Re: [PATCH v3] gdb/testsuite: add test for backtracing for threaded inferiors from a corefile

[Andrew Burgess <aburgess@redhat.com>]

Luis Machado <luis.machado@arm.com> writes:

> On 11/24/23 12:26, Luis Machado wrote:
>> On 10/25/23 12:42, Guinevere Larsen wrote:
>>> This patch is based on an out-of-tree patch that fedora has been
>>> carrying for a while. It tests if GDB is able to properly unwind a
>>> threaded program in the following situations:
>>> * regular threads
>>> * in a signal handler
>>> * in a signal handler executing on an alternate stack
>>>
>>> And the final frame can either be in a syscall or in an infinite loop.
>>>
>>> The test works by running the inferior until a crash to generate a
>>> corefile, or until right before the crash. Then applies a backtrace to
>>> all threads to see if any frame can't be identified, and the order of
>>> the threads in GDB. Finally, it goes thread by thread and tries to
>>> collect a large part of the backtrace, to confirm that everything is
>>> being unwound correctly.
>>>
>>> Co-Authored-By: Andrew Burgess <aburgess@redhat.com>
>>> ---
>>>
>>> Changes for v3:
>>> * Resolved Lancelot's comment
>>> * undid early exit in favor of more readable gdb_test usage to load the
>>>   corefile
>>>
>>> Changes for v2:
>>> * Linaro CI identified an issue with the test, which made the test fail
>>>   when using read1. Fixed here
>>> * Also added early exit on corefile tests, if the corefile isn't
>>>   properly loaded
>>>
>>> ---
>>>  gdb/testsuite/gdb.threads/threadcrash.c   | 443 ++++++++++++++++++++++
>>>  gdb/testsuite/gdb.threads/threadcrash.exp | 209 ++++++++++
>>>  2 files changed, 652 insertions(+)
>>>  create mode 100644 gdb/testsuite/gdb.threads/threadcrash.c
>>>  create mode 100644 gdb/testsuite/gdb.threads/threadcrash.exp
>>>
>>> diff --git a/gdb/testsuite/gdb.threads/threadcrash.c b/gdb/testsuite/gdb.threads/threadcrash.c
>>> new file mode 100644
>>> index 00000000000..e476ae7b07d
>>> --- /dev/null
>>> +++ b/gdb/testsuite/gdb.threads/threadcrash.c
>>> @@ -0,0 +1,443 @@
>>> +/* This testcase is part of GDB, the GNU debugger.
>>> +
>>> +   Copyright 2023 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 <pthread.h>
>>> +#include <assert.h>
>>> +#include <stdlib.h>
>>> +#include <signal.h>
>>> +#include <unistd.h>
>>> +
>>> +/* The delay that the main thread gives once all the worker threads have
>>> +   reached the barrier before the main thread enters the function on which
>>> +   GDB will have placed a breakpoint.  */
>>> +
>>> +#define MAIN_THREAD_DELAY 2
>>> +
>>> +/* The maximum time we allow this test program to run for before an alarm
>>> +   signal is sent and everything will exit.  */
>>> +#define WATCHDOG_ALARM_TIME 600
>>> +
>>> +/* Aliases for the signals used within this script.  Each signal
>>> +   corresponds to an action (from the FINAL_ACTION enum) that the signal
>>> +   handler will perform.  */
>>> +
>>> +#define SPIN_SIGNAL SIGUSR1
>>> +#define SYSCALL_SIGNAL SIGUSR2
>>> +
>>> +/* Describe the final action that a thread should perform.  */
>>> +
>>> +enum final_action
>>> +  {
>>> +    /* Thread should spin in an infinite loop.  */
>>> +    SPIN = 0,
>>> +
>>> +    /* Thread should block in a syscall.  */
>>> +    SYSCALL,
>>> +
>>> +    /* This is just a marker to allow for looping over the enum.  */
>>> +    LAST_ACTION
>>> +  };
>>> +
>>> +/* Where should the thread perform this action?  */
>>> +
