The VM can now ask the platform dependent part if it supports a specified protection.

create_area() and friends should fail if it's not supported.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@12248 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/arch/vm.h

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2004, Axel Dörfler, [email protected].
+ * Copyright 2002-2005, Axel Dörfler, [email protected].
  * Distributed under the terms of the MIT License.
  *
  * Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
@@ -21,6 +21,7 @@ status_t arch_vm_init(struct kernel_args *args);
 status_t arch_vm_init_post_area(struct kernel_args *args);
 status_t arch_vm_init_end(struct kernel_args *args);
 void arch_vm_aspace_swap(vm_address_space *aspace);
+bool arch_vm_supports_protection(uint32 protection);
 
 #ifdef __cplusplus
 }

src/kernel/core/arch/x86/arch_vm.c

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2004, Axel Dörfler, [email protected].
+ * Copyright 2002-2005, Axel Dörfler, [email protected].
  * Distributed under the terms of the MIT License.
  *
  * Copyright 2001, Travis Geiselbrecht. All rights reserved.
@@ -77,3 +77,18 @@ arch_vm_aspace_swap(vm_address_space *aspace)
 	i386_swap_pgdir((addr_t)i386_translation_map_get_pgdir(&aspace->translation_map));
 }
 
+
+bool
+arch_vm_supports_protection(uint32 protection)
+{
+	// x86 always has the same read/write properties for userland and the kernel.
+	// That's why we do not support user-read/kernel-write access. While the
+	// other way around is not supported either, we don't care in this case
+	// and give the kernel full access.
+	if ((protection & (B_READ_AREA | B_WRITE_AREA)) == B_READ_AREA
+		&& protection & B_KERNEL_WRITE_AREA)
+		return false;
+
+	return true;
+}
+