---

yaml
---
r: 256841
b: refs/heads/master
c: 3544d72
h: refs/heads/master
i:
  256839: f4f0f8a
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 73ddff2bee159ffb580bd24faf625cd5e628f5ec
+refs/heads/master: 3544d72a0e10d0aa1c1bd59ed77a53a59cdc12f7

trunk/include/linux/ptrace.h

@@ -47,6 +47,11 @@
 #define PTRACE_GETREGSET	0x4204
 #define PTRACE_SETREGSET	0x4205
 
+#define PTRACE_SEIZE		0x4206
+
+/* flags in @data for PTRACE_SEIZE */
+#define PTRACE_SEIZE_DEVEL	0x80000000 /* temp flag for development */
+
 /* options set using PTRACE_SETOPTIONS */
 #define PTRACE_O_TRACESYSGOOD	0x00000001
 #define PTRACE_O_TRACEFORK	0x00000002
@@ -65,6 +70,7 @@
 #define PTRACE_EVENT_EXEC	4
 #define PTRACE_EVENT_VFORK_DONE	5
 #define PTRACE_EVENT_EXIT	6
+#define PTRACE_EVENT_STOP	7
 
 #include <asm/ptrace.h>
 
@@ -77,6 +83,7 @@
  * flags.  When the a task is stopped the ptracer owns task->ptrace.
  */
 
+#define PT_SEIZED	0x00010000	/* SEIZE used, enable new behavior */
 #define PT_PTRACED	0x00000001
 #define PT_DTRACE	0x00000002	/* delayed trace (used on m68k, i386) */
 #define PT_TRACESYSGOOD	0x00000004

trunk/kernel/ptrace.c

@@ -209,10 +209,28 @@ bool ptrace_may_access(struct task_struct *task, unsigned int mode)
 	return !err;
 }
 
-static int ptrace_attach(struct task_struct *task)
+static int ptrace_attach(struct task_struct *task, long request,
+			 unsigned long flags)
 {
+	bool seize = (request == PTRACE_SEIZE);
 	int retval;
 
+	/*
+	 * SEIZE will enable new ptrace behaviors which will be implemented
+	 * gradually.  SEIZE_DEVEL is used to prevent applications
+	 * expecting full SEIZE behaviors trapping on kernel commits which
+	 * are still in the process of implementing them.
+	 *
+	 * Only test programs for new ptrace behaviors being implemented
+	 * should set SEIZE_DEVEL.  If unset, SEIZE will fail with -EIO.
+	 *
+	 * Once SEIZE behaviors are completely implemented, this flag and
+	 * the following test will be removed.
+	 */
+	retval = -EIO;
+	if (seize && !(flags & PTRACE_SEIZE_DEVEL))
+		goto out;
+
 	audit_ptrace(task);
 
 	retval = -EPERM;
@@ -244,11 +262,16 @@ static int ptrace_attach(struct task_struct *task)
 		goto unlock_tasklist;
 
 	task->ptrace = PT_PTRACED;
+	if (seize)
+		task->ptrace |= PT_SEIZED;
 	if (task_ns_capable(task, CAP_SYS_PTRACE))
 		task->ptrace |= PT_PTRACE_CAP;
 
 	__ptrace_link(task, current);
-	send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
+
+	/* SEIZE doesn't trap tracee on attach */
+	if (!seize)
+		send_sig_info(SIGSTOP, SEND_SIG_FORCED, task);
 
 	spin_lock(&task->sighand->siglock);
 
@@ -785,8 +808,8 @@ SYSCALL_DEFINE4(ptrace, long, request, long, pid, unsigned long, addr,
 		goto out;
 	}
 
-	if (request == PTRACE_ATTACH) {
-		ret = ptrace_attach(child);
+	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
+		ret = ptrace_attach(child, request, data);
 		/*
 		 * Some architectures need to do book-keeping after
 		 * a ptrace attach.
@@ -927,8 +950,8 @@ asmlinkage long compat_sys_ptrace(compat_long_t request, compat_long_t pid,
 		goto out;
 	}
 
-	if (request == PTRACE_ATTACH) {
-		ret = ptrace_attach(child);
+	if (request == PTRACE_ATTACH || request == PTRACE_SEIZE) {
+		ret = ptrace_attach(child, request, data);
 		/*
 		 * Some architectures need to do book-keeping after
 		 * a ptrace attach.

trunk/kernel/signal.c

@@ -1873,21 +1873,26 @@ static void ptrace_stop(int exit_code, int why, int clear_code, siginfo_t *info)
 	recalc_sigpending_tsk(current);
 }
 
-void ptrace_notify(int exit_code)
+static void ptrace_do_notify(int signr, int exit_code, int why)
 {
 	siginfo_t info;
 
-	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
-
 	memset(&info, 0, sizeof info);
-	info.si_signo = SIGTRAP;
+	info.si_signo = signr;
 	info.si_code = exit_code;
 	info.si_pid = task_pid_vnr(current);
 	info.si_uid = current_uid();
 
 	/* Let the debugger run.  */
+	ptrace_stop(exit_code, why, 1, &info);
+}
+
+void ptrace_notify(int exit_code)
+{
+	BUG_ON((exit_code & (0x7f | ~0xffff)) != SIGTRAP);
+
 	spin_lock_irq(&current->sighand->siglock);
-	ptrace_stop(exit_code, CLD_TRAPPED, 1, &info);
+	ptrace_do_notify(SIGTRAP, exit_code, CLD_TRAPPED);
 	spin_unlock_irq(&current->sighand->siglock);
 }
 
@@ -2017,19 +2022,35 @@ static bool do_signal_stop(int signr)
 /**
  * do_jobctl_trap - take care of ptrace jobctl traps
  *
- * It is currently used only to trap for group stop while ptraced.
+ * When PT_SEIZED, it's used for both group stop and explicit
+ * SEIZE/INTERRUPT traps.  Both generate PTRACE_EVENT_STOP trap with
+ * accompanying siginfo.  If stopped, lower eight bits of exit_code contain
+ * the stop signal; otherwise, %SIGTRAP.
+ *
+ * When !PT_SEIZED, it's used only for group stop trap with stop signal
+ * number as exit_code and no siginfo.
  *
  * CONTEXT:
  * Must be called with @current->sighand->siglock held, which may be
  * released and re-acquired before returning with intervening sleep.
  */
 static void do_jobctl_trap(void)
 {
+	struct signal_struct *signal = current->signal;
 	int signr = current->jobctl & JOBCTL_STOP_SIGMASK;
 
-	WARN_ON_ONCE(!signr);
-	ptrace_stop(signr, CLD_STOPPED, 0, NULL);
-	current->exit_code = 0;
+	if (current->ptrace & PT_SEIZED) {
+		if (!signal->group_stop_count &&
+		    !(signal->flags & SIGNAL_STOP_STOPPED))
+			signr = SIGTRAP;
+		WARN_ON_ONCE(!signr);
+		ptrace_do_notify(signr, signr | (PTRACE_EVENT_STOP << 8),
+				 CLD_STOPPED);
+	} else {
+		WARN_ON_ONCE(!signr);
+		ptrace_stop(signr, CLD_STOPPED, 0, NULL);
+		current->exit_code = 0;
+	}
 }
 
 static int ptrace_signal(int signr, siginfo_t *info,