xnu-7195.50.7.100.1.tar.gz

[apple/xnu.git] / libkern / kxld / kxld_seg.c

/*
 * 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 <string.h>
#include <mach/vm_prot.h>
#include <mach-o/loader.h>
#include <sys/types.h>

#if KERNEL
    #include <mach/vm_param.h>
#else
    #include <mach/mach_init.h>
#endif /* KERNEL */

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

#include "kxld_reloc.h"
#include "kxld_sect.h"
#include "kxld_seg.h"
#include "kxld_symtab.h"
#include "kxld_util.h"

#define MAX_SEGS 20

#define TEXT_SEG_PROT (VM_PROT_READ | VM_PROT_EXECUTE)
#define DATA_SEG_PROT (VM_PROT_READ | VM_PROT_WRITE)

extern boolean_t isSplitKext;
extern boolean_t isOldInterface;

#if KXLD_USER_OR_OBJECT
static kern_return_t reorder_sections(KXLDSeg *seg, KXLDArray *section_order);
static void reorder_section(KXLDArray *sects, u_int *sect_reorder_index,
    KXLDSect **reorder_buffer, u_int reorder_buffer_index);
#endif /* KXLD_USER_OR_OBJECT */

#if 0
static KXLDSeg * get_segment_by_name(KXLDArray *segarray, const char *name);
#endif

#if KXLD_USER_OR_ILP32
static kern_return_t seg_export_macho_header_32(const KXLDSeg *seg, u_char *buf,
    u_long *header_offset, u_long header_size, u_long data_offset);
#endif
#if KXLD_USER_OR_LP64
static kern_return_t seg_export_macho_header_64(const KXLDSeg *seg, u_char *buf,
    u_long *header_offset, u_long header_size, u_long data_offset);
#endif

static KXLDSect * get_sect_by_index(const KXLDSeg *seg, u_int idx);

#if KXLD_USER_OR_ILP32
/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_seg_init_from_macho_32(KXLDSeg *seg, struct segment_command *src)
{
	kern_return_t rval = KERN_FAILURE;
	check(seg);
	check(src);

	strlcpy(seg->segname, src->segname, sizeof(seg->segname));
	seg->base_addr = src->vmaddr;
	seg->link_addr = src->vmaddr;
	seg->vmsize = src->vmsize;
	seg->fileoff = src->fileoff;
	seg->maxprot = src->maxprot;
	seg->initprot = src->initprot;
	seg->flags = src->flags;

	rval = kxld_array_init(&seg->sects, sizeof(KXLDSect *), src->nsects);
	require_noerr(rval, finish);

	rval = KERN_SUCCESS;

finish:
	return rval;
}
#endif /* KXLD_USER_OR_ILP32 */

#if KXLD_USER_OR_LP64
/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_seg_init_from_macho_64(KXLDSeg *seg, struct segment_command_64 *src)
{
	kern_return_t rval = KERN_FAILURE;
	check(seg);
	check(src);

	strlcpy(seg->segname, src->segname, sizeof(seg->segname));
	seg->base_addr = src->vmaddr;
	seg->link_addr = src->vmaddr;
	seg->vmsize = src->vmsize;

	seg->fileoff = src->fileoff;
	seg->maxprot = src->maxprot;
	seg->initprot = src->initprot;
	seg->flags = src->flags;

	rval = kxld_array_init(&seg->sects, sizeof(KXLDSect *), src->nsects);
	require_noerr(rval, finish);

	rval = KERN_SUCCESS;

finish:
	return rval;
}
#endif /* KXLD_USER_OR_LP64 */

#if KXLD_USER_OR_OBJECT
/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_seg_create_seg_from_sections(KXLDArray *segarray, KXLDArray *sectarray)
{
	kern_return_t rval = KERN_FAILURE;
	KXLDSeg *seg = NULL;
	KXLDSect *sect = NULL;
	KXLDSect **sectp = NULL;
	u_int i = 0;

	/* Initialize the segment array to one segment */

	rval = kxld_array_init(segarray, sizeof(KXLDSeg), 1);
	require_noerr(rval, finish);

