diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index 6e655a6..8345fdc 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -33,6 +33,12 @@ static inline int secure_computing(void)
 		return  __secure_computing();
 	return 0;
 }
+
+#define SECCOMP_PHASE1_OK	0
+#define SECCOMP_PHASE1_SKIP	1
+
+extern u32 seccomp_phase1(void);
+int seccomp_phase2(u32 phase1_result);
 #else
 extern void secure_computing_strict(int this_syscall);
 #endif
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 15ee9d6..d737445 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -19,8 +19,6 @@
 #include <linux/sched.h>
 #include <linux/seccomp.h>
 
-/* #define SECCOMP_DEBUG 1 */
-
 #ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
 #include <asm/syscall.h>
 #endif
@@ -417,79 +415,135 @@ void secure_computing_strict(int this_syscall)
 #else
 int __secure_computing(void)
 {
+	u32 phase1_result = seccomp_phase1();
+
+	if (likely(phase1_result == SECCOMP_PHASE1_OK))
+		return 0;
+	else if (likely(phase1_result == SECCOMP_PHASE1_SKIP))
+		return -1;
+	else
+		return seccomp_phase2(phase1_result);
+}
+
+#ifdef CONFIG_SECCOMP_FILTER
+static u32 __seccomp_phase1_filter(int this_syscall, struct pt_regs *regs)
+{
+	u32 filter_ret = seccomp_run_filters();
+	int data = filter_ret & SECCOMP_RET_DATA;
+	u32 action = filter_ret & SECCOMP_RET_ACTION;
+
+	switch (action) {
+	case SECCOMP_RET_ERRNO:
+		/* Set the low-order 16-bits as a errno. */
+		syscall_set_return_value(current, regs,
+					 -data, 0);
+		goto skip;
+
+	case SECCOMP_RET_TRAP:
+		/* Show the handler the original registers. */
+		syscall_rollback(current, regs);
+		/* Let the filter pass back 16 bits of data. */
+		seccomp_send_sigsys(this_syscall, data);
+		goto skip;
+
+	case SECCOMP_RET_TRACE:
+		return filter_ret;  /* Save the rest for phase 2. */
+
+	case SECCOMP_RET_ALLOW:
+		return SECCOMP_PHASE1_OK;
+
+	case SECCOMP_RET_KILL:
+	default:
+		audit_seccomp(this_syscall, SIGSYS, action);
+		do_exit(SIGSYS);
+	}
+
+	unreachable();
+
+skip:
+	audit_seccomp(this_syscall, 0, action);
+	return SECCOMP_PHASE1_SKIP;
+}
+#endif
+
+/**
+ * seccomp_phase1() - run fast path seccomp checks on the current syscall
+ *
+ * This only reads pt_regs via the syscall_xyz helpers.  The only change
+ * it will make to pt_regs is via syscall_set_return_value, and it will
+ * only do that if it returns SECCOMP_PHASE1_SKIP.
+ *
+ * It may also call do_exit or force a signal; these actions must be
+ * safe.
+ *
+ * If it returns SECCOMP_PHASE1_OK, the syscall passes checks and should
+ * be processed normally.
+ *
+ * If it returns SECCOMP_PHASE1_SKIP, then the syscall should not be
+ * invoked.  In this case, seccomp_phase1 will have set the return value
+ * using syscall_set_return_value.
+ *
+ * If it returns anything else, then the return value should be passed
+ * to seccomp_phase2 from a context in which ptrace hooks are safe.
+ */
+u32 seccomp_phase1(void)
+{
 	int mode = current->seccomp.mode;
 	struct pt_regs *regs = task_pt_regs(current);
 	int this_syscall = syscall_get_nr(current, regs);
-	int exit_sig = 0;
-	u32 ret;
 
 	switch (mode) {
 	case SECCOMP_MODE_STRICT:
-		__secure_computing_strict(this_syscall);
-		return 0;
+		__secure_computing_strict(this_syscall);  /* may call do_exit */
+		return SECCOMP_PHASE1_OK;
 #ifdef CONFIG_SECCOMP_FILTER
-	case SECCOMP_MODE_FILTER: {
-		int data;
-		ret = seccomp_run_filters();
-		data = ret & SECCOMP_RET_DATA;
-		ret &= SECCOMP_RET_ACTION;
-		switch (ret) {
-		case SECCOMP_RET_ERRNO:
-			/* Set the low-order 16-bits as a errno. */
-			syscall_set_return_value(current, regs,
-						 -data, 0);
-			goto skip;
-		case SECCOMP_RET_TRAP:
-			/* Show the handler the original registers. */
-			syscall_rollback(current, regs);
-			/* Let the filter pass back 16 bits of data. */
-			seccomp_send_sigsys(this_syscall, data);
-			goto skip;
-		case SECCOMP_RET_TRACE:
-			/* Skip these calls if there is no tracer. */
-			if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
-				syscall_set_return_value(current, regs,
-							 -ENOSYS, 0);
-				goto skip;
-			}
-			/* Allow the BPF to provide the event message */
-			ptrace_event(PTRACE_EVENT_SECCOMP, data);
-			/*
-			 * The delivery of a fatal signal during event
-			 * notification may silently skip tracer notification.
-			 * Terminating the task now avoids executing a system
-			 * call that may not be intended.
-			 */
-			if (fatal_signal_pending(current))
-				break;
-			if (syscall_get_nr(current, regs) < 0)
-				goto skip;  /* Explicit request to skip. */
-
-			return 0;
-		case SECCOMP_RET_ALLOW:
-			return 0;
-		case SECCOMP_RET_KILL:
-		default:
-			break;
-		}
-		exit_sig = SIGSYS;
-		break;
-	}
+	case SECCOMP_MODE_FILTER:
+		return __seccomp_phase1_filter(this_syscall, regs);
 #endif
 	default:
 		BUG();
 	}
+}
 
-#ifdef SECCOMP_DEBUG
-	dump_stack();
-#endif
-	audit_seccomp(this_syscall, exit_sig, ret);
-	do_exit(exit_sig);
-#ifdef CONFIG_SECCOMP_FILTER
-skip:
-	audit_seccomp(this_syscall, exit_sig, ret);
-	return -1;
-#endif
+/**
+ * seccomp_phase2() - finish slow path seccomp work for the current syscall
+ * @phase1_result: The return value from seccomp_phase1()
+ *
+ * This must be called from a context in which ptrace hooks can be used.
+ *
+ * Returns 0 if the syscall should be processed or -1 to skip the syscall.
+ */
+int seccomp_phase2(u32 phase1_result)
+{
+	struct pt_regs *regs = task_pt_regs(current);
+	u32 action = phase1_result & SECCOMP_RET_ACTION;
+	int data = phase1_result & SECCOMP_RET_DATA;
+
+	BUG_ON(action != SECCOMP_RET_TRACE);
+
+	audit_seccomp(syscall_get_nr(current, regs), 0, action);
+
+	/* Skip these calls if there is no tracer. */
+	if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP)) {
+		syscall_set_return_value(current, regs,
+					 -ENOSYS, 0);
+		return -1;
+	}
+
+	/* Allow the BPF to provide the event message */
+	ptrace_event(PTRACE_EVENT_SECCOMP, data);
+	/*
+	 * The delivery of a fatal signal during event
+	 * notification may silently skip tracer notification.
+	 * Terminating the task now avoids executing a system
+	 * call that may not be intended.
+	 */
+	if (fatal_signal_pending(current))
+		do_exit(SIGSYS);
+	if (syscall_get_nr(current, regs) < 0)
+		return -1;  /* Explicit request to skip. */
+
+	return 0;
 }
 #endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
 
