kxld_reloc.c   [plain text]

/*
 * Copyright (c) 2007-2020 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 <string.h>
#include <mach/boolean.h>
#include <sys/types.h>
#include <os/base.h>

#if KERNEL
    #include <libkern/libkern.h>
    #include <mach/machine.h>
#else
    #include <stdlib.h>
    #include <libkern/OSByteOrder.h>

/* Get machine.h from the kernel source so we can support all platforms
 * that the kernel supports. Otherwise we're at the mercy of the host.
 */
    #include "../../osfmk/mach/machine.h"
#endif

#define DEBUG_ASSERT_COMPONENT_NAME_STRING "kxld"
#include <AssertMacros.h>

#include "kxld_array.h"
#include "kxld_demangle.h"
#include "kxld_dict.h"
#include "kxld_reloc.h"
#include "kxld_sect.h"
#include "kxld_seg.h"
#include "kxld_sym.h"
#include "kxld_symtab.h"
#include "kxld_util.h"
#include "kxld_vtable.h"

#if KXLD_PIC_KEXTS
/* This will try to pull in mach/machine.h, so it has to come after the
 * explicit include above.
 */
#include <mach-o/loader.h>
#endif

/* include target-specific relocation prototypes */
#include <mach-o/reloc.h>
#if KXLD_USER_OR_X86_64
#include <mach-o/x86_64/reloc.h>
#endif
#if KXLD_USER_OR_ARM
#include <mach-o/arm/reloc.h>
#endif
#if KXLD_USER_OR_ARM64
#include <mach-o/arm64/reloc.h>
#endif

extern uint32_t     kaslr_offsets_index;
extern uint32_t     kaslr_offsets_count;
extern uint32_t    *kaslr_offsets;

#define KXLD_TARGET_NONE        (u_int) 0x0
#define KXLD_TARGET_VALUE       (u_int) 0x1
#define KXLD_TARGET_SECTNUM     (u_int) 0x2
#define KXLD_TARGET_SYMBOLNUM   (u_int) 0x3
#define KXLD_TARGET_LOOKUP      (u_int) 0x4
#define KXLD_TARGET_GOT         (u_int) 0x5

#define ABSOLUTE_VALUE(x) (((x) < 0) ? -(x) : (x))

#define LO16(x) (0x0000FFFF & x)
#define LO16S(x) ((0x0000FFFF & x) << 16)
#define HI16(x) (0xFFFF0000 & x)
#define HI16S(x) ((0xFFFF0000 & x) >> 16)
#define BIT15(x) (0x00008000 & x)
#define BR14I(x) (0xFFFF0003 & x)
#define BR14D(x) (0x0000FFFC & x)
#define BR24I(x) (0xFC000003 & x)
#define BR24D(x) (0x03FFFFFC & x)
#define HADISP 0x00010000
#define BR14_LIMIT 0x00008000
#define BR24_LIMIT 0x02000000
#define IS_COND_BR_INSTR(x) ((x & 0xFC000000) == 0x40000000)
#define IS_NOT_ALWAYS_TAKEN(x) ((x & 0x03E00000) != 0x02800000)
#define FLIP_PREDICT_BIT(x) x ^= 0x00200000

#define SIGN_EXTEND_MASK(n) (1 << ((n) - 1))
#define SIGN_EXTEND(x, n) (((x) ^ SIGN_EXTEND_MASK(n)) - SIGN_EXTEND_MASK(n))
#define BR14_NBITS_DISPLACEMENT 16
#define BR24_NBITS_DISPLACEMENT 26

#define X86_64_RIP_RELATIVE_LIMIT 0x80000000UL

/*******************************************************************************
* Prototypes
*******************************************************************************/
#if KXLD_USER_OR_I386
static boolean_t generic_reloc_has_pair(u_int _type)
__attribute__((const));
static u_int generic_reloc_get_pair_type(u_int _prev_type)
__attribute__((const));
static boolean_t generic_reloc_has_got(u_int _type)
__attribute__((const));
static kern_return_t generic_process_reloc(const KXLDRelocator *relocator,
    u_char *instruction, u_int length, u_int pcrel, kxld_addr_t base_pc,
    kxld_addr_t link_pc, kxld_addr_t link_disp, u_int type, kxld_addr_t target,
    kxld_addr_t pair_target, boolean_t swap);
#endif /* KXLD_USER_OR_I386 */

#if KXLD_USER_OR_X86_64
static boolean_t x86_64_reloc_has_pair(u_int _type)
__attribute__((const));
static u_int x86_64_reloc_get_pair_type(u_int _prev_type)
__attribute__((const));
static boolean_t x86_64_reloc_has_got(u_int _type)
__attribute__((const));
static kern_return_t x86_64_process_reloc(const KXLDRelocator *relocator,
    u_char *instruction, u_int length, u_int pcrel, kxld_addr_t base_pc,
    kxld_addr_t link_pc, kxld_addr_t link_disp, u_int type, kxld_addr_t target,
    kxld_addr_t pair_target, boolean_t swap);
static kern_return_t calculate_displacement_x86_64(uint64_t target,
    uint64_t adjustment, int32_t *instr32);
#endif /* KXLD_USER_OR_X86_64 */

#if KXLD_USER_OR_ARM
static boolean_t arm_reloc_has_pair(u_int _type)
__attribute__((const));
static u_int arm_reloc_get_pair_type(u_int _prev_type)
__attribute__((const));
static boolean_t arm_reloc_has_got(u_int _type)
__attribute__((const));
static kern_return_t arm_process_reloc(const KXLDRelocator *relocator,
    u_char *instruction, u_int length, u_int pcrel, kxld_addr_t base_pc,
    kxld_addr_t link_pc, kxld_addr_t link_disp, u_int type, kxld_addr_t target,
    kxld_addr_t pair_target, boolean_t swap);
#endif /* KXLD_USER_OR_ARM */

#if KXLD_USER_OR_ARM64
static boolean_t arm64_reloc_has_pair(u_int _type)
__attribute__((const));
static u_int arm64_reloc_get_pair_type(u_int _prev_type)
__attribute__((const));
static boolean_t arm64_reloc_has_got(u_int _type)
__attribute__((const));
static kern_return_t arm64_process_reloc(const KXLDRelocator *relocator,
    u_char *instruction, u_int length, u_int pcrel, kxld_addr_t base_pc,
    kxld_addr_t link_pc, kxld_addr_t link_disp, u_int type, kxld_addr_t target,
    kxld_addr_t pair_target, boolean_t swap);
#endif /* KXLD_USER_OR_ARM64 */

#if KXLD_USER_OR_ILP32
static kxld_addr_t get_pointer_at_addr_32(const KXLDRelocator *relocator,
    const u_char *data, u_long offset)
__attribute__((pure, nonnull));
#endif /* KXLD_USER_OR_ILP32 */
#if KXLD_USER_OR_LP64
static kxld_addr_t get_pointer_at_addr_64(const KXLDRelocator *relocator,
    const u_char *data, u_long offset)
__attribute__((pure, nonnull));
#endif /* KXLD_USER_OR_LP64 */

static u_int count_relocatable_relocs(const KXLDRelocator *relocator,
    const struct relocation_info *relocs, u_int nrelocs)
__attribute__((pure));

static kern_return_t calculate_targets(KXLDRelocator *relocator,
    kxld_addr_t *_target, kxld_addr_t *_pair_target, const KXLDReloc *reloc);

static kxld_addr_t align_raw_function_address(const KXLDRelocator *relocator,
    kxld_addr_t value);

static kern_return_t get_target_by_address_lookup(kxld_addr_t *target,
    kxld_addr_t addr, const KXLDArray *sectarray);

static kern_return_t check_for_direct_pure_virtual_call(
	const KXLDRelocator *relocator, u_long offset);