>>> +enum exec_location
>>> +  {
>>> +    /* Just a normal thread, on a normal stack.  */
>>> +    NORMAL = 0,
>>> +
>>> +    /* In a signal handler, but use the normal stack.  */
>>> +    SIGNAL_HANDLER,
>>> +
>>> +    /* In a signal handler using an alternative stack.  */
>>> +    SIGNAL_ALT_STACK,
>>> +
>>> +    /* This is just a marker to allow for looping over the enum.  */
>>> +    LAST_LOCACTION
>>> +  };
>>> +
>>> +/* A descriptor for a single thread job.  We create a new thread for each
>>> +   job_description.  */
>>> +
>>> +struct job_description
>>> +{
>>> +  /* What action should this thread perform.  */
>>> +  enum final_action action;
>>> +
>>> +  /* Where should the thread perform the action.  */
>>> +  enum exec_location location;
>>> +
>>> +  /* The actual thread handle, so we can join with the thread.  */
>>> +  pthread_t thread;
>>> +};
>>> +
>>> +/* A pthread barrier, used to (try) and synchronise the threads.  */
>>> +pthread_barrier_t global_barrier;
>>> +
>>> +/* Return a list of jobs, and place the length of the list in *COUNT.  */
>>> +
>>> +struct job_description *
>>> +get_job_list (int *count)
>>> +{
>>> +  /* The number of jobs.  */
>>> +  int num = LAST_ACTION * LAST_LOCACTION;
>>> +
>>> +  /* The uninitialised array of jobs.  */
>>> +  struct job_description *list
>>> +    = malloc (num * sizeof (struct job_description));
>>> +  assert (list != NULL);
>>> +
>>> +  /* Fill the array with all possible jobs.  */
>>> +  for (int i = 0; i < (int) LAST_ACTION; ++i)
>>> +    for (int j = 0; j < (int) LAST_LOCACTION; ++j)
>>> +      {
>>> +	int idx = (i * LAST_LOCACTION) + j;
>>> +	list[idx].action = (enum final_action) i;
>>> +	list[idx].location = (enum exec_location) j;
>>> +      }
>>> +
>>> +  /* Return the array of jobs.  */
>>> +  *count = num;
>>> +  return list;
>>> +}
>>> +
>>> +/* This function should never be called.  If it is then an assertion will
>>> +   trigger.  */
>>> +
>>> +void
>>> +assert_not_reached (void)
>>> +{
>>> +  assert (0);
>>> +}
>>> +
>>> +/* The function for a SPIN action.  Just spins in a loop.  The LOCATION
>>> +   argument exists so GDB can identify the expected context for this
>>> +   function.  */
>>> +
>>> +void
>>> +do_spin_task (enum exec_location location)
>>> +{
>>> +  (void) location;
>>> +
>>> +  /* Let everyone know that we're about to perform our action.  */
>>> +  int res = pthread_barrier_wait (&global_barrier);
>>> +  assert (res == PTHREAD_BARRIER_SERIAL_THREAD || res == 0);
>>> +
>>> +  while (1)
>>> +    {
>>> +      /* Nothing.  */
>>> +    }
>>> +}
>>> +
>>> +/* The function for a SYSCALL action.  Just spins in a loop.  The LOCATION
>>> +   argument exists so GDB can identify the expected context for this
>>> +   function.  */
>>> +
>>> +void
>>> +do_syscall_task (enum exec_location location)
>>> +{
>>> +  (void) location;
>>> +
>>> +  /* Let everyone know that we're about to perform our action.  */
>>> +  int res = pthread_barrier_wait (&global_barrier);
>>> +  assert (res == PTHREAD_BARRIER_SERIAL_THREAD || res == 0);
>>> +
>>> +  sleep (600);
>>> +}
>>> +
>>> +/* Return the required size for a sigaltstack.  We start with a single
>>> +   page, but do check against the system defined minimums.  We don't run
>>> +   much on the alternative stacks, so we don't need a huge one.  */
>>> +
>>> +size_t
>>> +get_stack_size (void)
>>> +{
>>> +  size_t size = getpagesize ();	/* Arbitrary starting size.  */
>>> +  if (size < SIGSTKSZ)
