Date: Wed, 8 Feb 2012 16:51:57 -0800 From: Dmitry Mikulin <dmitrym@juniper.net> Cc: Konstantin Belousov <kostikbel@gmail.com>, freebsd-current Current <freebsd-current@freebsd.org>, Marcel Moolenaar <marcelm@juniper.net> Subject: Re: [ptrace] please review follow fork/exec changes Message-ID: <4F3318AD.6000607@juniper.net> In-Reply-To: <4F31C89C.7010705@juniper.net> References: <20120125074824.GD2726@deviant.kiev.zoral.com.ua> <4F2094B4.70707@juniper.net> <20120126122326.GT2726@deviant.kiev.zoral.com.ua> <4F22E8FD.6010201@juniper.net> <20120129074843.GL2726@deviant.kiev.zoral.com.ua> <4F26E0D1.8040100@juniper.net> <20120130192727.GZ2726@deviant.kiev.zoral.com.ua> <4F2C756A.80900@juniper.net> <20120204204218.GC3283@deviant.kiev.zoral.com.ua> <4F3043E2.6090607@juniper.net> <20120207121022.GC3283@deviant.kiev.zoral.com.ua> <4F318D74.9030506@juniper.net> <4F31C89C.7010705@juniper.net>
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The patch I sent earlier works for me. Just wanted to let you know to illustrate what I would like to see from the kernel.
I'm trying to see if there's way not to add flags with semantics similar to TDB_EXEC. I think the problem with TDB_EXEC is that is serves a trigger for a stop as well as an indicator to return PL_FLAG_EXEC. And in my case I still want to see all the stops but I only want to see the PL_FLAG_EXEC when PT_FOLLOW_EXEC is specified.
Do you think the attached patch will do what I'd like without compromising existing functionality?
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Index: sys/proc.h
===================================================================
--- sys/proc.h (revision 231228)
+++ sys/proc.h (working copy)
@@ -384,6 +384,7 @@ do { \
process */
#define TDB_STOPATFORK 0x00000080 /* Stop at the return from fork (child
only) */
+#define TDB_CHILD 0x00000100 /* New child indicator for ptrace() */
/*
* "Private" flags kept in td_pflags:
@@ -613,6 +614,7 @@ struct proc {
#define P_HWPMC 0x800000 /* Process is using HWPMCs */
#define P_JAILED 0x1000000 /* Process is in jail. */
+#define P_FOLLOWEXEC 0x2000000 /* Report execs with ptrace. */
#define P_INEXEC 0x4000000 /* Process is in execve(). */
#define P_STATCHILD 0x8000000 /* Child process stopped or exited. */
#define P_INMEM 0x10000000 /* Loaded into memory. */
Index: sys/ptrace.h
===================================================================
--- sys/ptrace.h (revision 231228)
+++ sys/ptrace.h (working copy)
@@ -64,6 +64,7 @@
#define PT_SYSCALL 22
#define PT_FOLLOW_FORK 23
+#define PT_FOLLOW_EXEC 24
#define PT_GETREGS 33 /* get general-purpose registers */
#define PT_SETREGS 34 /* set general-purpose registers */
@@ -106,7 +107,8 @@ 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 */
+#define PL_FLAG_FORKED 0x40 /* child born */
+#define PL_FLAG_CHILD 0x80 /* I am from child */
sigset_t pl_sigmask; /* LWP signal mask */
sigset_t pl_siglist; /* LWP pending signal */
struct __siginfo pl_siginfo; /* siginfo for signal */
Index: kern/kern_exec.c
===================================================================
--- kern/kern_exec.c (revision 231228)
+++ kern/kern_exec.c (working copy)
@@ -56,6 +56,7 @@ __FBSDID("$FreeBSD$");
#include <sys/proc.h>
#include <sys/pioctl.h>
#include <sys/namei.h>
+#include <sys/ptrace.h>
#include <sys/resourcevar.h>
#include <sys/sdt.h>
#include <sys/sf_buf.h>
Index: kern/kern_fork.c
===================================================================
--- kern/kern_fork.c (revision 231228)
+++ kern/kern_fork.c (working copy)
@@ -1035,7 +1035,9 @@ fork_return(struct thread *td, struct trapframe *f
p->p_oppid = p->p_pptr->p_pid;
proc_reparent(p, dbg);
sx_xunlock(&proctree_lock);
+ td->td_dbgflags |= TDB_CHILD;
ptracestop(td, SIGSTOP);
+ td->td_dbgflags &= ~TDB_CHILD;
} else {
/*
* ... otherwise clear the request.
Index: kern/sys_process.c
===================================================================
--- kern/sys_process.c (revision 231228)
+++ kern/sys_process.c (working copy)
@@ -660,6 +660,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid,
case PT_TO_SCX:
case PT_SYSCALL:
case PT_FOLLOW_FORK:
+ case PT_FOLLOW_EXEC:
case PT_DETACH:
sx_xlock(&proctree_lock);
proctree_locked = 1;
@@ -873,6 +874,12 @@ kern_ptrace(struct thread *td, int req, pid_t pid,
else
p->p_flag &= ~P_FOLLOWFORK;
break;
+ case PT_FOLLOW_EXEC:
+ if (data)
+ p->p_flag |= P_FOLLOWEXEC;
+ else
+ p->p_flag &= ~P_FOLLOWEXEC;
+ break;
case PT_STEP:
case PT_CONTINUE:
@@ -936,7 +943,8 @@ kern_ptrace(struct thread *td, int req, pid_t pid,
p->p_sigparent = SIGCHLD;
}
p->p_oppid = 0;
- p->p_flag &= ~(P_TRACED | P_WAITED | P_FOLLOWFORK);
+ p->p_flag &= ~(P_TRACED | P_WAITED | P_FOLLOWFORK |
+ P_FOLLOWEXEC);
/* should we send SIGCHLD? */
/* childproc_continued(p); */
@@ -1139,12 +1147,15 @@ kern_ptrace(struct thread *td, int req, pid_t pid,
pl->pl_flags |= PL_FLAG_SCE;
else if (td2->td_dbgflags & TDB_SCX)
pl->pl_flags |= PL_FLAG_SCX;
- if (td2->td_dbgflags & TDB_EXEC)
+ if (td2->td_dbgflags & TDB_EXEC &&
+ (p->p_stops & S_PT_SCX || p->p_flag & P_FOLLOWEXEC))
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;
}
+ if (td2->td_dbgflags & TDB_CHILD)
+ pl->pl_flags |= PL_FLAG_CHILD;
pl->pl_sigmask = td2->td_sigmask;
pl->pl_siglist = td2->td_siglist;
strcpy(pl->pl_tdname, td2->td_name);
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