Re: [patch 2/2] Displaced stepping across fork/vfork : test case

[Yao Qi <yao@codesourcery.com>]

On 09/15/2011 11:52 PM, Pedro Alves wrote:
>> > +    set syscall_insn_bp 0
>> > +    gdb_test_multiple "break \*$syscall_insn_addr"  "break on syscall insn" {
>> > +       -re "Breakpoint (\[0-9\]*) at .*$gdb_prompt $" {
>> > +           set syscall_insn_bp $expect_out(1,string)
>> > +           pass "break on syscall insns"
>> > +       }
>> > +       -re "Cannot insert breakpoint .*${gdb_prompt} $" {
>> > +           # This syscall insn may be in vsyscall page, and we can't set a breakpoint
>> > +           # there on some systems.
>> > +           fail "break on syscall insns"
> Please don't make this is a fail.  It is not GDB's fault.  "unsupported"
> or "xfail" would be better.
> 

"unsupported" is used here.

>> > +           set pf_prefix $old_pf_prefix
>> > +           return -1
>> > +       }
>> > +    }
> But this won't work as is.  Breakpoints will only be inserted on the
> next resume, not immediately.  Unless you enable always-inserted mode,
> that is.

I can set breakpoint on vsyscall page of my system, so I have to imagine
what will happen if I can't set breakpoint.  As you said, breakpoints
will be inserted on the next resume, so I check the "Cannot insert
breakpoint" in next "continue" operation, like this,

    gdb_test_multiple "continue" "continue to syscall insn $syscall" {
	-re "Cannot insert breakpoint .*${gdb_prompt} $" {
	    # This syscall insn may be in vsyscall page, and we can't set a
breakpoint
	    # there on some systems.
	    unsupported "break on syscall insns"
	    set pf_prefix $old_pf_prefix
	    return -1
	}
	-re "Continuing\\..*Breakpoint \[0-9\]+, .*${gdb_prompt} $" {
	    pass "break on syscall insns"
	}
    }

-- 
Yao (齐尧)

	gdb/testsuite/
	* gdb.base/disp-step-fork.c: New.
	* gdb.base/disp-step-syscall.exp: New.
	* gdb.base/disp-step-vfork.c: New.
---
 gdb/testsuite/gdb.base/disp-step-fork.c      |   57 ++++++++++
 gdb/testsuite/gdb.base/disp-step-syscall.exp |  148
++++++++++++++++++++++++++
 gdb/testsuite/gdb.base/disp-step-vfork.c     |   70 ++++++++++++
 3 files changed, 275 insertions(+), 0 deletions(-)
 create mode 100644 gdb/testsuite/gdb.base/disp-step-fork.c
 create mode 100644 gdb/testsuite/gdb.base/disp-step-syscall.exp
 create mode 100644 gdb/testsuite/gdb.base/disp-step-vfork.c