>>> +    size = SIGSTKSZ;
>>> +  if (size < MINSIGSTKSZ)
>>> +    size = MINSIGSTKSZ;
>>> +  return size;
>>> +}
>>> +
>>> +/* A descriptor for an alternative stack.  */
>>> +
>>> +struct stack_descriptor
>>> +{
>>> +  /* The base address of the alternative stack.  This is the address that
>>> +     must be freed to release the memory used by this stack.  */
>>> +  void *base;
>>> +
>>> +  /* The size of this alternative stack.  Tracked just so we can query this
>>> +     from GDB.  */
>>> +  size_t size;
>>> +};
>>> +
>>> +/* Install an alternative signal stack.  Return a descriptor for the newly
>>> +   allocated alternative stack.  */
>>> +
>>> +struct stack_descriptor
>>> +setup_alt_stack (void)
>>> +{
>>> +  size_t stack_size = get_stack_size ();
>>> +
>>> +  void *stack_area = malloc (stack_size);
>>> +
>>> +  stack_t stk;
>>> +  stk.ss_sp = stack_area;
>>> +  stk.ss_flags = 0;
>>> +  stk.ss_size = stack_size;
>>> +
>>> +  int res = sigaltstack (&stk, NULL);
>>> +  assert (res == 0);
>>> +
>>> +  struct stack_descriptor desc;
>>> +  desc.base = stack_area;
>>> +  desc.size = stack_size;
>>> +
>>> +  return desc;
>>> +}
>>> +
>>> +/* Return true (non-zero) if we are currently on the alternative stack,
>>> +   otherwise, return false (zero).  */
>>> +
>>> +int
>>> +on_alt_stack_p (void)
>>> +{
>>> +  stack_t stk;
>>> +  int res = sigaltstack (NULL, &stk);
>>> +  assert (res == 0);
>>> +
>>> +  return (stk.ss_flags & SS_ONSTACK) != 0;
>>> +}
>>> +
>>> +/* The signal handler function.  All signals call here, so we use SIGNO
>>> +   (the signal that was delivered) to decide what action to perform.  This
>>> +   function might, or might not, have been called on an alternative signal
>>> +   stack.  */
>>> +
>>> +void
>>> +signal_handler (int signo)
>>> +{
>>> +  enum exec_location location
>>> +    = on_alt_stack_p () ? SIGNAL_ALT_STACK : SIGNAL_HANDLER;
>>> +
>>> +  switch (signo)
>>> +    {
>>> +    case SPIN_SIGNAL:
>>> +      do_spin_task (location);
>>> +      break;
>>> +
>>> +    case SYSCALL_SIGNAL:
>>> +      do_syscall_task (location);
>>> +      break;
>>> +
>>> +    default:
>>> +      assert_not_reached ();
>>> +    }
>>> +}
>>> +
>>> +/* The thread worker function.  ARG is a job_description pointer which
>>> +   describes what this thread is expected to do.  This function always
>>> +   returns a NULL pointer.  */
>>> +
>>> +void *
>>> +thread_function (void *arg)
>>> +{
>>> +  struct job_description *job = (struct job_description *) arg;
>>> +  struct stack_descriptor desc = { NULL, 0 };
>>> +  int sa_flags = 0;
>>> +
>>> +  switch (job->location)
>>> +    {
>>> +    case NORMAL:
>>> +      /* This thread performs the worker action on the current thread,
>>> +	 select the correct worker function based on the requested
>>> +	 action.  */
>>> +      switch (job->action)
>>> +	{
>>> +	case SPIN:
>>> +	  do_spin_task (NORMAL);
>>> +	  break;
>>> +
>>> +	case SYSCALL:
>>> +	  do_syscall_task (NORMAL);
>>> +	  break;
>>> +
>>> +	default:
>>> +	  assert_not_reached ();
>>> +	}
>>> +      break;
>>> +
>>> +    case SIGNAL_ALT_STACK:
>>> +      /* This thread is to perform its action in a signal handler on the
>>> +	 alternative stack.  Install the alternative stack now, and then
>>> +	 fall through to the normal signal handler location code.  */
>>> +      desc = setup_alt_stack ();
>>> +      assert (desc.base != NULL);
>>> +      assert (desc.size > 0);
