UVM: basic anon implementation

include/sys/vm_anon.h

@@ -0,0 +1,42 @@
+#ifndef _SYS_UVM_ANON_H_
+#define _SYS_UVM_ANON_H_
+
+#ifndef _KERNEL
+#error "Do not use this header file outside kernel code!"
+#endif
+
+#include <sys/mutex.h>
+#include <sys/vm.h>
+
+typedef struct vm_anon vm_anon_t;
+
+/*
+ * Field markings and the corresponding locks:
+ *  (@) vm_anon:an_lock
+ */
+
+struct vm_anon {
+  mtx_t an_lock;
+  int an_ref;         /* (@) Reference counter */
+  vm_page_t *an_page; /* (@) Pointer to holded page */
+};
+
+/* Allocate new anon. */
+vm_anon_t *vm_anon_alloc(void);
+/* Acquire anon->an_lock. */
+void vm_anon_lock(vm_anon_t *anon);
+/* Release anon->an_lock. */
+void vm_anon_unlock(vm_anon_t *anon);
+
+/* Increase anon's reference counter.
+ *
+ * Must be called with anon:an_lock held. */
+void vm_anon_hold(vm_anon_t *anon);
+
+/* Decrease anon's reference counter and destroy anon if it reached 0.
+ *
+ * Must be called with anon:an_lock held.
+ * Releases anon:an_lock. */
+void vm_anon_drop(vm_anon_t *anon);
+
+#endif /* !_SYS_UVM_ANON_H_ */

sys/kern/Makefile

@@ -68,6 +68,7 @@ SOURCES = \
 	uart_tty.c \
 	uio.c \
 	ustack.c \
+	uvm_anon.c \
 	vfs.c \
 	vfs_name.c \
 	vfs_readdir.c \

sys/kern/vm_anon.c

@@ -0,0 +1,42 @@
+#define KL_LOG KL_VM
+#include <sys/mimiker.h>
+#include <sys/klog.h>
+#include <sys/pool.h>
+#include <sys/vm.h>
+#include <sys/vm_physmem.h>
+#include <sys/vm_anon.h>
+
+static POOL_DEFINE(P_ANON, "vm_anon", sizeof(vm_anon_t));
+
+vm_anon_t *vm_anon_alloc(void) {
+  vm_anon_t *anon = pool_alloc(P_ANON, M_ZERO);
+  mtx_init(&anon->an_lock, 0);
+  return anon;
+}
+
+void vm_anon_lock(vm_anon_t *anon) {
+  mtx_lock(&anon->an_lock);
+}
+
+void vm_anon_unlock(vm_anon_t *anon) {
+  mtx_unlock(&anon->an_lock);
+}
+
+void vm_anon_hold(vm_anon_t *anon) {
+  assert(mtx_owned(&anon->an_lock));
+  anon->an_ref++;
+}
+
+static void anon_free(vm_anon_t *anon) {
+  /* TODO(fz): free anon->an_page */
+  pool_free(P_ANON, anon);
+}
+
+void vm_anon_drop(vm_anon_t *anon) {
+  assert(mtx_owned(&anon->an_lock));
+  anon->an_ref--;
+
+  vm_anon_unlock(anon);
+  if (anon->an_ref == 0)
+    anon_free(anon);
+}

sys/tests/Makefile

@@ -30,6 +30,7 @@ SOURCES = \
 	turnstile_propagate_many.c \
 	uiomove.c \
 	utest.c \
+	uvm.c \
 	vm_map.c \
 	devclass.c \
 	vfs.c \

sys/tests/vm_anon.c

@@ -0,0 +1,25 @@
+#include <sys/klog.h>
+#include <sys/ktest.h>
+#include <sys/vm_anon.h>
+
+static int test_anon_simple(void) {
+
+  vm_anon_t *anon = vm_anon_alloc();
+  assert(anon != NULL);
+
+  vm_anon_lock(anon);
+
+  vm_anon_hold(anon);
+  vm_anon_hold(anon);
+  assert(anon->an_ref == 2);
+
+  vm_anon_drop(anon);
+  assert(anon->an_ref == 1);
+
+  vm_anon_lock(anon);
+  vm_anon_drop(anon);
+
+  return KTEST_SUCCESS;
+}
+
+KTEST_ADD(vm_anon_simple, test_anon_simple, 0);