/*
 * Copyright (c) 2007-2011 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 <mach_debug.h>
#include <mach_kdp.h>
#include <debug.h>

#include <kern/assert.h>
#include <kern/misc_protos.h>
#include <kern/monotonic.h>
#include <mach/vm_types.h>
#include <mach/vm_param.h>
#include <vm/vm_kern.h>
#include <vm/vm_page.h>
#include <vm/pmap.h>

#include <machine/atomic.h>
#include <arm64/proc_reg.h>
#include <arm64/lowglobals.h>
#include <arm/cpu_data_internal.h>
#include <arm/misc_protos.h>
#include <pexpert/arm64/boot.h>
#include <pexpert/device_tree.h>

#include <libkern/kernel_mach_header.h>
#include <libkern/section_keywords.h>

#include <san/kasan.h>

#if __ARM_KERNEL_PROTECT__
/*
 * If we want to support __ARM_KERNEL_PROTECT__, we need a sufficient amount of
 * mappable space preceeding the kernel (as we unmap the kernel by cutting the
 * range covered by TTBR1 in half).  This must also cover the exception vectors.
 */
static_assert(KERNEL_PMAP_HEAP_RANGE_START > ARM_KERNEL_PROTECT_EXCEPTION_START);

/* The exception vectors and the kernel cannot share root TTEs. */
static_assert((KERNEL_PMAP_HEAP_RANGE_START & ~ARM_TT_ROOT_OFFMASK) > ARM_KERNEL_PROTECT_EXCEPTION_START);

/*
 * We must have enough space in the TTBR1_EL1 range to create the EL0 mapping of
 * the exception vectors.
 */
static_assert((((~ARM_KERNEL_PROTECT_EXCEPTION_START) + 1) * 2ULL) <= (ARM_TT_ROOT_SIZE + ARM_TT_ROOT_INDEX_MASK));
#endif /* __ARM_KERNEL_PROTECT__ */

#define ARM_DYNAMIC_TABLE_XN (ARM_TTE_TABLE_PXN | ARM_TTE_TABLE_XN)

#if KASAN
extern vm_offset_t shadow_pbase;
extern vm_offset_t shadow_ptop;
extern vm_offset_t physmap_vbase;
extern vm_offset_t physmap_vtop;
#endif

/*
 * Denotes the end of xnu.
 */
extern void *last_kernel_symbol;

extern void arm64_replace_bootstack(cpu_data_t*);
extern void PE_slide_devicetree(vm_offset_t);

/*
 * KASLR parameters
 */
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kernel_base;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kernel_top;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kext_base;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kext_top;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kernel_stext;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kernel_etext;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kernel_slide;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kernel_slid_base;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kernel_slid_top;

SECURITY_READ_ONLY_LATE(vm_offset_t) vm_prelink_stext;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_prelink_etext;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_prelink_sdata;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_prelink_edata;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_prelink_sinfo;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_prelink_einfo;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_slinkedit;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_elinkedit;

SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kernel_builtinkmod_text;
SECURITY_READ_ONLY_LATE(vm_offset_t) vm_kernel_builtinkmod_text_end;

/* Used by <mach/arm/vm_param.h> */
SECURITY_READ_ONLY_LATE(unsigned long) gVirtBase;
SECURITY_READ_ONLY_LATE(unsigned long) gPhysBase;
SECURITY_READ_ONLY_LATE(unsigned long) gPhysSize;
SECURITY_READ_ONLY_LATE(unsigned long) gT0Sz = T0SZ_BOOT;
SECURITY_READ_ONLY_LATE(unsigned long) gT1Sz = T1SZ_BOOT;

/* 23543331 - step 1 of kext / kernel __TEXT and __DATA colocation is to move
 * all kexts before the kernel.  This is only for arm64 devices and looks
 * something like the following:
 * -- vmaddr order --
 * 0xffffff8004004000 __PRELINK_TEXT
 * 0xffffff8007004000 __TEXT (xnu)
 * 0xffffff80075ec000 __DATA (xnu)
 * 0xffffff80076dc000 __KLD (xnu)
 * 0xffffff80076e0000 __LAST (xnu)
 * 0xffffff80076e4000 __LINKEDIT (xnu)
 * 0xffffff80076e4000 __PRELINK_DATA (not used yet)
 * 0xffffff800782c000 __PRELINK_INFO
 * 0xffffff80078e4000 -- End of kernelcache
 */