>>> +      sa_flags = SA_ONSTACK;
>>> +
>>> +      /* Fall through.  */
>>> +    case SIGNAL_HANDLER:
>>> +      {
>>> +	/* This thread is to perform its action in a signal handler.  We
>>> +	   might have just installed an alternative signal stack.  */
>>> +	int signo, res;
>>> +
>>> +	/* Select the correct signal number so that the signal handler will
>>> +	   perform the required action.  */
>>> +	switch (job->action)
>>> +	  {
>>> +	  case SPIN:
>>> +	    signo = SPIN_SIGNAL;
>>> +	    break;
>>> +
>>> +	  case SYSCALL:
>>> +	    signo = SYSCALL_SIGNAL;
>>> +	    break;
>>> +
>>> +	  default:
>>> +	    assert_not_reached ();
>>> +	  }
>>> +
>>> +	/* Now setup the signal handler.  */
>>> +	struct sigaction sa;
>>> +	sa.sa_handler = signal_handler;
>>> +	sigfillset (&sa.sa_mask);
>>> +	sa.sa_flags = sa_flags;
>>> +	res = sigaction (signo, &sa, NULL);
>>> +	assert (res == 0);
>>> +
>>> +	/* Send the signal to this thread.  */
>>> +	res = pthread_kill (job->thread, signo);
>>> +	assert (res == 0);
>>> +      }
>>> +      break;
>>> +
>>> +    default:
>>> +      assert_not_reached ();
>>> +    };
>>> +
>>> +  /* Free the alt-stack if we allocated one, if not DESC.BASE will be
>>> +     NULL so this call is fine.  */
>>> +  free (desc.base);
>>> +
>>> +  /* Thread complete.  */
>>> +  return NULL;
>>> +}
>>> +
>>> +void
>>> +start_job (struct job_description *job)
>>> +{
>>> +  int res;
>>> +
>>> +  res = pthread_create (&job->thread, NULL, thread_function, job);
>>> +  assert (res == 0);
>>> +}
>>> +
>>> +/* Join with the thread for JOB.  This will block until the thread for JOB
>>> +   has finished.  */
>>> +
>>> +void
>>> +finalise_job (struct job_description *job)
>>> +{
>>> +  int res;
>>> +  void *retval;
>>> +
>>> +  res = pthread_join (job->thread, &retval);
>>> +  assert (res == 0);
>>> +  assert (retval == NULL);
>>> +}
>>> +
>>> +/* Function that GDB can place a breakpoint on.  */
>>> +
>>> +void
>>> +breakpt (void)
>>> +{
>>> +  /* Nothing.  */
>>> +}
>>> +
>>> +/* Function that triggers a crash, if the user has setup their environment
>>> +   correctly this will dump a core file, which GDB can then examine.  */
>>> +
>>> +void
>>> +crash_function (void)
>>> +{
>>> +  volatile int *p = 0;
>>> +  volatile int n = *p;
>>> +  (void) n;
>>> +}
>>> +
>>> +/* Entry point.  */
>>> +
>>> +int
>>> +main ()
>>> +{
>>> +  int job_count, res;
>>> +  struct job_description *jobs = get_job_list (&job_count);
>>> +
>>> +  /* This test is going to park some threads inside infinite loops.  Just
>>> +     in case this program is left running, install an alarm that will cause
>>> +     everything to exit.  */
>>> +  alarm (WATCHDOG_ALARM_TIME);
>>> +
>>> +  /* We want each worker thread (of which there are JOB_COUNT) plus the
>>> +     main thread (hence + 1) to wait at the barrier.  */
>>> +  res = pthread_barrier_init (&global_barrier, NULL, job_count + 1);
>>> +  assert (res == 0);
>>> +
>>> +  /* Start all the jobs.  */
>>> +  for (int i = 0; i < job_count; ++i)
>>> +    start_job (&jobs[i]);
>>> +
>>> +  /* Notify all the worker threads that we're waiting for them.  */
>>> +  res = pthread_barrier_wait (&global_barrier);
>>> +  assert (res == PTHREAD_BARRIER_SERIAL_THREAD || res == 0);
>>> +
>>> +  /* All we know at this point is that all the worker threads have reached
>>> +     the barrier, which is just before they perform their action.  But we
>>> +     really want them to start their action.