	/* Initialize the segment */

	seg = kxld_array_get_item(segarray, 0);
	seg->initprot = VM_PROT_ALL;
	seg->maxprot = VM_PROT_ALL;
	seg->link_addr = 0;

	/* Add the sections to the segment */

	rval = kxld_array_init(&seg->sects, sizeof(KXLDSect *), sectarray->nitems);
	require_noerr(rval, finish);

	for (i = 0; i < sectarray->nitems; ++i) {
		sect = kxld_array_get_item(sectarray, i);
		sectp = kxld_array_get_item(&seg->sects, i);

		*sectp = sect;
	}

	rval = KERN_SUCCESS;
finish:
	return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_seg_finalize_object_segment(KXLDArray *segarray, KXLDArray *section_order,
    u_long hdrsize)
{
	kern_return_t rval = KERN_FAILURE;
	KXLDSeg *seg = NULL;
	KXLDSect *sect = NULL;
	u_long sect_offset = 0;
	u_int i = 0;

	check(segarray);
	check(section_order);
	require_action(segarray->nitems == 1, finish, rval = KERN_FAILURE);

	seg = kxld_array_get_item(segarray, 0);

	/* Reorder the sections */

	rval = reorder_sections(seg, section_order);
	require_noerr(rval, finish);

	/* Set the initial link address at the end of the header pages */

	seg->link_addr = kxld_round_page_cross_safe(hdrsize);

	/* Fix up all of the section addresses */

	sect_offset = (u_long) seg->link_addr;
	for (i = 0; i < seg->sects.nitems; ++i) {
		sect = *(KXLDSect **)kxld_array_get_item(&seg->sects, i);

		sect->link_addr = kxld_sect_align_address(sect, sect_offset);
		sect_offset = (u_long) (sect->link_addr + sect->size);
	}

	/* Finish initializing the segment */

	seg->vmsize = kxld_round_page_cross_safe(sect_offset) - seg->link_addr;

	rval = KERN_SUCCESS;
finish:
	return rval;
}

/*******************************************************************************
* The legacy section ordering used by kld was based of the order of sections
* in the kernel file.  To achieve the same layout, we save the kernel's
* section ordering as an array of section names when the kernel file itself
* is linked.  Then, when kexts are linked with the KXLD_LEGACY_LAYOUT flag,
* we refer to the kernel's section layout to order the kext's sections.
*
* The algorithm below is as follows.  We iterate through all of the kernel's
* sections grouped by segment name, so that we are processing all of the __TEXT
* sections, then all of the __DATA sections, etc.  We then iterate through the
* kext's sections with a similar grouping, looking for sections that match
* the current kernel's section.  In this way, we order all of the matching
* kext sections in the order in which they appear in the kernel, and then place
* all remaining kext sections at the end of the current segment grouping in
* the order in which they originally appeared.  Sections that only appear in
* the kernel are not created.  segments that only appear in the kext are
* left in their original ordering.
*
* An example:
*
* Kernel sections:
* __TEXT,__text
* __TEXT,__const
* __DATA,__data
*
* Kext sections:
* __TEXT,__const
* __TEXT,__literal4
* __TEXT,__text
* __DATA,__const
* __DATA,__data
*
* Reordered kext sections:
* __TEXT,__text
* __TEXT,__const
* __TEXT,__literal4
* __DATA,__data
* __DATA,__const
*
* In the implementation below, we use a reorder buffer to hold pointers to the
* sections of the current working segment.  We scan this buffer looking for
* matching sections, placing them in the segment's section index as we find them.
* If this function must exit early, the segment's section index is left in an
* unusable state.
*******************************************************************************/
static kern_return_t
reorder_sections(KXLDSeg *seg, KXLDArray *section_order)
{
	kern_return_t rval = KERN_FAILURE;
	KXLDSect *sect = NULL;
	KXLDSect **reorder_buffer = NULL;
	KXLDSectionName *section_name = NULL;
	const char *segname = NULL;
	u_int sect_index = 0, legacy_index = 0, sect_reorder_index = 0;
	u_int i = 0, j = 0;
	u_int sect_start = 0, sect_end = 0, legacy_start = 0, legacy_end = 0;
	u_int nsects = 0;

	check(seg);
	check(section_order);

