Author: kib
Date: Tue Jan 25 10:59:21 2011
New Revision: 217819
URL: http://svn.freebsd.org/changeset/base/217819
Log:
Allow debugger to specify that children of the traced process should be
automatically traced. Extend the ptrace(PL_LWPINFO) to report that child
just forked.
Reviewed by: davidxu, jhb
MFC after: 2 weeks
Modified:
head/sys/kern/kern_fork.c
head/sys/kern/kern_proc.c
head/sys/kern/kern_sig.c
head/sys/kern/subr_trap.c
head/sys/kern/sys_process.c
head/sys/sys/proc.h
head/sys/sys/ptrace.h
Modified: head/sys/kern/kern_fork.c
==============================================================================
--- head/sys/kern/kern_fork.c Tue Jan 25 10:20:36 2011 (r217818)
+++ head/sys/kern/kern_fork.c Tue Jan 25 10:59:21 2011 (r217819)
@@ -338,7 +338,7 @@ do_fork(struct thread *td, int flags, st
struct vmspace *vm2)
{
struct proc *p1, *pptr;
- int trypid;
+ int p2_held, trypid;
struct filedesc *fd;
struct filedesc_to_leader *fdtol;
struct sigacts *newsigacts;
@@ -346,6 +346,7 @@ do_fork(struct thread *td, int flags, st
sx_assert(&proctree_lock, SX_SLOCKED);
sx_assert(&allproc_lock, SX_XLOCKED);
+ p2_held = 0;
p1 = td->td_proc;
/*
@@ -632,6 +633,8 @@ do_fork(struct thread *td, int flags, st
PROC_SLOCK(p2);
p2->p_state = PRS_NORMAL;
PROC_SUNLOCK(p2);
+
+ PROC_LOCK(p1);
#ifdef KDTRACE_HOOKS
/*
* Tell the DTrace fasttrap provider about the new process
@@ -640,19 +643,33 @@ do_fork(struct thread *td, int flags, st
* later on.
*/
if (dtrace_fasttrap_fork) {
- PROC_LOCK(p1);
PROC_LOCK(p2);
dtrace_fasttrap_fork(p1, p2);
PROC_UNLOCK(p2);
- PROC_UNLOCK(p1);
}
#endif
-
- /*
- * If RFSTOPPED not requested, make child runnable and add to
- * run queue.
- */
+ if ((p1->p_flag & (P_TRACED | P_FOLLOWFORK)) == (P_TRACED |
+ P_FOLLOWFORK)) {
+ /*
+ * Arrange for debugger to receive the fork event.
+ *
+ * We can report PL_FLAG_FORKED regardless of
+ * P_FOLLOWFORK settings, but it does not make a sense
+ * for runaway child.
+ */
+ td->td_dbgflags |= TDB_FORK;
+ td->td_dbg_forked = p2->p_pid;
+ PROC_LOCK(p2);
+ td2->td_dbgflags |= TDB_STOPATFORK;
+ _PHOLD(p2);
+ p2_held = 1;
+ PROC_UNLOCK(p2);
+ }
if ((flags & RFSTOPPED) == 0) {
+ /*
+ * If RFSTOPPED not requested, make child runnable and
+ * add to run queue.
+ */
thread_lock(td2);
TD_SET_CAN_RUN(td2);
sched_add(td2, SRQ_BORING);
@@ -662,7 +679,6 @@ do_fork(struct thread *td, int flags, st
/*
* Now can be swapped.
*/
- PROC_LOCK(p1);
_PRELE(p1);
PROC_UNLOCK(p1);
@@ -673,11 +689,19 @@ do_fork(struct thread *td, int flags, st
SDT_PROBE(proc, kernel, , create, p2, p1, flags, 0, 0);
/*
+ * Wait until debugger is attached to child.
+ */
+ PROC_LOCK(p2);
+ while ((td2->td_dbgflags & TDB_STOPATFORK) != 0)
+ cv_wait(&p2->p_dbgwait, &p2->p_mtx);
+ if (p2_held)
+ _PRELE(p2);
+
+ /*
* Preserve synchronization semantics of vfork. If waiting for
* child to exec or exit, set P_PPWAIT on child, and sleep on our
* proc (in case of exit).
*/
- PROC_LOCK(p2);
while (p2->p_flag & P_PPWAIT)
cv_wait(&p2->p_pwait, &p2->p_mtx);
PROC_UNLOCK(p2);
@@ -883,8 +907,37 @@ fork_exit(void (*callout)(void *, struct
void
fork_return(struct thread *td, struct trapframe *frame)
{
+ struct proc *p, *dbg;
+
+ if (td->td_dbgflags & TDB_STOPATFORK) {
+ p = td->td_proc;
+ sx_xlock(&proctree_lock);
+ PROC_LOCK(p);
+ if ((p->p_pptr->p_flag & (P_TRACED | P_FOLLOWFORK)) ==
+ (P_TRACED | P_FOLLOWFORK)) {
+ /*
+ * 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_oppid = p->p_pptr->p_pid;
+ proc_reparent(p, dbg);
+ sx_xunlock(&proctree_lock);
+ ptracestop(td, SIGSTOP);
+ } else {
+ /*
+ * ... otherwise clear the request.
