gdb/

	* solib-svr4.c (svr4_current_sos): New comment on
	svr4_current_sos_via_xfer_libraries fall back.

gdb/gdbserver/
	* linux-low.c (linux_qxfer_libraries_svr4): Return -1 if R_DEBUG is -1.

gdb/testsuite/
	* gdb.server/solib-list-lib.c: New file.
	* gdb.server/solib-list-main.c: New file.
	* gdb.server/solib-list.exp: New file.

8 files changed, 187 insertions, 1 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 10f1ce8dc57..49e7259f786 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2012-05-28  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* solib-svr4.c (svr4_current_sos): New comment on
+	svr4_current_sos_via_xfer_libraries fall back.
+
 2012-05-24  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	* psymtab.c (lookup_symbol_aux_psymtabs): New variable stab_best.  Use
diff --git a/gdb/gdbserver/ChangeLog b/gdb/gdbserver/ChangeLog
index 22e00e2a827..f060255f500 100644
--- a/gdb/gdbserver/ChangeLog
+++ b/gdb/gdbserver/ChangeLog
@@ -1,3 +1,7 @@
+2012-05-28  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* linux-low.c (linux_qxfer_libraries_svr4): Return -1 if R_DEBUG is -1.
+
 2012-05-24  Pedro Alves  <palves@redhat.com>
 
 	PR gdb/7205
diff --git a/gdb/gdbserver/linux-low.c b/gdb/gdbserver/linux-low.c
index e1ea64ab669..c015a6183e9 100644
--- a/gdb/gdbserver/linux-low.c
+++ b/gdb/gdbserver/linux-low.c
@@ -5651,7 +5651,13 @@ linux_qxfer_libraries_svr4 (const char *annex, unsigned char *readbuf,
   if (priv->r_debug == 0)
     priv->r_debug = get_r_debug (pid, is_elf64);
 
-  if (priv->r_debug == (CORE_ADDR) -1 || priv->r_debug == 0)
+  /* We failed to find DT_DEBUG.  Such situation will not change for this
+     inferior - do not retry it.  Report it to GDB as E01, see for the reasons
+     at the GDB solib-svr4.c side.  */
+  if (priv->r_debug == (CORE_ADDR) -1)
+    return -1;
+
+  if (priv->r_debug == 0)
     {
       document = xstrdup ("<library-list-svr4 version=\"1.0\"/>\n");
     }
diff --git a/gdb/solib-svr4.c b/gdb/solib-svr4.c
index a639f4dabcb..bd0141acef8 100644
--- a/gdb/solib-svr4.c
+++ b/gdb/solib-svr4.c
@@ -1260,6 +1260,14 @@ svr4_current_sos (void)
   int ignore_first;
   struct svr4_library_list library_list;
 
+  /* Fall back to manual examination of the target if the packet is not
+     supported or gdbserver failed to find DT_DEBUG.  gdb.server/solib-list.exp
+     tests a case where gdbserver cannot find the shared libraries list while
+     GDB itself is able to find it via SYMFILE_OBJFILE.
+
+     Unfortunately statically linked inferiors will also fall back through this
+     suboptimal code path.  */
+
   if (svr4_current_sos_via_xfer_libraries (&library_list))
     {
       if (library_list.main_lm)
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index c09f5a1d1c7..f7227cfa8c1 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2012-05-28  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* gdb.server/solib-list-lib.c: New file.
+	* gdb.server/solib-list-main.c: New file.
+	* gdb.server/solib-list.exp: New file.
+
 2012-05-25  Maciej W. Rozycki  <macro@codesourcery.com>
 
