Add a new gdbarch method to resolve the address of TLS variables.

Permit TLS variable addresses to be resolved purely by an ABI rather
than requiring a target method.  This doesn't try the target method if
the ABI function is present (even if the ABI function fails) to
simplify error handling.

gdb/ChangeLog:

	* gdbarch.sh (get_thread_local_address): New method.
	* gdbarch.h, gdbarch.c: Regenerate.
	* target.c (target_translate_tls_address): Use
	gdbarch_get_thread_local_address if present instead of
	target::get_thread_local_address.

gdb/ChangeLog

@@ -1,3 +1,11 @@
+2019-03-12  John Baldwin  <jhb@FreeBSD.org>
+
+	* gdbarch.sh (get_thread_local_address): New method.
+	* gdbarch.h, gdbarch.c: Regenerate.
+	* target.c (target_translate_tls_address): Use
+	gdbarch_get_thread_local_address if present instead of
+	target::get_thread_local_address.
+
 2019-03-12  John Baldwin  <jhb@FreeBSD.org>
 
 	* target.h (target::get_thread_local_address): Update comment.

gdb/gdbarch.c

@@ -251,6 +251,7 @@ struct gdbarch
   CORE_ADDR deprecated_function_start_offset;
   gdbarch_remote_register_number_ftype *remote_register_number;
   gdbarch_fetch_tls_load_module_address_ftype *fetch_tls_load_module_address;
+  gdbarch_get_thread_local_address_ftype *get_thread_local_address;
   CORE_ADDR frame_args_skip;
   gdbarch_unwind_pc_ftype *unwind_pc;
   gdbarch_unwind_sp_ftype *unwind_sp;
@@ -613,6 +614,7 @@ verify_gdbarch (struct gdbarch *gdbarch)
   /* Skip verify of deprecated_function_start_offset, invalid_p == 0 */
   /* Skip verify of remote_register_number, invalid_p == 0 */
   /* Skip verify of fetch_tls_load_module_address, has predicate.  */
+  /* Skip verify of get_thread_local_address, has predicate.  */
   /* Skip verify of frame_args_skip, invalid_p == 0 */
   /* Skip verify of unwind_pc, invalid_p == 0 */
   /* Skip verify of unwind_sp, invalid_p == 0 */
@@ -1073,6 +1075,12 @@ gdbarch_dump (struct gdbarch *gdbarch, struct ui_file *file)
   fprintf_unfiltered (file,
                       "gdbarch_dump: get_syscall_number = <%s>\n",
                       host_address_to_string (gdbarch->get_syscall_number));
+  fprintf_unfiltered (file,
+                      "gdbarch_dump: gdbarch_get_thread_local_address_p() = %d\n",
+                      gdbarch_get_thread_local_address_p (gdbarch));
+  fprintf_unfiltered (file,
+                      "gdbarch_dump: get_thread_local_address = <%s>\n",
+                      host_address_to_string (gdbarch->get_thread_local_address));
   fprintf_unfiltered (file,
                       "gdbarch_dump: gnu_triplet_regexp = <%s>\n",
                       host_address_to_string (gdbarch->gnu_triplet_regexp));
@@ -3018,6 +3026,30 @@ set_gdbarch_fetch_tls_load_module_address (struct gdbarch *gdbarch,
   gdbarch->fetch_tls_load_module_address = fetch_tls_load_module_address;
 }
 
+int
+gdbarch_get_thread_local_address_p (struct gdbarch *gdbarch)
+{
+  gdb_assert (gdbarch != NULL);
+  return gdbarch->get_thread_local_address != NULL;
+}
+
+CORE_ADDR
+gdbarch_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid, CORE_ADDR lm_addr, CORE_ADDR offset)
+{
+  gdb_assert (gdbarch != NULL);
+  gdb_assert (gdbarch->get_thread_local_address != NULL);
+  if (gdbarch_debug >= 2)
+    fprintf_unfiltered (gdb_stdlog, "gdbarch_get_thread_local_address called\n");
+  return gdbarch->get_thread_local_address (gdbarch, ptid, lm_addr, offset);
+}
+
+void
+set_gdbarch_get_thread_local_address (struct gdbarch *gdbarch,
+                                      gdbarch_get_thread_local_address_ftype get_thread_local_address)
+{
+  gdbarch->get_thread_local_address = get_thread_local_address;
+}
+
 CORE_ADDR
 gdbarch_frame_args_skip (struct gdbarch *gdbarch)
 {

gdb/gdbarch.h

@@ -649,6 +649,18 @@ typedef CORE_ADDR (gdbarch_fetch_tls_load_module_address_ftype) (struct objfile
 extern CORE_ADDR gdbarch_fetch_tls_load_module_address (struct gdbarch *gdbarch, struct objfile *objfile);
 extern void set_gdbarch_fetch_tls_load_module_address (struct gdbarch *gdbarch, gdbarch_fetch_tls_load_module_address_ftype *fetch_tls_load_module_address);
 
