# 
# commit f8aeae347377f3dfa8cbadde057adf1827fb1d44
# Author: Alexandre Oliva <aoliva@redhat.com>
# Date:   Tue Mar 17 01:14:11 2015 -0300
# 
#     Fix DTV race, assert, DTV_SURPLUS Static TLS limit, and nptl_db garbage
#     
#     for  ChangeLog
#     
#         [BZ #17090]
#         [BZ #17620]
#         [BZ #17621]
#         [BZ #17628]
#         * NEWS: Update.
#         * elf/dl-tls.c (_dl_update_slotinfo): Clean up outdated DTV
#         entries with Static TLS too.  Skip entries past the end of the
#         allocated DTV, from Alan Modra.
#         (tls_get_addr_tail): Update to glibc_likely/unlikely.  Move
#         Static TLS DTV entry set up from...
#          (_dl_allocate_tls_init): ... here (fix modid assertion), ...
#         * elf/dl-reloc.c (_dl_nothread_init_static_tls): ... here...
#         * nptl/allocatestack.c (init_one_static_tls): ... and here...
#         * elf/dlopen.c (dl_open_worker): Drop l_tls_modid upper bound
#         for Static TLS.
#         * elf/tlsdeschtab.h (map_generation): Return size_t.  Check
#         that the slot we find is associated with the given map before
#         using its generation count.
#         * nptl_db/db_info.c: Include ldsodefs.h.
#         (rtld_global, dtv_slotinfo_list, dtv_slotinfo): New typedefs.
#         * nptl_db/structs.def (DB_RTLD_VARIABLE): New macro.
#         (DB_MAIN_VARIABLE, DB_RTLD_GLOBAL_FIELD): Likewise.
#         (link_map::l_tls_offset): New struct field.
#         (dtv_t::counter): Likewise.
#         (rtld_global): New struct.
#         (_rtld_global): New rtld variable.
#         (dl_tls_dtv_slotinfo_list): New rtld global field.
#         (dtv_slotinfo_list): New struct.
#         (dtv_slotinfo): Likewise.
#         * nptl_db/td_symbol_list.c: Drop gnu/lib-names.h include.
#         (td_lookup): Rename to...
#         (td_mod_lookup): ... this.  Use new mod parameter instead of
#         LIBPTHREAD_SO.
#         * nptl_db/td_thr_tlsbase.c: Include link.h.
#         (dtv_slotinfo_list, dtv_slotinfo): New functions.
#         (td_thr_tlsbase): Check DTV generation.  Compute Static TLS
#         addresses even if the DTV is out of date or missing them.
#         * nptl_db/fetch-value.c (_td_locate_field): Do not refuse to
#         index zero-length arrays.
#         * nptl_db/thread_dbP.h: Include gnu/lib-names.h.
#         (td_lookup): Make it a macro implemented in terms of...
#         (td_mod_lookup): ... this declaration.
#         * nptl_db/db-symbols.awk (DB_RTLD_VARIABLE): Override.
#         (DB_MAIN_VARIABLE): Likewise.
# 
diff -urN glibc-2.17-c758a686/elf/dl-open.c glibc-2.17-c758a686/elf/dl-open.c
--- glibc-2.17-c758a686/elf/dl-open.c	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/elf/dl-open.c	2015-03-17 14:39:47.746505786 -0400
@@ -535,17 +535,7 @@
 	  && imap->l_tls_blocksize > 0)
 	{
 	  /* For static TLS we have to allocate the memory here and
-	     now.  This includes allocating memory in the DTV.  But we
-	     cannot change any DTV other than our own.  So, if we
-	     cannot guarantee that there is room in the DTV we don't
-	     even try it and fail the load.
-
-	     XXX We could track the minimum DTV slots allocated in
-	     all threads.  */
-	  if (! RTLD_SINGLE_THREAD_P && imap->l_tls_modid > DTV_SURPLUS)
-	    _dl_signal_error (0, "dlopen", NULL, N_("\
-cannot load any more object with static TLS"));
-
+	     now, but we can delay updating the DTV.  */
 	  imap->l_need_tls_init = 0;
 #ifdef SHARED
 	  /* Update the slot information data for at least the
diff -urN glibc-2.17-c758a686/elf/dl-reloc.c glibc-2.17-c758a686/elf/dl-reloc.c
--- glibc-2.17-c758a686/elf/dl-reloc.c	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/elf/dl-reloc.c	2015-03-17 14:39:47.747505754 -0400
@@ -136,12 +136,6 @@
 # error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
 #endif
 