/* 24921709 - make XNU ready for KTRR
 *
 * Two possible kernel cache layouts, depending on which kcgen is being used.
 * VAs increasing downwards.
 * Old KCGEN:
 *
 * __PRELINK_TEXT
 * __TEXT
 * __DATA_CONST
 * __TEXT_EXEC
 * __KLD
 * __LAST
 * __DATA
 * __PRELINK_DATA (expected empty)
 * __LINKEDIT
 * __PRELINK_INFO
 *
 * New kcgen:
 *
 * __PRELINK_TEXT    <--- First KTRR (ReadOnly) segment
 * __PLK_DATA_CONST
 * __PLK_TEXT_EXEC
 * __TEXT
 * __DATA_CONST
 * __TEXT_EXEC
 * __KLD
 * __LAST            <--- Last KTRR (ReadOnly) segment
 * __DATA
 * __BOOTDATA (if present)
 * __LINKEDIT
 * __PRELINK_DATA (expected populated now)
 * __PLK_LINKEDIT
 * __PRELINK_INFO
 *
 */

vm_offset_t mem_size;                             /* Size of actual physical memory present
                                                   * minus any performance buffer and possibly
                                                   * limited by mem_limit in bytes */
uint64_t    mem_actual;                           /* The "One True" physical memory size
                                                   * actually, it's the highest physical
                                                   * address + 1 */
uint64_t    max_mem;                              /* Size of physical memory (bytes), adjusted
                                                   * by maxmem */
uint64_t    sane_size;                            /* Memory size to use for defaults
                                                   * calculations */
/* This no longer appears to be used; kill it? */
addr64_t    vm_last_addr = VM_MAX_KERNEL_ADDRESS; /* Highest kernel
                                                   * virtual address known
                                                   * to the VM system */

SECURITY_READ_ONLY_LATE(vm_offset_t)		  segEXTRADATA;
SECURITY_READ_ONLY_LATE(unsigned long)		  segSizeEXTRADATA;

SECURITY_READ_ONLY_LATE(vm_offset_t)          segLOWESTTEXT;
SECURITY_READ_ONLY_LATE(vm_offset_t)          segLOWEST;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segTEXTB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizeTEXT;


SECURITY_READ_ONLY_LATE(static vm_offset_t)   segDATACONSTB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizeDATACONST;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segTEXTEXECB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizeTEXTEXEC;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segDATAB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizeDATA;


SECURITY_READ_ONLY_LATE(vm_offset_t)          segBOOTDATAB;
SECURITY_READ_ONLY_LATE(unsigned long)        segSizeBOOTDATA;
extern vm_offset_t                            intstack_low_guard;
extern vm_offset_t                            intstack_high_guard;
extern vm_offset_t                            excepstack_high_guard;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segLINKB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizeLINK;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segKLDB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizeKLD;
SECURITY_READ_ONLY_LATE(vm_offset_t)          segLASTB;
SECURITY_READ_ONLY_LATE(unsigned long)        segSizeLAST;

SECURITY_READ_ONLY_LATE(vm_offset_t)          segPRELINKTEXTB;
SECURITY_READ_ONLY_LATE(unsigned long)        segSizePRELINKTEXT;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segPLKTEXTEXECB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizePLKTEXTEXEC;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segPLKDATACONSTB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizePLKDATACONST;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segPRELINKDATAB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizePRELINKDATA;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segPLKLLVMCOVB = 0;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizePLKLLVMCOV = 0;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segPLKLINKEDITB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizePLKLINKEDIT;

SECURITY_READ_ONLY_LATE(static vm_offset_t)   segPRELINKINFOB;
SECURITY_READ_ONLY_LATE(static unsigned long) segSizePRELINKINFO;

SECURITY_READ_ONLY_LATE(static boolean_t) use_contiguous_hint = TRUE;

SECURITY_READ_ONLY_LATE(unsigned) PAGE_SHIFT_CONST;

SECURITY_READ_ONLY_LATE(vm_offset_t) end_kern;
SECURITY_READ_ONLY_LATE(vm_offset_t) etext;
SECURITY_READ_ONLY_LATE(vm_offset_t) sdata;
SECURITY_READ_ONLY_LATE(vm_offset_t) edata;

vm_offset_t alloc_ptpage(boolean_t map_static);
SECURITY_READ_ONLY_LATE(vm_offset_t) ropage_next;

