New test case gdb.trace/signal.exp

This is to test whether GDBserver deliver signal to the inferior while
doing the step over.  Nowadays, GDBserver doesn't deliver signal, so
there won't be spurious collection, however, if GDBserver does deliver
signal, there might be spurious collection.

gdb/testsuite:

2016-04-22  Yao Qi  <[email protected]>

	* gdb.trace/signal.c: New file.
	* gdb.trace/signal.exp: New file.

gdb/testsuite/ChangeLog

@@ -1,3 +1,8 @@
+2016-04-22  Yao Qi  <[email protected]>
+
+	* gdb.trace/signal.c: New file.
+	* gdb.trace/signal.exp: New file.
+
 2016-04-19  Doug Evans  <[email protected]>
 
 	* gdb.base/bad-file.exp: New file.

gdb/testsuite/gdb.trace/signal.c

@@ -0,0 +1,68 @@
+/* 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/>.  */
+
+#include <signal.h>
+#include <string.h>
+#include <unistd.h>
+
+static int counter = 0;
+
+static void
+handler (int sig)
+{
+  counter++;
+}
+
+static int iterations = 3;
+
+static void
+start (int pid)
+{
+  int i;
+
+  for (i = 0; i < iterations; i++)
+    {
+      kill (pid, SIGABRT);
+    }
+}
+
+static void
+end (void)
+{}
+
+int
+main (void)
+{
+  struct sigaction act;
+  int i;
+
+  memset (&act, 0, sizeof act);
+  act.sa_handler = handler;
+  act.sa_flags = SA_NODEFER;
+  sigaction (SIGABRT, &act, NULL);
+
+  for (i = 0; i < 3; i++)
+    {
+      kill (getpid (), SIGABRT);
+    }
+
+  counter = 0;
+  start (getpid ());
+
+  end ();
+  return 0;
+}