diff --git a/gdb/testsuite/gdb.base/disp-step-fork.c
b/gdb/testsuite/gdb.base/disp-step-fork.c
new file mode 100644
index 0000000..ab4f3b4
--- /dev/null
+++ b/gdb/testsuite/gdb.base/disp-step-fork.c
@@ -0,0 +1,57 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2011 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 <stdlib.h>
+
+static void
+marker () {}
+
+int
+main (void)
+{
+  int  pid;
+
+  pid = fork ();
+  if (pid == 0) /* child */
+    {
+      exit (0); /* at exit */
+    }
+  else
+    {
+    }
+
+  pid = fork ();
+  if (pid == 0) /* child */
+    {
+      exit (0); /* at exit */
+    }
+  else
+    {
+    }
+
+  pid = fork ();
+  if (pid == 0) /* child */
+    {
+      exit (0); /* at exit */
+    }
+  else
+    {
+    }
+
+  marker ();
+
+}
diff --git a/gdb/testsuite/gdb.base/disp-step-syscall.exp
b/gdb/testsuite/gdb.base/disp-step-syscall.exp
new file mode 100644
index 0000000..4860c48
--- /dev/null
+++ b/gdb/testsuite/gdb.base/disp-step-syscall.exp
@@ -0,0 +1,148 @@
+# This testcase is part of GDB, the GNU debugger.
+
+# Copyright 2011 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/>.
+
+if { ![support_displaced_stepping] } {
+    unsupported "displaced stepping"
+    return -1
+}
+
+set syscall_insn ""
+
+# Define the syscall instruction for each target.
+
+if { [istarget "i\[34567\]86-*-linux*"] || [istarget "x86_64-*-linux*"] } {
+    set syscall_insn "(int|syscall|sysenter)"
+} else {
+    return -1
+}
+
+proc disp_step_cross_syscall { syscall } {
+    global syscall_insn
+    global gdb_prompt
+    global pf_prefix
+
+    set testfile "disp-step-$syscall"
+
+    if [prepare_for_testing ${testfile}.exp ${testfile} ${testfile}.c
{debug}] {
+	untested ${testfile}.exp
+	return -1
+    }
+
+    if { ![runto main] } then {
+	fail "run to main ($syscall)"
+	return
+    }
+
+    set old_pf_prefix $pf_prefix
+    lappend pf_prefix "$syscall:"
+
+    # Delete the breakpoint on main.
+    gdb_test_no_output "delete break 1"
+
+    gdb_test "break marker" "Breakpoint.*at.* file .*${testfile}.c, line.*"
+    gdb_test_no_output "set displaced-stepping off"
+
+    set syscall_bp 0
+    gdb_test_multiple "break $syscall"  "break $syscall" {
+	-re "Breakpoint (\[0-9\]*) at .*$gdb_prompt $" {
+	    set syscall_bp $expect_out(1,string)
+	    pass "break $syscall"
+	}
+    }
+
+    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, .* in
$syscall ().*" \
+	"continue to $syscall (1st time)"
+    # Hit the breakpoint on $syscall for the first time.  In this time,
we will let PLT
+    # resolution done, and the number single steps we will do later will be
+    # reduced.
+
+    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, .* in
$syscall ().*" \
+	"continue to $syscall (2nd time)"
+    # Hit the breakpoint on $syscall for the second time.  In this
time, the address
+    # of syscall insn and next insn of syscall are recorded.
+
+    gdb_test "display/i \$pc" ".*"
+
+
+    # Single step until we see sysall insn or we reach the upper bound
of loop
+    # iterations.
+    set see_syscall_insn 0
+
+    for {set i 0} {$i < 1000 && $see_syscall_insn == 0} {incr i} {
+	send_gdb "stepi\n"
+	gdb_expect {
+	    -re ".*$syscall_insn.*$gdb_prompt $" {
+		set see_syscall_insn 1
+	    }
+	    -re ".*$gdb_prompt $" {}
+	}
+    }
+
+    if {$see_syscall_insn == 0} then {
+	fail "find syscall insn in $syscall"
+	set pf_prefix $old_pf_prefix
+	return -1
+    }
+
+    set syscall_insn_addr [get_hexadecimal_valueof "\$pc" "0"]
+    gdb_test "stepi" ".*" "stepi $syscall insn"
+    set syscall_insn_next_addr [get_hexadecimal_valueof "\$pc" "0"]
+
+    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, .* in
$syscall ().*" \
+	"continue to $syscall (3rd time)"
+
+    # Hit the breakpoint on $syscall for the third time.  In this time,
we'll set
+    # breakpoint on the syscall insn we recorded previously, and single
step over it.
+
+    set syscall_insn_bp 0
+    gdb_test_multiple "break \*$syscall_insn_addr"  "break on syscall
insn" {
+	-re "Breakpoint (\[0-9\]*) at .*$gdb_prompt $" {
+	    set syscall_insn_bp $expect_out(1,string)
+	    pass "break on syscall insns"
+	}
+    }
+    gdb_test_no_output "delete $syscall_bp" "delete break $syscall"
+
+    gdb_test_multiple "continue" "continue to syscall insn $syscall" {
+	-re "Cannot insert breakpoint .*${gdb_prompt} $" {
+	    # This syscall insn may be in vsyscall page, and we can't set a
breakpoint
+	    # there on some systems.
+	    unsupported "break on syscall insns"
+	    set pf_prefix $old_pf_prefix
+	    return -1
+	}
+	-re "Continuing\\..*Breakpoint \[0-9\]+, .*${gdb_prompt} $" {
+	    pass "break on syscall insns"
+	}
+    }
+
+    gdb_test_no_output "set displaced-stepping on"
+
+    # Check the address of next instruction of syscall.
+    gdb_test "stepi" ".*$syscall_insn_next_addr.*" "single step over
$syscall"
+
+    # Delete breakpoint syscall insns to avoid interference to other
syscalls.
+    gdb_test_no_output "delete $syscall_insn_bp" "delete break $syscall
insn"
+
+    gdb_test "continue" "Continuing\\..*Breakpoint \[0-9\]+, marker
\\(\\) at.*" \
+	"continue to marker ($syscall)"
+
+    set pf_prefix $old_pf_prefix
+}
+
+disp_step_cross_syscall "fork"
+disp_step_cross_syscall "vfork"
diff --git a/gdb/testsuite/gdb.base/disp-step-vfork.c
b/gdb/testsuite/gdb.base/disp-step-vfork.c
new file mode 100644
index 0000000..fdc7914
--- /dev/null
+++ b/gdb/testsuite/gdb.base/disp-step-vfork.c
@@ -0,0 +1,70 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2011 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 <unistd.h>
+
+static void
+marker () {}
+
+int
+main (void)
+{
+  int pid;
+
+  pid = vfork ();
+  if (pid == -1)
+    {
+      return 1;
+    }
+  else if (pid != 0)
+    {
+    }
+  else
+    {
+      _exit (0);
+    }
+
+  pid = vfork ();
+  if (pid == -1)
+    {
+      return 1;
+    }
+  else if (pid != 0)
+    {
+    }
+  else
+    {
+      _exit (0);
+    }
+
+  pid = vfork ();
+  if (pid == -1)
+    {
+      return 1;
+    }
+  else if (pid != 0)
+    {
+    }
+  else
+    {
+      _exit (0);
+    }
+
+  marker ();
+  return 0;
+
+}
-- 
1.7.0.4