#if KXLD_PIC_KEXTS
static u_long get_macho_data_size_for_array(const KXLDArray *relocs);

static kern_return_t export_macho_for_array(const KXLDRelocator *relocator,
    const KXLDArray *relocs, struct relocation_info **dstp);
#endif /* KXLD_PIC_KEXTS */

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_relocator_init(KXLDRelocator *relocator, u_char *file,
    const KXLDSymtab *symtab, const KXLDArray *sectarray, cpu_type_t cputype,
    cpu_subtype_t cpusubtype __unused, boolean_t swap)
{
	kern_return_t rval = KERN_FAILURE;

	check(relocator);

	switch (cputype) {
#if KXLD_USER_OR_I386
	case CPU_TYPE_I386:
		relocator->reloc_has_pair = generic_reloc_has_pair;
		relocator->reloc_get_pair_type = generic_reloc_get_pair_type;
		relocator->reloc_has_got = generic_reloc_has_got;
		relocator->process_reloc = generic_process_reloc;
		relocator->function_align = 0;
		relocator->is_32_bit = TRUE;
		relocator->may_scatter = TRUE;
		break;
#endif /* KXLD_USER_OR_I386 */
#if KXLD_USER_OR_X86_64
	case CPU_TYPE_X86_64:
		relocator->reloc_has_pair = x86_64_reloc_has_pair;
		relocator->reloc_get_pair_type = x86_64_reloc_get_pair_type;
		relocator->reloc_has_got = x86_64_reloc_has_got;
		relocator->process_reloc = x86_64_process_reloc;
		relocator->function_align = 0;
		relocator->is_32_bit = FALSE;
		relocator->may_scatter = FALSE;
		break;
#endif /* KXLD_USER_OR_X86_64 */
#if KXLD_USER_OR_ARM
	case CPU_TYPE_ARM:
		relocator->reloc_has_pair = arm_reloc_has_pair;
		relocator->reloc_get_pair_type = arm_reloc_get_pair_type;
		relocator->reloc_has_got = arm_reloc_has_got;
		relocator->process_reloc = arm_process_reloc;
		relocator->function_align = 1;
		relocator->is_32_bit = TRUE;
		relocator->may_scatter = FALSE;
		break;
#endif /* KXLD_USER_OR_ARM */
#if KXLD_USER_OR_ARM64
	case CPU_TYPE_ARM64:
		relocator->reloc_has_pair = arm64_reloc_has_pair;
		relocator->reloc_get_pair_type = arm64_reloc_get_pair_type;
		relocator->reloc_has_got = arm64_reloc_has_got;
		relocator->process_reloc = arm64_process_reloc;
		relocator->function_align = 0;
		relocator->is_32_bit = FALSE;
		relocator->may_scatter = FALSE;
		break;
#endif /* KXLD_USER_OR_ARM64 */

	default:
		rval = KERN_FAILURE;
		kxld_log(kKxldLogLinking, kKxldLogErr,
		    kKxldLogArchNotSupported, cputype);
		goto finish;
	}

	relocator->file = file;
	relocator->symtab = symtab;
	relocator->sectarray = sectarray;
	relocator->is_32_bit = kxld_is_32_bit(cputype);
	relocator->swap = swap;

	rval = KERN_SUCCESS;

finish:
	return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_reloc_create_macho(KXLDArray *relocarray, const KXLDRelocator *relocator,
    const struct relocation_info *srcs, u_int nsrcs)
{
	kern_return_t rval = KERN_FAILURE;
	KXLDReloc *reloc = NULL;
	u_int nrelocs = 0;
	const struct relocation_info *src = NULL;
	const struct scattered_relocation_info *scatsrc = NULL;
	u_int i = 0;
	u_int reloc_index = 0;

	check(relocarray);
	check(srcs);

	/* If there are no relocation entries, just return */
	if (!nsrcs) {
		rval = KERN_SUCCESS;
		goto finish;
	}

	/* Count the number of non-pair relocs */
	nrelocs = count_relocatable_relocs(relocator, srcs, nsrcs);

	if (nrelocs) {
		/* Allocate the array of relocation entries */

		rval = kxld_array_init(relocarray, sizeof(KXLDReloc), nrelocs);
		require_noerr(rval, finish);

		/* Initialize the relocation entries */

		for (i = 0; i < nsrcs; ++i) {
			src = srcs + i;
			scatsrc = (const struct scattered_relocation_info *) src;

			/* A section-based relocation entry can be skipped for absolute
			 * symbols.
			 */

			if (!(relocator->may_scatter && (src->r_address & R_SCATTERED)) &&
			    !(src->r_extern) && (R_ABS == src->r_symbolnum)) {
				continue;
			}

			/* Pull out the data from the relocation entries.  The target_type
			 * depends on the r_extern bit:
			 *  Scattered -> Section Lookup by Address
			 *  Local (not extern) -> Section by Index
			 *  Extern -> Symbolnum by Index
			 */
			reloc = kxld_array_get_item(relocarray, reloc_index++);
			if (relocator->may_scatter && (src->r_address & R_SCATTERED)) {
				reloc->address = scatsrc->r_address;
				reloc->pcrel = scatsrc->r_pcrel;
				reloc->length = scatsrc->r_length;
				reloc->reloc_type = scatsrc->r_type;
				reloc->target = scatsrc->r_value;
				reloc->target_type = KXLD_TARGET_LOOKUP;
			} else {
				reloc->address = src->r_address;
				reloc->pcrel = src->r_pcrel;
				reloc->length = src->r_length;
				reloc->reloc_type = src->r_type;
				reloc->target = src->r_symbolnum;

				if (0 == src->r_extern) {
					reloc->target_type = KXLD_TARGET_SECTNUM;
					reloc->target -= 1;
				} else {
					reloc->target_type = KXLD_TARGET_SYMBOLNUM;
				}
			}