/*
 * Bootstrap the system enough to run with virtual memory.
 * Map the kernel's code and data, and allocate the system page table.
 * Page_size must already be set.
 *
 * Parameters:
 * first_avail: first available physical page -
 *              after kernel page tables
 * avail_start: PA of first physical page
 * avail_end:   PA of last physical page
 */
SECURITY_READ_ONLY_LATE(vm_offset_t)     first_avail;
SECURITY_READ_ONLY_LATE(vm_offset_t)     static_memory_end;
SECURITY_READ_ONLY_LATE(pmap_paddr_t)    avail_start;
SECURITY_READ_ONLY_LATE(pmap_paddr_t)    avail_end;
SECURITY_READ_ONLY_LATE(pmap_paddr_t)    real_avail_end;
SECURITY_READ_ONLY_LATE(unsigned long)   real_phys_size;

#if __ARM_KERNEL_PROTECT__
extern void ExceptionVectorsBase;
extern void ExceptionVectorsEnd;
#endif /* __ARM_KERNEL_PROTECT__ */

typedef struct {
	pmap_paddr_t pa;
	vm_map_address_t va;
	vm_size_t len;
} ptov_table_entry;

#define PTOV_TABLE_SIZE	8
SECURITY_READ_ONLY_LATE(static ptov_table_entry)	ptov_table[PTOV_TABLE_SIZE];
SECURITY_READ_ONLY_LATE(static boolean_t)		kva_active = FALSE;


vm_map_address_t
phystokv(pmap_paddr_t pa)
{
	for (size_t i = 0; (i < PTOV_TABLE_SIZE) && (ptov_table[i].len != 0); i++) {
		if ((pa >= ptov_table[i].pa) && (pa < (ptov_table[i].pa + ptov_table[i].len)))
			return (pa - ptov_table[i].pa + ptov_table[i].va);
	}
	assertf((pa - gPhysBase) < real_phys_size, "%s: illegal PA: 0x%llx", __func__, (uint64_t)pa);
	return (pa - gPhysBase + gVirtBase);
}

vm_map_address_t
phystokv_range(pmap_paddr_t pa, vm_size_t *max_len)
{
	vm_size_t len;
	for (size_t i = 0; (i < PTOV_TABLE_SIZE) && (ptov_table[i].len != 0); i++) {
		if ((pa >= ptov_table[i].pa) && (pa < (ptov_table[i].pa + ptov_table[i].len))) {
			len = ptov_table[i].len - (pa - ptov_table[i].pa);
			if (*max_len > len)
				*max_len = len;
			return (pa - ptov_table[i].pa + ptov_table[i].va);
		}
	}
	len = PAGE_SIZE - (pa & PAGE_MASK);
	if (*max_len > len)
		*max_len = len;
	assertf((pa - gPhysBase) < real_phys_size, "%s: illegal PA: 0x%llx", __func__, (uint64_t)pa);
	return (pa - gPhysBase + gVirtBase);
}

vm_offset_t
ml_static_vtop(vm_offset_t va)
{
	for (size_t i = 0; (i < PTOV_TABLE_SIZE) && (ptov_table[i].len != 0); i++) {
		if ((va >= ptov_table[i].va) && (va < (ptov_table[i].va + ptov_table[i].len)))
			return (va - ptov_table[i].va + ptov_table[i].pa);
	}
	assertf(((vm_address_t)(va) - gVirtBase) < gPhysSize, "%s: illegal VA: %p", __func__, (void*)va);
	return ((vm_address_t)(va) - gVirtBase + gPhysBase);
}

/*
 * This rounds the given address up to the nearest boundary for a PTE contiguous
 * hint.
 */
static vm_offset_t
round_up_pte_hint_address(vm_offset_t address)
{
	vm_offset_t hint_size = ARM_PTE_SIZE << ARM_PTE_HINT_ENTRIES_SHIFT;
	return ((address + (hint_size - 1)) & ~(hint_size - 1));
}

