1 files changed, 64 insertions, 14 deletions

diff --git a/sys/sparc64/sparc64/pmap.c b/sys/sparc64/sparc64/pmap.c
index 4485a55..60c264d 100644
--- a/sys/sparc64/sparc64/pmap.c
+++ b/sys/sparc64/sparc64/pmap.c
@@ -951,31 +951,41 @@ pmap_qremove(vm_offset_t sva, int count)
 	tlb_range_demap(kernel_pmap, sva, sva + (count * PAGE_SIZE) - 1);
 }
 
+#ifndef KSTACK_MAX_PAGES
+#define KSTACK_MAX_PAGES 32
+#endif
+
 /*
  * Create the kernel stack and pcb 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)
+pmap_new_thread(struct thread *td, int pages)
 {
-	vm_page_t ma[KSTACK_PAGES];
+	vm_page_t ma[KSTACK_MAX_PAGES];
 	vm_object_t ksobj;
 	vm_offset_t ks;
 	vm_page_t m;
 	u_int i;
 
+	/* 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, KSTACK_PAGES);
+	ksobj = vm_object_allocate(OBJT_DEFAULT, pages);
 	td->td_kstack_obj = ksobj;
 
 	/*
 	 * Get a kernel virtual address for the kstack for this thread.
 	 */
 	ks = kmem_alloc_nofault(kernel_map,
-	   (KSTACK_PAGES + KSTACK_GUARD_PAGES) * PAGE_SIZE);
+	   (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
 	if (ks == 0)
 		panic("pmap_new_thread: kstack allocation failed");
 	if (KSTACK_GUARD_PAGES != 0) {
@@ -984,7 +994,13 @@ pmap_new_thread(struct thread *td)
 	}
 	td->td_kstack = ks;
 
-	for (i = 0; i < KSTACK_PAGES; i++) {
+	/*
+	 * Knowing the number of pages allocated is useful when you
+	 * want to deallocate them.
+	 */
+	td->td_kstack_pages = pages;
+
+	for (i = 0; i < pages; i++) {
 		/*
 		 * Get a kernel stack page.
 		 */
@@ -1000,7 +1016,7 @@ pmap_new_thread(struct thread *td)
 	/*
 	 * Enter the page into the kernel address space.
 	 */
-	pmap_qenter(ks, ma, KSTACK_PAGES);
+	pmap_qenter(ks, ma, pages);
 }
 
 /*
@@ -1014,10 +1030,12 @@ pmap_dispose_thread(struct thread *td)
 	vm_offset_t ks;
 	vm_page_t m;
 	int i;
+	int pages;
 
+	pages = td->td_kstack_pages;
 	ksobj = td->td_kstack_obj;
 	ks = td->td_kstack;
-	for (i = 0; i < KSTACK_PAGES; i++) {
+	for (i = 0; i < pages ; i++) {
 		m = vm_page_lookup(ksobj, i);
 		if (m == NULL)
 			panic("pmap_dispose_thread: kstack already missing?");
@@ -1027,13 +1045,41 @@ pmap_dispose_thread(struct thread *td)
 		vm_page_free(m);
 		vm_page_unlock_queues();
 	}
-	pmap_qremove(ks, KSTACK_PAGES);
+	pmap_qremove(ks, pages);
 	kmem_free(kernel_map, ks - (KSTACK_GUARD_PAGES * PAGE_SIZE),
-	    (KSTACK_PAGES + KSTACK_GUARD_PAGES) * PAGE_SIZE);
+	    (pages + KSTACK_GUARD_PAGES) * PAGE_SIZE);
 	vm_object_deallocate(ksobj);
 }
 
 /*
+ * Set up a variable sized alternate kstack.
+ */
+void
+pmap_new_altkstack(struct thread *td, int pages)
+{
+	/* shuffle the original stack */
+	td->td_altkstack_obj = td->td_kstack_obj;
+	td->td_altkstack = td->td_kstack;
+	td->td_altkstack_pages = td->td_kstack_pages;
+
+	pmap_new_thread(td, pages);
+}
+
+void
+pmap_dispose_altkstack(struct thread *td)
+{
+	pmap_dispose_thread(td);
+
+	/* restore the original kstack */
+	td->td_kstack = td->td_altkstack;
+	td->td_kstack_obj = td->td_altkstack_obj;
+	td->td_kstack_pages = td->td_altkstack_pages;
+	td->td_altkstack = 0;
+	td->td_altkstack_obj = NULL;
+	td->td_altkstack_pages = 0;
+}
+
+/*
  * Allow the kernel stack for a thread to be prejudicially paged out.
  */
 void
@@ -1043,10 +1089,12 @@ pmap_swapout_thread(struct thread *td)
 	vm_offset_t ks;
 	vm_page_t m;
 	int i;
+	int pages;
 
+	pages = td->td_kstack_pages;
 	ksobj = td->td_kstack_obj;
 	ks = (vm_offset_t)td->td_kstack;
-	for (i = 0; i < KSTACK_PAGES; i++) {
+	for (i = 0; i < pages; i++) {
 		m = vm_page_lookup(ksobj, i);
 		if (m == NULL)
 			panic("pmap_swapout_thread: kstack already missing?");
@@ -1055,7 +1103,7 @@ pmap_swapout_thread(struct thread *td)
 		vm_page_unwire(m, 0);
 		vm_page_unlock_queues();
 	}
-	pmap_qremove(ks, KSTACK_PAGES);
+	pmap_qremove(ks, pages);
 }
 
 /*
@@ -1064,16 +1112,18 @@ pmap_swapout_thread(struct thread *td)
 void
 pmap_swapin_thread(struct thread *td)
 {
-	vm_page_t ma[KSTACK_PAGES];
+	vm_page_t ma[KSTACK_MAX_PAGES];
 	vm_object_t ksobj;
 	vm_offset_t ks;
 	vm_page_t m;
 	int rv;
 	int i;
+	int pages;
 
+	pages = td->td_kstack_pages;
 	ksobj = td->td_kstack_obj;
 	ks = td->td_kstack;
-	for (i = 0; i < KSTACK_PAGES; i++) {
+	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);
@@ -1088,7 +1138,7 @@ pmap_swapin_thread(struct thread *td)
 		vm_page_wakeup(m);
 		vm_page_unlock_queues();
 	}
-	pmap_qenter(ks, ma, KSTACK_PAGES);
+	pmap_qenter(ks, ma, pages);
 }
 
 /*