			/* Find the pair entry if it exists */

			if (relocator->reloc_has_pair(reloc->reloc_type)) {
				++i;
				require_action(i < nsrcs, finish, rval = KERN_FAILURE);

				src = srcs + i;
				scatsrc = (const struct scattered_relocation_info *) src;

				if (relocator->may_scatter && (src->r_address & R_SCATTERED)) {
					require_action(relocator->reloc_get_pair_type(
						    reloc->reloc_type) == scatsrc->r_type,
					    finish, rval = KERN_FAILURE);
					reloc->pair_address = scatsrc->r_address;
					reloc->pair_target = scatsrc->r_value;
					reloc->pair_target_type = KXLD_TARGET_LOOKUP;
				} else {
					require_action(relocator->reloc_get_pair_type(
						    reloc->reloc_type) == scatsrc->r_type,
					    finish, rval = KERN_FAILURE);
					reloc->pair_address = scatsrc->r_address;
					if (src->r_extern) {
						reloc->pair_target = src->r_symbolnum;
						reloc->pair_target_type = KXLD_TARGET_SYMBOLNUM;
					} else {
						reloc->pair_target = src->r_address;
						reloc->pair_target_type = KXLD_TARGET_VALUE;
					}
				}
			} else {
				reloc->pair_target = 0;
				if (relocator->reloc_has_got(reloc->reloc_type)) {
					reloc->pair_target_type = KXLD_TARGET_GOT;
				} else {
					reloc->pair_target_type = KXLD_TARGET_NONE;
				}
			}
		} // for...
	}
	rval = KERN_SUCCESS;

finish:
	return rval;
}


/*******************************************************************************
* Relocatable relocs :
*   1) Are not _PAIR_ relocs
*   2) Don't reference N_ABS symbols
*******************************************************************************/
static u_int
count_relocatable_relocs(const KXLDRelocator *relocator,
    const struct relocation_info *relocs, u_int nrelocs)
{
	u_int num_nonpair_relocs = 0;
	u_int i = 0;
	const struct relocation_info *reloc = NULL;
	const struct scattered_relocation_info *sreloc = NULL;

	check(relocator);
	check(relocs);

	/* Loop over all of the relocation entries */

	num_nonpair_relocs = 1;
	for (i = 1; i < nrelocs; ++i) {
		reloc = relocs + i;

		if (reloc->r_address & R_SCATTERED) {
			/* A scattered relocation entry is relocatable as long as it's not a
			 * pair.
			 */
			sreloc = (const struct scattered_relocation_info *) reloc;

			num_nonpair_relocs +=
			    !relocator->reloc_has_pair(sreloc->r_type);
		} else {
			/* A normal relocation entry is relocatable if it is not a pair and
			 * if it is not a section-based relocation for an absolute symbol.
			 */
			num_nonpair_relocs +=
			    !(relocator->reloc_has_pair(reloc->r_type)
			    || (0 == reloc->r_extern && R_ABS == reloc->r_symbolnum));
		}
	}

	return num_nonpair_relocs;
}

/*******************************************************************************
*******************************************************************************/
void
kxld_relocator_clear(KXLDRelocator *relocator)
{
	bzero(relocator, sizeof(*relocator));
}

/*******************************************************************************
*******************************************************************************/
boolean_t
kxld_relocator_has_pair(const KXLDRelocator *relocator, u_int r_type)
{
	check(relocator);

	return relocator->reloc_has_pair(r_type);
}

/*******************************************************************************
*******************************************************************************/
u_int
kxld_relocator_get_pair_type(const KXLDRelocator *relocator,
    u_int prev_r_type)
{
	check(relocator);

	return relocator->reloc_get_pair_type(prev_r_type);
}

/*******************************************************************************
*******************************************************************************/
boolean_t
kxld_relocator_has_got(const KXLDRelocator *relocator, u_int r_type)
{
	check(relocator);

	return relocator->reloc_has_got(r_type);
}

/*******************************************************************************
*******************************************************************************/
KXLDSym *
kxld_reloc_get_symbol(const KXLDRelocator *relocator, const KXLDReloc *reloc,
    const u_char *data)
{
	KXLDSym *sym = NULL;
	kxld_addr_t value = 0;

	check(reloc);

	switch (reloc->target_type) {
	case KXLD_TARGET_SYMBOLNUM:
		sym = kxld_symtab_get_symbol_by_index(relocator->symtab, reloc->target);
		break;
	case KXLD_TARGET_SECTNUM:
		if (data) {
			value = kxld_relocator_get_pointer_at_addr(relocator, data,
			    reloc->address);
			sym = kxld_symtab_get_cxx_symbol_by_value(relocator->symtab, value);
		}
		break;
	default:
		sym = NULL;
		break;
	}

	return sym;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_reloc_get_reloc_index_by_offset(const KXLDArray *relocs,
    kxld_size_t offset, u_int *idx)
{
	kern_return_t rval = KERN_FAILURE;
	KXLDReloc *reloc = NULL;
	u_int i = 0;

	for (i = 0; i < relocs->nitems; ++i) {
		reloc = kxld_array_get_item(relocs, i);
		if (reloc->address == offset) {
			break;
		}
	}

	if (i >= relocs->nitems) {
		rval = KERN_FAILURE;
		goto finish;
	}

	*idx = i;
	rval = KERN_SUCCESS;

finish:
	return rval;
}

/*******************************************************************************
*******************************************************************************/
KXLDReloc *
kxld_reloc_get_reloc_by_offset(const KXLDArray *relocs, kxld_addr_t offset)
{
	kern_return_t rval = KERN_FAILURE;
	KXLDReloc *reloc = NULL;
	u_int i = 0;

	rval = kxld_reloc_get_reloc_index_by_offset(relocs, offset, &i);
	if (rval) {
		goto finish;
	}

	reloc = kxld_array_get_item(relocs, i);

finish:
	return reloc;
}

#if KXLD_PIC_KEXTS
/*******************************************************************************
*******************************************************************************/
u_long
kxld_reloc_get_macho_header_size()
{
	return sizeof(struct dysymtab_command);
}

/*******************************************************************************
*******************************************************************************/
u_long
kxld_reloc_get_macho_data_size(
	const KXLDArray *locrelocs,
	const KXLDArray *extrelocs)
{
	u_long    rval = 0;

	rval += get_macho_data_size_for_array(locrelocs);
	rval += get_macho_data_size_for_array(extrelocs);

	return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_reloc_export_macho(const KXLDRelocator *relocator,
    const KXLDArray *locrelocs, const KXLDArray *extrelocs,
    u_char *buf, u_long *header_offset, u_long header_size,
    u_long *data_offset, u_long size)
{
	kern_return_t rval = KERN_FAILURE;
	struct dysymtab_command *dysymtabhdr = NULL;
	struct relocation_info *start = NULL;
	struct relocation_info *dst = NULL;
	u_long count = 0;
	u_long data_size = 0;

	check(locrelocs);
	check(extrelocs);
	check(buf);
	check(header_offset);
	check(data_offset);

	require_action(sizeof(*dysymtabhdr) <= header_size - *header_offset, finish, rval = KERN_FAILURE);
	dysymtabhdr = (struct dysymtab_command *) ((void *) (buf + *header_offset));
	*header_offset += sizeof(*dysymtabhdr);

	data_size = kxld_reloc_get_macho_data_size(locrelocs, extrelocs);
	require_action((*data_offset + data_size) <= size, finish, rval = KERN_FAILURE);

	start = dst = (struct relocation_info *) ((void *) (buf + *data_offset));

	if (kaslr_offsets == NULL) {
		kaslr_offsets_index = 0;
		kaslr_offsets_count = locrelocs->nitems + extrelocs->nitems;
		kaslr_offsets = (uint32_t *)calloc(kaslr_offsets_count, sizeof(*kaslr_offsets));
	}