 	* gdb.trace/unavailable.exp (gdb_collect_globals_test): Update
diff --git a/gdb/testsuite/gdb.server/solib-list-lib.c b/gdb/testsuite/gdb.server/solib-list-lib.c
new file mode 100644
index 00000000000..504a34eeb4b
--- /dev/null
+++ b/gdb/testsuite/gdb.server/solib-list-lib.c
@@ -0,0 +1,28 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2012 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+#include <signal.h>
+
+static int libvar = 23;
+
+int
+libfunc (void)
+{
+  raise (SIGUSR1);
+
+  return libvar;
+}
diff --git a/gdb/testsuite/gdb.server/solib-list-main.c b/gdb/testsuite/gdb.server/solib-list-main.c
new file mode 100644
index 00000000000..8abee3f59ab
--- /dev/null
+++ b/gdb/testsuite/gdb.server/solib-list-main.c
@@ -0,0 +1,25 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2012 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+extern int libfunc (void);
+
+int
+main (void)
+{
+  libfunc ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.server/solib-list.exp b/gdb/testsuite/gdb.server/solib-list.exp
new file mode 100644
index 00000000000..a25a235dc95
--- /dev/null
+++ b/gdb/testsuite/gdb.server/solib-list.exp
@@ -0,0 +1,104 @@
+# Copyright 2010-2012 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+# In some cases gdbserver cannot find the DT_DEBUG library list on its own and
+# it needs to fall back to GDB solib-svr4.c look up via symbols from the main
+# executable.
+# gdbserver :1234 ld-linux-x86-64.so.2 /bin/prog
+# gdb /bin/prog
+# (gdb) target remote ...
+
+load_lib gdbserver-support.exp
+load_lib prelink-support.exp
+
+if {[skip_gdbserver_tests] || [skip_shlib_tests]} {
+    return
+}
+
+set testfile "solib-list"
+set srclibfile ${testfile}-lib.c
+set srcfile ${testfile}-main.c
+set binlibfile ${objdir}/${subdir}/${testfile}.so
+set executable ${testfile}
+set objfile ${objdir}/${subdir}/${executable}.o
+set binfile ${objdir}/${subdir}/${executable}
+
+if { [get_compiler_info unused]
+     || [gdb_compile_shlib "${srcdir}/${subdir}/${srclibfile}" "${binlibfile}" [list debug ldflags=-Wl,-soname,${binlibfile}]] != ""
+     || [gdb_compile "${srcdir}/${subdir}/${srcfile}" "${objfile}" object {debug}] != ""
+     || [gdb_compile "${objfile} ${binlibfile}" "${binfile}" executable {}] != "" } {
+    untested "could not compile sources"
+    return -1
+}
+
+set interp_system [section_get ${binfile} .interp]
+verbose -log "system interpreter is: $interp_system"
+
+foreach nonstop { 0 1 } { with_test_prefix "non-stop $nonstop" {
+
+    # clean_restart assumes ${objdir}/${subdir}/ which is not applicable
+    # for ${interp_system}.
+    gdb_exit
+    gdb_start
+    gdb_reinitialize_dir $srcdir/$subdir
+    gdb_load ${interp_system}
+    gdb_load_shlibs ${binfile}
+    gdb_load_shlibs ${binlibfile}
+
+    # Make sure we're disconnected, in case we're testing with an
+    # extended-remote board, therefore already connected.
+    gdb_test "disconnect" ".*"
+
+    gdb_test "set non-stop $nonstop"
+    gdb_test "set target-async $nonstop"
+
+    # It is required for the non-stop mode, GDB would try to step over
+    # _dl_debug_state breakpoint will still only ld.so loaded in gdbserver.
+    # But GDB having symbols from the main executable it would try to use
+    # displaced-stepping buffer at unmapped that time address _start.
+    gdb_test "set displaced-stepping off"
+	
+    set res [gdbserver_spawn ${binfile}]
+    set gdbserver_protocol [lindex $res 0]
+    set gdbserver_gdbport [lindex $res 1]
+
+    # Load BINFILE after gdbserver_spawn (so that gdbserver executes ld.so)
+    # but before "target remote" below so that qSymbol data get already
+    # initialized from BINFILE (and not from ld.so first needing a change to
+    # BINFILE later).
+    gdb_test "file ${binfile}" {Reading symbols from .*\.\.\.done\..*} "file binfile" \
+	     {(Are you sure you want to change the file|Load new symbol table from ".*")\? \(y or n\) } "y"
+
+    set test "target $gdbserver_protocol"
+    gdb_test_multiple "target $gdbserver_protocol $gdbserver_gdbport" $test {
+	-re "Remote debugging using .*\r\n$gdb_prompt " {
+	    # Do not anchor end, there may be more output in non-stop mode.
+	    pass $test
+	}
+    }
+
+    if $nonstop {
+	set test "non-stop interior stop"
+	gdb_test_multiple "" $test {
+	    -re " #1 stopped\\.\r\n" {
+		pass $test
+	    }
+	}
+    }
+
+    gdb_test "continue" "Program received signal SIGUSR1, .*"
+    gdb_test "sharedlibrary" ".*"
+    gdb_test "p libvar" " = 23"
+}}