+/* Return the thread-local address at OFFSET in the thread-local
+   storage for the thread PTID and the shared library or executable
+   file given by LM_ADDR.  If that block of thread-local storage hasn't
+   been allocated yet, this function may throw an error.  LM_ADDR may
+   be zero for statically linked multithreaded inferiors. */
+
+extern int gdbarch_get_thread_local_address_p (struct gdbarch *gdbarch);
+
+typedef CORE_ADDR (gdbarch_get_thread_local_address_ftype) (struct gdbarch *gdbarch, ptid_t ptid, CORE_ADDR lm_addr, CORE_ADDR offset);
+extern CORE_ADDR gdbarch_get_thread_local_address (struct gdbarch *gdbarch, ptid_t ptid, CORE_ADDR lm_addr, CORE_ADDR offset);
+extern void set_gdbarch_get_thread_local_address (struct gdbarch *gdbarch, gdbarch_get_thread_local_address_ftype *get_thread_local_address);
+
 extern CORE_ADDR gdbarch_frame_args_skip (struct gdbarch *gdbarch);
 extern void set_gdbarch_frame_args_skip (struct gdbarch *gdbarch, CORE_ADDR frame_args_skip);
 

gdb/gdbarch.sh

@@ -602,6 +602,14 @@ m;int;remote_register_number;int regno;regno;;default_remote_register_number;;0
 
 # Fetch the target specific address used to represent a load module.
 F;CORE_ADDR;fetch_tls_load_module_address;struct objfile *objfile;objfile
+
+# Return the thread-local address at OFFSET in the thread-local
+# storage for the thread PTID and the shared library or executable
+# file given by LM_ADDR.  If that block of thread-local storage hasn't
+# been allocated yet, this function may throw an error.  LM_ADDR may
+# be zero for statically linked multithreaded inferiors.
+
+M;CORE_ADDR;get_thread_local_address;ptid_t ptid, CORE_ADDR lm_addr, CORE_ADDR offset;ptid, lm_addr, offset
 #
 v;CORE_ADDR;frame_args_skip;;;0;;;0
 m;CORE_ADDR;unwind_pc;struct frame_info *next_frame;next_frame;;default_unwind_pc;;0

gdb/target.c

@@ -698,8 +698,9 @@ target_translate_tls_address (struct objfile *objfile, CORE_ADDR offset)
 {
   volatile CORE_ADDR addr = 0;
   struct target_ops *target = current_top_target ();
+  struct gdbarch *gdbarch = target_gdbarch ();
 
-  if (gdbarch_fetch_tls_load_module_address_p (target_gdbarch ()))
+  if (gdbarch_fetch_tls_load_module_address_p (gdbarch))
     {
       ptid_t ptid = inferior_ptid;
 
@@ -708,10 +709,14 @@ target_translate_tls_address (struct objfile *objfile, CORE_ADDR offset)
 	  CORE_ADDR lm_addr;
 	  
 	  /* Fetch the load module address for this objfile.  */
-	  lm_addr = gdbarch_fetch_tls_load_module_address (target_gdbarch (),
+	  lm_addr = gdbarch_fetch_tls_load_module_address (gdbarch,
 	                                                   objfile);
 
-	  addr = target->get_thread_local_address (ptid, lm_addr, offset);
+	  if (gdbarch_get_thread_local_address_p (gdbarch))
+	    addr = gdbarch_get_thread_local_address (gdbarch, ptid, lm_addr,
+						     offset);
+	  else
+	    addr = target->get_thread_local_address (ptid, lm_addr, offset);
 	}
       /* If an error occurred, print TLS related messages here.  Otherwise,
          throw the error to some higher catcher.  */
@@ -766,8 +771,6 @@ target_translate_tls_address (struct objfile *objfile, CORE_ADDR offset)
 	}
       END_CATCH
     }
-  /* It wouldn't be wrong here to try a gdbarch method, too; finding
-     TLS is an ABI-specific thing.  But we don't do that yet.  */
   else
     error (_("Cannot find thread-local variables on this target"));