http://sourceware.org/ml/gdb-patches/2014-04/msg00155.html

Subject: [patch] Fix TLS access for -static -pthread

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Hi,

testcase results may depend on patch:

	[patch] Fix gdbserver qGetTLSAddr for x86_64 -m32

	https://sourceware.org/ml/gdb-patches/2014-04/msg00154.html

	Message-ID: <20140410114901.GA16411@host2.jankratochvil.net>

There is:

 * gdb.threads/staticthreads.exp to test -static -pthread 'info threads'

 * gdb.threads/tls.exp to test TLS access (__thread variables)

but no testcase to test both together - it even does not work.

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.

Future glibcs may implement more native support for -static -pthread TLS

	https://sourceware.org/bugzilla/show_bug.cgi?id=16828

which will require also some new GDB support.

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;

No regressions on {x86_64,x86_64-m32}-fedorarawhide-linux-gnu.

Thanks,

Jan

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gdb/

2014-04-10  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/

2014-04-10  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/

2014-04-10  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.

diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c

index ca614a3..4578610 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 +1815,34 @@ 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"));

+

+	  /* GNU __libc_setup_tls initializes l_tls_modid as 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.  */

diff --git a/gdb/target.c b/gdb/target.c

index 1b48f79..fce646c 100644

--- a/gdb/target.c

+++ b/gdb/target.c

@@ -753,10 +753,6 @@ target_translate_tls_address (struct objfile *objfile, CORE_ADDR offset)

 	  /* Fetch the load module address for this objfile.  */

 	  lm_addr = gdbarch_fetch_tls_load_module_address (target_gdbarch (),

 	                                                   objfile);

-	  /* If it's 0, throw the appropriate exception.  */

-	  if (lm_addr == 0)

-	    throw_error (TLS_LOAD_MODULE_NOT_FOUND_ERROR,

-			 _("TLS load module not found"));

 	  addr = target->to_get_thread_local_address (target, ptid,

 						      lm_addr, offset);

diff --git a/gdb/target.h b/gdb/target.h

index d7c6c3d..1aba9e1 100644

--- a/gdb/target.h

+++ b/gdb/target.h

@@ -605,7 +605,8 @@ struct target_ops

        thread-local storage for the thread PTID and the shared library

        or executable file given by OBJFILE.  If that block of

        thread-local storage hasn't been allocated yet, this function

-       may return an error.  */

+       may return an error.  LOAD_MODULE_ADDR may be zero for statically

+       linked multithreaded inferiors.  */

     CORE_ADDR (*to_get_thread_local_address) (struct target_ops *ops,

 					      ptid_t ptid,

 					      CORE_ADDR load_module_addr,

diff --git a/gdb/gdbserver/thread-db.c b/gdb/gdbserver/thread-db.c

index f63e39e..f2335ab 100644

--- a/gdb/gdbserver/thread-db.c

+++ b/gdb/gdbserver/thread-db.c

@@ -88,6 +88,9 @@ struct thread_db

   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);

   const char ** (*td_symbol_list_p) (void);

 };

@@ -497,7 +500,10 @@ thread_db_get_tls_address (struct thread_info *thread, CORE_ADDR offset,

   if (thread_db == NULL || !thread_db->all_symbols_looked_up)

     return TD_ERR;

-  if (thread_db->td_thr_tls_get_addr_p == NULL)

+  /* If td_thr_tls_get_addr is missing rather do not expect td_thr_tlsbase

+     could work.  */

+  if (thread_db->td_thr_tls_get_addr_p == NULL

+      || (load_module == 0 && thread_db->td_thr_tlsbase_p == NULL))

     return -1;

   lwp = get_thread_lwp (thread);

@@ -508,12 +514,23 @@ thread_db_get_tls_address (struct thread_info *thread, CORE_ADDR offset,

   saved_inferior = current_inferior;

   current_inferior = thread;

-  /* 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 = thread_db->td_thr_tls_get_addr_p (&lwp->th,

-					  (psaddr_t) (uintptr_t) load_module,

-					  offset, &addr);

+

+  if (load_module != 0)

+    {

+      /* 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 = thread_db->td_thr_tls_get_addr_p (&lwp->th,