	/* Allocate the reorder buffer with enough space to hold all of the
	 * sections.
	 */

	reorder_buffer = kxld_alloc(
		seg->sects.nitems * sizeof(*reorder_buffer));
	require_action(reorder_buffer, finish, rval = KERN_RESOURCE_SHORTAGE);

	while (legacy_index < section_order->nitems) {
		/* Find the next group of sections with a common segment in the
		 * section_order array.
		 */

		legacy_start = legacy_index++;
		legacy_end = legacy_index;

		section_name = kxld_array_get_item(section_order, legacy_start);
		segname = section_name->segname;
		while (legacy_index < section_order->nitems) {
			section_name = kxld_array_get_item(section_order, legacy_index);
			if (!streq_safe(segname, section_name->segname,
			    sizeof(section_name->segname))) {
				break;
			}

			++legacy_index;
			++legacy_end;
		}

		/* Find a group of sections in the kext that match the current
		 * section_order segment.
		 */

		sect_start = sect_index;
		sect_end = sect_index;

		while (sect_index < seg->sects.nitems) {
			sect = *(KXLDSect **) kxld_array_get_item(&seg->sects, sect_index);
			if (!streq_safe(segname, sect->segname, sizeof(sect->segname))) {
				break;
			}

			++sect_index;
			++sect_end;
		}
		nsects = sect_end - sect_start;

		if (!nsects) {
			continue;
		}

		/* Populate the reorder buffer with the current group of kext sections */

		for (i = sect_start; i < sect_end; ++i) {
			reorder_buffer[i - sect_start] =
			    *(KXLDSect **) kxld_array_get_item(&seg->sects, i);
		}

		/* For each section_order section, scan the reorder buffer for a matching
		 * kext section.  If one is found, copy it into the next slot in the
		 * segment's section index.
		 */

		sect_reorder_index = sect_start;
		for (i = legacy_start; i < legacy_end; ++i) {
			section_name = kxld_array_get_item(section_order, i);
			sect = NULL;

			for (j = 0; j < nsects; ++j) {
				sect = reorder_buffer[j];
				if (!sect) {
					continue;
				}

				if (streq_safe(section_name->sectname, sect->sectname,
				    sizeof(section_name->sectname))) {
					break;
				}

				sect = NULL;
			}

			if (sect) {
				(void) reorder_section(&seg->sects, &sect_reorder_index,
				    reorder_buffer, j);
			}
		}

		/* If any sections remain in the reorder buffer, they are not specified
		 * in the section_order array, so append them to the section index in
		 * in the order they are found.
		 */

		for (i = 0; i < nsects; ++i) {
			if (!reorder_buffer[i]) {
				continue;
			}
			reorder_section(&seg->sects, &sect_reorder_index, reorder_buffer, i);
		}
	}

	rval = KERN_SUCCESS;

finish:

	if (reorder_buffer) {
		kxld_free(reorder_buffer, seg->sects.nitems * sizeof(*reorder_buffer));
		reorder_buffer = NULL;
	}

	return rval;
}

/*******************************************************************************
*******************************************************************************/
static void
reorder_section(KXLDArray *sects, u_int *sect_reorder_index,
    KXLDSect **reorder_buffer, u_int reorder_buffer_index)
{
	KXLDSect **tmp = NULL;

	tmp = kxld_array_get_item(sects, *sect_reorder_index);

	*tmp = reorder_buffer[reorder_buffer_index];
	reorder_buffer[reorder_buffer_index]->sectnum = *sect_reorder_index;
	reorder_buffer[reorder_buffer_index] = NULL;

	++(*sect_reorder_index);
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_seg_init_linkedit(KXLDArray *segs)
{
	kern_return_t rval = KERN_FAILURE;
	KXLDSeg *seg = NULL;
	KXLDSeg *le = NULL;

	rval = kxld_array_resize(segs, 2);
	require_noerr(rval, finish);

	seg = kxld_array_get_item(segs, 0);
	le = kxld_array_get_item(segs, 1);

	strlcpy(le->segname, SEG_LINKEDIT, sizeof(le->segname));
	le->link_addr = kxld_round_page_cross_safe(seg->link_addr + seg->vmsize);
	le->maxprot = VM_PROT_ALL;
	le->initprot = VM_PROT_DEFAULT;

	rval = KERN_SUCCESS;

