Fix TLS access for -static -pthread

I have posted:
	TLS variables access for -static -lpthread executables
	https://sourceware.org/ml/libc-help/2014-03/msg00024.html
and the GDB patch below has been confirmed as OK for current glibcs.

Further work should be done for newer glibcs:
	Improve TLS variables glibc compatibility
	https://sourceware.org/bugzilla/show_bug.cgi?id=16954

Still the patch below implements the feature in a fully functional way backward
compatible with current glibcs, it depends on the following glibc source line:
	csu/libc-tls.c
	main_map->l_tls_modid = 1;

gdb/
2014-05-21  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix TLS access for -static -pthread.
	* linux-thread-db.c (struct thread_db_info): Add td_thr_tlsbase_p.
	(try_thread_db_load_1): Initialize it.
	(thread_db_get_thread_local_address): Call it if LM is zero.
	* target.c (target_translate_tls_address): Remove LM_ADDR zero check.
	* target.h (struct target_ops) (to_get_thread_local_address): Add
	load_module_addr comment.

gdb/gdbserver/
2014-05-21  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix TLS access for -static -pthread.
	* gdbserver/thread-db.c (struct thread_db): Add td_thr_tlsbase_p.
	(thread_db_get_tls_address): Call it if LOAD_MODULE is zero.
	(thread_db_load_search, try_thread_db_load_1): Initialize it.

gdb/testsuite/
2014-05-21  Jan Kratochvil  <jan.kratochvil@redhat.com>

	Fix TLS access for -static -pthread.
	* gdb.threads/staticthreads.c <HAVE_TLS> (tlsvar): New.
	<HAVE_TLS> (thread_function, main): Initialize it.
	* gdb.threads/staticthreads.exp: Try gdb_compile_pthreads for $have_tls.
	Add clean_restart.
	<$have_tls != "">: Check TLSVAR.

Message-ID: <20140410115204.GB16411@host2.jankratochvil.net>

1 files changed, 36 insertions, 14 deletions

diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
index ca614a3..c0f7b1a 100644
--- a/gdb/linux-thread-db.c
+++ b/gdb/linux-thread-db.c
@@ -196,6 +196,9 @@ struct thread_db_info
   td_err_e (*td_thr_tls_get_addr_p) (const td_thrhandle_t *th,
 				     psaddr_t map_address,
 				     size_t offset, psaddr_t *address);
+  td_err_e (*td_thr_tlsbase_p) (const td_thrhandle_t *th,
+				unsigned long int modid,
+				psaddr_t *base);
 };
 
 /* List of known processes using thread_db, and the required
@@ -799,6 +802,7 @@ try_thread_db_load_1 (struct thread_db_info *info)
   info->td_ta_event_getmsg_p = dlsym (info->handle, "td_ta_event_getmsg");
   info->td_thr_event_enable_p = dlsym (info->handle, "td_thr_event_enable");
   info->td_thr_tls_get_addr_p = dlsym (info->handle, "td_thr_tls_get_addr");
+  info->td_thr_tlsbase_p = dlsym (info->handle, "td_thr_tlsbase");
 
   if (thread_db_find_new_threads_silently (inferior_ptid) != 0)
     {
@@ -1811,21 +1815,39 @@ thread_db_get_thread_local_address (struct target_ops *ops,
 
       info = get_thread_db_info (ptid_get_pid (ptid));
 
-      /* glibc doesn't provide the needed interface.  */
-      if (!info->td_thr_tls_get_addr_p)
-	throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR,
-		     _("No TLS library support"));
-
-      /* Caller should have verified that lm != 0.  */
-      gdb_assert (lm != 0);
-
       /* Finally, get the address of the variable.  */
-      /* Note the cast through uintptr_t: this interface only works if
-	 a target address fits in a psaddr_t, which is a host pointer.
-	 So a 32-bit debugger can not access 64-bit TLS through this.  */
-      err = info->td_thr_tls_get_addr_p (&thread_info->private->th,
-					 (psaddr_t)(uintptr_t) lm,
-					 offset, &address);
+      if (lm != 0)
+	{
+	  /* glibc doesn't provide the needed interface.  */
+	  if (!info->td_thr_tls_get_addr_p)
+	    throw_error (TLS_NO_LIBRARY_SUPPORT_ERROR,
+			 _("No TLS library support"));
+
+	  /* Note the cast through uintptr_t: this interface only works if
+	     a target address fits in a psaddr_t, which is a host pointer.
+	     So a 32-bit debugger can not access 64-bit TLS through this.  */
+	  err = info->td_thr_tls_get_addr_p (&thread_info->private->th,
+					     (psaddr_t)(uintptr_t) lm,
+					     offset, &address);
+	}
+      else
+	{
+	  /* If glibc doesn't provide the needed interface throw an error
+	     that LM is zero - normally cases it should not be.  */
+	  if (!info->td_thr_tlsbase_p)
+	    throw_error (TLS_LOAD_MODULE_NOT_FOUND_ERROR,
+			 _("TLS load module not found"));
+
+	  /* This code path handles the case of -static -pthread executables:
+	     https://sourceware.org/ml/libc-help/2014-03/msg00024.html
+	     For older GNU libc r_debug.r_map is NULL.  For GNU libc after
+	     PR libc/16831 due to GDB PR threads/16954 LOAD_MODULE is also NULL.
+	     The constant number 1 depends on GNU __libc_setup_tls
+	     initialization of l_tls_modid to 1.  */
+	  err = info->td_thr_tlsbase_p (&thread_info->private->th,
+					1, &address);
+	  address = (char *) address + offset;
+	}
 
 #ifdef THREAD_DB_HAS_TD_NOTALLOC
       /* The memory hasn't been allocated, yet.  */