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Always run the PTRACE_O_TRACESYSGOOD tests even if PTRACE_O_TRACEFORK is not supported. 

If enabling PTRACE_O_TRACEFORK fails, we never test for
PTRACE_O_TRACESYSGOOD support.  Before PTRACE_O_TRACESYSGOOD is checked,
we have:

  /* First, set the PTRACE_O_TRACEFORK option.  If this fails, we
     know for sure that it is not supported.  */
  ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
		(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);

  if (ret != 0)
    {
      ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
		    (PTRACE_TYPE_ARG4) 0);
      if (ret != 0)
	{
	  warning (_("linux_check_ptrace_features: failed to kill child"));
	  return;
	}

      ret = my_waitpid (child_pid, &status, 0);
      if (ret != child_pid)
	warning (_("linux_check_ptrace_features: failed "
		   "to wait for killed child"));
      else if (!WIFSIGNALED (status))
	warning (_("linux_check_ptrace_features: unexpected "
		   "wait status 0x%x from killed child"), status);

      return; <<<<<<<<<<<<<<<<<
    }

Note that early return.  If PTRACE_O_TRACEFORK isn't supported, we're
not checking PTRACE_O_TRACESYSGOOD.  This didn't use to be a problem
before the unification of this whole detection business in
linux-ptrace.c.  Before, the sysgood detection was completely
separate:

static void
linux_test_for_tracesysgood (int original_pid)
{
  int ret;
  sigset_t prev_mask;

  /* We don't want those ptrace calls to be interrupted.  */
  block_child_signals (&prev_mask);

  linux_supports_tracesysgood_flag = 0;

  ret = ptrace (PTRACE_SETOPTIONS, original_pid, 0, PTRACE_O_TRACESYSGOOD);
  if (ret != 0)
    goto out;

  linux_supports_tracesysgood_flag = 1;
out:
  restore_child_signals_mask (&prev_mask);
}

So we need to get back the decoupling somehow.  I think it's cleaner
to split the seperate feature detections to separate functions.  This
patch does that.  The new functions are named for their counterparts
that existed before this code was moved to linux-ptrace.c.

Note I've used forward declarations for the new functions to make the
patch clearer, as otherwise the patch would look like I'd be adding a
bunch of new code.  A reorder can be done in a follow up patch.

Tested on x86_64 Fedora 17.

gdb/
2013-10-03  Pedro Alves  <palves@redhat.com>

	* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
	the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
	functions.  Always test for PTRACE_O_TRACESYSGOOD even if
	PTRACE_O_TRACEFORK is not supported.
	(linux_test_for_tracesysgood): New function.
	(linux_test_for_tracefork): New function, factored out from
	linux_check_ptrace_features, and also don't kill child_pid here.
This commit is contained in:
Pedro Alves 2013-10-03 10:13:34 +00:00
parent b1328b1b18
commit 8ae377e842
2 changed files with 61 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
gdb/ChangeLog
View File

@ -1,3 +1,13 @@
2013-10-03 Pedro Alves <palves@redhat.com>
* common/linux-ptrace.c (linux_check_ptrace_features): Factor out
the PTRACE_O_TRACESYSGOOD and PTRACE_O_TRACEFORK to separate
functions. Always test for PTRACE_O_TRACESYSGOOD even if
PTRACE_O_TRACEFORK is not supported.
(linux_test_for_tracesysgood): New function.
(linux_test_for_tracefork): New function, factored out from
linux_check_ptrace_features, and also don't kill child_pid here.
2013-10-03 Tristan Gingold <gingold@adacore.com>
* i386-darwin-nat.c (i386_darwin_dr_set): Fix argument type.

93
gdb/common/linux-ptrace.c
View File

@ -308,13 +308,15 @@ linux_child_function (gdb_byte *child_stack)
_exit (0);
}
static void linux_test_for_tracesysgood (int child_pid);
static void linux_test_for_tracefork (int child_pid);
/* Determine ptrace features available on this target. */
static void
linux_check_ptrace_features (void)
{
int child_pid, ret, status;
long second_pid;
/* Initialize the options. */
current_ptrace_options = 0;
@ -335,42 +337,60 @@ linux_check_ptrace_features (void)
error (_("linux_check_ptrace_features: waitpid: unexpected status %d."),
status);
linux_test_for_tracesysgood (child_pid);
linux_test_for_tracefork (child_pid);
/* Clean things up and kill any pending children. */
do
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
warning (_("linux_check_ptrace_features: failed to kill child"));
my_waitpid (child_pid, &status, 0);
}
while (WIFSTOPPED (status));
}
/* Determine if PTRACE_O_TRACESYSGOOD can be used to catch
syscalls. */
static void
linux_test_for_tracesysgood (int child_pid)
{
#ifdef GDBSERVER
/* gdbserver does not support PTRACE_O_TRACESYSGOOD. */
#else
int ret;
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACESYSGOOD);
if (ret == 0)
current_ptrace_options |= PTRACE_O_TRACESYSGOOD;
#endif
}
/* Determine if PTRACE_O_TRACEFORK can be used to follow fork
events. */
static void
linux_test_for_tracefork (int child_pid)
{
int ret, status;
long second_pid;
/* First, set the PTRACE_O_TRACEFORK option. If this fails, we
know for sure that it is not supported. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACEFORK);
if (ret != 0)
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
{
warning (_("linux_check_ptrace_features: failed to kill child"));
return;
}
ret = my_waitpid (child_pid, &status, 0);
if (ret != child_pid)
warning (_("linux_check_ptrace_features: failed "
"to wait for killed child"));
else if (!WIFSIGNALED (status))
warning (_("linux_check_ptrace_features: unexpected "
"wait status 0x%x from killed child"), status);
return;
}
return;
#ifdef GDBSERVER
/* gdbserver does not support PTRACE_O_TRACESYSGOOD or
PTRACE_O_TRACEVFORKDONE yet. */
/* gdbserver does not support PTRACE_O_TRACEVFORKDONE yet. */
#else
/* Check if the target supports PTRACE_O_TRACESYSGOOD. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) PTRACE_O_TRACESYSGOOD);
if (ret == 0)
current_ptrace_options |= PTRACE_O_TRACESYSGOOD;
/* Check if the target supports PTRACE_O_TRACEVFORKDONE. */
ret = ptrace (PTRACE_SETOPTIONS, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) (PTRACE_O_TRACEFORK
@ -394,7 +414,7 @@ linux_check_ptrace_features (void)
ret = ptrace (PTRACE_CONT, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
warning (_("linux_check_ptrace_features: failed to resume child"));
warning (_("linux_test_for_tracefork: failed to resume child"));
ret = my_waitpid (child_pid, &status, 0);
@ -431,25 +451,14 @@ linux_check_ptrace_features (void)
ret = ptrace (PTRACE_KILL, second_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
warning (_("linux_check_ptrace_features: "
warning (_("linux_test_for_tracefork: "
"failed to kill second child"));
my_waitpid (second_pid, &status, 0);
}
}
else
warning (_("linux_check_ptrace_features: unexpected result from waitpid "
warning (_("linux_test_for_tracefork: unexpected result from waitpid "
"(%d, status 0x%x)"), ret, status);
/* Clean things up and kill any pending children. */
do
{
ret = ptrace (PTRACE_KILL, child_pid, (PTRACE_TYPE_ARG3) 0,
(PTRACE_TYPE_ARG4) 0);
if (ret != 0)
warning (_("linux_check_ptrace_features: failed to kill child"));
my_waitpid (child_pid, &status, 0);
}
while (WIFSTOPPED (status));
}
/* Enable reporting of all currently supported ptrace events. */