>>> +
>>> +     There's really no way we can be 100% certain that the worker threads
>>> +     have started their action, all we can do is wait for a short while and
>>> +     hope that the machine we're running on is not too slow.  */
>>> +  sleep (MAIN_THREAD_DELAY);
>>> +
>>> +  /* A function that GDB can place a breakpoint on.  By the time we get
>>> +     here we are as sure as we can be that all of the worker threads have
>>> +     started and are in their worker action (spinning, or syscall).  */
>>> +  breakpt ();
>>> +
>>> +  /* If GDB is not attached then this function will cause a crash, which
>>> +     can be used to dump a core file, which GDB can then analyse.  */
>>> +  crash_function ();
>>> +
>>> +  /* Due to the crash we never expect to get here.  Plus the worker actions
>>> +     never terminate.  But for completeness, here's where we join with all
>>> +     the worker threads.  */
>>> +  for (int i = 0; i < job_count; ++i)
>>> +    finalise_job (&jobs[i]);
>>> +
>>> +  /* Cleanup the barrier.  */
>>> +  res = pthread_barrier_destroy (&global_barrier);
>>> +  assert (res == 0);
>>> +
>>> +  /* And clean up the jobs list.  */
>>> +  free (jobs);
>>> +
>>> +  return 0;
>>> +}
>>> diff --git a/gdb/testsuite/gdb.threads/threadcrash.exp b/gdb/testsuite/gdb.threads/threadcrash.exp
>>> new file mode 100644
>>> index 00000000000..ee81b5c32f2
>>> --- /dev/null
>>> +++ b/gdb/testsuite/gdb.threads/threadcrash.exp
>>> @@ -0,0 +1,209 @@
>>> +# This testcase is part of GDB, the GNU debugger.
>>> +
>>> +# Copyright 2023 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 test case looks at GDB's ability to get correct backtraces for a
>>> +# crashed inferior, recreating it from a live inferior, a corefile and
>>> +# a gcore.
>>> +
>>> +
>>> +# First check that we have 7 threads.
>>> +
>>> +proc test_thread_count {} {
>>> +    set thread_count 0
>>> +
>>> +    gdb_test_multiple "info threads" "getting thread count" -lbl {
>>> +	-re "Thread" {
>>> +	    incr thread_count
>>> +	    exp_continue
>>> +	}
>>> +	-re "$::gdb_prompt " {
>>> +	    gdb_assert {$thread_count == 7}
>>> +	}
>>> +    }
>>> +
>>> +    return $thread_count
>>> +}
>>> +
>>> +# Apply all to quickly check if all expected states are
>>> +# present.  Then, save the full desired backtrace in a list
>>> +# so we can check full backtraces later.