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

/*******************************************************************************
*******************************************************************************/
void
kxld_seg_clear(KXLDSeg *seg)
{
	check(seg);

	bzero(seg->segname, sizeof(seg->segname));
	seg->base_addr = 0;
	seg->link_addr = 0;
	seg->vmsize = 0;
	seg->flags = 0;
	seg->maxprot = 0;
	seg->initprot = 0;

	/* Don't clear the individual sections here because kxld_kext.c will take
	 * care of that.
	 */
	kxld_array_clear(&seg->sects);
}

/*******************************************************************************
*******************************************************************************/
void
kxld_seg_deinit(KXLDSeg *seg)
{
	check(seg);

	kxld_array_deinit(&seg->sects);
	bzero(seg, sizeof(*seg));
}

/*******************************************************************************
*******************************************************************************/
kxld_size_t
kxld_seg_get_vmsize(const KXLDSeg *seg)
{
	check(seg);

	return seg->vmsize;
}

/*******************************************************************************
*******************************************************************************/
u_long
kxld_seg_get_macho_header_size(const KXLDSeg *seg, boolean_t is_32_bit)
{
	u_long size = 0;

	check(seg);

	if (is_32_bit) {
		size += sizeof(struct segment_command);
	} else {
		size += sizeof(struct segment_command_64);
	}
	size += seg->sects.nitems * kxld_sect_get_macho_header_size(is_32_bit);

	return size;
}

/*******************************************************************************
*******************************************************************************/
/* This is no longer used, but may be useful some day... */
#if 0
u_long
kxld_seg_get_macho_data_size(const KXLDSeg *seg)
{
	u_long size = 0;
	u_int i = 0;
	KXLDSect *sect = NULL;

	check(seg);

	for (i = 0; i < seg->sects.nitems; ++i) {
		sect = get_sect_by_index(seg, i);
		size = (u_long) kxld_sect_align_address(sect, size);
		size += kxld_sect_get_macho_data_size(sect);
	}

	return kxld_round_page_cross_safe(size);
}
#endif

/*******************************************************************************
*******************************************************************************/
static KXLDSect *
get_sect_by_index(const KXLDSeg *seg, u_int idx)
{
	check(seg);

	return *(KXLDSect **) kxld_array_get_item(&seg->sects, idx);
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_seg_export_macho_to_file_buffer(const KXLDSeg *seg, u_char *buf,
    u_long *header_offset, u_long header_size,
    u_long *data_offset, u_long data_size,
    boolean_t is_32_bit)
{
	kern_return_t rval = KERN_FAILURE;
	KXLDSect *sect = NULL;
	u_long base_data_offset = *data_offset;
	u_int i = 0;
	struct segment_command *hdr32 =
	    (struct segment_command *) ((void *) (buf + *header_offset));
	struct segment_command_64 *hdr64 =
	    (struct segment_command_64 *) ((void *) (buf + *header_offset));

	check(seg);
	check(buf);
	check(header_offset);
	check(data_offset);

	/* Write out the header */

	KXLD_3264_FUNC(is_32_bit, rval,
	    seg_export_macho_header_32, seg_export_macho_header_64,
	    seg, buf, header_offset, header_size, *data_offset);
	require_noerr(rval, finish);

	/* Write out each section */

	for (i = 0; i < seg->sects.nitems; ++i) {
		sect = get_sect_by_index(seg, i);

		rval = kxld_sect_export_macho_to_file_buffer(sect, buf, header_offset,
		    header_size, data_offset, data_size, is_32_bit);
		require_noerr(rval, finish);
	}

	/* Update the filesize */

	if (is_32_bit) {
		hdr32->filesize = (uint32_t) (*data_offset - base_data_offset);
	} else {
		hdr64->filesize = (uint64_t) (*data_offset - base_data_offset);
	}

