New test about step over clone syscall

This patch adds a new test for stepping over clone syscall.

2016-03-03  Yao Qi  <yao.qi@linaro.org>

	* gdb.base/step-over-syscall.exp (step_over_syscall): Kfail.
	Invoke step_over_syscall "clone" and break_cond_on_syscall
	"clone".
	* gdb.base/step-over-clone.c: New file.

gdb/testsuite/ChangeLog

@@ -1,3 +1,10 @@
+2016-03-03  Yao Qi  <yao.qi@linaro.org>
+
+	* gdb.base/step-over-syscall.exp (step_over_syscall): Kfail.
+	Invoke step_over_syscall "clone" and break_cond_on_syscall
+	"clone".
+	* gdb.base/step-over-clone.c: New file.
+
 2016-03-03  Yao Qi  <yao.qi@linaro.org>
 
 	* gdb.base/step-over-syscall.exp (disp_step_cross_syscall): Fix

gdb/testsuite/gdb.base/step-over-clone.c

@@ -0,0 +1,54 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2016 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/>.  */
+
+#define _GNU_SOURCE
+#include <stdlib.h>
+#include <unistd.h>
+#include <sched.h>
+
+static void
+marker ()
+{}
+
+#define STACK_SIZE 0x1000
+
+static int
+clone_fn (void *unused)
+{
+  return 0;
+}
+
+int
+main (void)
+{
+  int i, pid;
+  unsigned char *stack[6];
+
+  for (i = 0; i < (sizeof (stack) / sizeof (stack[0])); i++)
+    stack[i] = malloc (STACK_SIZE);
+
+  for (i = 0; i < (sizeof (stack) / sizeof (stack[0])); i++)
+    {
+      pid = clone (clone_fn, stack[i] + STACK_SIZE, CLONE_FILES | CLONE_VM,
+		   NULL);
+    }
+
+  for (i = 0; i < (sizeof (stack) / sizeof (stack[0])); i++)
+    free (stack[i]);
+
+  marker ();
+}

gdb/testsuite/gdb.base/step-over-syscall.exp

@@ -124,6 +124,13 @@ proc step_over_syscall { syscall } {
 		continue
 	    }
 
+	    if { $displaced == "on" && $syscall == "clone" } {
+		# GDB doesn't support stepping over clone syscall with
+		# displaced stepping.
+		kfail "gdb/19675" "single step over clone"
+		continue
+	    }
+
 	    set ret [setup $syscall]
 
 	    set syscall_insn_addr [lindex $ret 0]
@@ -193,6 +200,18 @@ proc break_cond_on_syscall { syscall } {
 	gdb_test "break \*$syscall_insn_addr if main == 0" \
 	    "Breakpoint \[0-9\]* at .*"
 
+	if { $syscall == "clone" } {
+	    # Create a breakpoint in the child with the condition that
+	    # evals false, so that GDBserver can get the event from the
+	    # child but GDB doesn't see it.  In this way, we don't have
+	    # to adjust the test flow for "clone".
+	    # This is a regression test for PR server/19736.  In this way,
+	    # we can test that GDBserver gets an event from the child and
+	    # set suspend count correctly while the parent is stepping over
+	    # the breakpoint.
+	    gdb_test "break clone_fn if main == 0"
+	}
+
 	gdb_test "break marker" "Breakpoint.*at.* file .*${testfile}.c, line.*"
 	gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, marker \\(\\) at.*" \
 	    "continue to marker ($syscall)"
@@ -201,6 +220,7 @@ proc break_cond_on_syscall { syscall } {
 
 step_over_syscall "fork"
 step_over_syscall "vfork"
+step_over_syscall "clone"
 
 set testfile "step-over-fork"
 clean_restart $testfile
@@ -225,4 +245,5 @@ gdb_test_multiple $test $test {
 if { $cond_bp_target } {
     break_cond_on_syscall "fork"
     break_cond_on_syscall "vfork"
+    break_cond_on_syscall "clone"
 }