	// copies the reloc data into the __LINKEDIT segment
	// data_offset is the new value for locreloff
	rval = export_macho_for_array(relocator, locrelocs, &dst);
	require_noerr(rval, finish);

	rval = export_macho_for_array(relocator, extrelocs, &dst);
	require_noerr(rval, finish);

	count = dst - start;

	memset(dysymtabhdr, 0, sizeof(*dysymtabhdr));
	dysymtabhdr->cmd = LC_DYSYMTAB;
	dysymtabhdr->cmdsize = (uint32_t) sizeof(*dysymtabhdr);
	dysymtabhdr->locreloff = (uint32_t) *data_offset;
	dysymtabhdr->nlocrel = (uint32_t) count;

	*data_offset += count * sizeof(struct relocation_info);

#if SPLIT_KEXTS_DEBUG
	kxld_log(kKxldLogLinking, kKxldLogErr,
	    "%p >>> Start of dysymtabhdr (size %lu) <%s> ",
	    (void *) dysymtabhdr,
	    sizeof(*dysymtabhdr),
	    __func__);
	kxld_log(kKxldLogLinking, kKxldLogErr,
	    "%p <<< End of dysymtabhdr <%s> ",
	    (void *) ((u_char *)dysymtabhdr + sizeof(*dysymtabhdr)),
	    __func__);

	kxld_log(kKxldLogLinking, kKxldLogErr,
	    "dysymtabhdr at %p: cmdsize %u indirectsymoff %u nindirectsyms %u extreloff %u nextrel %u locreloff %u nlocrel %u <%s>",
	    (void *) dysymtabhdr,
	    dysymtabhdr->cmdsize,
	    dysymtabhdr->indirectsymoff,
	    dysymtabhdr->nindirectsyms,
	    dysymtabhdr->extreloff,
	    dysymtabhdr->nextrel,
	    dysymtabhdr->locreloff,
	    dysymtabhdr->nlocrel,
	    __func__);
#endif

	rval = KERN_SUCCESS;
finish:
	return rval;
}
#endif /* KXLD_PIC_KEXTS */

/*******************************************************************************
*******************************************************************************/
kxld_addr_t
kxld_relocator_get_pointer_at_addr(const KXLDRelocator *relocator,
    const u_char *data, u_long offset)
{
	kxld_addr_t value;

	KXLD_3264_FUNC(relocator->is_32_bit, value,
	    get_pointer_at_addr_32, get_pointer_at_addr_64,
	    relocator, data, offset);

	return value;
}

#if KXLD_USER_OR_ILP32
/*******************************************************************************
*******************************************************************************/
static kxld_addr_t
get_pointer_at_addr_32(const KXLDRelocator *relocator,
    const u_char *data, u_long offset)
{
	uint32_t addr = 0;

	check(relocator);

	addr = *(const uint32_t *) ((const void *) (data + offset));
#if !KERNEL
	if (relocator->swap) {
		addr = OSSwapInt32(addr);
	}
#endif

	return align_raw_function_address(relocator, addr);
}
#endif /* KXLD_USER_OR_ILP32 */

#if KXLD_USER_OR_LP64
/*******************************************************************************
*******************************************************************************/
static kxld_addr_t
get_pointer_at_addr_64(const KXLDRelocator *relocator,
    const u_char *data, u_long offset)
{
	uint64_t addr = 0;

	check(relocator);

	addr = *(const uint64_t *) ((const void *) (data + offset));

#if !KERNEL
	if (relocator->swap) {
		addr = OSSwapInt64(addr);
	}
#endif

	return align_raw_function_address(relocator, addr);
}
#endif /* KXLD_USER_OR_LP64 */

/*******************************************************************************
*******************************************************************************/
void
kxld_relocator_set_vtables(KXLDRelocator *relocator, const KXLDDict *vtables)
{
	relocator->vtables = vtables;
}

/*******************************************************************************
* When we're inspecting the raw binary and not the symbol table, value may
* hold a THUMB address (with bit 0 set to 1) but the index will have the real
* address (bit 0 set to 0). So if bit 0 is set here, we clear it. This only
* impacts ARM for now, but it's implemented as a generic function alignment
* mask.
*******************************************************************************/
static kxld_addr_t
align_raw_function_address(const KXLDRelocator *relocator, kxld_addr_t value)
{
	if (relocator->function_align) {
		value &= ~((1ULL << relocator->function_align) - 1);
	}

	return value;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_relocator_process_sect_reloc(KXLDRelocator *relocator,
    const KXLDReloc *reloc, const KXLDSect *sect)
{
	kern_return_t rval = KERN_FAILURE;
	u_char *instruction = NULL;
	kxld_addr_t target = 0;
	kxld_addr_t pair_target = 0;
	kxld_addr_t base_pc = 0;
	kxld_addr_t link_pc = 0;
	kxld_addr_t link_disp = 0;

	check(relocator);
	check(reloc);
	check(sect);

	/* Find the instruction */

	instruction = sect->data + reloc->address;

	/* Calculate the target */

	rval = calculate_targets(relocator, &target, &pair_target, reloc);
	require_noerr(rval, finish);

	base_pc = reloc->address;
	link_pc = base_pc + sect->link_addr;
	link_disp = sect->link_addr - sect->base_addr;

	/* Relocate */

	rval = relocator->process_reloc(relocator, instruction, reloc->length,
	    reloc->pcrel, base_pc, link_pc, link_disp, reloc->reloc_type, target,
	    pair_target, relocator->swap);
	require_noerr(rval, finish);

	/* Return */

	relocator->current_vtable = NULL;
	rval = KERN_SUCCESS;

finish:
	return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_reloc_update_symindex(KXLDReloc *reloc, u_int symindex)
{
	kern_return_t rval = KERN_FAILURE;

	require_action(reloc->target_type == KXLD_TARGET_SYMBOLNUM,
	    finish, rval = KERN_FAILURE);

	reloc->target = symindex;

	rval = KERN_SUCCESS;

finish:
	return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_relocator_process_table_reloc(KXLDRelocator *relocator,
    const KXLDReloc *reloc,
    const KXLDSeg *seg,
    kxld_addr_t link_addr)
{
	kern_return_t rval = KERN_FAILURE;
	u_char *instruction = NULL;
	kxld_addr_t target = 0;
	kxld_addr_t pair_target = 0;
	kxld_addr_t base_pc = 0;
	kxld_addr_t link_pc = 0;
	u_long offset = 0;

	check(relocator);
	check(reloc);

	/* Find the instruction in original kext file we are trying to link */

	offset = (u_long)(seg->fileoff + (reloc->address - seg->base_addr));
	instruction = relocator->file + offset;

	/* Calculate the target */

	rval = calculate_targets(relocator, &target, &pair_target, reloc);
	require_noerr(rval, finish);

	base_pc = reloc->address;
	link_pc = base_pc + link_addr;
	if (kxld_seg_is_split_seg(seg)) {
		// link_pc for split segment special case, do not add in the base_pc
		link_pc = link_addr;
	}

	/* Relocate */

	rval = relocator->process_reloc(relocator, instruction, reloc->length,
	    reloc->pcrel, base_pc, link_pc, link_addr, reloc->reloc_type, target,
	    pair_target, relocator->swap);
	require_noerr(rval, finish);