gdb/testsuite/gdb.trace/signal.exp

@@ -0,0 +1,179 @@
+#   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/>.
+
+# This is to test whether GDBserver or other remote stubs deliver signal
+# to the inferior while step over thread.  The program signal.c sends
+# signal SIGABRT to itself via kill syscall.  The test sets tracepoints
+# syscall instruction and the next one, and it is quite likely that
+# GDBserver gets the signal when it steps over thread and does the
+# collection.  If GDBserver doesn't deliver signal in thread step over,
+# one collection is got for one tracepoint hit.  Otherwise, there may
+# be two collections for one tracepoint hit, because tracepoint is
+# collected once before step over, the program goes into signal handler
+# (because signal is delivered in step over), and program goes back
+# to the tracepoint again (one more collection) after returns from
+# signal handler.
+
+load_lib "trace-support.exp"
+
+standard_testfile
+
+if {[prepare_for_testing $testfile.exp $testfile $srcfile debug]} {
+    untested $testfile.exp
+    return -1
+}
+
+if ![runto_main] {
+    fail "Can't run to main to check for trace support"
+    return -1
+}
+
+if ![gdb_target_supports_trace] {
+    unsupported "target does not support trace"
+    return -1
+}
+
+# Step 1, find the syscall instruction address.
+
+set syscall_insn ""
+
+# Define the syscall instruction for each target.
+
+if { [istarget "i\[34567\]86-*-linux*"] || [istarget "x86_64-*-linux*"] } {
+    set syscall_insn "\[ \t\](int|syscall|sysenter)\[ \t\]"
+} elseif { [istarget "aarch64*-*-linux*"] || [istarget "arm*-*-linux*"] } {
+    set syscall_insn "\[ \t\](swi|svc)\[ \t\]"
+} else {
+    unsupported "unknown syscall instruction"
+    return -1
+}
+
+# Start with a fresh gdb.
+clean_restart ${testfile}
+if ![runto_main] {
+    fail "Can't run to main"
+    return -1
+}
+
+gdb_test "break kill" "Breakpoint $decimal at .*"
+gdb_test "handle SIGABRT nostop noprint pass" ".*" "pass SIGABRT"
+
+# 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 $decimal, (.* in |__libc_|)kill \\(\\).*" \
+    "continue to kill, 1st 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 "continue" "Continuing\\..*Breakpoint $decimal, (.* in |__libc_|)kill \\(\\).*" \
+    "continue to kill, 2nd time"
+
+gdb_test "display/i \$pc" ".*"
+
+# Single step until we see a syscall insn or we reach the
+# upper bound of loop iterations.
+set msg "find syscall insn in kill"
+set steps 0
+set max_steps 1000
+gdb_test_multiple "stepi" $msg {
+    -re ".*$syscall_insn.*$gdb_prompt $" {
+	pass $msg
+    }
+    -re "x/i .*=>.*\r\n$gdb_prompt $" {
+	incr steps
+	if {$steps == $max_steps} {
+	    fail $msg
+	} else {
+	    send_gdb "stepi\n"
+	    exp_continue
+	}
+    }
+}
+
+if {$steps == $max_steps} {
+    return
+}
+
+# Remove the display
+gdb_test_no_output "delete display 1"
+
+set syscall_insn_addr [get_hexadecimal_valueof "\$pc" "0"]
+set syscall_insn_next 0
+set test "x/2i \$pc"
+gdb_test_multiple $test $test {
+    -re "$hex .*:\[^\r\n\]+\r\n\[ \]+($hex).*\.\r\n$gdb_prompt $" {
+	set syscall_insn_next $expect_out(1,string)
+    }
+}
+
+delete_breakpoints
+gdb_test "break start" "Breakpoint $decimal at .*"
+gdb_continue_to_breakpoint "continue to start"
+
+gdb_assert { 0 == [get_integer_valueof "counter" "1"] } "counter is zero"
+
+delete_breakpoints
+
+# Step 2, set tracepoints on syscall instruction and the next one.
+# It is more likely to get signal on these two places when GDBserver
+# is doing step-over.
+gdb_test "trace *$syscall_insn_addr" "Tracepoint $decimal at .*" \
+    "tracepoint on syscall instruction"
+set tpnum [get_integer_valueof "\$bpnum" 0]
+gdb_test "trace *$syscall_insn_next" "Tracepoint $decimal at .*" \
+    "tracepoint on instruction following syscall instruction"
+
+gdb_test "break end" "Breakpoint $decimal at .*"
+
+gdb_test_no_output "tstart"
+gdb_test "continue" ".*Breakpoint.* end .*at.*$srcfile.*" \
+    "continue to end"
+gdb_test_no_output "tstop"
+
+set iterations [get_integer_valueof "iterations" "0"]
+
+gdb_assert { $iterations == [get_integer_valueof "counter" "0"] } \
+    "iterations equals to counter"
+
+# Record the hit times of each tracepoint in this array.
+array set tracepoint_hits { }
+for { set i $tpnum } { $i < [expr $tpnum + 2] } { incr i } {
+  set tracepoint_hits($i) 0
+}
+
+while { 1 } {
+   set test "tfind"
+   set idx 0
+   gdb_test_multiple $test $test {
+	-re "Found trace frame $decimal, tracepoint ($decimal).*\r\n$gdb_prompt $" {
+	    set idx [expr $expect_out(1,string)]
+	    incr tracepoint_hits($idx)
+	}
+       -re "Target failed to find requested trace frame\..*\r\n$gdb_prompt $" {
+	   set idx 0
+       }
+   }
+   if {$idx == 0} {
+	break
+   }
+}
+
+# Step 3, check the number of collections on each tracepoint.
+
+for { set i $tpnum } { $i < [expr $tpnum + 2] } { incr i } {
+    gdb_assert { $tracepoint_hits($i) == $iterations } \
+	"tracepoint $i hit $iterations times"
+}