+ */
+ sx_xunlock(&proctree_lock);
+ td->td_dbgflags &= ~TDB_STOPATFORK;
+ cv_broadcast(&p->p_dbgwait);
+ }
+ PROC_UNLOCK(p);
+ }
userret(td, frame);
+
#ifdef KTRACE
if (KTRPOINT(td, KTR_SYSRET))
ktrsysret(SYS_fork, 0, 0);
Modified: head/sys/kern/kern_proc.c
==============================================================================
--- head/sys/kern/kern_proc.c Tue Jan 25 10:20:36 2011 (r217818)
+++ head/sys/kern/kern_proc.c Tue Jan 25 10:59:21 2011 (r217819)
@@ -230,6 +230,7 @@ proc_init(void *mem, int size, int flags
mtx_init(&p->p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
mtx_init(&p->p_slock, "process slock", NULL, MTX_SPIN | MTX_RECURSE);
cv_init(&p->p_pwait, "ppwait");
+ cv_init(&p->p_dbgwait, "dbgwait");
TAILQ_INIT(&p->p_threads); /* all threads in proc */
EVENTHANDLER_INVOKE(process_init, p);
p->p_stats = pstats_alloc();
Modified: head/sys/kern/kern_sig.c
==============================================================================
--- head/sys/kern/kern_sig.c Tue Jan 25 10:20:36 2011 (r217818)
+++ head/sys/kern/kern_sig.c Tue Jan 25 10:59:21 2011 (r217819)
@@ -2393,6 +2393,10 @@ ptracestop(struct thread *td, int sig)
p->p_xthread = td;
p->p_flag |= (P_STOPPED_SIG|P_STOPPED_TRACE);
sig_suspend_threads(td, p, 0);
+ if ((td->td_dbgflags & TDB_STOPATFORK) != 0) {
+ td->td_dbgflags &= ~TDB_STOPATFORK;
+ cv_broadcast(&p->p_dbgwait);
+ }
stopme:
thread_suspend_switch(td);
if (!(p->p_flag & P_TRACED)) {
Modified: head/sys/kern/subr_trap.c
==============================================================================
--- head/sys/kern/subr_trap.c Tue Jan 25 10:20:36 2011 (r217818)
+++ head/sys/kern/subr_trap.c Tue Jan 25 10:59:21 2011 (r217819)
@@ -392,9 +392,9 @@ syscallret(struct thread *td, int error,
*/
STOPEVENT(p, S_SCX, sa->code);
PTRACESTOP_SC(p, td, S_PT_SCX);
- if (traced || (td->td_dbgflags & TDB_EXEC) != 0) {
+ if (traced || (td->td_dbgflags & (TDB_EXEC | TDB_FORK)) != 0) {
PROC_LOCK(p);
- td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC);
+ td->td_dbgflags &= ~(TDB_SCX | TDB_EXEC | TDB_FORK);
PROC_UNLOCK(p);
}
}
Modified: head/sys/kern/sys_process.c
==============================================================================
--- head/sys/kern/sys_process.c Tue Jan 25 10:20:36 2011 (r217818)
+++ head/sys/kern/sys_process.c Tue Jan 25 10:59:21 2011 (r217819)
@@ -94,6 +94,7 @@ struct ptrace_lwpinfo32 {
sigset_t pl_siglist; /* LWP pending signal */
struct siginfo32 pl_siginfo; /* siginfo for signal */
char pl_tdname[MAXCOMLEN + 1]; /* LWP name. */
+ int pl_child_pid; /* New child pid */
};
#endif
@@ -476,6 +477,7 @@ ptrace_lwpinfo_to32(const struct ptrace_
pl32->pl_siglist = pl->pl_siglist;
siginfo_to_siginfo32(&pl->pl_siginfo, &pl32->pl_siginfo);
strcpy(pl32->pl_tdname, pl->pl_tdname);
+ pl32->pl_child_pid = pl->pl_child_pid;
}
#endif /* COMPAT_FREEBSD32 */
@@ -657,6 +659,7 @@ kern_ptrace(struct thread *td, int req,
case PT_TO_SCE:
case PT_TO_SCX:
case PT_SYSCALL:
+ case PT_FOLLOW_FORK:
case PT_DETACH:
sx_xlock(&proctree_lock);
proctree_locked = 1;
@@ -852,6 +855,13 @@ kern_ptrace(struct thread *td, int req,
td2->td_dbgflags &= ~TDB_SUSPEND;
break;
+ case PT_FOLLOW_FORK:
+ if (data)
+ p->p_flag |= P_FOLLOWFORK;
+ else
+ p->p_flag &= ~P_FOLLOWFORK;
+ break;
+
case PT_STEP:
case PT_CONTINUE:
case PT_TO_SCE:
@@ -912,7 +922,7 @@ kern_ptrace(struct thread *td, int req,
if (pp == initproc)
p->p_sigparent = SIGCHLD;
}
- p->p_flag &= ~(P_TRACED | P_WAITED);