	/* Return */

	relocator->current_vtable = NULL;
	rval = KERN_SUCCESS;

finish:
	return rval;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
calculate_targets(KXLDRelocator *relocator, kxld_addr_t *_target,
    kxld_addr_t *_pair_target, const KXLDReloc *reloc)
{
	kern_return_t rval = KERN_FAILURE;
	const KXLDSect *sect = NULL;
	const KXLDSym *sym = NULL;
	kxld_addr_t target = 0;
	kxld_addr_t pair_target = 0;
	char *demangled_name = NULL;
	size_t demangled_length = 0;

	check(_target);
	check(_pair_target);
	*_target = 0;
	*_pair_target = 0;

	/* Find the target based on the lookup type */

	switch (reloc->target_type) {
	case KXLD_TARGET_LOOKUP:
		require_action(reloc->pair_target_type == KXLD_TARGET_NONE ||
		    reloc->pair_target_type == KXLD_TARGET_LOOKUP ||
		    reloc->pair_target_type == KXLD_TARGET_VALUE,
		    finish, rval = KERN_FAILURE);

		rval = get_target_by_address_lookup(&target, reloc->target,
		    relocator->sectarray);
		require_noerr(rval, finish);

		if (reloc->pair_target_type == KXLD_TARGET_LOOKUP) {
			rval = get_target_by_address_lookup(&pair_target,
			    reloc->pair_target, relocator->sectarray);
			require_noerr(rval, finish);
		} else if (reloc->pair_target_type == KXLD_TARGET_VALUE) {
			pair_target = reloc->pair_target;
		}
		break;
	case KXLD_TARGET_SECTNUM:
		require_action(reloc->pair_target_type == KXLD_TARGET_NONE ||
		    reloc->pair_target_type == KXLD_TARGET_VALUE,
		    finish, rval = KERN_FAILURE);

		/* Get the target's section by section number */
		sect = kxld_array_get_item(relocator->sectarray, reloc->target);
		require_action(sect, finish, rval = KERN_FAILURE);

		/* target is the change in the section's address */
		target = sect->link_addr - sect->base_addr;

		if (reloc->pair_target_type) {
			pair_target = reloc->pair_target;
		} else {
			/* x86_64 needs to know when we have a non-external relocation,
			 * so we hack that information in here.
			 */
			pair_target = TRUE;
		}
		break;
	case KXLD_TARGET_SYMBOLNUM:
		require_action(reloc->pair_target_type == KXLD_TARGET_NONE ||
		    reloc->pair_target_type == KXLD_TARGET_GOT ||
		    reloc->pair_target_type == KXLD_TARGET_SYMBOLNUM ||
		    reloc->pair_target_type == KXLD_TARGET_VALUE, finish,
		    rval = KERN_FAILURE);

		/* Get the target's symbol by symbol number */
		sym = kxld_symtab_get_symbol_by_index(relocator->symtab, reloc->target);
		require_action(sym, finish, rval = KERN_FAILURE);

		/* If this symbol is a padslot that has already been replaced, then the
		 * only way a relocation entry can still reference it is if there is a
		 * vtable that has not been patched.  The vtable patcher uses the
		 * MetaClass structure to find classes for patching, so an unpatched
		 * vtable means that there is an OSObject-dervied class that is missing
		 * its OSDeclare/OSDefine macros.
		 */
		if (kxld_sym_is_padslot(sym) && kxld_sym_is_replaced(sym)) {
			kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogRelocatingPatchedSym,
			    kxld_demangle(sym->name, &demangled_name, &demangled_length));
		}

		target = sym->link_addr;

		if (kxld_sym_is_vtable(sym)) {
			relocator->current_vtable = kxld_dict_find(relocator->vtables, sym->name);
		}

		/* Some relocation types need the GOT entry address instead of the
		 * symbol's actual address.  These types don't have pair relocation
		 * entries, so we store the GOT entry address as the pair target.
		 */
		if (reloc->pair_target_type == KXLD_TARGET_VALUE) {
			pair_target = reloc->pair_target;
		} else if (reloc->pair_target_type == KXLD_TARGET_SYMBOLNUM) {
			sym = kxld_symtab_get_symbol_by_index(relocator->symtab,
			    reloc->pair_target);
			require_action(sym, finish, rval = KERN_FAILURE);
			pair_target = sym->link_addr;
		} else if (reloc->pair_target_type == KXLD_TARGET_GOT) {
			pair_target = sym->got_addr;
		}
		break;
	default:
		rval = KERN_FAILURE;
		goto finish;
	}

	*_target = target;
	*_pair_target = pair_target;
	rval = KERN_SUCCESS;

finish:
	if (demangled_name) {
		kxld_free(demangled_name, demangled_length);
	}
	return rval;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
get_target_by_address_lookup(kxld_addr_t *target, kxld_addr_t addr,
    const KXLDArray *sectarray)
{
	kern_return_t rval = KERN_FAILURE;
	const KXLDSect *sect = NULL;
	kxld_addr_t start = 0;
	kxld_addr_t end = 0;
	u_int i = 0;

	check(target);
	check(sectarray);
	*target = 0;

	for (i = 0; i < sectarray->nitems; ++i) {
		sect = kxld_array_get_item(sectarray, i);
		start = sect->base_addr;
		end = start + sect->size;

		if (start <= addr && addr < end) {
			break;
		}

		sect = NULL;
	}
	require_action(sect, finish, rval = KERN_FAILURE);

	*target = sect->link_addr - sect->base_addr;
	rval = KERN_SUCCESS;

finish:
	return rval;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
check_for_direct_pure_virtual_call(const KXLDRelocator *relocator, u_long offset)
{
	kern_return_t rval = KERN_FAILURE;
	const KXLDVTableEntry *entry = NULL;

	if (relocator->current_vtable) {
		entry = kxld_vtable_get_entry_for_offset(relocator->current_vtable,
		    offset, relocator->is_32_bit);
		require_action(!entry || !entry->patched.name ||
		    !kxld_sym_name_is_pure_virtual(entry->patched.name),
		    finish, rval = KERN_FAILURE;
		    kxld_log(kKxldLogLinking, kKxldLogErr,
		    kKxldLogDirectPureVirtualCall));
	}

	rval = KERN_SUCCESS;
finish:
	return rval;
}

#if KXLD_PIC_KEXTS
/*******************************************************************************
*******************************************************************************/
static u_long
get_macho_data_size_for_array(const KXLDArray *relocs)
{
	const KXLDReloc *reloc = NULL;
	u_int i = 0;
	u_long size = 0;

	check(relocs);

	for (i = 0; i < relocs->nitems; ++i) {
		reloc = kxld_array_get_item(relocs, i);
		if (!reloc->pcrel) {
			size += sizeof(struct relocation_info);
			if (reloc->pair_target_type != KXLD_TARGET_NONE) {
				size += sizeof(struct relocation_info);
			}
		}
	}

	return size;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
export_macho_for_array(const KXLDRelocator *relocator,
    const KXLDArray *relocs, struct relocation_info **dstp)
{
	kern_return_t rval = KERN_FAILURE;
	const KXLDReloc *reloc = NULL;
	struct relocation_info *dst = NULL;
	struct scattered_relocation_info *scatdst = NULL;
	u_int i = 0;

