Date: Fri, 10 Feb 2012 02:17:25 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: Dmitry Mikulin <dmitrym@juniper.net> Cc: freebsd-current Current <freebsd-current@freebsd.org>, Marcel Moolenaar <marcelm@juniper.net> Subject: Re: [ptrace] please review follow fork/exec changes Message-ID: <20120210001725.GJ3283@deviant.kiev.zoral.com.ua> In-Reply-To: <4F34311A.9050702@juniper.net> References: <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> <4F3318AD.6000607@juniper.net> <20120209122908.GD3283@deviant.kiev.zoral.com.ua> <4F34311A.9050702@juniper.net>
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On Thu, Feb 09, 2012 at 12:48:26PM -0800, Dmitry Mikulin wrote:
>=20
> >The semantic of PL_FLAG_EXEC up until now is very simple: it indicates
> >that current stop occured during the first return to usermode after
> >successful exec. The proposed patch breaks the semantic, because now
> >some stops which satisfy the stated condition are no longer marked with
> >the flag.
> >
> >That said, I am lost. You stated that you still need some stops at
> >exec even when not PT_FOLLOW_EXEC is requested. Why usermode cannot
> >remember whether the PT_FOLLOW_EXEC was set for the process, and ignore
> >PL_FLAG_EXEC if not requested ?
>=20
> I was trying to avoid making ugly changes in gdb if it was possible not t=
o=20
> make ugly changes in the kernel. I changed gdb to work without=20
> PT_FOLLOW_EXEC.
So, does the patch below helps you, or did I missed something again ?
>=20
> >I just gave up and added PL_FLAG_EXECF, which is set when PT_FOLLOW_EXEC
> >was set and exec is active. Would this work for your purposes ?
> >PL_FLAG_EXECF has the same semantic as PL_FLAG_EXEC had in your
> >follow-exec.patch. But the stop set is not changed comparing with the
> >stock src.
> >
> >Are you fine with PL_FLAG_CHILD part of the changes ? If yes, I will
> >commit it to make some progress.
>=20
> yes, the PL_FLAG_CHILD part works for me.
> Please commit it and we can move on to the next part of the review.
Committed as r231320. Below is what left for PT_FOLLOWEXEC.
diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c
index 2060efe..4f93a79 100644
--- a/sys/kern/sys_process.c
+++ b/sys/kern/sys_process.c
@@ -660,6 +660,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void=
*addr, int data)
case PT_TO_SCX:
case PT_SYSCALL:
case PT_FOLLOW_FORK:
+ case PT_FOLLOW_EXEC:
case PT_DETACH:
sx_xlock(&proctree_lock);
proctree_locked =3D 1;
@@ -873,6 +874,12 @@ kern_ptrace(struct thread *td, int req, pid_t pid, voi=
d *addr, int data)
else
p->p_flag &=3D ~P_FOLLOWFORK;
break;
+ case PT_FOLLOW_EXEC:
+ if (data)
+ p->p_flag |=3D P_FOLLOWEXEC;
+ else
+ p->p_flag &=3D ~P_FOLLOWEXEC;
+ break;
=20
case PT_STEP:
case PT_CONTINUE:
@@ -936,7 +943,8 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void=
*addr, int data)
p->p_sigparent =3D SIGCHLD;
}
p->p_oppid =3D 0;
- p->p_flag &=3D ~(P_TRACED | P_WAITED | P_FOLLOWFORK);
+ p->p_flag &=3D ~(P_TRACED | P_WAITED | P_FOLLOWFORK |
+ P_FOLLOWEXEC);
=20
/* should we send SIGCHLD? */
/* childproc_continued(p); */
@@ -1139,8 +1147,11 @@ kern_ptrace(struct thread *td, int req, pid_t pid, v=
oid *addr, int data)
pl->pl_flags |=3D PL_FLAG_SCE;
else if (td2->td_dbgflags & TDB_SCX)
pl->pl_flags |=3D PL_FLAG_SCX;
- if (td2->td_dbgflags & TDB_EXEC)
+ if (td2->td_dbgflags & TDB_EXEC) {
pl->pl_flags |=3D PL_FLAG_EXEC;
+ if (p->p_flag & P_FOLLOWEXEC)
+ pl->pl_flags |=3D PL_FLAG_EXECF;
+ }
if (td2->td_dbgflags & TDB_FORK) {
pl->pl_flags |=3D PL_FLAG_FORKED;
pl->pl_child_pid =3D td2->td_dbg_forked;
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 0245e88..bec7223 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -614,6 +614,7 @@ struct proc {
#define P_HWPMC 0x800000 /* Process is using HWPMCs */
=20
#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. */
diff --git a/sys/sys/ptrace.h b/sys/sys/ptrace.h
index 8a02495..81cebfc 100644
--- a/sys/sys/ptrace.h
+++ b/sys/sys/ptrace.h
@@ -64,6 +64,7 @@
#define PT_SYSCALL 22
=20
#define PT_FOLLOW_FORK 23
+#define PT_FOLLOW_EXEC 24
=20
#define PT_GETREGS 33 /* get general-purpose registers */
#define PT_SETREGS 34 /* set general-purpose registers */
@@ -100,14 +101,15 @@ struct ptrace_lwpinfo {
#define PL_EVENT_NONE 0
#define PL_EVENT_SIGNAL 1
int pl_flags; /* LWP flags. */
-#define PL_FLAG_SA 0x01 /* M:N thread */
-#define PL_FLAG_BOUND 0x02 /* M:N bound thread */
-#define PL_FLAG_SCE 0x04 /* syscall enter point */
-#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_CHILD 0x80 /* I am from child */
+#define PL_FLAG_SA 0x0001 /* M:N thread */
+#define PL_FLAG_BOUND 0x0002 /* M:N bound thread */
+#define PL_FLAG_SCE 0x0004 /* syscall enter point */
+#define PL_FLAG_SCX 0x0008 /* syscall leave point */
+#define PL_FLAG_EXEC 0x0010 /* exec(2) succeeded */
+#define PL_FLAG_SI 0x0020 /* siginfo is valid */
+#define PL_FLAG_FORKED 0x0040 /* child born */
+#define PL_FLAG_CHILD 0x0080 /* I am from child */
+#define PL_FLAG_EXECF 0x0100 /* exec and PT_FOLLOW_EXEC was set */
sigset_t pl_sigmask; /* LWP signal mask */
sigset_t pl_siglist; /* LWP pending signal */
struct __siginfo pl_siginfo; /* siginfo for signal */
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