aarch64: detect atomic sequences like other ll/sc architectures

gdb/Changelog:

        * aarch64-tdep.c (aarch64_software_single_step): New function.
        (aarch64_gdbarch_init): Handle single stepping of atomic sequences
        with aarch64_software_single_step.

gdb/testsuite/ChangeLog:

        * gdb.arch/aarch64-atomic-inst.c: New file.
        * gdb.arch/aarch64-atomic-inst.exp: New file.

3 files changed, 102 insertions, 0 deletions

diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 106ba11..66d151b 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,3 +1,9 @@
+2014-05-07  Kyle McMartin  <kyle@redhat.com>
+
+	Pushed by Joel Brobecker  <brobecker@adacore.com>.
+	* gdb.arch/aarch64-atomic-inst.c: New file.
+	* gdb.arch/aarch64-atomic-inst.exp: New file.
+
 2014-05-07  Yao Qi  <yao@codesourcery.com>
 
 	* gdb.dwarf2/dwzbuildid.exp: Match output "No symbol "the_int"
diff --git a/gdb/testsuite/gdb.arch/aarch64-atomic-inst.c b/gdb/testsuite/gdb.arch/aarch64-atomic-inst.c
new file mode 100644
index 0000000..9a73c7a
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-atomic-inst.c
@@ -0,0 +1,48 @@
+/* This file is part of GDB, the GNU debugger.
+
+   Copyright 2008-2014 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/>.  */
+
+int main(void)
+{
+  unsigned long tmp, cond;
+  unsigned long dword = 0;
+
+  /* Test that we can step over ldxr/stxr. This sequence should step from
+     ldxr to the following __asm __volatile.  */
+  __asm __volatile ("1:     ldxr    %0,%2\n"                             \
+                    "       cmp     %0,#1\n"                             \
+                    "       b.eq    out\n"                               \
+                    "       add     %0,%0,1\n"                           \
+                    "       stxr    %w1,%0,%2\n"                         \
+                    "       cbnz    %w1,1b"                              \
+                    : "=&r" (tmp), "=&r" (cond), "+Q" (dword)            \
+                    : : "memory");
+
+  /* This sequence should take the conditional branch and step from ldxr
+     to the return dword line.  */
+  __asm __volatile ("1:     ldxr    %0,%2\n"                             \
+                    "       cmp     %0,#1\n"                             \
+                    "       b.eq    out\n"                               \
+                    "       add     %0,%0,1\n"                           \
+                    "       stxr    %w1,%0,%2\n"                         \
+                    "       cbnz    %w1,1b\n"                            \
+                    : "=&r" (tmp), "=&r" (cond), "+Q" (dword)            \
+                    : : "memory");
+
+  dword = -1;
+__asm __volatile ("out:\n");
+  return dword;
+}
diff --git a/gdb/testsuite/gdb.arch/aarch64-atomic-inst.exp b/gdb/testsuite/gdb.arch/aarch64-atomic-inst.exp
new file mode 100644
index 0000000..377aebc
--- /dev/null
+++ b/gdb/testsuite/gdb.arch/aarch64-atomic-inst.exp
@@ -0,0 +1,48 @@
+# Copyright 2008-2014 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, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+#
+# This file is part of the gdb testsuite.
+
+# Test single stepping through atomic sequences beginning with
+# a ldxr instruction and ending with a stxr instruction.
+
+if {![istarget "aarch64*"]} {
+    verbose "Skipping ${gdb_test_file_name}."
+    return
+}
+
+standard_testfile
+if { [prepare_for_testing ${testfile}.exp ${testfile} ${srcfile}] } {
+    return -1
+}
+
+if ![runto_main] {
+    untested "could not run to main"
+    return -1
+}
+
+gdb_breakpoint "[gdb_get_line_number "ldxr"]" \
+  "Breakpoint $decimal at $hex" \
+  "Set the breakpoint at the start of the sequence"
+
+gdb_test "continue" "Continuing.*Breakpoint $decimal.*" \
+  "Continue until breakpoint"
+
+gdb_test "next" ".*__asm __volatile.*" \
+  "Step through the ldxr/stxr sequence"
+
+gdb_test "next" ".*return dword.*" \
+  "Stepped through sequence through conditional branch"