	dst = *dstp;

	for (i = 0; i < relocs->nitems; ++i) {
		reloc = kxld_array_get_item(relocs, i);
		scatdst = (struct scattered_relocation_info *) dst;

		if (reloc->pcrel) {
			continue;
		}

		switch (reloc->target_type) {
		case KXLD_TARGET_LOOKUP:
			if (kaslr_offsets) {
				if (kaslr_offsets_index >= kaslr_offsets_count) {
					kxld_log(kKxldLogLinking, kKxldLogErr,
					    "kaslr_offsets overflow %d > %d <%s> ",
					    kaslr_offsets_index, kaslr_offsets_count,
					    __func__);
					abort();
				}
				// reloc->address is really an offset from the start of the kext
				*(kaslr_offsets + kaslr_offsets_index++) = reloc->address;
			}
			scatdst->r_address = reloc->address;
			scatdst->r_pcrel = reloc->pcrel;
			scatdst->r_length = reloc->length;
			scatdst->r_type = reloc->reloc_type;
			scatdst->r_value = reloc->target;
			scatdst->r_scattered = 1;
			break;
		case KXLD_TARGET_SECTNUM:
			if (kaslr_offsets) {
				if (kaslr_offsets_index >= kaslr_offsets_count) {
					kxld_log(kKxldLogLinking, kKxldLogErr,
					    "kaslr_offsets overflow <%s> ", __func__);
					abort();
				}
				// reloc->address is really an offset from the start of the kext
				*(kaslr_offsets + kaslr_offsets_index++) = reloc->address;
			}
			dst->r_address = reloc->address;
			dst->r_pcrel = reloc->pcrel;
			dst->r_length = reloc->length;
			dst->r_type = reloc->reloc_type;
			dst->r_symbolnum = reloc->target + 1;
			dst->r_extern = 0;
			break;
		case KXLD_TARGET_SYMBOLNUM:
			/* Assume that everything will be slid together; otherwise,
			 * there is no sensible value for the section number.
			 */
			if (kaslr_offsets) {
				if (kaslr_offsets_index >= kaslr_offsets_count) {
					kxld_log(kKxldLogLinking, kKxldLogErr,
					    "kaslr_offsets overflow <%s> ", __func__);
					abort();
				}
				// reloc->address is really an offset from the start of the kext
				*(kaslr_offsets + kaslr_offsets_index++) = reloc->address;
			}
			dst->r_address = reloc->address;
			dst->r_pcrel = reloc->pcrel;
			dst->r_length = reloc->length;
			dst->r_type = reloc->reloc_type;
			dst->r_symbolnum = 1;
			dst->r_extern = 0;
			break;
		default:
			rval = KERN_FAILURE;
			goto finish;
		}

		++dst;

		if (reloc->pair_target_type != KXLD_TARGET_NONE) {
			++i;
			require_action(i < relocs->nitems, finish, rval = KERN_FAILURE);
			scatdst = (struct scattered_relocation_info *) dst;
			switch (reloc->pair_target_type) {
			case KXLD_TARGET_LOOKUP:
				scatdst->r_address = reloc->pair_address;
				scatdst->r_pcrel = reloc->pcrel;
				scatdst->r_length = reloc->length;
				scatdst->r_type = relocator->reloc_get_pair_type(reloc->reloc_type);
				scatdst->r_value = reloc->pair_target;
				scatdst->r_scattered = 1;
				break;
			case KXLD_TARGET_SECTNUM:
				dst->r_address = reloc->pair_address;
				dst->r_pcrel = reloc->pcrel;
				dst->r_length = reloc->length;
				dst->r_type = relocator->reloc_get_pair_type(reloc->reloc_type);
				dst->r_symbolnum = reloc->pair_target + 1;
				dst->r_extern = 0;
				break;
			case KXLD_TARGET_SYMBOLNUM:
				dst->r_address = reloc->pair_address;
				dst->r_pcrel = reloc->pcrel;
				dst->r_length = reloc->length;
				dst->r_type = relocator->reloc_get_pair_type(reloc->reloc_type);
				dst->r_symbolnum = 1;
				dst->r_extern = 0;
				break;
			default:
				rval = KERN_FAILURE;
				goto finish;
			}
			++dst;
		}
	}

	rval = KERN_SUCCESS;
finish:
	*dstp = dst;
	return rval;
}
#endif /* KXLD_PIC_KEXTS */

#if KXLD_USER_OR_I386
/*******************************************************************************
*******************************************************************************/
static boolean_t
generic_reloc_has_pair(u_int _type)
{
	enum reloc_type_generic type = _type;

	return type == GENERIC_RELOC_SECTDIFF ||
	       type == GENERIC_RELOC_LOCAL_SECTDIFF;
}

/*******************************************************************************
*******************************************************************************/
static u_int
generic_reloc_get_pair_type(u_int _prev_type __unused)
{
	return GENERIC_RELOC_PAIR;
}

/*******************************************************************************
*******************************************************************************/
static boolean_t
generic_reloc_has_got(u_int _type __unused)
{
	return FALSE;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
generic_process_reloc(const KXLDRelocator *relocator, u_char *instruction,
    u_int length, u_int pcrel, kxld_addr_t _base_pc, kxld_addr_t _link_pc,
    kxld_addr_t _link_disp __unused, u_int _type, kxld_addr_t _target,
    kxld_addr_t _pair_target, boolean_t swap __unused)
{
	kern_return_t rval = KERN_FAILURE;
	uint32_t base_pc = (uint32_t) _base_pc;
	uint32_t link_pc = (uint32_t) _link_pc;
	uint32_t *instr_addr = NULL;
	uint32_t instr_data = 0;
	uint32_t target = (uint32_t) _target;
	uint32_t pair_target = (uint32_t) _pair_target;
	enum reloc_type_generic type = _type;

	check(instruction);
	require_action(length == 2, finish, rval = KERN_FAILURE);

	if (pcrel) {
		target = target + base_pc - link_pc;
	}

	instr_addr = (uint32_t *) ((void *) instruction);
	instr_data = *instr_addr;

#if !KERNEL
	if (swap) {
		instr_data = OSSwapInt32(instr_data);
	}
#endif

	rval = check_for_direct_pure_virtual_call(relocator, instr_data);
	require_noerr(rval, finish);

	switch (type) {
	case GENERIC_RELOC_VANILLA:
		instr_data += target;
		break;
	case GENERIC_RELOC_SECTDIFF:
	case GENERIC_RELOC_LOCAL_SECTDIFF:
		instr_data = instr_data + target - pair_target;
		break;
	case GENERIC_RELOC_PB_LA_PTR:
		rval = KERN_FAILURE;
		goto finish;
	case GENERIC_RELOC_PAIR:
	default:
		rval = KERN_FAILURE;
		goto finish;
	}

