Migrate the thread stack management functions from the machine-dependent

to the machine-independent parts of the VM.  At the same time, this
introduces vm object locking for the non-i386 platforms.

Two details:

1. KSTACK_GUARD has been removed in favor of KSTACK_GUARD_PAGES.  The
different machine-dependent implementations used various combinations
of KSTACK_GUARD and KSTACK_GUARD_PAGES.  To disable guard page, set
KSTACK_GUARD_PAGES to 0.

2. Remove the (unnecessary) clearing of PG_ZERO in vm_thread_new.  In
5.x, (but not 4.x,) PG_ZERO can only be set if VM_ALLOC_ZERO is passed
to vm_page_alloc() or vm_page_grab().

2 files changed, 1 insertions, 177 deletions

diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 38a5f5b..3e26cfa 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -883,182 +883,6 @@ retry:
 	return m;
 }
 
-#ifndef KSTACK_MAX_PAGES
-#define KSTACK_MAX_PAGES 32
-#endif
-
-/*
- * Create the kernel stack (including pcb for amd64) for a new thread.
- * This routine directly affects the fork perf for a process and
- * create performance for a thread.
- */
-void
-pmap_new_thread(struct thread *td, int pages)
-{
-	int i;
-	vm_page_t ma[KSTACK_MAX_PAGES];
-	vm_object_t ksobj;
-	vm_page_t m;
-	vm_offset_t ks;
-
-	/* Bounds check */
-	if (pages <= 1)
-		pages = KSTACK_PAGES;
-	else if (pages > KSTACK_MAX_PAGES)
-		pages = KSTACK_MAX_PAGES;
-
-	/*
-	 * allocate object for the kstack
-	 */
-	ksobj = vm_object_allocate(OBJT_DEFAULT, pages);
-	td->td_kstack_obj = ksobj;
-
-	/* get a kernel virtual address for the kstack for this thread */
-#ifdef KSTACK_GUARD
-	ks = kmem_alloc_nofault(kernel_map, (pages + 1) * PAGE_SIZE);
-	if (ks == 0)
-		panic("pmap_new_thread: kstack allocation failed");
-	if (*vtopte(ks) != 0)
-		pmap_qremove(ks, 1);
-	ks += PAGE_SIZE;
-	td->td_kstack = ks;
-#else
-	/* get a kernel virtual address for the kstack for this thread */
-	ks = kmem_alloc_nofault(kernel_map, pages * PAGE_SIZE);
-	if (ks == 0)
-		panic("pmap_new_thread: kstack allocation failed");
-	td->td_kstack = ks;
-#endif
-	/*
-	 * Knowing the number of pages allocated is useful when you
-	 * want to deallocate them.
-	 */
-	td->td_kstack_pages = pages;
-
-	/* 
-	 * For the length of the stack, link in a real page of ram for each
-	 * page of stack.
-	 */
-	for (i = 0; i < pages; i++) {
-		/*
-		 * Get a kernel stack page
-		 */
-		m = vm_page_grab(ksobj, i,
-		    VM_ALLOC_NORMAL | VM_ALLOC_RETRY | VM_ALLOC_WIRED);
-		ma[i] = m;
-
-		vm_page_lock_queues();
-		vm_page_wakeup(m);
-		vm_page_flag_clear(m, PG_ZERO);
-		m->valid = VM_PAGE_BITS_ALL;
-		vm_page_unlock_queues();
-	}
-	pmap_qenter(ks, ma, pages);
-}
-
-/*
- * Dispose the kernel stack for a thread that has exited.
- * This routine directly impacts the exit perf of a process and thread.
- */
-void
-pmap_dispose_thread(td)
-	struct thread *td;
-{
-	int i;
