Assert vm map locks

Introduce vm_map_assert_{wrlock,rdlock,anylock,unlocked}() in rwlock(9)
fashion and back up function comments about locking assumptions with proper
assertions.

Also add new comments/assertions based on code analysis and sync with
NetBSD as much as possible.

vm_map_lock() and vm_map_lock_read() are used for exclusive and shared
access respectively;  currently no code path is purely protected by
vm_map_lock_read() alone, i.e. functions called with a read lock held by the
callee are also called with a write lock elsewhere.

Thus only vm_map_assert_{wrlock,anylock}() are used as of now.

This should help with unlocking UVM related syscalls

Tested as part of a larger diff through
- amd64 package bulk build by naddy
- amd64, arm64, powerpc64 base builds and regress by bluhm
- amd64 and sparc64 base builds and regress by me

Input mpi
Feedback OK kettenis

1 files changed, 2 insertions, 1 deletions

diff --git a/sys/uvm/uvm_fault.c b/sys/uvm/uvm_fault.c
index e7a54be4c5a..e2a8186fd14 100644
--- a/sys/uvm/uvm_fault.c
+++ b/sys/uvm/uvm_fault.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_fault.c,v 1.126 2022/02/03 19:57:11 guenther Exp $	*/
+/*	$OpenBSD: uvm_fault.c,v 1.127 2022/02/10 10:15:35 kn Exp $	*/
 /*	$NetBSD: uvm_fault.c,v 1.51 2000/08/06 00:22:53 thorpej Exp $	*/
 
 /*
@@ -1616,6 +1616,7 @@ uvm_fault_unwire_locked(vm_map_t map, vaddr_t start, vaddr_t end)
 	struct vm_page *pg;
 
 	KASSERT((map->flags & VM_MAP_INTRSAFE) == 0);
+	vm_map_assert_anylock(map);
 
 	/*
 	 * we assume that the area we are unwiring has actually been wired