#if !KERNEL
	if (swap) {
		instr_data = OSSwapInt32(instr_data);
	}
#endif

	*instr_addr = instr_data;

	rval = KERN_SUCCESS;

finish:
	return rval;
}
#endif /* KXLD_USER_OR_I386 */

#if KXLD_USER_OR_X86_64
/*******************************************************************************
*******************************************************************************/
static boolean_t
x86_64_reloc_has_pair(u_int _type)
{
	enum reloc_type_x86_64 type = _type;

	return type == X86_64_RELOC_SUBTRACTOR;
}

/*******************************************************************************
*******************************************************************************/
static u_int
x86_64_reloc_get_pair_type(u_int _prev_type __unused)
{
	return X86_64_RELOC_UNSIGNED;
}

/*******************************************************************************
*******************************************************************************/
static boolean_t
x86_64_reloc_has_got(u_int _type)
{
	enum reloc_type_x86_64 type = _type;

	return type == X86_64_RELOC_GOT_LOAD || type == X86_64_RELOC_GOT;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
x86_64_process_reloc(const KXLDRelocator *relocator __unused, u_char *instruction,
    u_int length, u_int pcrel, kxld_addr_t _base_pc __unused,
    kxld_addr_t _link_pc, kxld_addr_t _link_disp, u_int _type,
    kxld_addr_t _target, kxld_addr_t _pair_target, boolean_t swap __unused)
{
	kern_return_t rval = KERN_FAILURE;
	enum reloc_type_x86_64 type = _type;
	int32_t *instr32p = NULL;
	int32_t instr32 = 0;
	uint64_t *instr64p = NULL;
	uint64_t instr64 = 0;
	uint64_t target = _target;
	uint64_t pair_target = _pair_target;
	uint64_t link_pc = (uint64_t) _link_pc;
	uint64_t link_disp = (uint64_t) _link_disp;
	uint64_t adjustment = 0;

	check(instruction);
	require_action(length == 2 || length == 3,
	    finish, rval = KERN_FAILURE);

	if (length == 2) {
		instr32p = (int32_t *) ((void *) instruction);
		instr32 = *instr32p;

#if !KERNEL
		if (swap) {
			instr32 = OSSwapInt32(instr32);
		}
#endif

		rval = check_for_direct_pure_virtual_call(relocator, instr32);
		require_noerr(rval, finish);

		/* There are a number of different small adjustments for pc-relative
		 * relocation entries.  The general case is to subtract the size of the
		 * relocation (represented by the length parameter), and it applies to
		 * the GOT types and external SIGNED types.  The non-external signed types
		 * have a different adjustment corresponding to the specific type.
		 */
		switch (type) {
		case X86_64_RELOC_SIGNED:
			if (pair_target) {
				adjustment = 0;
				break;
			}
			OS_FALLTHROUGH;
		case X86_64_RELOC_SIGNED_1:
			if (pair_target) {
				adjustment = 1;
				break;
			}
			OS_FALLTHROUGH;
		case X86_64_RELOC_SIGNED_2:
			if (pair_target) {
				adjustment = 2;
				break;
			}
			OS_FALLTHROUGH;
		case X86_64_RELOC_SIGNED_4:
			if (pair_target) {
				adjustment = 4;
				break;
			}
			OS_FALLTHROUGH;
		case X86_64_RELOC_BRANCH:
		case X86_64_RELOC_GOT:
		case X86_64_RELOC_GOT_LOAD:
			adjustment = (1 << length);
			break;
		default:
			break;
		}

		/* Perform the actual relocation.  All of the 32-bit relocations are
		 * pc-relative except for SUBTRACTOR, so a good chunk of the logic is
		 * stuck in calculate_displacement_x86_64.  The signed relocations are
		 * a special case, because when they are non-external, the instruction
		 * already contains the pre-relocation displacement, so we only need to
		 * find the difference between how far the PC was relocated, and how
		 * far the target is relocated.  Since the target variable already
		 * contains the difference between the target's base and link
		 * addresses, we add the difference between the PC's base and link
		 * addresses to the adjustment variable.  This will yield the
		 * appropriate displacement in calculate_displacement.
		 */
		switch (type) {
		case X86_64_RELOC_BRANCH:
			require_action(pcrel, finish, rval = KERN_FAILURE);
			adjustment += link_pc;
			break;
		case X86_64_RELOC_SIGNED:
		case X86_64_RELOC_SIGNED_1:
		case X86_64_RELOC_SIGNED_2:
		case X86_64_RELOC_SIGNED_4:
			require_action(pcrel, finish, rval = KERN_FAILURE);
			adjustment += (pair_target) ? (link_disp) : (link_pc);
			break;
		case X86_64_RELOC_GOT:
		case X86_64_RELOC_GOT_LOAD:
			require_action(pcrel, finish, rval = KERN_FAILURE);
			adjustment += link_pc;
			target = pair_target;
			break;
		case X86_64_RELOC_SUBTRACTOR:
			require_action(!pcrel, finish, rval = KERN_FAILURE);
			instr32 = (int32_t) (target - pair_target);
			break;
		case X86_64_RELOC_UNSIGNED:
		default:
			rval = KERN_FAILURE;
			goto finish;
		}

		/* Call calculate_displacement for the pc-relative relocations */
		if (pcrel) {
			rval = calculate_displacement_x86_64(target, adjustment, &instr32);
			require_noerr(rval, finish);
		}

#if !KERNEL
		if (swap) {
			instr32 = OSSwapInt32(instr32);
		}
#endif

		*instr32p = instr32;
	} else {
		instr64p = (uint64_t *) ((void *) instruction);
		instr64 = *instr64p;

#if !KERNEL
		if (swap) {
			instr64 = OSSwapInt64(instr64);
		}
#endif

		rval = check_for_direct_pure_virtual_call(relocator, (u_long) instr64);
		require_noerr(rval, finish);

		switch (type) {
		case X86_64_RELOC_UNSIGNED:
			require_action(!pcrel, finish, rval = KERN_FAILURE);

			instr64 += target;
			break;
		case X86_64_RELOC_SUBTRACTOR:
			require_action(!pcrel, finish, rval = KERN_FAILURE);

			instr64 = target - pair_target;
			break;
		case X86_64_RELOC_SIGNED_1:
		case X86_64_RELOC_SIGNED_2:
		case X86_64_RELOC_SIGNED_4:
		case X86_64_RELOC_GOT_LOAD:
		case X86_64_RELOC_BRANCH:
		case X86_64_RELOC_SIGNED:
		case X86_64_RELOC_GOT:
		default:
			rval = KERN_FAILURE;
			goto finish;
		}

#if !KERNEL
		if (swap) {
			instr64 = OSSwapInt64(instr64);
		}
#endif
		*instr64p = instr64;
	}

	rval = KERN_SUCCESS;

finish:
	return rval;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
calculate_displacement_x86_64(uint64_t target, uint64_t adjustment,
    int32_t *instr32)
{
	kern_return_t rval = KERN_FAILURE;
	int64_t displacement;
	uint64_t difference;

	displacement = *instr32 + target - adjustment;
	difference = ABSOLUTE_VALUE(displacement);
	require_action(difference < X86_64_RIP_RELATIVE_LIMIT, finish,
	    rval = KERN_FAILURE;
	    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogRelocationOverflow));