+ p->p_flag &= ~(P_TRACED | P_WAITED | P_FOLLOWFORK);
p->p_oppid = 0;
/* should we send SIGCHLD? */
@@ -1118,6 +1128,10 @@ kern_ptrace(struct thread *td, int req,
pl->pl_flags |= PL_FLAG_SCX;
if (td2->td_dbgflags & TDB_EXEC)
pl->pl_flags |= PL_FLAG_EXEC;
+ if (td2->td_dbgflags & TDB_FORK) {
+ pl->pl_flags |= PL_FLAG_FORKED;
+ pl->pl_child_pid = td2->td_dbg_forked;
+ }
pl->pl_sigmask = td2->td_sigmask;
pl->pl_siglist = td2->td_siglist;
strcpy(pl->pl_tdname, td2->td_name);
Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h Tue Jan 25 10:20:36 2011 (r217818)
+++ head/sys/sys/proc.h Tue Jan 25 10:59:21 2011 (r217819)
@@ -265,6 +265,7 @@ struct thread {
int td_ng_outbound; /* (k) Thread entered ng from above. */
struct osd td_osd; /* (k) Object specific data. */
struct vm_map_entry *td_map_def_user; /* (k) Deferred entries. */
+ pid_t td_dbg_forked; /* (c) Child pid for debugger. */
#define td_endzero td_rqindex
/* Copied during fork1() or thread_sched_upcall(). */
@@ -374,6 +375,10 @@ do {
\
#define TDB_SCE 0x00000008 /* Thread performs syscall enter */
#define TDB_SCX 0x00000010 /* Thread performs syscall exit */
#define TDB_EXEC 0x00000020 /* TDB_SCX from exec(2) family */
+#define TDB_FORK 0x00000040 /* TDB_SCX from fork(2) that created
new
+ process */
+#define TDB_STOPATFORK 0x00000080 /* Stop at the return from fork
(child
+ only) */
/*
* "Private" flags kept in td_pflags:
@@ -557,7 +562,9 @@ struct proc {
STAILQ_HEAD(, ktr_request) p_ktr; /* (o) KTR event queue. */
LIST_HEAD(, mqueue_notifier) p_mqnotifier; /* (c) mqueue notifiers.*/
struct kdtrace_proc *p_dtrace; /* (*) DTrace-specific data. */
- struct cv p_pwait; /* (*) wait cv for exit/exec */
+ struct cv p_pwait; /* (*) wait cv for exit/exec. */
+ struct cv p_dbgwait; /* (*) wait cv for debugger attach
+ after fork. */
};
#define p_session p_pgrp->pg_session
@@ -573,7 +580,7 @@ struct proc {
#define P_ADVLOCK 0x00001 /* Process may hold a POSIX advisory
lock. */
#define P_CONTROLT 0x00002 /* Has a controlling terminal. */
#define P_KTHREAD 0x00004 /* Kernel thread (*). */
-#define P_UNUSED0 0x00008 /* available. */
+#define P_FOLLOWFORK 0x00008 /* Attach parent debugger to children.
*/
#define P_PPWAIT 0x00010 /* Parent is waiting for child to
exec/exit. */
#define P_PROFIL 0x00020 /* Has started profiling. */
#define P_STOPPROF 0x00040 /* Has thread requesting to stop
profiling. */
Modified: head/sys/sys/ptrace.h
==============================================================================
--- head/sys/sys/ptrace.h Tue Jan 25 10:20:36 2011 (r217818)
+++ head/sys/sys/ptrace.h Tue Jan 25 10:59:21 2011 (r217819)
@@ -63,6 +63,8 @@
#define PT_TO_SCX 21
#define PT_SYSCALL 22
+#define PT_FOLLOW_FORK 23
+
#define PT_GETREGS 33 /* get general-purpose registers */
#define PT_SETREGS 34 /* set general-purpose registers */
#define PT_GETFPREGS 35 /* get floating-point registers */
@@ -104,10 +106,12 @@ struct ptrace_lwpinfo {
#define PL_FLAG_SCX 0x08 /* syscall leave point */
#define PL_FLAG_EXEC 0x10 /* exec(2) succeeded */
#define PL_FLAG_SI 0x20 /* siginfo is valid */
+#define PL_FLAG_FORKED 0x40 /* new child */
sigset_t pl_sigmask; /* LWP signal mask */
sigset_t pl_siglist; /* LWP pending signal */
struct __siginfo pl_siginfo; /* siginfo for signal */
char pl_tdname[MAXCOMLEN + 1]; /* LWP name */
+ int pl_child_pid; /* New child pid */
};
/* Argument structure for PT_VM_ENTRY. */
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