-  /* Fill in the DTV slot so that a later LD/GD access will find it.  */
-  dtv_t *dtv = THREAD_DTV ();
-  assert (map->l_tls_modid <= dtv[-1].counter);
-  dtv[map->l_tls_modid].pointer.val = dest;
-  dtv[map->l_tls_modid].pointer.is_static = true;
-
   /* Initialize the memory.  */
   memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size),
 	  '\0', map->l_tls_blocksize - map->l_tls_initimage_size);
diff -urN glibc-2.17-c758a686/elf/dl-tls.c glibc-2.17-c758a686/elf/dl-tls.c
--- glibc-2.17-c758a686/elf/dl-tls.c	2015-03-17 14:39:31.335019227 -0400
+++ glibc-2.17-c758a686/elf/dl-tls.c	2015-03-17 14:42:48.443852579 -0400
@@ -432,17 +432,14 @@
 	  assert (listp->slotinfo[cnt].gen <= GL(dl_tls_generation));
 	  maxgen = MAX (maxgen, listp->slotinfo[cnt].gen);
 
+	  dtv[map->l_tls_modid].pointer.val = TLS_DTV_UNALLOCATED;
+	  dtv[map->l_tls_modid].pointer.is_static = false;
+
 	  if (map->l_tls_offset == NO_TLS_OFFSET
 	      || map->l_tls_offset == FORCED_DYNAMIC_TLS_OFFSET)
-	    {
-	      /* For dynamically loaded modules we simply store
-		 the value indicating deferred allocation.  */
-	      dtv[map->l_tls_modid].pointer.val = TLS_DTV_UNALLOCATED;
-	      dtv[map->l_tls_modid].pointer.is_static = false;
-	      continue;
-	    }
+	    continue;
 
-	  assert (map->l_tls_modid == cnt);
+	  assert (map->l_tls_modid == total + cnt);
 	  assert (map->l_tls_blocksize >= map->l_tls_initimage_size);
 #if TLS_TCB_AT_TP
 	  assert ((size_t) map->l_tls_offset >= map->l_tls_blocksize);
@@ -454,8 +451,6 @@
 #endif
 
 	  /* Copy the initialization image and clear the BSS part.  */
-	  dtv[map->l_tls_modid].pointer.val = dest;
-	  dtv[map->l_tls_modid].pointer.is_static = true;
 	  memset (__mempcpy (dest, map->l_tls_initimage,
 			     map->l_tls_initimage_size), '\0',
 		  map->l_tls_blocksize - map->l_tls_initimage_size);
@@ -623,13 +618,16 @@
 	      struct link_map *map = listp->slotinfo[cnt].map;
 	      if (map == NULL)
 		{
-		  /* If this modid was used at some point the memory
-		     might still be allocated.  */
-		  if (! dtv[total + cnt].pointer.is_static
-		      && dtv[total + cnt].pointer.val != TLS_DTV_UNALLOCATED)
+		  if (dtv[-1].counter >= total + cnt)
 		    {
-		      free (dtv[total + cnt].pointer.val);
+		      /* If this modid was used at some point the memory
+			 might still be allocated.  */
+		      if (! dtv[total + cnt].pointer.is_static
+			  && (dtv[total + cnt].pointer.val
+			      != TLS_DTV_UNALLOCATED))
+			free (dtv[total + cnt].pointer.val);
 		      dtv[total + cnt].pointer.val = TLS_DTV_UNALLOCATED;
+		      dtv[total + cnt].pointer.is_static = false;
 		    }
 
 		  continue;
@@ -693,10 +691,8 @@
 		   memalign and not malloc.  */
 		free (dtv[modid].pointer.val);
 
-	      /* This module is loaded dynamically- We defer memory
-		 allocation.  */
-	      dtv[modid].pointer.is_static = false;
 	      dtv[modid].pointer.val = TLS_DTV_UNALLOCATED;
+	      dtv[modid].pointer.is_static = false;
 
 	      if (modid == req_modid)
 		the_map = map;
@@ -734,13 +730,12 @@
       the_map = listp->slotinfo[idx].map;
     }
 
