MFC 302900,302902,302921,303461,304009:

Add a mask of optional ptrace() events.

302900:
Add a test for user signal delivery.

This test verifies we get the correct ptrace event details when a signal
is posted to a traced process from userland.

302902:
Add a mask of optional ptrace() events.

ptrace() now stores a mask of optional events in p_ptevents.  Currently
this mask is a single integer, but it can be expanded into an array of
integers in the future.

Two new ptrace requests can be used to manipulate the event mask:
PT_GET_EVENT_MASK fetches the current event mask and PT_SET_EVENT_MASK
sets the current event mask.

The current set of events include:
- PTRACE_EXEC: trace calls to execve().
- PTRACE_SCE: trace system call entries.
- PTRACE_SCX: trace syscam call exits.
- PTRACE_FORK: trace forks and auto-attach to new child processes.
- PTRACE_LWP: trace LWP events.

The S_PT_SCX and S_PT_SCE events in the procfs p_stops flags have
been replaced by PTRACE_SCE and PTRACE_SCX.  PTRACE_FORK replaces
P_FOLLOW_FORK and PTRACE_LWP replaces P2_LWP_EVENTS.

The PT_FOLLOW_FORK and PT_LWP_EVENTS ptrace requests remain for
compatibility but now simply toggle corresponding flags in the
event mask.

While here, document that PT_SYSCALL, PT_TO_SCE, and PT_TO_SCX both
modify the event mask and continue the traced process.

302921:
Rename PTRACE_SYSCALL to LINUX_PTRACE_SYSCALL.

303461:
Note that not all optional ptrace events use SIGTRAP.

New child processes attached due to PTRACE_FORK use SIGSTOP instead of
SIGTRAP.  All other ptrace events use SIGTRAP.

304009:
Remove description of P_FOLLOWFORK as this flag was removed.

1 files changed, 5 insertions, 5 deletions

diff --git a/sys/kern/kern_fork.c b/sys/kern/kern_fork.c
index 2c98551..84bef4f 100644
--- a/sys/kern/kern_fork.c
+++ b/sys/kern/kern_fork.c
@@ -414,6 +414,7 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
 
 	bzero(&p2->p_startzero,
 	    __rangeof(struct proc, p_startzero, p_endzero));
+	p2->p_ptevents = 0;
 
 	/* Tell the prison that we exist. */
 	prison_proc_hold(p2->p_ucred->cr_prison);
@@ -720,8 +721,7 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
 	 * but before we wait for the debugger.
 	 */
 	_PHOLD(p2);
-	if ((p1->p_flag & (P_TRACED | P_FOLLOWFORK)) == (P_TRACED |
-	    P_FOLLOWFORK)) {
+	if (p1->p_ptevents & PTRACE_FORK) {
 		/*
 		 * Arrange for debugger to receive the fork event.
 		 *
@@ -1068,14 +1068,14 @@ fork_return(struct thread *td, struct trapframe *frame)
 	if (td->td_dbgflags & TDB_STOPATFORK) {
 		sx_xlock(&proctree_lock);
 		PROC_LOCK(p);
-		if ((p->p_pptr->p_flag & (P_TRACED | P_FOLLOWFORK)) ==
-		    (P_TRACED | P_FOLLOWFORK)) {
+		if (p->p_pptr->p_ptevents & PTRACE_FORK) {
 			/*
 			 * If debugger still wants auto-attach for the
 			 * parent's children, do it now.
 			 */
 			dbg = p->p_pptr->p_pptr;
 			p->p_flag |= P_TRACED;
+			p->p_ptevents = PTRACE_DEFAULT;
 			p->p_oppid = p->p_pptr->p_pid;
 			CTR2(KTR_PTRACE,
 		    "fork_return: attaching to new child pid %d: oppid %d",
@@ -1102,7 +1102,7 @@ fork_return(struct thread *td, struct trapframe *frame)
 		PROC_LOCK(p);
 		td->td_dbgflags |= TDB_SCX;
 		_STOPEVENT(p, S_SCX, td->td_dbg_sc_code);
-		if ((p->p_stops & S_PT_SCX) != 0 ||
+		if ((p->p_ptevents & PTRACE_SCX) != 0 ||
 		    (td->td_dbgflags & TDB_BORN) != 0)
 			ptracestop(td, SIGTRAP);
 		td->td_dbgflags &= ~(TDB_SCX | TDB_BORN);