Author: kib
Date: Thu Feb 7 15:34:22 2013
New Revision: 246484
URL: http://svnweb.freebsd.org/changeset/base/246484
Log:
When vforked child is traced, the debugging events are not generated
until child performs exec(). The behaviour is reasonable when a
debugger is the real parent, because the parent is stopped until
exec(), and sending a debugging event to the debugger would deadlock
both parent and child.
On the other hand, when debugger is not the parent of the vforked
child, not sending debugging signals makes it impossible to debug
across vfork.
Fix the issue by declining generating debug signals only when vfork()
was done and child called ptrace(PT_TRACEME). Set a new process flag
P_PPTRACE from the attach code for PT_TRACEME, if P_PPWAIT flag is
set, which indicates that the process was created with vfork() and
still did not execed. Check P_PPTRACE from issignal(), instead of
refusing the trace outright for the P_PPWAIT case. The scope of
P_PPTRACE is exactly contained in the scope of P_PPWAIT.
Found and tested by: zont
Reviewed by: pluknet
MFC after: 2 weeks
Modified:
head/sys/kern/kern_exec.c
head/sys/kern/kern_exit.c
head/sys/kern/kern_sig.c
head/sys/kern/sys_process.c
head/sys/sys/proc.h
Modified: head/sys/kern/kern_exec.c
==============================================================================
--- head/sys/kern/kern_exec.c Thu Feb 7 15:22:50 2013 (r246483)
+++ head/sys/kern/kern_exec.c Thu Feb 7 15:34:22 2013 (r246484)
@@ -640,7 +640,7 @@ interpret:
*/
p->p_flag |= P_EXEC;
if (p->p_pptr && (p->p_flag & P_PPWAIT)) {
- p->p_flag &= ~P_PPWAIT;
+ p->p_flag &= ~(P_PPWAIT | P_PPTRACE);
cv_broadcast(&p->p_pwait);
}
Modified: head/sys/kern/kern_exit.c
==============================================================================
--- head/sys/kern/kern_exit.c Thu Feb 7 15:22:50 2013 (r246483)
+++ head/sys/kern/kern_exit.c Thu Feb 7 15:34:22 2013 (r246484)
@@ -266,7 +266,7 @@ exit1(struct thread *td, int rv)
PROC_LOCK(p);
rv = p->p_xstat; /* Event handler could change exit status */
stopprofclock(p);
- p->p_flag &= ~(P_TRACED | P_PPWAIT);
+ p->p_flag &= ~(P_TRACED | P_PPWAIT | P_PPTRACE);
/*
* Stop the real interval timer. If the handler is currently
Modified: head/sys/kern/kern_sig.c
==============================================================================
--- head/sys/kern/kern_sig.c Thu Feb 7 15:22:50 2013 (r246483)
+++ head/sys/kern/kern_sig.c Thu Feb 7 15:34:22 2013 (r246484)
@@ -2618,7 +2618,7 @@ issignal(struct thread *td, int stop_all
sigqueue_delete(&p->p_sigqueue, sig);
continue;
}
- if (p->p_flag & P_TRACED && (p->p_flag & P_PPWAIT) == 0) {
+ if (p->p_flag & P_TRACED && (p->p_flag & P_PPTRACE) == 0) {
/*
* If traced, always stop.
* Remove old signal from queue before the stop.
Modified: head/sys/kern/sys_process.c
==============================================================================
--- head/sys/kern/sys_process.c Thu Feb 7 15:22:50 2013 (r246483)
+++ head/sys/kern/sys_process.c Thu Feb 7 15:34:22 2013 (r246484)
@@ -822,6 +822,8 @@ kern_ptrace(struct thread *td, int req,
case PT_TRACE_ME:
/* set my trace flag and "owner" so it can read/write me */
p->p_flag |= P_TRACED;
+ if (p->p_flag & P_PPWAIT)
+ p->p_flag |= P_PPTRACE;
p->p_oppid = p->p_pptr->p_pid;
break;
Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h Thu Feb 7 15:22:50 2013 (r246483)
+++ head/sys/sys/proc.h Thu Feb 7 15:34:22 2013 (r246484)
@@ -636,6 +636,7 @@ struct proc {
#define P_INMEM 0x10000000 /* Loaded into memory. */
#define P_SWAPPINGOUT 0x20000000 /* Process is being swapped out. */
#define P_SWAPPINGIN 0x40000000 /* Process is being swapped in. */
+#define P_PPTRACE 0x80000000 /* PT_TRACEME by vforked child. */
#define P_STOPPED (P_STOPPED_SIG|P_STOPPED_SINGLE|P_STOPPED_TRACE)
#define P_SHOULDSTOP(p) ((p)->p_flag & P_STOPPED)
_______________________________________________
svn-src-head@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/svn-src-head
To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
