itself, the offset *is* the
+  // address.
+  s.op->newline() << "if (vm_flags & VM_EXECUTABLE) {";
+  s.op->indent(1);
+  s.op->newline() << "p->sdt_sem_address = addr + p->sdt_sem_offset;";
+  s.op->newline(-1) << "}";
+  // If the probe is in a .so, we have to calculate the address.
+  s.op->newline() << "else {";
+  s.op->indent(1);
+  s.op->newline() << "p->sdt_sem_address = (addr - offset) + p->sdt_sem_offset;";
+  s.op->newline(-1) << "}";
+  s.op->newline(-1) << "}";
+
+  s.op->newline() << "if (p->sdt_sem_address) {";
+  s.op->newline(1) << "unsigned short sdt_semaphore = 0;"; // NB: fixed size
+  s.op->newline() << "if (__access_process_vm (tsk, p->sdt_sem_address, &sdt_semaphore, sizeof (sdt_semaphore), 0) == sizeof (sdt_semaphore)) {";
+
+  s.op->newline(1) << "if (vm_flags & VM_WRITE) {";
+  s.op->indent(1);
+  s.op->newline() << "sdt_semaphore ++;";
+  s.op->newline() << "#ifdef DEBUG_UTRACE";
+  s.op->newline() << "_stp_dbug (__FUNCTION__,__LINE__, \"+semaphore %#x @ %#lx\\n\", sdt_semaphore, p->sdt_sem_address);";
+  s.op->newline() << "#endif";
+  s.op->newline() << "__access_process_vm (tsk, p->sdt_sem_address, &sdt_semaphore, sizeof (sdt_semaphore), 1);";
+  s.op->newline(-1) << "}";
+  s.op->newline(-1) << "}";
+  s.op->newline(-1) << "}";
+  s.op->newline() << "return 0;";
+  s.op->newline(-1) << "}";
+
   s.op->newline() << "static struct stap_utrace_probe stap_utrace_probes[] = {";
   s.op->indent(1);
 
@@ -1055,14 +1126,15 @@ utrace_derived_probe_group::emit_module_exit (systemtap_session& s)
   s.op->newline() << "if (p->engine_attached) {";
   s.op->newline(1) << "stap_utrace_detach_ops(&p->ops);";
 
+  // Before writing to the semaphore, we need to check for VM_WRITE access.
   s.op->newline() << "if (p->sdt_sem_address) {";
   s.op->newline(1) << "size_t sdt_semaphore;";
   // XXX p could get registered to more than one task!
-  s.op->newline() << "__access_process_vm (p->tsk, p->sdt_sem_address, &sdt_semaphore, sizeof (sdt_semaphore), 0);";
-  s.op->newline() << "sdt_semaphore -= 1;";
+  s.op->newline() << "if (__access_process_vm (p->tsk, p->sdt_sem_address, &sdt_semaphore, sizeof (sdt_semaphore), 0) == sizeof (sdt_semaphore)) {";
+  s.op->newline(1) << "sdt_semaphore --;";
   s.op->newline() << "__access_process_vm (p->tsk, p->sdt_sem_address, &sdt_semaphore, sizeof (sdt_semaphore), 1);";
   s.op->newline(-1) << "}";
-
+  s.op->newline(-1) << "}";
   s.op->newline(-1) << "}";
 
   s.op->newline(-1) << "}";
@@ -1094,6 +1166,8 @@ register_tapset_utrace(systemtap_session& s)
 	->bind(builder);
       roots[i]->bind(TOK_SYSCALL)->bind(TOK_RETURN)
 	->bind(builder);
+      roots[i]->bind_str(TOK_LIBRARY)->bind(TOK_SYSCALL)
+	->bind(builder);
     }
 }