	*data_offset = (u_long)kxld_round_page_cross_safe(*data_offset);

	rval = KERN_SUCCESS;

finish:
	return rval;
}


/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_seg_export_macho_to_vm(const KXLDSeg *seg,
    u_char *buf,
    u_long *header_offset,
    u_long header_size,
    u_long data_size,
    kxld_addr_t file_link_addr,
    boolean_t is_32_bit)
{
	kern_return_t   rval = KERN_FAILURE;
	KXLDSect *      sect = NULL;

	// data_offset is used to set fileoff field in segment header
	u_long          data_offset;
	u_int           i = 0;

	check(seg);
	check(buf);
	check(header_offset);

	data_offset = (u_long) (seg->link_addr - file_link_addr);

	/* Write out the header */

	KXLD_3264_FUNC(is_32_bit, rval,
	    seg_export_macho_header_32, seg_export_macho_header_64,
	    seg,
	    buf,
	    header_offset, header_size, data_offset);
	require_noerr(rval, finish);

	/* Write out each section */

	for (i = 0; i < seg->sects.nitems; ++i) {
		sect = get_sect_by_index(seg, i);

		rval = kxld_sect_export_macho_to_vm(sect, buf, header_offset,
		    header_size, file_link_addr, data_size, is_32_bit);
		require_noerr(rval, finish);
	}

	rval = KERN_SUCCESS;

finish:
	return rval;
}

#if KXLD_USER_OR_ILP32
/*******************************************************************************
*******************************************************************************/
static kern_return_t
seg_export_macho_header_32(const KXLDSeg *seg, u_char *buf,
    u_long *header_offset, u_long header_size, u_long data_offset)
{
	kern_return_t rval = KERN_FAILURE;
	struct segment_command *seghdr = NULL;

	check(seg);
	check(buf);
	check(header_offset);

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

	seghdr->cmd = LC_SEGMENT;
	seghdr->cmdsize = (uint32_t) sizeof(*seghdr);
	seghdr->cmdsize +=
	    (uint32_t) (seg->sects.nitems * kxld_sect_get_macho_header_size(TRUE));
	strlcpy(seghdr->segname, seg->segname, sizeof(seghdr->segname));
	seghdr->vmaddr = (uint32_t) seg->link_addr;
	seghdr->vmsize = (uint32_t) seg->vmsize;
	seghdr->fileoff = (uint32_t) data_offset;
	seghdr->filesize = (uint32_t) seg->vmsize;
	seghdr->maxprot = seg->maxprot;
	seghdr->initprot = seg->initprot;
	seghdr->nsects = seg->sects.nitems;
	seghdr->flags = 0;

#if SPLIT_KEXTS_DEBUG
	{
		kxld_log(kKxldLogLinking, kKxldLogErr,
		    "segname %s seghdr %p vmaddr %p vmsize 0x%02X %u fileoff 0x%02X %u <%s>",
		    seg->segname[0] ? seg->segname : "none",
		    (void *) seghdr,
		    (void *) ((uint64_t)seghdr->vmaddr),
		    seghdr->vmsize,
		    seghdr->vmsize,
		    seghdr->fileoff,
		    seghdr->fileoff,
		    __func__);
	}
#endif

	rval = KERN_SUCCESS;

finish:
	return rval;
}
#endif /* KXLD_USER_OR_ILP32 */

#if KXLD_USER_OR_LP64
/*******************************************************************************
*******************************************************************************/
static kern_return_t
seg_export_macho_header_64(const KXLDSeg *seg, u_char *buf,
    u_long *header_offset, u_long header_size, u_long data_offset)
{
	kern_return_t rval = KERN_FAILURE;
	struct segment_command_64 *seghdr = NULL;

	check(seg);
	check(buf);
	check(header_offset);

	require_action(sizeof(*seghdr) <= header_size - *header_offset, finish,
	    rval = KERN_FAILURE);