- again:
   /* Make sure that, if a dlopen running in parallel forces the
      variable into static storage, we'll wait until the address in the
      static TLS block is set up, and use that.  If we're undecided
      yet, make sure we make the decision holding the lock as well.  */
-  if (__builtin_expect (the_map->l_tls_offset
-			!= FORCED_DYNAMIC_TLS_OFFSET, 0))
+  if (__glibc_unlikely (the_map->l_tls_offset
+			!= FORCED_DYNAMIC_TLS_OFFSET))
     {
       __rtld_lock_lock_recursive (GL(dl_load_lock));
       if (__builtin_expect (the_map->l_tls_offset == NO_TLS_OFFSET, 1))
@@ -748,22 +743,28 @@
 	  the_map->l_tls_offset = FORCED_DYNAMIC_TLS_OFFSET;
 	  __rtld_lock_unlock_recursive (GL(dl_load_lock));
 	}
-      else
+      else if (__glibc_likely (the_map->l_tls_offset
+			       != FORCED_DYNAMIC_TLS_OFFSET))
 	{
+#if TLS_TCB_AT_TP
+	  void *p = (char *) THREAD_SELF - the_map->l_tls_offset;
+#elif TLS_DTV_AT_TP
+	  void *p = (char *) THREAD_SELF + the_map->l_tls_offset + TLS_PRE_TCB_SIZE;
+#else
+# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
+#endif
 	  __rtld_lock_unlock_recursive (GL(dl_load_lock));
-	  if (__builtin_expect (the_map->l_tls_offset
-				!= FORCED_DYNAMIC_TLS_OFFSET, 1))
-	    {
-	      void *p = dtv[GET_ADDR_MODULE].pointer.val;
-	      if (__builtin_expect (p == TLS_DTV_UNALLOCATED, 0))
-		goto again;
+	  dtv[GET_ADDR_MODULE].pointer.is_static = true;
+	  dtv[GET_ADDR_MODULE].pointer.val = p;
 
-	      return (char *) p + GET_ADDR_OFFSET;
-	    }
+	  return (char *) p + GET_ADDR_OFFSET;
 	}
+      else
+	__rtld_lock_unlock_recursive (GL(dl_load_lock));
+
     }
   void *p = dtv[GET_ADDR_MODULE].pointer.val = allocate_and_init (the_map);
-  dtv[GET_ADDR_MODULE].pointer.is_static = false;
+  assert (!dtv[GET_ADDR_MODULE].pointer.is_static);
 
   return (char *) p + GET_ADDR_OFFSET;
 }
diff -urN glibc-2.17-c758a686/elf/tlsdeschtab.h glibc-2.17-c758a686/elf/tlsdeschtab.h
--- glibc-2.17-c758a686/elf/tlsdeschtab.h	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/elf/tlsdeschtab.h	2015-03-17 14:39:47.747505754 -0400
@@ -42,7 +42,7 @@
   return tdp->tlsinfo.ti_offset == tdq->tlsinfo.ti_offset;
 }
 
-inline static int
+inline static size_t
 map_generation (struct link_map *map)
 {
   size_t idx = map->l_tls_modid;
@@ -58,7 +58,7 @@
 	     we can assume that, if the generation count is zero, we
 	     still haven't determined the generation count for this
 	     module.  */
-	  if (listp->slotinfo[idx].gen)
+	  if (listp->slotinfo[idx].map == map && listp->slotinfo[idx].gen)
 	    return listp->slotinfo[idx].gen;
 	  else
 	    break;
diff -urN glibc-2.17-c758a686/nptl/allocatestack.c glibc-2.17-c758a686/nptl/allocatestack.c
--- glibc-2.17-c758a686/nptl/allocatestack.c	2015-03-17 14:39:31.342019008 -0400
+++ glibc-2.17-c758a686/nptl/allocatestack.c	2015-03-17 14:39:47.747505754 -0400
@@ -1157,7 +1157,6 @@
 static inline void __attribute__((always_inline))
 init_one_static_tls (struct pthread *curp, struct link_map *map)
 {
-  dtv_t *dtv = GET_DTV (TLS_TPADJ (curp));
 # if TLS_TCB_AT_TP
   void *dest = (char *) curp - map->l_tls_offset;
 # elif TLS_DTV_AT_TP
@@ -1166,11 +1165,9 @@
 #  error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
 # endif
 