>>> +
>>> +proc thread_apply_all {} {
>>> +    global test_list
>>> +
>>> +    set unwind_fail false
>>> +
>>> +    gdb_test_multiple "thread apply all backtrace" \
>>> +	"Get thread information" -lbl {
>>> +	    -re "#\[0-9\]+\\\?\\\?\[^\n\]*" {
>>> +		set unwind_fail true
>>> +		exp_continue
>>> +	    }
>>> +	    -re "\[^\n\]*syscall_task .location=SIGNAL_ALT_STACK\[^\n\]*" {
>>> +		set test_list [linsert $test_list end [multi_line ".*sleep.*" \
>>> +					      ".*do_syscall_task .location=SIGNAL_ALT_STACK.*" \
>>> +					      ".*signal_handler.*" \
>>> +					      ".*signal handler called.*" \
>>> +					      ".*pthread_kill.*" \
>>> +					      ".*thread_function.*"]]
>>> +		exp_continue
>>> +	    }
>>> +	    -re "\[^\n\]*syscall_task .location=SIGNAL_HANDLER\[^\n\]*" {
>>> +		set test_list [linsert $test_list end [multi_line ".*sleep.*" \
>>> +					      ".*do_syscall_task .location=SIGNAL_HANDLER.*" \
>>> +					      ".*signal_handler.*" \
>>> +					      ".*signal handler called.*" \
>>> +					      ".*pthread_kill.*" \
>>> +					      ".*thread_function.*"]]
>>> +		exp_continue
>>> +	    }
>>> +	    -re "\[^\n\]*syscall_task .location=NORMAL\[^\n\]*" {
>>> +		set test_list [linsert $test_list end [multi_line ".*sleep.*" \
>>> +					      ".*do_syscall_task .location=NORMAL.*" \
>>> +					      ".*thread_function.*"]]
>>> +		exp_continue
>>> +	    }
>>> +	    -re "\[^\n\]*spin_task .location=SIGNAL_ALT_STACK\[^\n\]*" {
>>> +		set test_list [linsert $test_list end [multi_line ".*do_spin_task .location=SIGNAL_ALT_STACK.*" \
>>> +					      ".*signal_handler.*" \
>>> +					      ".*signal handler called.*" \
>>> +					      ".*pthread_kill.*" \
>>> +					      ".*thread_function.*"]]
>>> +		exp_continue
>>> +	    }
>>> +	    -re "\[^\n\]*spin_task .location=SIGNAL_HANDLER\[^\n\]*" {
>>> +		set test_list [linsert $test_list end [multi_line ".*do_spin_task .location=SIGNAL_HANDLER.*" \
>>> +					      ".*signal_handler.*" \
>>> +					      ".*signal handler called.*" \
>>> +					      ".*pthread_kill.*" \
>>> +					      ".*thread_function.*"]]
>>> +		exp_continue
>>> +	    }
>>> +	    -re "\[^\n\]*spin_task .location=NORMAL\[^\n\]*" {
>>> +		set test_list [linsert $test_list end [multi_line ".*do_spin_task .location=NORMAL..*" \
>>> +					      ".*thread_function.*"]]
>>> +		exp_continue
>>> +	    }
>>> +	    -re "\[^\n\]*main\[^\n\]*" {
>>> +		set test_list [linsert $test_list end ".*main.*"]
>>> +		exp_continue
>>> +	    }
>>> +	    -re "$::gdb_prompt " {
>>> +		pass $gdb_test_name
>>> +	    }
>>> +    }
>>> +
>>> +    gdb_assert {$unwind_fail == false}
>>> +}
>>> +
>>> +proc do_full_test {} {
>>> +    global test_list
>>> +    set thread_count [test_thread_count]
>>> +
>>> +    thread_apply_all
>>> +
>>> +    gdb_assert {$thread_count == [llength $test_list]}
>>> +
>>> +    for {set i 0} {$i < $thread_count } {incr i} {
>>> +	set thread_num [expr [llength $test_list] - $i]
>>> +
>>> +	gdb_test "thread apply $thread_num backtrace" [lindex $test_list $i]
>>> +    }
