sandbox: vm: enforce alignment requirements for multi-page blocks

sandbox/vm/include/socks/vm.h

@@ -6,7 +6,11 @@
 #include <socks/status.h>
 #include <socks/queue.h>
 
-#define VM_PAGE_SIZE 0x1000
+#define VM_CHECK_ALIGN(p, mask) ((((p) & (mask)) == (p)) ? 1 : 0)
+#define VM_PAGE_SIZE  0x1000
+#define VM_PAGE_SHIFT 12
+
+typedef phys_addr_t vm_alignment_t;
 
 typedef struct vm_object {
 	unsigned int reserved;
@@ -39,6 +43,7 @@ typedef enum vm_page_order {
 	VM_PAGE_256M,
 	VM_PAGE_512M,
 	VM_PAGE_1G,
+	VM_PAGE_MIN_ORDER = VM_PAGE_4K,
 	VM_PAGE_MAX_ORDER = VM_PAGE_1G,
 } vm_page_order_t;
 
@@ -96,6 +101,10 @@ extern kern_status_t vm_bootstrap(const vm_zone_descriptor_t *zones, size_t nr_z
 extern void vm_page_init_array();
 extern vm_page_t *vm_page_get(phys_addr_t addr);
 extern size_t vm_page_order_to_bytes(vm_page_order_t order);
+extern size_t vm_page_order_to_pages(vm_page_order_t order);
+extern vm_alignment_t vm_page_order_to_alignment(vm_page_order_t order);
+
+extern size_t vm_bytes_to_pages(size_t bytes);
 
 extern void vm_zone_init(vm_zone_t *z, const char *name, uintptr_t base, uintptr_t limit);
 

sandbox/vm/vm_page.c

@@ -85,3 +85,33 @@ size_t vm_page_order_to_bytes(vm_page_order_t order)
 
 	return page_order_bytes[order];
 }
+
+phys_addr_t vm_page_order_to_pages(vm_page_order_t order)
+{
+	if (order < 0 || order > VM_PAGE_MAX_ORDER) {
+		return 0;
+	}
+
+	return page_order_bytes[order] >> VM_PAGE_SHIFT;
+}
+
+vm_alignment_t vm_page_order_to_alignment(vm_page_order_t order)
+{
+	if (order < 0 || order > VM_PAGE_MAX_ORDER) {
+		return 0;
+	}
+
+	return ~(page_order_bytes[order] - 1);
+}
+
+
+size_t vm_bytes_to_pages(size_t bytes)
+{
+	if (bytes & (VM_PAGE_SIZE-1)) {
+		bytes &= ~(VM_PAGE_SIZE-1);
+		bytes += VM_PAGE_SIZE;
+	}
+
+	bytes >>= VM_PAGE_SHIFT;
+	return bytes;
+}

sandbox/vm/vm_zone.c

@@ -3,38 +3,88 @@
 #include <string.h>
 #include <stdio.h>
 #include <inttypes.h>
+#include <stdlib.h>
+
+static void convert_region_to_blocks(vm_zone_t *zone, phys_addr_t base, phys_addr_t limit, int reserved)
+{
+	size_t block_frames = vm_bytes_to_pages(limit - base);
+	printf("adding region %08zx-%08zx (%zu frames) to zone %s\n", base, limit, block_frames, zone->z_name);
+	int reset_order = 0;
+
+	for (int order = VM_PAGE_MAX_ORDER; order >= VM_PAGE_MIN_ORDER; ) {
+		size_t order_frames = vm_page_order_to_pages(order);
+		vm_alignment_t order_alignment = vm_page_order_to_alignment(order);
+
+		if (order_frames > block_frames) {
+			order--;
+			continue;
+		}
+
+		if (!VM_CHECK_ALIGN(base, order_alignment)) {
+			reset_order = 1;
+			order--;
+			continue;
+		}
+		
+		printf("%s: %zu %s pages at %08" PRIxPTR "\n",
+		       zone->z_name,
+		       order_frames,
+		       reserved == 1 ? "reserved" : "free",
+		       base);
+		
+		base += order_frames * VM_PAGE_SIZE;
+		block_frames -= order_frames;
+
+		if (reset_order) {
+			order = VM_PAGE_MAX_ORDER;
+			reset_order = 0;
+		} else {
+			order--;
+		}
+
+		if (base > limit) {
+			printf("too many pages created!\n");
+			abort();
+		} 
+
+		if (base == limit) {
+			break;
+		}
+	}
+}
 
 void vm_zone_init(vm_zone_t *z, const char *name, uintptr_t base, uintptr_t limit)
 {
+	printf("initialising zone %s (%08zx-%08zx)\n", name, base, limit);
 	memset(z, 0x0, sizeof *z);
 	z->z_name = name;
 
-	phys_addr_t block_start = 0;
+	phys_addr_t block_start = base, block_end = base;
-	int last_page_reserved = -1;
+	int this_page_reserved = 0, last_page_reserved = -1;
 	for (uintptr_t i = base; i < limit; i += VM_PAGE_SIZE) {
 		vm_page_t *pg = vm_page_get(i);
 		if (!pg) {
 			break;
 		}
 		
-		int this_page_reserved = (pg->p_flags & VM_PAGE_RESERVED) ? 1 : 0;
+		this_page_reserved = (pg->p_flags & VM_PAGE_RESERVED) ? 1 : 0;
 
 		if (last_page_reserved == -1) {
 			last_page_reserved = this_page_reserved;
 		}
 
 		if (this_page_reserved == last_page_reserved) {
+			block_end = i;
 			continue;
 		}
 
-		printf("%s: %zu %s pages at %" PRIxPTR "\n",
+		convert_region_to_blocks(z, block_start, i, this_page_reserved);
-		       name,
-		       (i - block_start) / VM_PAGE_SIZE,
-		       this_page_reserved == 1 ? "reserved" : "free",
-		       block_start);
 
 		block_start = i;
-		vm_page_order_t order = VM_PAGE_MAX_ORDER;
 		last_page_reserved = this_page_reserved;
 	}
+
+	if (block_start != block_end) {
+		convert_region_to_blocks(z, block_start, block_end, this_page_reserved);
+	}
 }