-  /* Fill in the DTV slot so that a later LD/GD access will find it.  */
-  dtv[map->l_tls_modid].pointer.val = dest;
-  dtv[map->l_tls_modid].pointer.is_static = true;
-
-  /* Initialize the memory.  */
+  /* We cannot delay the initialization of the Static TLS area, since
+     it can be accessed with LE or IE, but since the DTV is only used
+     by GD and LD, we can delay its update to avoid a race.  */
   memset (__mempcpy (dest, map->l_tls_initimage, map->l_tls_initimage_size),
 	  '\0', map->l_tls_blocksize - map->l_tls_initimage_size);
 }
diff -urN glibc-2.17-c758a686/nptl_db/db_info.c glibc-2.17-c758a686/nptl_db/db_info.c
--- glibc-2.17-c758a686/nptl_db/db_info.c	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/nptl_db/db_info.c	2015-03-17 14:39:47.747505754 -0400
@@ -20,6 +20,7 @@
 
 #include "thread_dbP.h"
 #include <tls.h>
+#include <ldsodefs.h>
 
 typedef struct pthread pthread;
 typedef struct pthread_key_struct pthread_key_struct;
@@ -36,6 +37,9 @@
 } dtv;
 
 typedef struct link_map link_map;
+typedef struct rtld_global rtld_global;
+typedef struct dtv_slotinfo_list dtv_slotinfo_list;
+typedef struct dtv_slotinfo dtv_slotinfo;
 
 /* Actually static in nptl/init.c, but we only need it for typeof.  */
 extern bool __nptl_initial_report_events;
diff -urN glibc-2.17-c758a686/nptl_db/db-symbols.awk glibc-2.17-c758a686/nptl_db/db-symbols.awk
--- glibc-2.17-c758a686/nptl_db/db-symbols.awk	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/nptl_db/db-symbols.awk	2015-03-17 14:39:47.747505754 -0400
@@ -2,6 +2,8 @@
 # we've just built.  It checks for all the symbols used in td_symbol_list.
 
 BEGIN {
+%define DB_RTLD_VARIABLE(name) /* Nothing. */
+%define DB_MAIN_VARIABLE(name) /* Nothing. */
 %define DB_LOOKUP_NAME(idx, name)		required[STRINGIFY (name)] = 1;
 %define DB_LOOKUP_NAME_TH_UNIQUE(idx, name)	th_unique[STRINGIFY (name)] = 1;
 %include "db-symbols.h"
diff -urN glibc-2.17-c758a686/nptl_db/fetch-value.c glibc-2.17-c758a686/nptl_db/fetch-value.c
--- glibc-2.17-c758a686/nptl_db/fetch-value.c	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/nptl_db/fetch-value.c	2015-03-17 14:39:47.747505754 -0400
@@ -68,7 +68,8 @@
 	}
     }
 
-  if (idx != 0 && idx - (psaddr_t) 0 > DB_DESC_NELEM (desc))
+  if (idx != 0 && DB_DESC_NELEM (desc) != 0
+      && idx - (psaddr_t) 0 > DB_DESC_NELEM (desc))
     /* This is an internal indicator to callers with nonzero IDX
        that the IDX value is too big.  */
     return TD_NOAPLIC;
diff -urN glibc-2.17-c758a686/nptl_db/structs.def glibc-2.17-c758a686/nptl_db/structs.def
--- glibc-2.17-c758a686/nptl_db/structs.def	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/nptl_db/structs.def	2015-03-17 14:44:29.779682236 -0400
@@ -22,6 +22,28 @@
 # define STRUCTS_DEF_DEFAULTS 1
 #endif
 