>>> +}
>>> +
>>> +proc_with_prefix test_corefile {} {
>>> +    set corefile [core_find $::binfile]
>>> +    if { $corefile == "" } {
>>> +	untested "couldn't generate corefile"
>>> +	return
>>> +    }
>>> +    set corefile [gdb_remote_download host $corefile]
>>> +
>>> +    gdb_test "core-file $corefile" \
>>> +	     "" \
>>> +	     "loading_corefile" \
>>> +	     "A program is being debugged already\\\.  Kill it\\\? \\\(y or n\\\) " \
>>> +	     "y"
>>> +
>>> +    do_full_test
>>> +}
>>> +
>>> +proc_with_prefix test_gcore {} {
>>> +
>>> +    clean_restart "$::binfile"
>>> +
>>> +    gdb_test "handle SIGUSR1 nostop print pass" \
>>> +	".*SIGUSR1.*No.*Yes.*Yes.*User defined signal 1" \
>>> +	"setup SIGUSR1"
>>> +    gdb_test "handle SIGUSR2 nostop print pass" \
>>> +	".*SIGUSR2.*No.*Yes.*Yes.*User defined signal 2" \
>>> +	"setup SIGUSR2"
>>> +
>>> +    gdb_test "run" ".*Segmentation fault.*" "continue to crash"
>>> +
>>> +    set gcore_name "${::binfile}.gcore"
>>> +    set gcore_supported [gdb_gcore_cmd "$gcore_name" "saving gcore"]
>>> +
>>> +    if {!$gcore_supported} {
>>> +	unsupported "couldn't generate gcore file"
>>> +	return
>>> +    }
>>> +
>>> +    set corefile [gdb_remote_download host $gcore_name]
>>> +
>>> +    gdb_test "core-file $corefile" \
>>> +	     "" \
>>> +	     "loading_corefile" \
>>> +	     "A program is being debugged already\\\.  Kill it\\\? \\\(y or n\\\) " \
>>> +	     "y"
>>> +
>>> +    do_full_test
>>> +}
>>> +
>>> +standard_testfile
>>> +
>>> +if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" executable {debug}] != "" } {
>>> +    return -1
>>> +}
>>> +
>>> +clean_restart ${binfile}
>>> +
>>> +gdb_test_no_output "set backtrace limit unlimited"
>>> +
>>> +set test_list { }
>>> +
>>> +with_test_prefix "live inferior" {
>>> +    gdb_test "handle SIGUSR1 nostop print pass" \
>>> +	".*SIGUSR1.*No.*Yes.*Yes.*User defined signal 1" \
>>> +	"setup SIGUSR1"
>>> +    gdb_test "handle SIGUSR2 nostop print pass" \
>>> +	".*SIGUSR2.*No.*Yes.*Yes.*User defined signal 2" \
>>> +	"setup SIGUSR2"
>>> +
>>> +    gdb_breakpoint "breakpt"
>>> +    gdb_test "run" ".*breakpt.*" "run to break function"
>>> +
>>> +    do_full_test
>>> +}
>>> +
>>> +set test_list { }
>>> +
>>> +test_corefile
>>> +
>>> +set test_list { }
>>> +
>>> +test_gcore
>> 
>> I gave this a try on aarch64-linux arm-linux and it works as expected.
>> 
>> Unless others have further objections, I think this looks good.
>> 
>> Reviewed-By:  Luis Machado  <luis.machado@arm.com>
>
>
> Just to complement, a small nit about the current patch is that it throws an ERROR when running the
> testsuite using the native-gdbserver board.
>
> ERROR: gdbserver does not support run without extended-remote
>     while executing
> "error "gdbserver does not support $command without extended-remote""
>
> Maybe we should punt when testing against native-gdbserver, or start
> the program differently.

Disagree that this is a small nit :)  I think this does need fixing
before the patch can be merged.

Thanks,
Andrew