-	int pages;
-	vm_object_t ksobj;
-	vm_offset_t ks;
-	vm_page_t m;
-
-	pages = td->td_kstack_pages;
-	ksobj = td->td_kstack_obj;
-	ks = td->td_kstack;
-	pmap_qremove(ks, pages);
-	for (i = 0; i < pages; i++) {
-		m = vm_page_lookup(ksobj, i);
-		if (m == NULL)
-			panic("pmap_dispose_thread: kstack already missing?");
-		vm_page_lock_queues();
-		vm_page_busy(m);
-		vm_page_unwire(m, 0);
-		vm_page_free(m);
-		vm_page_unlock_queues();
-	}
-	/*
-	 * Free the space that this stack was mapped to in the kernel
-	 * address map.
-	 */
-#ifdef KSTACK_GUARD
-	kmem_free(kernel_map, ks - PAGE_SIZE, (pages + 1) * PAGE_SIZE);
-#else
-	kmem_free(kernel_map, ks, pages * PAGE_SIZE);
-#endif
-	vm_object_deallocate(ksobj);
-}
-
-/*
- * Allow the Kernel stack for a thread to be prejudicially paged out.
- */
-void
-pmap_swapout_thread(td)
-	struct thread *td;
-{
-	int i;
-	int pages;
-	vm_object_t ksobj;
-	vm_offset_t ks;
-	vm_page_t m;
-
-	pages = td->td_kstack_pages;
-	ksobj = td->td_kstack_obj;
-	ks = td->td_kstack;
-	pmap_qremove(ks, pages);
-	for (i = 0; i < pages; i++) {
-		m = vm_page_lookup(ksobj, i);
-		if (m == NULL)
-			panic("pmap_swapout_thread: kstack already missing?");
-		vm_page_lock_queues();
-		vm_page_dirty(m);
-		vm_page_unwire(m, 0);
-		vm_page_unlock_queues();
-	}
-}
-
-/*
- * Bring the kernel stack for a specified thread back in.
- */
-void
-pmap_swapin_thread(td)
-	struct thread *td;
-{
-	int i, rv;
-	int pages;
-	vm_page_t ma[KSTACK_MAX_PAGES];
-	vm_object_t ksobj;
-	vm_offset_t ks;
-	vm_page_t m;
-
-	pages = td->td_kstack_pages;
-	ksobj = td->td_kstack_obj;
-	ks = td->td_kstack;
-	for (i = 0; i < pages; i++) {
-		m = vm_page_grab(ksobj, i, VM_ALLOC_NORMAL | VM_ALLOC_RETRY);
-		if (m->valid != VM_PAGE_BITS_ALL) {
-			rv = vm_pager_get_pages(ksobj, &m, 1, 0);
-			if (rv != VM_PAGER_OK)
-				panic("pmap_swapin_thread: cannot get kstack for proc: %d\n", td->td_proc->p_pid);
-			m = vm_page_lookup(ksobj, i);
-			m->valid = VM_PAGE_BITS_ALL;
-		}
-		ma[i] = m;
-		vm_page_lock_queues();
-		vm_page_wire(m);
-		vm_page_wakeup(m);
-		vm_page_unlock_queues();
-	}
-	pmap_qenter(ks, ma, pages);
-}
-
 /***************************************************
  * Page table page management routines.....
  ***************************************************/
diff --git a/sys/amd64/include/param.h b/sys/amd64/include/param.h
index c1dccb9..6a86a62 100644
--- a/sys/amd64/include/param.h
+++ b/sys/amd64/include/param.h
@@ -118,9 +118,9 @@
 #define IOPAGES	2		/* pages of i/o permission bitmap */
 
 #define	KSTACK_PAGES	4	/* pages of kstack (with pcb) */
+#define	KSTACK_GUARD_PAGES 1	/* pages of kstack guard; 0 disables */
 #define UAREA_PAGES	1	/* holds struct user WITHOUT PCB (see def.) */
 
-#define KSTACK_GUARD	1	/* compile in the kstack guard page */
 
 /*
  * Ceiling on amount of swblock kva space, can be changed via