+#ifndef DB_RTLD_VARIABLE
+# define DB_RTLD_VARIABLE(name) DB_VARIABLE (name)
+#endif
+
+#ifndef DB_MAIN_VARIABLE
+# define DB_MAIN_VARIABLE(name) DB_VARIABLE (name)
+#endif
+
+#ifndef DB_RTLD_GLOBAL_FIELD
+# if !defined IS_IN_libpthread
+#  define DB_RTLD_GLOBAL_FIELD(field)		\
+  DB_STRUCT_FIELD (rtld_global, _##field)	\
+  DB_MAIN_VARIABLE (_##field)
+# elif defined SHARED
+#  define DB_RTLD_GLOBAL_FIELD(field)		\
+  DB_STRUCT_FIELD (rtld_global, _##field)
+# else
+#  define DB_RTLD_GLOBAL_FIELD(field)		\
+  DB_MAIN_VARIABLE (_##field)
+# endif
+#endif /* DB_RTLD_GLOBAL_FIELD */
+
 DB_STRUCT (pthread)
 DB_STRUCT_FIELD (pthread, list)
 DB_STRUCT_FIELD (pthread, report_events)
@@ -70,14 +92,31 @@
 DB_STRUCT_ARRAY_FIELD (pthread_key_data_level2, data)
 
 DB_STRUCT_FIELD (link_map, l_tls_modid)
+DB_STRUCT_FIELD (link_map, l_tls_offset)
 
 DB_STRUCT_ARRAY_FIELD (dtv, dtv)
 #define pointer_val pointer.val /* Field of anonymous struct in dtv_t.  */
 DB_STRUCT_FIELD (dtv_t, pointer_val)
+DB_STRUCT_FIELD (dtv_t, counter)
 #if !defined IS_IN_libpthread || TLS_TCB_AT_TP
 DB_STRUCT_FIELD (pthread, dtvp)
 #endif
 
+#if !(defined IS_IN_libpthread && !defined SHARED)
+DB_STRUCT (rtld_global)
+DB_RTLD_VARIABLE (_rtld_global)
+#endif
+DB_RTLD_GLOBAL_FIELD (dl_tls_dtv_slotinfo_list)
+
+DB_STRUCT (dtv_slotinfo_list)
+DB_STRUCT_FIELD (dtv_slotinfo_list, len)
+DB_STRUCT_FIELD (dtv_slotinfo_list, next)
+DB_STRUCT_ARRAY_FIELD (dtv_slotinfo_list, slotinfo)
+
+DB_STRUCT (dtv_slotinfo)
+DB_STRUCT_FIELD (dtv_slotinfo, gen)
+DB_STRUCT_FIELD (dtv_slotinfo, map)
+
 #ifdef STRUCTS_DEF_DEFAULTS
 # undef DB_STRUCT_ARRAY_FIELD
 # undef DB_ARRAY_VARIABLE
diff -urN glibc-2.17-c758a686/nptl_db/td_symbol_list.c glibc-2.17-c758a686/nptl_db/td_symbol_list.c
--- glibc-2.17-c758a686/nptl_db/td_symbol_list.c	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/nptl_db/td_symbol_list.c	2015-03-17 14:39:47.747505754 -0400
@@ -18,7 +18,6 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <assert.h>
-#include <gnu/lib-names.h>
 #include "thread_dbP.h"
 
 static const char *symbol_list_arr[] =
@@ -41,12 +40,12 @@
 
 
 ps_err_e
-td_lookup (struct ps_prochandle *ps, int idx, psaddr_t *sym_addr)
+td_mod_lookup (struct ps_prochandle *ps, const char *mod,
+	       int idx, psaddr_t *sym_addr)
 {
   ps_err_e result;
   assert (idx >= 0 && idx < SYM_NUM_MESSAGES);
-  result = ps_pglobal_lookup (ps, LIBPTHREAD_SO, symbol_list_arr[idx],
-			      sym_addr);
+  result = ps_pglobal_lookup (ps, mod, symbol_list_arr[idx], sym_addr);
 
 #ifdef HAVE_ASM_GLOBAL_DOT_NAME
   /* For PowerPC, 64-bit uses dot symbols but 32-bit does not.
diff -urN glibc-2.17-c758a686/nptl_db/td_thr_tlsbase.c glibc-2.17-c758a686/nptl_db/td_thr_tlsbase.c
--- glibc-2.17-c758a686/nptl_db/td_thr_tlsbase.c	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/nptl_db/td_thr_tlsbase.c	2015-03-17 14:39:47.748505723 -0400
@@ -17,14 +17,118 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include "thread_dbP.h"
+#include <link.h>
 
