vm: refactor page_array and functions into a separate source file

vm/bootstrap.c

@@ -18,7 +18,8 @@ kern_status_t vm_bootstrap(const vm_zone_descriptor_t *zones, size_t nr_zones)
 	node_data = memblock_alloc(sizeof(vm_pg_data_t) * numa_count, 8);
 	printk("vm: initialising %u node%s", numa_count, numa_count > 1 ? "s" : "");
 
-	vm_page_init_array();
+	vm_set_memory_model(VM_MODEL_FLAT);
+	vm_flat_init();
 
 	for (size_t i = 0; i < nr_zones; i++) {
 		vm_zone_init(&node_data->pg_zones[zones[i].zd_id],  &zones[i]);

vm/flat.c

@@ -0,0 +1,58 @@
+#include <socks/vm.h>
+#include <socks/memblock.h>
+#include <socks/printk.h>
+
+/* array of pages, one for each physical page frame present in RAM */
+static vm_page_t *page_array = NULL;
+
+/* number of pages stored in page_array */
+static size_t page_array_count = 0;
+
+void vm_flat_init()
+{
+	printk("vm: using flat memory model");
+	size_t pmem_size = 0;
+
+	memblock_iter_t it;
+	for_each_free_mem_range (&it, 0x0, UINTPTR_MAX) {
+		if (pmem_size < it.it_limit + 1) {
+			pmem_size = it.it_limit + 1;
+		}
+	}
+
+	size_t nr_pages = pmem_size / VM_PAGE_SIZE;
+	if (pmem_size % VM_PAGE_SIZE) {
+		nr_pages++;
+	}
+
+	page_array = memblock_alloc(sizeof(vm_page_t) * nr_pages, 8);
+	page_array_count = nr_pages;
+
+	size_t nr_reserved = nr_pages;
+
+	for (size_t i = 0; i < nr_pages; i++) {
+		page_array[i].p_flags = VM_PAGE_RESERVED;
+	}
+
+	for_each_free_mem_range(&it, 0x0, UINTPTR_MAX) {
+		for (uintptr_t i = it.it_base; i < it.it_limit; i += VM_PAGE_SIZE) {
+			size_t pfn = i / VM_PAGE_SIZE;
+
+			page_array[pfn].p_flags = 0;
+			nr_reserved--;
+		}
+	}
+
+	printk("vm: page array has %zu pages, %zu reserved", nr_pages, nr_reserved);
+}
+
+vm_page_t *vm_page_get_flat(phys_addr_t addr)
+{
+	size_t pfn = addr / VM_PAGE_SIZE;
+	return pfn < page_array_count ? &page_array[pfn] : NULL;
+}
+
+size_t vm_page_get_pfn_flat(vm_page_t *pg)
+{
+	return ((uintptr_t)pg - (uintptr_t)page_array) / sizeof *pg;
+}

vm/model.c

@@ -0,0 +1,13 @@
+#include <socks/vm.h>
+
+static vm_model_t model;
+
+vm_model_t vm_memory_model(void)
+{
+	return model;
+}
+
+void vm_set_memory_model(vm_model_t m)
+{
+	model = m;
+}

vm/page.c

@@ -4,12 +4,6 @@
 #include <socks/vm.h>
 #include <socks/libc/string.h>
 
-/* array of pages, one for each physical page frame present in RAM */
-static vm_page_t *page_array = NULL;
-
-/* number of pages stored in page_array */
-static size_t page_array_count = 0;
-
 /* Pre-calculated page order -> size conversion table */
 static size_t page_order_bytes[] = {
 	[VM_PAGE_4K]   = 0x1000,
@@ -64,47 +58,14 @@ void *vm_phys_to_virt(phys_addr_t p)
 	return (void *)(VM_PAGEMAP_BASE + p);
 }
 
-void vm_page_init_array()
-{
-	size_t pmem_size = 0;
-
-	memblock_iter_t it;
-	for_each_free_mem_range (&it, 0x0, UINTPTR_MAX) {
-		if (pmem_size < it.it_limit + 1) {
-			pmem_size = it.it_limit + 1;
-		}
-	}
-
-	size_t nr_pages = pmem_size / VM_PAGE_SIZE;
-	if (pmem_size % VM_PAGE_SIZE) {
-		nr_pages++;
-	}
-
-	page_array = memblock_alloc(sizeof(vm_page_t) * nr_pages, 8);
-	page_array_count = nr_pages;
-
-	size_t nr_reserved = nr_pages;
-
-	for (size_t i = 0; i < nr_pages; i++) {
-		page_array[i].p_flags = VM_PAGE_RESERVED;
-	}
-
-	for_each_free_mem_range(&it, 0x0, UINTPTR_MAX) {
-		for (uintptr_t i = it.it_base; i < it.it_limit; i += VM_PAGE_SIZE) {
-			size_t pfn = i / VM_PAGE_SIZE;
-
-			page_array[pfn].p_flags = 0;
-			nr_reserved--;
-		}
-	}
-
-	printk("vm: page array has %zu pages, %zu reserved", nr_pages, nr_reserved);
-}
-
 vm_page_t *vm_page_get(phys_addr_t addr)
 {
-	size_t pfn = addr / VM_PAGE_SIZE;
-	return pfn < page_array_count ? &page_array[pfn] : NULL;
+	switch (vm_memory_model()) {
+	case VM_MODEL_FLAT:
+		return vm_page_get_flat(addr);
+	default:
+		return NULL;
+	}
 }
 
 phys_addr_t vm_page_get_paddr(vm_page_t *pg)
@@ -119,7 +80,12 @@ void *vm_page_get_vaddr(vm_page_t *pg)
 
 size_t vm_page_get_pfn(vm_page_t *pg)
 {
-	return ((uintptr_t)pg - (uintptr_t)page_array) / sizeof *pg;
+	switch (vm_memory_model()) {
+	case VM_MODEL_FLAT:
+		return vm_page_get_pfn_flat(pg);
+	default:
+		return 0;
+	}
 }
 
 size_t vm_page_order_to_bytes(vm_page_order_t order)