#if SPLIT_KEXTS_DEBUG
	{
		struct mach_header_64 *mach;

		mach = (struct mach_header_64 *) ((void *) buf);

		if (mach->magic != MH_MAGIC_64) {
			kxld_log(kKxldLogLinking, kKxldLogErr,
			    "bad macho header at %p <%s>",
			    (void *) mach, __func__);
			goto finish;
		}
	}
#endif

	seghdr = (struct segment_command_64 *) ((void *) (buf + *header_offset));
	*header_offset += sizeof(*seghdr);

	seghdr->cmd = LC_SEGMENT_64;
	seghdr->cmdsize = (uint32_t) sizeof(*seghdr);
	seghdr->cmdsize +=
	    (uint32_t) (seg->sects.nitems * kxld_sect_get_macho_header_size(FALSE));
	strlcpy(seghdr->segname, seg->segname, sizeof(seghdr->segname));
	seghdr->vmaddr = (uint64_t) seg->link_addr;
	seghdr->vmsize = (uint64_t) seg->vmsize;
	seghdr->fileoff = (uint64_t) data_offset;
	seghdr->filesize = (uint64_t) seg->vmsize;
	seghdr->maxprot = seg->maxprot;
	seghdr->initprot = seg->initprot;
	seghdr->nsects = seg->sects.nitems;
	seghdr->flags = 0;

#if SPLIT_KEXTS_DEBUG
	{
		kxld_log(kKxldLogLinking, kKxldLogErr,
		    "%p >>> Start of %s seghdr (size %lu) <%s>",
		    (void *) seghdr,
		    seg->segname[0] ? seg->segname : "none",
		    sizeof(*seghdr),
		    __func__);
		kxld_log(kKxldLogLinking, kKxldLogErr,
		    "%p <<< End of %s seghdr <%s>",
		    (void *) ((u_char *)seghdr + sizeof(*seghdr)),
		    seg->segname[0] ? seg->segname : "none",
		    __func__);

		kxld_log(kKxldLogLinking, kKxldLogErr,
		    "%s seghdr, cmdsize %d vmaddr %p vmsize %p %llu fileoff %p %llu <%s>",
		    seg->segname[0] ? seg->segname : "none",
		    seghdr->cmdsize,
		    (void *) seghdr->vmaddr,
		    (void *) seghdr->vmsize,
		    seghdr->vmsize,
		    (void *) seghdr->fileoff,
		    seghdr->fileoff,
		    __func__);
	}
#endif

	rval = KERN_SUCCESS;

finish:
	return rval;
}
#endif /* KXLD_USER_OR_LP64 */

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_seg_add_section(KXLDSeg *seg, KXLDSect *sect)
{
	kern_return_t rval = KERN_FAILURE;
	KXLDSect **sectp = NULL;
	u_int i;

	check(seg);
	check(sect);
	require_action(streq_safe(seg->segname, sect->segname, sizeof(seg->segname)),
	    finish, rval = KERN_FAILURE);

	/* Add the section into the section index */

	for (i = 0; i < seg->sects.nitems; ++i) {
		sectp = kxld_array_get_item(&seg->sects, i);
		if (NULL == *sectp) {
			*sectp = sect;
			break;
		}
	}
	require_action(i < seg->sects.nitems, finish, rval = KERN_FAILURE);

	rval = KERN_SUCCESS;

finish:

	return rval;
}

/*******************************************************************************
*******************************************************************************/
kern_return_t
kxld_seg_finish_init(KXLDSeg *seg)
{
	kern_return_t rval = KERN_FAILURE;
	u_int i = 0;
	KXLDSect *sect = NULL;
	kxld_addr_t maxaddr = 0;
	kxld_size_t maxsize = 0;