+					     (psaddr_t) (uintptr_t) load_module,

+					      offset, &addr);

+    }

+  else

+    {

+      /* GNU __libc_setup_tls initializes l_tls_modid as 1.  */

+      err = thread_db->td_thr_tlsbase_p (&lwp->th, 1, &addr);

+      addr = (char *) addr + offset;

+    }

+

   current_inferior = saved_inferior;

   if (err == TD_OK)

     {

@@ -565,6 +582,7 @@ thread_db_load_search (void)

   tdb->td_ta_set_event_p = &td_ta_set_event;

   tdb->td_ta_event_getmsg_p = &td_ta_event_getmsg;

   tdb->td_thr_tls_get_addr_p = &td_thr_tls_get_addr;

+  tdb->td_thr_tlsbase_p = &td_thr_tlsbase;

   return 1;

 }

@@ -633,6 +651,7 @@ try_thread_db_load_1 (void *handle)

   CHK (0, tdb->td_ta_set_event_p = dlsym (handle, "td_ta_set_event"));

   CHK (0, tdb->td_ta_event_getmsg_p = dlsym (handle, "td_ta_event_getmsg"));

   CHK (0, tdb->td_thr_tls_get_addr_p = dlsym (handle, "td_thr_tls_get_addr"));

+  CHK (0, tdb->td_thr_tlsbase_p = dlsym (handle, "td_thr_tlsbase"));

 #undef CHK

diff --git a/gdb/testsuite/gdb.threads/staticthreads.c b/gdb/testsuite/gdb.threads/staticthreads.c

index f98f4f1..93bef56 100644

--- a/gdb/testsuite/gdb.threads/staticthreads.c

+++ b/gdb/testsuite/gdb.threads/staticthreads.c

@@ -28,10 +28,17 @@

 sem_t semaphore;

+#ifdef HAVE_TLS

+__thread int tlsvar;

+#endif

+

 void *

 thread_function (void *arg)

 {

-  printf ("Thread executing\n");

+#ifdef HAVE_TLS

+  tlsvar = 2;

+#endif

+  printf ("Thread executing\n"); /* tlsvar-is-set */

   while (sem_wait (&semaphore) != 0)

     {

       if (errno != EINTR)

@@ -57,6 +64,9 @@ main (int argc, char **argv)

       return -1;

     }

+#ifdef HAVE_TLS

+  tlsvar = 1;

+#endif

   /* Create a thread, wait for it to complete.  */

   {

diff --git a/gdb/testsuite/gdb.threads/staticthreads.exp b/gdb/testsuite/gdb.threads/staticthreads.exp

index 80b0ba8..9fa625a 100644

--- a/gdb/testsuite/gdb.threads/staticthreads.exp

+++ b/gdb/testsuite/gdb.threads/staticthreads.exp

@@ -22,11 +22,16 @@

 standard_testfile

 set static_flag "-static"

-if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" \

-	 executable \

-	 [list debug "additional_flags=${static_flag}" \

-	     ]] != "" } {

-    return -1

+foreach have_tls { "-DHAVE_TLS" "" } {

+    if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" \

+	     executable \

+	     [list debug "additional_flags=${static_flag} ${have_tls}" \

+		 ]] == "" } {

+	break

+    }

+    if { $have_tls == "" } {

+	return -1

+    }

 }

 clean_restart ${binfile}

@@ -89,3 +94,18 @@ gdb_test_multiple "quit" "$test" {

         pass "$test"

     }

 }

+clean_restart ${binfile}

+

+

+if { "$have_tls" != "" } {

+    if ![runto_main] {

+	return -1

+    }

+    gdb_breakpoint [gdb_get_line_number "tlsvar-is-set"]

+    gdb_continue_to_breakpoint "tlsvar-is-set" ".* tlsvar-is-set .*"

+    gdb_test "p tlsvar" " = 2" "tlsvar in thread"

+    gdb_test "thread 1" ".*"

+    # Unwind from pthread_join.

+    gdb_test "up 10" " in main .*"

+    gdb_test "p tlsvar" " = 1" "tlsvar in main"

+}

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