+/* Get the DTV slotinfo list head entry from the dynamic loader state
+   into *LISTHEAD.  */
+static td_err_e
+dtv_slotinfo_list (td_thragent_t *ta,
+		   psaddr_t *listhead)
+{
+  td_err_e err;
+  psaddr_t head;
+
+  if (ta->ta_addr__rtld_global == 0
+      && td_mod_lookup (ta->ph, LD_SO, SYM__rtld_global,
+			&ta->ta_addr__rtld_global) != PS_OK)
+    ta->ta_addr__rtld_global = (void*)-1;
+
+  if (ta->ta_addr__rtld_global != (void*)-1)
+    {
+      err = DB_GET_FIELD (head, ta, ta->ta_addr__rtld_global,
+			  rtld_global, _dl_tls_dtv_slotinfo_list, 0);
+      if (err != TD_OK)
+	return err;
+    }
+  else
+    {
+      if (ta->ta_addr__dl_tls_dtv_slotinfo_list == 0
+	  && td_mod_lookup (ta->ph, NULL, SYM__dl_tls_dtv_slotinfo_list,
+			    &ta->ta_addr__dl_tls_dtv_slotinfo_list) != PS_OK)
+	return TD_ERR;
+
+      err = _td_fetch_value (ta, ta->ta_var__dl_tls_dtv_slotinfo_list,
+			     SYM_DESC__dl_tls_dtv_slotinfo_list,
+			     0, ta->ta_addr__dl_tls_dtv_slotinfo_list, &head);
+      if (err != TD_OK)
+	return err;
+    }
+
+  *listhead = head;
+  return TD_OK;
+}
+
+/* Get the address of the DTV slotinfo entry for MODID into
+   *DTVSLOTINFO.  */
+static td_err_e
+dtv_slotinfo (td_thragent_t *ta,
+	      unsigned long int modid,
+	      psaddr_t *dtvslotinfo)
+{
+  td_err_e err;
+  psaddr_t slot, temp;
+  size_t slbase = 0;
+
+  err = dtv_slotinfo_list (ta, &slot);
+  if (err != TD_OK)
+    return err;
+
+  while (slot)
+    {
+      /* Get the number of entries in this list entry's array.  */
+      err = DB_GET_FIELD (temp, ta, slot, dtv_slotinfo_list, len, 0);
+      if (err != TD_OK)
+	return err;
+      size_t len = (uintptr_t)temp;
+
+      /* Did we find the list entry for modid?  */
+      if (modid < slbase + len)
+	break;
+
+      /* We didn't, so get the next list entry.  */
+      slbase += len;
+      err = DB_GET_FIELD (temp, ta, slot, dtv_slotinfo_list,
+			  next, 0);
+      if (err != TD_OK)
+	return err;
+      slot = temp;
+    }
+
+  /* We reached the end of the list and found nothing.  */
+  if (!slot)
+    return TD_ERR;
+
+  /* Take the slotinfo for modid from the list entry.  */
+  err = DB_GET_FIELD_ADDRESS (temp, ta, slot, dtv_slotinfo_list,
+			      slotinfo, modid - slbase);
+  if (err != TD_OK)
+    return err;
+  slot = temp;
+
+  *dtvslotinfo = slot;
+  return TD_OK;
+}
+
+/* Return in *BASE the base address of the TLS block for MODID within
+   TH.
+
+   It should return success and yield the correct pointer in any
+   circumstance where the TLS block for the module and thread
+   requested has already been initialized.
+
+   It should fail with TD_TLSDEFER only when the thread could not
+   possibly have observed any values in that TLS block.  That way, the
+   debugger can fall back to showing initial values from the PT_TLS
+   segment (and refusing attempts to mutate) for the TD_TLSDEFER case,
+   and never fail to make the values the program will actually see
+   available to the user of the debugger.  */
 td_err_e
 td_thr_tlsbase (const td_thrhandle_t *th,
 		unsigned long int modid,
 		psaddr_t *base)
 {
   td_err_e err;
-  psaddr_t dtv, dtvslot, dtvptr;
+  psaddr_t dtv, dtvslot, dtvptr, temp;
 
   if (modid < 1)
     return TD_NOTLS;
@@ -50,11 +154,75 @@
 	return TD_TLSDEFER;
     }
 