	/* If we already have a size for this segment (e.g. from the mach-o load
	 * command) then don't recalculate the segment size. This is safer since
	 * when we recalculate we are making assumptions about page alignment and
	 * padding that the kext mach-o file was built with. Better to trust the
	 * macho-o info, if we have it. If we don't (i.e. vmsize == 0) then add up
	 * the section sizes and take a best guess at page padding.
	 */
	if ((seg->vmsize == 0) && (seg->sects.nitems)) {
		for (i = 0; i < seg->sects.nitems; ++i) {
			sect = get_sect_by_index(seg, i);
			require_action(sect, finish, rval = KERN_FAILURE);
			if (sect->base_addr > maxaddr) {
				maxaddr = sect->base_addr;
				maxsize = sect->size;
			}
		}
		seg->vmsize = kxld_round_page_cross_safe(maxaddr +
		    maxsize - seg->base_addr);
	}

	rval = KERN_SUCCESS;

finish:
	return rval;
}

/*******************************************************************************
*******************************************************************************/
void
kxld_seg_set_vm_protections(KXLDSeg *seg, boolean_t strict_protections)
{
	if (strict_protections) {
		if (!strncmp(seg->segname, SEG_TEXT, sizeof(seg->segname))) {
			seg->initprot = TEXT_SEG_PROT;
			seg->maxprot = TEXT_SEG_PROT;
		} else {
			seg->initprot = DATA_SEG_PROT;
			seg->maxprot = DATA_SEG_PROT;
		}
	} else {
		seg->initprot = VM_PROT_ALL;
		seg->maxprot = VM_PROT_ALL;
	}
}

/*******************************************************************************
*******************************************************************************/
void
kxld_seg_relocate(KXLDSeg *seg, kxld_addr_t link_addr)
{
	KXLDSect *sect = NULL;
	u_int i = 0;
	splitKextLinkInfo * link_info = (splitKextLinkInfo *) link_addr;
	kxld_addr_t         my_link_addr;

	if (isOldInterface) {
		seg->link_addr += link_addr;
	} else {
		if (isSplitKext) {
			// we have a split kext
			if (kxld_seg_is_text_seg(seg)) {
				// assumes this is the beginning of the kext
				my_link_addr = link_info->vmaddr_TEXT;
				seg->link_addr = my_link_addr;
			} else if (kxld_seg_is_text_exec_seg(seg)) {
				my_link_addr = link_info->vmaddr_TEXT_EXEC;
				seg->link_addr = my_link_addr;
				// vmaddr_TEXT_EXEC is the actual vmaddr for this segment so we need
				// to adjust for kxld_sect_relocate assuming the link addr is
				// the address of the kext (macho header in __TEXT)
				my_link_addr -= seg->base_addr;
			} else if (kxld_seg_is_data_seg(seg)) {
				my_link_addr = link_info->vmaddr_DATA;
				seg->link_addr = my_link_addr;
				// vmaddr_DATA is the actual vmaddr for this segment so we need
				// to adjust for kxld_sect_relocate assuming the link addr is
				// the address of the kext (macho header in __TEXT)
				my_link_addr -= seg->base_addr;
			} else if (kxld_seg_is_data_const_seg(seg)) {
				my_link_addr = link_info->vmaddr_DATA_CONST;
				seg->link_addr = my_link_addr;
				// vmaddr_DATA_CONST is the actual vmaddr for this segment so we need
				// to adjust for kxld_sect_relocate assuming the link addr is
				// the address of the kext (macho header in __TEXT)
				my_link_addr -= seg->base_addr;
			} else if (kxld_seg_is_llvm_cov_seg(seg)) {
				my_link_addr = link_info->vmaddr_LLVM_COV;
				seg->link_addr = my_link_addr;
				// vmaddr_LLVM_COV is the actual vmaddr for this segment so we need
				// to adjust for kxld_sect_relocate assuming the link addr is
				// the address of the kext (macho header in __TEXT)
				my_link_addr -= seg->base_addr;
			} else if (kxld_seg_is_linkedit_seg(seg)) {
				my_link_addr = link_info->vmaddr_LINKEDIT;
				seg->link_addr = my_link_addr;
				// vmaddr_DATA is the actual vmaddr for this segment so we need
				// to adjust for kxld_sect_relocate assuming the link addr is
				// the address of the kext (macho header in __TEXT)
				my_link_addr -= seg->base_addr;
			} else {
				kxld_log(kKxldLogLinking, kKxldLogErr,
				    " not expecting this segment %s!!! <%s>",
				    seg->segname[0] ? seg->segname : "none",
				    __func__);
				my_link_addr = link_info->vmaddr_TEXT;
				seg->link_addr += my_link_addr;
			}
		} else {
			my_link_addr = link_info->vmaddr_TEXT;
			seg->link_addr += my_link_addr;
		}
	}