/* allocate a page for a page table: we support static and dynamic mappings.
 *
 * returns a virtual address for the allocated page
 *
 * for static mappings, we allocate from the region ropagetable_begin to ro_pagetable_end-1,
 * which is defined in the DATA_CONST segment and will be protected RNX when vm_prot_finalize runs.
 *
 * for dynamic mappings, we allocate from avail_start, which should remain RWNX.
 */

vm_offset_t alloc_ptpage(boolean_t map_static) {
	vm_offset_t vaddr;

#if !(defined(KERNEL_INTEGRITY_KTRR))
	map_static = FALSE;
#endif

	if (!ropage_next) {
		ropage_next = (vm_offset_t)&ropagetable_begin;
	}

	if (map_static) {
		assert(ropage_next < (vm_offset_t)&ropagetable_end);

		vaddr = ropage_next;
		ropage_next += ARM_PGBYTES;

		return vaddr;
	} else {
		vaddr = phystokv(avail_start);
		avail_start += ARM_PGBYTES;

		return vaddr;
	}
}

#if DEBUG

void dump_kva_l2(vm_offset_t tt_base, tt_entry_t *tt, int indent, uint64_t *rosz_out, uint64_t *rwsz_out);

void dump_kva_l2(vm_offset_t tt_base, tt_entry_t *tt, int indent, uint64_t *rosz_out, uint64_t *rwsz_out) {
	unsigned int i;
	boolean_t cur_ro, prev_ro = 0;
	int start_entry = -1;
	tt_entry_t cur, prev = 0;
	pmap_paddr_t robegin = kvtophys((vm_offset_t)&ropagetable_begin);
	pmap_paddr_t roend = kvtophys((vm_offset_t)&ropagetable_end);
	boolean_t tt_static = kvtophys((vm_offset_t)tt) >= robegin &&
	                      kvtophys((vm_offset_t)tt) < roend;

	for(i=0; i<TTE_PGENTRIES; i++) {
		int tte_type = tt[i] & ARM_TTE_TYPE_MASK;
		cur = tt[i] & ARM_TTE_TABLE_MASK;

		if (tt_static) {
			/* addresses mapped by this entry are static if it is a block mapping,
			 * or the table was allocated from the RO page table region */
			cur_ro = (tte_type == ARM_TTE_TYPE_BLOCK) || (cur >= robegin && cur < roend);
		} else {
			cur_ro = 0;
		}

		if ((cur == 0 && prev != 0) || (cur_ro != prev_ro && prev != 0)) { // falling edge
			uintptr_t start,end,sz;

			start = (uintptr_t)start_entry << ARM_TT_L2_SHIFT;
			start += tt_base;
			end = ((uintptr_t)i << ARM_TT_L2_SHIFT) - 1;
			end += tt_base;

			sz = end - start + 1;
			printf("%*s0x%08x_%08x-0x%08x_%08x %s (%luMB)\n",
			       indent*4, "",
				   (uint32_t)(start >> 32),(uint32_t)start,
				   (uint32_t)(end >> 32),(uint32_t)end,
				   prev_ro ? "Static " : "Dynamic",
				   (sz >> 20));

			if (prev_ro) {
				*rosz_out += sz;
			} else {
				*rwsz_out += sz;
			}
		}

		if ((prev == 0 && cur != 0) || cur_ro != prev_ro) { // rising edge: set start
			start_entry = i;
		}

		prev = cur;
		prev_ro = cur_ro;
	}
}

void dump_kva_space() {
	uint64_t tot_rosz=0, tot_rwsz=0;
	int ro_ptpages, rw_ptpages;
	pmap_paddr_t robegin = kvtophys((vm_offset_t)&ropagetable_begin);
	pmap_paddr_t roend = kvtophys((vm_offset_t)&ropagetable_end);
	boolean_t root_static = kvtophys((vm_offset_t)cpu_tte) >= robegin &&
	                        kvtophys((vm_offset_t)cpu_tte) < roend;
	uint64_t kva_base = ~((1ULL << (64 - T1SZ_BOOT)) - 1);

	printf("Root page table: %s\n", root_static ? "Static" : "Dynamic");

	for(unsigned int i=0; i<TTE_PGENTRIES; i++) {
		pmap_paddr_t cur;
		boolean_t cur_ro;
		uintptr_t start,end;
		uint64_t rosz = 0, rwsz = 0;

		if ((cpu_tte[i] & ARM_TTE_VALID) == 0)
			continue;