+  err = dtv_slotinfo (th->th_ta_p, modid, &temp);
+  if (err != TD_OK)
+    return err;
+
+  psaddr_t slot;
+  err = DB_GET_STRUCT (slot, th->th_ta_p, temp, dtv_slotinfo);
+  if (err != TD_OK)
+    return err;
+
+  /* Take the link_map from the slotinfo.  */
+  psaddr_t map;
+  err = DB_GET_FIELD_LOCAL (map, th->th_ta_p, slot, dtv_slotinfo, map, 0);
+  if (err != TD_OK)
+    return err;
+  if (!map)
+    return TD_ERR;
+
+  /* Ok, the modid is good, now find out what DTV generation it
+     requires.  */
+  err = DB_GET_FIELD_LOCAL (temp, th->th_ta_p, slot, dtv_slotinfo, gen, 0);
+  if (err != TD_OK)
+    return err;
+  size_t modgen = (uintptr_t)temp;
+
   /* Get the DTV pointer from the thread descriptor.  */
   err = DB_GET_FIELD (dtv, th->th_ta_p, pd, pthread, dtvp, 0);
   if (err != TD_OK)
     return err;
 
+  psaddr_t dtvgenloc;
+  /* Get the DTV generation count at dtv[0].counter.  */
+  err = DB_GET_FIELD_ADDRESS (dtvgenloc, th->th_ta_p, dtv, dtv, dtv, 0);
+  if (err != TD_OK)
+    return err;
+  err = DB_GET_FIELD (temp, th->th_ta_p, dtvgenloc, dtv_t, counter, 0);
+  if (err != TD_OK)
+    return err;
+  size_t dtvgen = (uintptr_t)temp;
+
+  /* Is the DTV current enough?  */
+  if (dtvgen < modgen)
+    {
+    try_static_tls:
+      /* If the module uses Static TLS, we're still good.  */
+      err = DB_GET_FIELD (temp, th->th_ta_p, map, link_map, l_tls_offset, 0);
+      if (err != TD_OK)
+	return err;
+      ptrdiff_t tlsoff = (uintptr_t)temp;
+
+      if (tlsoff != FORCED_DYNAMIC_TLS_OFFSET
+	  && tlsoff != NO_TLS_OFFSET)
+	{
+	  psaddr_t tp = pd;
+
+#if TLS_TCB_AT_TP
+	  dtvptr = tp - tlsoff;
+#elif TLS_DTV_AT_TP
+	  dtvptr = tp + tlsoff + TLS_PRE_TCB_SIZE;
+#else
+# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
+#endif
+
+	  *base = dtvptr;
+	  return TD_OK;
+	}
+
+      return TD_TLSDEFER;
+    }
+
   /* Find the corresponding entry in the DTV.  */
   err = DB_GET_FIELD_ADDRESS (dtvslot, th->th_ta_p, dtv, dtv, dtv, modid);
   if (err != TD_OK)
@@ -68,7 +236,7 @@
   /* It could be that the memory for this module is not allocated for
      the given thread.  */
   if ((uintptr_t) dtvptr & 1)
-    return TD_TLSDEFER;
+    goto try_static_tls;
 
   *base = dtvptr;
   return TD_OK;
diff -urN glibc-2.17-c758a686/nptl_db/thread_dbP.h glibc-2.17-c758a686/nptl_db/thread_dbP.h
--- glibc-2.17-c758a686/nptl_db/thread_dbP.h	2012-12-24 22:02:13.000000000 -0500
+++ glibc-2.17-c758a686/nptl_db/thread_dbP.h	2015-03-17 14:39:47.748505723 -0400
@@ -29,6 +29,7 @@
 #include "thread_db.h"
 #include "../nptl/pthreadP.h"  	/* This is for *_BITMASK only.  */
 #include <list.h>
+#include <gnu/lib-names.h>
 
 /* Indeces for the symbol names.  */
 enum
@@ -139,11 +140,11 @@
 }
 
 
-/* Internal wrapper around ps_pglobal_lookup.  */
-extern ps_err_e td_lookup (struct ps_prochandle *ps,
-			   int idx, psaddr_t *sym_addr) attribute_hidden;
-
-
+/* Internal wrappers around ps_pglobal_lookup.  */
+extern ps_err_e td_mod_lookup (struct ps_prochandle *ps, const char *modname,
+			       int idx, psaddr_t *sym_addr) attribute_hidden;
+#define td_lookup(ps, idx, sym_addr) \
+  td_mod_lookup ((ps), LIBPTHREAD_SO, (idx), (sym_addr))
 
 
 /* Store in psaddr_t VAR the address of inferior's symbol NAME.  */