Module Name: src
Committed By: kamil
Date: Thu May 7 20:02:34 UTC 2020
Modified Files:
src/sys/kern: kern_exec.c kern_fork.c kern_sig.c
src/sys/sys: proc.h
Log Message:
On debugger attach to a prestarted process don't report SIGTRAP
Introduce PSL_TRACEDCHILD that indicates tracking of birth of a process.
A freshly forked process checks whether it is traced and if so, reports
SIGTRAP + TRAP_CHLD event to a debugger as a result of tracking forks-like
events. There is a time window when a debugger can attach to a newly
created process and receive SIGTRAP + TRAP_CHLD instead of SIGSTOP.
Fixes races in t_ptrace_wait* tests when a test hangs or misbehaves,
especially the ones reported in tracer_sysctl_lookup_without_duplicates.
To generate a diff of this commit:
cvs rdiff -u -r1.499 -r1.500 src/sys/kern/kern_exec.c
cvs rdiff -u -r1.223 -r1.224 src/sys/kern/kern_fork.c
cvs rdiff -u -r1.387 -r1.388 src/sys/kern/kern_sig.c
cvs rdiff -u -r1.364 -r1.365 src/sys/sys/proc.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/kern_exec.c
diff -u src/sys/kern/kern_exec.c:1.499 src/sys/kern/kern_exec.c:1.500
--- src/sys/kern/kern_exec.c:1.499 Fri Apr 24 03:22:06 2020
+++ src/sys/kern/kern_exec.c Thu May 7 20:02:34 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_exec.c,v 1.499 2020/04/24 03:22:06 thorpej Exp $ */
+/* $NetBSD: kern_exec.c,v 1.500 2020/05/07 20:02:34 kamil Exp $ */
/*-
* Copyright (c) 2008, 2019, 2020 The NetBSD Foundation, Inc.
@@ -62,7 +62,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.499 2020/04/24 03:22:06 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_exec.c,v 1.500 2020/05/07 20:02:34 kamil Exp $");
#include "opt_exec.h"
#include "opt_execfmt.h"
@@ -2279,8 +2279,10 @@ spawn_return(void *arg)
/* release our refcount on the data */
spawn_exec_data_release(spawn_data);
- if (p->p_slflag & PSL_TRACED)
+ if ((p->p_slflag & (PSL_TRACED|PSL_TRACEDCHILD)) ==
+ (PSL_TRACED|PSL_TRACEDCHILD)) {
eventswitchchild(p, TRAP_CHLD, PTRACE_POSIX_SPAWN);
+ }
/* and finally: leave to userland for the first time */
cpu_spawn_return(l);
@@ -2664,8 +2666,10 @@ do_posix_spawn(struct lwp *l1, pid_t *pi
p2->p_exitsig = SIGCHLD; /* signal for parent on exit */
if ((p1->p_slflag & (PSL_TRACEPOSIX_SPAWN|PSL_TRACED)) ==
- (PSL_TRACEPOSIX_SPAWN|PSL_TRACED))
+ (PSL_TRACEPOSIX_SPAWN|PSL_TRACED)) {
proc_changeparent(p2, p1->p_pptr);
+ SET(p2->p_slflag, PSL_TRACEDCHILD);
+ }
p2->p_oppid = p1->p_pid; /* Remember the original parent id. */
Index: src/sys/kern/kern_fork.c
diff -u src/sys/kern/kern_fork.c:1.223 src/sys/kern/kern_fork.c:1.224
--- src/sys/kern/kern_fork.c:1.223 Fri Apr 24 03:22:06 2020
+++ src/sys/kern/kern_fork.c Thu May 7 20:02:34 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_fork.c,v 1.223 2020/04/24 03:22:06 thorpej Exp $ */
+/* $NetBSD: kern_fork.c,v 1.224 2020/05/07 20:02:34 kamil Exp $ */
/*-
* Copyright (c) 1999, 2001, 2004, 2006, 2007, 2008, 2019
@@ -68,7 +68,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.223 2020/04/24 03:22:06 thorpej Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_fork.c,v 1.224 2020/05/07 20:02:34 kamil Exp $");
#include "opt_ktrace.h"
#include "opt_dtrace.h"
@@ -513,8 +513,10 @@ fork1(struct lwp *l1, int flags, int exi
/*
* Trace fork(2) and vfork(2)-like events on demand in a debugger.