		cur = cpu_tte[i] & ARM_TTE_TABLE_MASK;
		start = (uint64_t)i << ARM_TT_L1_SHIFT;
		start = start + kva_base;
		end = start + (ARM_TT_L1_SIZE - 1);
		cur_ro = cur >= robegin && cur < roend;

		printf("0x%08x_%08x-0x%08x_%08x %s\n",
		       (uint32_t)(start >> 32),(uint32_t)start,
			   (uint32_t)(end >> 32),(uint32_t)end,
			   cur_ro ? "Static " : "Dynamic");

		dump_kva_l2(start, (tt_entry_t*)phystokv(cur), 1, &rosz, &rwsz);
		tot_rosz += rosz;
		tot_rwsz += rwsz;
	}

	printf("L2 Address space mapped: Static %lluMB Dynamic %lluMB Total %lluMB\n",
	  tot_rosz >> 20,
	  tot_rwsz >> 20,
	  (tot_rosz >> 20) + (tot_rwsz >> 20));

	ro_ptpages = (int)((ropage_next - (vm_offset_t)&ropagetable_begin) >> ARM_PGSHIFT);
	rw_ptpages = (int)(lowGlo.lgStaticSize  >> ARM_PGSHIFT);
	printf("Pages used: static %d dynamic %d\n", ro_ptpages, rw_ptpages);
}

#endif /* DEBUG */

#if __ARM_KERNEL_PROTECT__
/*
 * arm_vm_map:
 *   root_ttp: The kernel virtual address for the root of the target page tables
 *   vaddr: The target virtual address
 *   pte: A page table entry value (may be ARM_PTE_EMPTY)
 *
 * This function installs pte at vaddr in root_ttp.  Any page table pages needed
 * to install pte will be allocated by this function.
 */
static void
arm_vm_map(tt_entry_t * root_ttp, vm_offset_t vaddr, pt_entry_t pte)
{
	vm_offset_t ptpage = 0;
	tt_entry_t * ttp = root_ttp;

	tt_entry_t * l1_ttep = NULL;
	tt_entry_t l1_tte = 0;

	tt_entry_t * l2_ttep = NULL;
	tt_entry_t l2_tte = 0;
	pt_entry_t * ptep = NULL;
	pt_entry_t cpte = 0;

	/*
	 * Walk the target page table to find the PTE for the given virtual
	 * address.  Allocate any page table pages needed to do this.
	 */
	l1_ttep = ttp + ((vaddr & ARM_TT_L1_INDEX_MASK) >> ARM_TT_L1_SHIFT);
	l1_tte = *l1_ttep;

	if (l1_tte == ARM_TTE_EMPTY) {
		ptpage = alloc_ptpage(TRUE);
		bzero((void *)ptpage, ARM_PGBYTES);
		l1_tte = kvtophys(ptpage);
		l1_tte &= ARM_TTE_TABLE_MASK;
		l1_tte |= ARM_TTE_VALID | ARM_TTE_TYPE_TABLE;
		*l1_ttep = l1_tte;
		ptpage = 0;
	}

	ttp = (tt_entry_t *)phystokv(l1_tte & ARM_TTE_TABLE_MASK);

	l2_ttep = ttp + ((vaddr & ARM_TT_L2_INDEX_MASK) >> ARM_TT_L2_SHIFT);
	l2_tte = *l2_ttep;

	if (l2_tte == ARM_TTE_EMPTY) {
		ptpage = alloc_ptpage(TRUE);
		bzero((void *)ptpage, ARM_PGBYTES);
		l2_tte = kvtophys(ptpage);
		l2_tte &= ARM_TTE_TABLE_MASK;
		l2_tte |= ARM_TTE_VALID | ARM_TTE_TYPE_TABLE;
		*l2_ttep = l2_tte;
		ptpage = 0;
	}

	ttp = (tt_entry_t *)phystokv(l2_tte & ARM_TTE_TABLE_MASK);

	ptep = ttp + ((vaddr & ARM_TT_L3_INDEX_MASK) >> ARM_TT_L3_SHIFT);
	cpte = *ptep;