	*instr32 = (int32_t) displacement;
	rval = KERN_SUCCESS;

finish:
	return rval;
}
#endif /* KXLD_USER_OR_X86_64 */

#if KXLD_USER_OR_ARM
/*******************************************************************************
*******************************************************************************/
static boolean_t
arm_reloc_has_pair(u_int _type)
{
	enum reloc_type_arm type = _type;

	switch (type) {
	case ARM_RELOC_SECTDIFF:
		return TRUE;
	default:
		return FALSE;
	}
	return FALSE;
}

/*******************************************************************************
*******************************************************************************/
static u_int
arm_reloc_get_pair_type(u_int _prev_type __unused)
{
	return ARM_RELOC_PAIR;
}

/*******************************************************************************
*******************************************************************************/
static boolean_t
arm_reloc_has_got(u_int _type __unused)
{
	return FALSE;
}

/*******************************************************************************
*******************************************************************************/
static kern_return_t
arm_process_reloc(const KXLDRelocator *relocator __unused, u_char *instruction,
    u_int length, u_int pcrel, kxld_addr_t _base_pc __unused,
    kxld_addr_t _link_pc __unused, kxld_addr_t _link_disp __unused,
    u_int _type __unused, kxld_addr_t _target __unused,
    kxld_addr_t _pair_target __unused, boolean_t swap __unused)
{
	kern_return_t rval = KERN_FAILURE;
	uint32_t *instr_addr = NULL;
	uint32_t instr_data = 0;
	uint32_t base_pc = (uint32_t) _base_pc;
	uint32_t link_pc = (uint32_t) _link_pc;
	uint32_t target = (uint32_t) _target;
	int32_t displacement = 0;
	enum reloc_type_arm type = _type;

	check(instruction);
	require_action(length == 2, finish, rval = KERN_FAILURE);

	if (pcrel) {
		displacement = target + base_pc - link_pc;
	}

	instr_addr = (uint32_t *) ((void *) instruction);
	instr_data = *instr_addr;

#if !KERNEL
	if (swap) {
		instr_data = OSSwapInt32(instr_data);
	}
#endif

	rval = check_for_direct_pure_virtual_call(relocator, instr_data);
	require_noerr(rval, finish);

	switch (type) {
	case ARM_RELOC_VANILLA:
		instr_data += target;
		break;

	/*
	 * If the displacement is 0 (the offset between the pc and the target has
	 * not changed), then we don't need to do anything for BR24 and BR22
	 * relocs.  As it turns out, because kexts build with -mlong-calls all
	 * relocations currently end up being either vanilla (handled above) or
	 * BR22/BR24 with a displacement of 0.
	 * We could handle other displacements here but to keep things simple, we
	 * won't until it is needed (at which point the kernelcache will fail to
	 * link)
	 */
	case ARM_RELOC_BR24:
		require_action(pcrel, finish, rval = KERN_FAILURE);
		require_action(displacement == 0, finish, rval = KERN_FAILURE);
		break;
	case ARM_THUMB_RELOC_BR22:
		require_action(pcrel, finish, rval = KERN_FAILURE);
		require_action(displacement == 0, finish, rval = KERN_FAILURE);
		break;

	case ARM_RELOC_SECTDIFF:
	case ARM_RELOC_LOCAL_SECTDIFF:
	case ARM_RELOC_PB_LA_PTR:
		rval = KERN_FAILURE;
		goto finish;

	case ARM_RELOC_PAIR:
	default:
		rval = KERN_FAILURE;
		goto finish;
	}

#if !KERNEL
	if (swap) {
		instr_data = OSSwapInt32(instr_data);
	}
#endif

	*instr_addr = instr_data;

	rval = KERN_SUCCESS;

finish:
	return rval;
}

#endif /* KXLD_USER_OR_ARM */

#if KXLD_USER_OR_ARM64
/*******************************************************************************
*******************************************************************************/
boolean_t
arm64_reloc_has_pair(u_int _type)
{
	return _type == ARM64_RELOC_SUBTRACTOR;
}

/*******************************************************************************
*******************************************************************************/
u_int
arm64_reloc_get_pair_type(u_int _prev_type __unused)
{
	if (_prev_type == ARM64_RELOC_SUBTRACTOR) {
		return ARM64_RELOC_UNSIGNED;
	} else {
		return -1u;
	}
}

/*******************************************************************************
*******************************************************************************/
boolean_t
arm64_reloc_has_got(u_int _type)
{
	return _type == ARM64_RELOC_GOT_LOAD_PAGE21 ||
	       _type == ARM64_RELOC_GOT_LOAD_PAGEOFF12;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
arm64_process_reloc(const KXLDRelocator *relocator __unused, u_char *instruction,
    u_int length, u_int pcrel, kxld_addr_t _base_pc __unused, kxld_addr_t _link_pc,
    kxld_addr_t _link_disp __unused, u_int _type, kxld_addr_t _target,
    kxld_addr_t _pair_target __unused, boolean_t swap)
{
	kern_return_t rval = KERN_FAILURE;
	enum reloc_type_arm64 type = _type;
	uint64_t target = _target;
	uint64_t link_pc = (uint64_t) _link_pc;
	uint64_t difference = 0;
	int64_t displacement = 0;
	uint32_t addend = 0;

	check(instruction);
	require_action((length == 2 || length == 3), finish, rval = KERN_FAILURE);

	if (length == 2) {
		uint32_t *instr32p = (uint32_t *) (void *) instruction;
		uint32_t instr32 = *instr32p;

#if !KERNEL
		if (swap) {
			instr32 = OSSwapInt32(instr32);
		}
#endif

		switch (type) {
		case ARM64_RELOC_BRANCH26:
			require_action(pcrel, finish, rval = KERN_FAILURE);
			addend = (instr32 & 0x03FFFFFF) << 2;
			addend = SIGN_EXTEND(addend, 27);
			displacement = (target - link_pc + addend);
			difference = ABSOLUTE_VALUE(displacement);
			displacement = (displacement >> 2);
			require_action(difference < (128 * 1024 * 1024), finish,
			    rval = KERN_FAILURE;
			    kxld_log(kKxldLogLinking, kKxldLogErr, kKxldLogRelocationOverflow));
			instr32 = (instr32 & 0xFC000000) | (displacement & 0x03FFFFFF);
			break;

		default:
			rval = KERN_FAILURE;
			goto finish;
		}

#if !KERNEL
		if (swap) {
			instr32 = OSSwapInt32(instr32);
		}
#endif

		*instr32p = instr32;
	} else { /* length == 3 */
		uint64_t *instr64p = (uint64_t *) (void *) instruction;
		uint64_t instr64 = *instr64p;

#if !KERNEL
		if (swap) {
			instr64 = OSSwapInt64(instr64);
		}
#endif

		switch (type) {
		case ARM64_RELOC_UNSIGNED:
			require_action(!pcrel, finish, rval = KERN_FAILURE);
			instr64 += target;
			break;
		default:
			rval = KERN_FAILURE;
			goto finish;
		}

#if !KERNEL
		if (swap) {
			instr64 = OSSwapInt64(instr64);
		}
#endif

		*instr64p = instr64;
	}

	rval = KERN_SUCCESS;
finish:
	return rval;
}


#endif /* KXLD_USER_OR_ARM64 */