*/
- if (tracefork(p1, flags) || tracevfork(p1, flags))
+ if (tracefork(p1, flags) || tracevfork(p1, flags)) {
proc_changeparent(p2, p1->p_pptr);
+ SET(p2->p_slflag, PSL_TRACEDCHILD);
+ }
p2->p_oppid = p1->p_pid; /* Remember the original parent id. */
@@ -634,7 +636,8 @@ child_return(void *arg)
struct lwp *l = curlwp;
struct proc *p = l->l_proc;
- if ((p->p_slflag & PSL_TRACED) != 0) {
+ if ((p->p_slflag & (PSL_TRACED|PSL_TRACEDCHILD)) ==
+ (PSL_TRACED|PSL_TRACEDCHILD)) {
eventswitchchild(p, TRAP_CHLD,
ISSET(p->p_lflag, PL_PPWAIT) ? PTRACE_VFORK : PTRACE_FORK);
}
Index: src/sys/kern/kern_sig.c
diff -u src/sys/kern/kern_sig.c:1.387 src/sys/kern/kern_sig.c:1.388
--- src/sys/kern/kern_sig.c:1.387 Mon Apr 6 08:20:05 2020
+++ src/sys/kern/kern_sig.c Thu May 7 20:02:34 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: kern_sig.c,v 1.387 2020/04/06 08:20:05 kamil Exp $ */
+/* $NetBSD: kern_sig.c,v 1.388 2020/05/07 20:02:34 kamil Exp $ */
/*-
* Copyright (c) 2006, 2007, 2008, 2019 The NetBSD Foundation, Inc.
@@ -70,7 +70,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.387 2020/04/06 08:20:05 kamil Exp $");
+__KERNEL_RCSID(0, "$NetBSD: kern_sig.c,v 1.388 2020/05/07 20:02:34 kamil Exp $");
#include "opt_ptrace.h"
#include "opt_dtrace.h"
@@ -1693,7 +1693,8 @@ eventswitchchild(struct proc *p, int cod
{
mutex_enter(proc_lock);
mutex_enter(p->p_lock);
- if (!(p->p_slflag & PSL_TRACED)) {
+ if ((p->p_slflag & (PSL_TRACED|PSL_TRACEDCHILD)) !=
+ (PSL_TRACED|PSL_TRACEDCHILD)) {
mutex_exit(p->p_lock);
mutex_exit(proc_lock);
return;
Index: src/sys/sys/proc.h
diff -u src/sys/sys/proc.h:1.364 src/sys/sys/proc.h:1.365
--- src/sys/sys/proc.h:1.364 Wed Apr 29 01:52:26 2020
+++ src/sys/sys/proc.h Thu May 7 20:02:34 2020
@@ -1,4 +1,4 @@
-/* $NetBSD: proc.h,v 1.364 2020/04/29 01:52:26 thorpej Exp $ */
+/* $NetBSD: proc.h,v 1.365 2020/05/07 20:02:34 kamil Exp $ */
/*-
* Copyright (c) 2006, 2007, 2008, 2020 The NetBSD Foundation, Inc.
@@ -413,6 +413,7 @@ struct proc {
0x00000020 /* traced process wants posix_spawn events */
#define PSL_TRACED 0x00000800 /* Debugged process being traced */
+#define PSL_TRACEDCHILD 0x00001000 /* Report process birth */
#define PSL_CHTRACED 0x00400000 /* Child has been traced & reparented */
#define PSL_SYSCALL 0x04000000 /* process has PT_SYSCALL enabled */
#define PSL_SYSCALLEMU 0x08000000 /* cancel in-progress syscall */
