kern/thread: fix thread stack guard support

Since the introduction of the kernel VM object, page referencing has
become more strict, preventing the thread stack guard code to function.
Work around the issue by keeping the physical pages at the stack
boundaries.

1 files changed, 4 insertions, 10 deletions

diff --git a/kern/thread.c b/kern/thread.c
index 976b464f..df32ab4c 100644
--- a/kern/thread.c
+++ b/kern/thread.c
@@ -1931,24 +1931,18 @@ thread_alloc_stack(void)
     pmap_remove(kernel_pmap, va + PAGE_SIZE + stack_size, cpumap_all());
     pmap_update(kernel_pmap);
 
-    vm_page_free(first_page, 0);
-    vm_page_free(last_page, 0);
-
-    return (char *)va + PAGE_SIZE;
+    return (void *)va + PAGE_SIZE;
 }
 
 static void
 thread_free_stack(void *stack)
 {
     size_t stack_size;
-    char *va;
+    void *va;
 
     stack_size = vm_page_round(TCB_STACK_SIZE);
-    va = (char *)stack - PAGE_SIZE;
-
-    vm_kmem_free_va(va, PAGE_SIZE);
-    vm_kmem_free(va + PAGE_SIZE, stack_size);
-    vm_kmem_free_va(va + PAGE_SIZE + stack_size, PAGE_SIZE);
+    va = (void *)stack - PAGE_SIZE;
+    vm_kmem_free(va, (PAGE_SIZE * 2) + stack_size);
 }
 
 #else /* X15_THREAD_STACK_GUARD */