#if SPLIT_KEXTS_DEBUG
	{
		kxld_log(kKxldLogLinking, kKxldLogErr,
		    "%p >>> Start of %s segment (vmsize %llu) <%s>)",
		    (void *) seg->link_addr,
		    seg->segname[0] ? seg->segname : "none",
		    seg->vmsize,
		    __func__);
		kxld_log(kKxldLogLinking, kKxldLogErr,
		    "%p <<< End of %s segment <%s>",
		    (void *) (seg->link_addr + seg->vmsize),
		    seg->segname[0] ? seg->segname : "none",
		    __func__);
	}
#endif

	for (i = 0; i < seg->sects.nitems; ++i) {
		sect = get_sect_by_index(seg, i);
		if (isOldInterface) {
			kxld_sect_relocate(sect, link_addr);
		} else {
			kxld_sect_relocate(sect, my_link_addr);
		}
	}
}

/*******************************************************************************
*******************************************************************************/
void
kxld_seg_populate_linkedit(KXLDSeg *seg, const KXLDSymtab *symtab, boolean_t is_32_bit
#if KXLD_PIC_KEXTS
    , const KXLDArray *locrelocs
    , const KXLDArray *extrelocs
    , boolean_t target_supports_slideable_kexts
#endif  /* KXLD_PIC_KEXTS */
    , uint32_t splitinfolc_size
    )
{
	u_long size = 0;

	size += kxld_symtab_get_macho_data_size(symtab, is_32_bit);

#if KXLD_PIC_KEXTS
	if (target_supports_slideable_kexts) {
		size += kxld_reloc_get_macho_data_size(locrelocs, extrelocs);
	}
#endif  /* KXLD_PIC_KEXTS */

	// 0 unless this is a split kext
	size += splitinfolc_size;

	seg->vmsize = kxld_round_page_cross_safe(size);
}

/*******************************************************************************
*******************************************************************************/
boolean_t
kxld_seg_is_split_seg(const KXLDSeg *seg)
{
	boolean_t       result = FALSE;

	check(seg);
	if (isSplitKext) {
		if (kxld_seg_is_data_seg(seg) || kxld_seg_is_linkedit_seg(seg) ||
		    kxld_seg_is_text_exec_seg(seg) || kxld_seg_is_data_const_seg(seg) ||
		    kxld_seg_is_llvm_cov_seg(seg)) {
			result = TRUE;
		}
	}

	return result;
}

boolean_t
kxld_seg_is_text_seg(const KXLDSeg *seg)
{
	boolean_t       result = FALSE;

	check(seg);
	result = !strncmp(seg->segname, SEG_TEXT, sizeof(seg->segname));

	return result;
}

boolean_t
kxld_seg_is_text_exec_seg(const KXLDSeg *seg)
{
	boolean_t       result = FALSE;

	check(seg);
	result = !strncmp(seg->segname, "__TEXT_EXEC", sizeof(seg->segname));

	return result;
}

boolean_t
kxld_seg_is_data_seg(const KXLDSeg *seg)
{
	boolean_t       result = FALSE;

	check(seg);
	result = !strncmp(seg->segname, SEG_DATA, sizeof(seg->segname));

	return result;
}

boolean_t
kxld_seg_is_data_const_seg(const KXLDSeg *seg)
{
	boolean_t       result = FALSE;

	check(seg);
	result = !strncmp(seg->segname, "__DATA_CONST", sizeof(seg->segname));

	return result;
}

boolean_t
kxld_seg_is_linkedit_seg(const KXLDSeg *seg)
{
	boolean_t       result = FALSE;

	check(seg);
	result = !strncmp(seg->segname, SEG_LINKEDIT, sizeof(seg->segname));

	return result;
}

boolean_t
kxld_seg_is_llvm_cov_seg(const KXLDSeg *seg)
{
	boolean_t       result = FALSE;

	check(seg);
	result = !strncmp(seg->segname, "__LLVM_COV", sizeof(seg->segname));

	return result;
}