xnu-1456.1.26.tar.gz

[apple/xnu.git] / osfmk / kern / kext_alloc.c

diff --git a/osfmk/kern/kext_alloc.c b/osfmk/kern/kext_alloc.c
new file mode 100644 (file)
index 0000000..407efcf
--- /dev/null
+++ b/osfmk/kern/kext_alloc.c
@@ -0,0 +1,140 @@
+/*
+ * Copyright (c) 2008 Apple Inc. All rights reserved.
+ *
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. The rights granted to you under the License
+ * may not be used to create, or enable the creation or redistribution of,
+ * unlawful or unlicensed copies of an Apple operating system, or to
+ * circumvent, violate, or enable the circumvention or violation of, any
+ * terms of an Apple operating system software license agreement.
+ * 
+ * Please obtain a copy of the License at
+ * http://www.opensource.apple.com/apsl/ and read it before using this file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
+ */
+#include <kern/assert.h>
+#include <kern/debug.h>
+#include <kern/kext_alloc.h>
+#include <kern/misc_protos.h>
+
+#include <mach/host_priv_server.h>
+#include <mach/kern_return.h>
+#include <mach/mach_vm.h>
+#include <mach/vm_map.h>
+#include <mach/vm_types.h>
+
+#include <mach-o/loader.h>
+#include <libkern/kernel_mach_header.h>
+
+#define KEXT_ALLOC_MAX_OFFSET (2 * 1024 * 1024 * 1024UL)
+
+vm_map_t g_kext_map = 0;
+static mach_vm_offset_t kext_alloc_base = 0;
+static mach_vm_offset_t kext_alloc_max = 0;
+
+/*
+ * On x86_64 systems, kernel extension text must remain within 2GB of the
+ * kernel's text segment.  To ensure this happens, we snag 2GB of kernel VM
+ * as early as possible for kext allocations.
+ */
+void 
+kext_alloc_init(void)
+{
+#if __x86_64__
+    kern_return_t rval = 0;
+    kernel_segment_command_t *text = NULL;
+    mach_vm_offset_t text_end, text_start;
+    mach_vm_size_t text_size;
+    mach_vm_size_t kext_alloc_size;
+
+    /* Determine the start of the kernel's __TEXT segment and determine the
+     * lower bound of the allocated submap for kext allocations.
+     */
+
+    text = getsegbyname(SEG_TEXT);
+    text_start = vm_map_trunc_page(text->vmaddr);
+    text_start &= ~((512ULL * 1024 * 1024 * 1024) - 1);
+    text_end = vm_map_round_page(text->vmaddr + text->vmsize);
+    text_size = text_end - text_start;
+
+    kext_alloc_base = text_end - KEXT_ALLOC_MAX_OFFSET;
+    kext_alloc_size = KEXT_ALLOC_MAX_OFFSET - text_size;
+    kext_alloc_max = kext_alloc_base + kext_alloc_size;
+
+    /* Allocate the subblock of the kernel map */
+
+    rval = kmem_suballoc(kernel_map, (vm_offset_t *) &kext_alloc_base, 
+                        kext_alloc_size, /* pageable */ TRUE,
+                        VM_FLAGS_FIXED|VM_FLAGS_OVERWRITE|VM_FLAGS_BELOW_MIN, 
+                        &g_kext_map);
+    if (rval != KERN_SUCCESS) {
+           panic("kext_alloc_init: kmem_suballoc failed 0x%x\n", rval);
+    }
+
+    if ((kext_alloc_base + kext_alloc_size) > kext_alloc_max) {
+        panic("kext_alloc_init: failed to get first 2GB\n");
+    }
+
+    if (kernel_map->min_offset > kext_alloc_base) {
+           kernel_map->min_offset = kext_alloc_base;
+    }
+
+    printf("kext submap [0x%llx - 0x%llx], kernel text [0x%llx - 0x%llx]\n",
+          kext_alloc_base, kext_alloc_max, text->vmaddr,
+          text->vmaddr + text->vmsize);
+#else
+    g_kext_map = kernel_map;
+    kext_alloc_base = VM_MIN_KERNEL_ADDRESS;
+    kext_alloc_max = VM_MAX_KERNEL_ADDRESS;
+#endif /* __x86_64__ */
+}
+
+kern_return_t
+kext_alloc(vm_offset_t *_addr, vm_size_t size, boolean_t fixed)
+{
+    kern_return_t rval = 0;
+    mach_vm_offset_t addr = (fixed) ? *_addr : kext_alloc_base;
+    int flags = (fixed) ? VM_FLAGS_FIXED : VM_FLAGS_ANYWHERE;
+ 
+    /* Allocate the kext virtual memory */
+    rval = mach_vm_allocate(g_kext_map, &addr, size, flags);
+    if (rval != KERN_SUCCESS) {
+        printf("vm_allocate failed - %d\n", rval);
+        goto finish;
+    }
+
+    /* Check that the memory is reachable by kernel text */
+    if ((addr + size) > kext_alloc_max) {
+        kext_free((vm_offset_t)addr, size);
+        goto finish;
+    }
+
+    *_addr = (vm_offset_t)addr;
+    rval = KERN_SUCCESS;
+
+finish:
+    return rval;
+}
+
+void 
+kext_free(vm_offset_t addr, vm_size_t size)
+{
+    kern_return_t rval;
+
+    rval = mach_vm_deallocate(g_kext_map, addr, size);
+    assert(rval == KERN_SUCCESS);
+}
+