From 40be1218187ac9a147eb467ab807421d2beeda1b Mon Sep 17 00:00:00 2001
From: kettenis <kettenis@openbsd.org>
Date: Mon, 21 Oct 2024 18:27:34 +0000
Subject: [PATCH] We have not been swapping out kernel stacks since forever. 
 So just allocate the uarea with zeroed pages using km_alloc(9).  Adjust the
 amd64 code that creates a guard page at the top of the kernel stack to use
 pmap_kremove(9) instead of pmap_remove(9) to reflect that the uarea no longer
 uses "managed" pages.

ok mpi@
---
 sys/arch/amd64/amd64/vm_machdep.c |  5 ++---
 sys/uvm/uvm_glue.c                | 18 ++++++++----------
 2 files changed, 10 insertions(+), 13 deletions(-)

diff --git a/sys/arch/amd64/amd64/vm_machdep.c b/sys/arch/amd64/amd64/vm_machdep.c
index 8be22524d5d..5275969ed39 100644
--- a/sys/arch/amd64/amd64/vm_machdep.c
+++ b/sys/arch/amd64/amd64/vm_machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: vm_machdep.c,v 1.47 2023/04/11 00:45:07 jsg Exp $	*/
+/*	$OpenBSD: vm_machdep.c,v 1.48 2024/10/21 18:27:34 kettenis Exp $	*/
 /*	$NetBSD: vm_machdep.c,v 1.1 2003/04/26 18:39:33 fvdl Exp $	*/
 
 /*-
@@ -135,8 +135,7 @@ cpu_exit(struct proc *p)
 void
 setguardpage(struct proc *p)
 {
-	pmap_remove(pmap_kernel(), (vaddr_t)p->p_addr + PAGE_SIZE,
-	    (vaddr_t)p->p_addr + 2 * PAGE_SIZE);
+	pmap_kremove((vaddr_t)p->p_addr + PAGE_SIZE, PAGE_SIZE);
 	pmap_update(pmap_kernel());
 }
 
diff --git a/sys/uvm/uvm_glue.c b/sys/uvm/uvm_glue.c
index 2d1a6b08fe4..603bdab582e 100644
--- a/sys/uvm/uvm_glue.c
+++ b/sys/uvm/uvm_glue.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: uvm_glue.c,v 1.85 2024/10/08 02:29:10 jsg Exp $	*/
+/*	$OpenBSD: uvm_glue.c,v 1.86 2024/10/21 18:27:34 kettenis Exp $	*/
 /*	$NetBSD: uvm_glue.c,v 1.44 2001/02/06 19:54:44 eeh Exp $	*/
 
 /* 
@@ -257,20 +257,18 @@ uvm_vsunlock_device(struct proc *p, void *addr, size_t len, void *map)
 	uvm_km_free(kernel_map, kva, sz);
 }
 
+const struct kmem_va_mode kv_uarea = {
+	.kv_map = &kernel_map,
+	.kv_align = USPACE_ALIGN
+};
+
 /*
  * uvm_uarea_alloc: allocate the u-area for a new thread
  */
 vaddr_t
 uvm_uarea_alloc(void)
 {
-	vaddr_t uaddr;
-
-	uaddr = uvm_km_kmemalloc_pla(kernel_map, uvm.kernel_object, USPACE,
-	    USPACE_ALIGN, UVM_KMF_ZERO,
-	    no_constraint.ucr_low, no_constraint.ucr_high,
-	    0, 0, USPACE/PAGE_SIZE);
-
-	return (uaddr);
+	return (vaddr_t)km_alloc(USPACE, &kv_uarea, &kp_zero, &kd_waitok);
 }
 
 /*
@@ -282,7 +280,7 @@ uvm_uarea_alloc(void)
 void
 uvm_uarea_free(struct proc *p)
 {
-	uvm_km_free(kernel_map, (vaddr_t)p->p_addr, USPACE);
+	km_free(p->p_addr, USPACE, &kv_uarea, &kp_zero);
 	p->p_addr = NULL;
 }
 
-- 
2.20.1