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Use a real vfork done event on FreeBSD when available. 

FreeBSD 12 recently added a new ptrace event to indicate when the vfork
parent resumes after the child process stops sharing the address space.
Use this event to report a proper TARGET_WAITKIND_VFORK_DONE rather than
faking a vfork done event after a delay.

gdb/ChangeLog:

	* fbsd-nat.c (fbsd_enable_proc_events): Enable "PTRACE_VFORK"
	events.
	(fbsd_pending_vfork_done): Only define if "PTRACE_VFORK" is not
	defined.
	(fbsd_add_vfork_done): Likewise.
	(fbsd_is_vfork_done_pending): Likewise.
	(fbsd_next_vfork_done): Likewise.
	(fbsd_resume): Only ignore pending vfork done events if
	"PTRACE_VFORK" is not defined.
	(fbsd_wait): Only look for pending vfork done events if
	"PTRACE_VFORK" is not defined.
	[PTRACE_VFORK]: Handle "PL_FLAG_VFORKED" and "PL_FLAG_VFORK_DONE"
	events.
	(fbsd_follow_fork): Only fake a vfork done event if "PTRACE_VFORK"
	is not defined.
This commit is contained in:
John Baldwin 2016-07-16 10:14:08 -07:00
parent 5fa14c6b97
commit dbaed38534
2 changed files with 45 additions and 3 deletions
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18
gdb/ChangeLog
View File

@ -1,3 +1,21 @@
2016-07-20 John Baldwin <jhb@FreeBSD.org>
* fbsd-nat.c (fbsd_enable_proc_events): Enable "PTRACE_VFORK"
events.
(fbsd_pending_vfork_done): Only define if "PTRACE_VFORK" is not
defined.
(fbsd_add_vfork_done): Likewise.
(fbsd_is_vfork_done_pending): Likewise.
(fbsd_next_vfork_done): Likewise.
(fbsd_resume): Only ignore pending vfork done events if
"PTRACE_VFORK" is not defined.
(fbsd_wait): Only look for pending vfork done events if
"PTRACE_VFORK" is not defined.
[PTRACE_VFORK]: Handle "PL_FLAG_VFORKED" and "PL_FLAG_VFORK_DONE"
events.
(fbsd_follow_fork): Only fake a vfork done event if "PTRACE_VFORK"
is not defined.
2016-07-20 John Baldwin <jhb@FreeBSD.org>
* fbsd-nat.c (fbsd_wait): Use "fbsd_enable_proc_events" on

30
gdb/fbsd-nat.c
View File

@ -435,6 +435,9 @@ fbsd_enable_proc_events (pid_t pid)
sizeof (events)) == -1)
perror_with_name (("ptrace"));
events |= PTRACE_FORK | PTRACE_LWP;
#ifdef PTRACE_VFORK
events |= PTRACE_VFORK;
#endif
if (ptrace (PT_SET_EVENT_MASK, pid, (PTRACE_TYPE_ARG3)&events,
sizeof (events)) == -1)
perror_with_name (("ptrace"));
@ -598,6 +601,7 @@ fbsd_is_child_pending (pid_t pid)
return null_ptid;
}
#ifndef PTRACE_VFORK
static struct fbsd_fork_info *fbsd_pending_vfork_done;
/* Record a pending vfork done event. */
@ -647,6 +651,7 @@ fbsd_next_vfork_done (void)
return null_ptid;
}
#endif
#endif
static int
resume_one_thread_cb (struct thread_info *tp, void *data)
@ -686,7 +691,7 @@ static void
fbsd_resume (struct target_ops *ops,
ptid_t ptid, int step, enum gdb_signal signo)
{
#ifdef TDP_RFPPWAIT
#if defined(TDP_RFPPWAIT) && !defined(PTRACE_VFORK)
pid_t pid;
/* Don't PT_CONTINUE a process which has a pending vfork done event. */
@ -731,12 +736,14 @@ fbsd_wait (struct target_ops *ops,
while (1)
{
#ifndef PTRACE_VFORK
wptid = fbsd_next_vfork_done ();
if (!ptid_equal (wptid, null_ptid))
{
ourstatus->kind = TARGET_WAITKIND_VFORK_DONE;
return wptid;
}
#endif
wptid = super_wait (ops, ptid, ourstatus, target_options);
if (ourstatus->kind == TARGET_WAITKIND_STOPPED)
{
@ -812,12 +819,18 @@ fbsd_wait (struct target_ops *ops,
#ifdef TDP_RFPPWAIT
if (pl.pl_flags & PL_FLAG_FORKED)
{
#ifndef PTRACE_VFORK
struct kinfo_proc kp;
#endif
ptid_t child_ptid;
pid_t child;
child = pl.pl_child_pid;
ourstatus->kind = TARGET_WAITKIND_FORKED;
#ifdef PTRACE_VFORK
if (pl.pl_flags & PL_FLAG_VFORKED)
ourstatus->kind = TARGET_WAITKIND_VFORKED;
#endif
/* Make sure the other end of the fork is stopped too. */
child_ptid = fbsd_is_child_pending (child);
@ -839,11 +852,13 @@ fbsd_wait (struct target_ops *ops,
/* Enable additional events on the child process. */
fbsd_enable_proc_events (ptid_get_pid (child_ptid));
#ifndef PTRACE_VFORK
/* For vfork, the child process will have the P_PPWAIT
flag set. */
fbsd_fetch_kinfo_proc (child, &kp);
if (kp.ki_flag & P_PPWAIT)
ourstatus->kind = TARGET_WAITKIND_VFORKED;
#endif
ourstatus->value.related_pid = child_ptid;
return wptid;
@ -857,6 +872,14 @@ fbsd_wait (struct target_ops *ops,
fbsd_remember_child (wptid);
continue;
}
#ifdef PTRACE_VFORK
if (pl.pl_flags & PL_FLAG_VFORK_DONE)
{
ourstatus->kind = TARGET_WAITKIND_VFORK_DONE;
return wptid;
}
#endif
#endif
#ifdef PL_FLAG_EXEC
@ -918,7 +941,6 @@ fbsd_follow_fork (struct target_ops *ops, int follow_child,
if (!follow_child && detach_fork)
{
struct thread_info *tp = inferior_thread ();
int has_vforked = tp->pending_follow.kind == TARGET_WAITKIND_VFORKED;
pid_t child_pid = ptid_get_pid (tp->pending_follow.value.related_pid);
/* Breakpoints have already been detached from the child by
@ -927,7 +949,8 @@ fbsd_follow_fork (struct target_ops *ops, int follow_child,
if (ptrace (PT_DETACH, child_pid, (PTRACE_TYPE_ARG3)1, 0) == -1)
perror_with_name (("ptrace"));
if (has_vforked)
#ifndef PTRACE_VFORK
if (tp->pending_follow.kind == TARGET_WAITKIND_VFORKED)
{
/* We can't insert breakpoints until the child process has
finished with the shared memory region. The parent
@ -953,6 +976,7 @@ fbsd_follow_fork (struct target_ops *ops, int follow_child,
wait. */
fbsd_add_vfork_done (inferior_ptid);
}
#endif
}
return 0;