	/*
	 * If the existing PTE is not empty, then we are replacing a valid
	 * mapping.
	 */
	if (cpte != ARM_PTE_EMPTY) {
		panic("%s: cpte=%#llx is not empty, "
		      "vaddr=%#lx, pte=%#llx",
		      __FUNCTION__, cpte,
		      vaddr, pte);
	}

	*ptep = pte;
}

#endif // __ARM_KERNEL_PROTECT

#if __ARM_KERNEL_PROTECT__

/*
 * arm_vm_kernel_el0_map:
 *   vaddr: The target virtual address
 *   pte: A page table entry value (may be ARM_PTE_EMPTY)
 *
 * This function installs pte at vaddr for the EL0 kernel mappings.
 */
static void
arm_vm_kernel_el0_map(vm_offset_t vaddr, pt_entry_t pte)
{
	/* Calculate where vaddr will be in the EL1 kernel page tables. */
	vm_offset_t kernel_pmap_vaddr = vaddr - ((ARM_TT_ROOT_INDEX_MASK + ARM_TT_ROOT_SIZE) / 2ULL);
	arm_vm_map(cpu_tte, kernel_pmap_vaddr, pte);
}

/*
 * arm_vm_kernel_el1_map:
 *   vaddr: The target virtual address
 *   pte: A page table entry value (may be ARM_PTE_EMPTY)
 *
 * This function installs pte at vaddr for the EL1 kernel mappings.
 */
static void
arm_vm_kernel_el1_map(vm_offset_t vaddr, pt_entry_t pte) {
	arm_vm_map(cpu_tte, vaddr, pte);
}

/*
 * arm_vm_kernel_pte:
 *   vaddr: The target virtual address
 *
 * This function returns the PTE value for the given vaddr from the kernel page
 * tables.  If the region has been been block mapped, we return what an
 * equivalent PTE value would be (as regards permissions and flags).  We also
 * remove the HINT bit (as we are not necessarily creating contiguous mappings.
 */
static pt_entry_t
arm_vm_kernel_pte(vm_offset_t vaddr)
{
	tt_entry_t * ttp = cpu_tte;
	tt_entry_t * ttep = NULL;
	tt_entry_t tte = 0;
	pt_entry_t * ptep = NULL;
	pt_entry_t pte = 0;

	ttep = ttp + ((vaddr & ARM_TT_L1_INDEX_MASK) >> ARM_TT_L1_SHIFT);
	tte = *ttep;

	assert(tte & ARM_TTE_VALID);

	if ((tte & ARM_TTE_TYPE_MASK) == ARM_TTE_TYPE_BLOCK) {
		/* This is a block mapping; return the equivalent PTE value. */
		pte = (pt_entry_t)(tte & ~ARM_TTE_TYPE_MASK);
		pte |= ARM_PTE_TYPE_VALID;
		pte |= vaddr & ((ARM_TT_L1_SIZE - 1) & ARM_PTE_PAGE_MASK);
		pte &= ~ARM_PTE_HINT_MASK;
		return pte;
	}

	ttp = (tt_entry_t *)phystokv(tte & ARM_TTE_TABLE_MASK);
	ttep = ttp + ((vaddr & ARM_TT_L2_INDEX_MASK) >> ARM_TT_L2_SHIFT);
	tte = *ttep;

	assert(tte & ARM_TTE_VALID);

	if ((tte & ARM_TTE_TYPE_MASK) == ARM_TTE_TYPE_BLOCK) {
		/* This is a block mapping; return the equivalent PTE value. */
		pte = (pt_entry_t)(tte & ~ARM_TTE_TYPE_MASK);
		pte |= ARM_PTE_TYPE_VALID;
		pte |= vaddr & ((ARM_TT_L2_SIZE - 1) & ARM_PTE_PAGE_MASK);
		pte &= ~ARM_PTE_HINT_MASK;
		return pte;
	}

	ttp = (tt_entry_t *)phystokv(tte & ARM_TTE_TABLE_MASK);

	ptep = ttp + ((vaddr & ARM_TT_L3_INDEX_MASK) >> ARM_TT_L3_SHIFT);
	pte = *ptep;
	pte &= ~ARM_PTE_HINT_MASK;
	return pte;
}

/*
 * arm_vm_prepare_kernel_el0_mappings:
 *   alloc_only: Indicates if PTE values should be copied from the EL1 kernel
 *     mappings.
 *
 * This function expands the kernel page tables to support the EL0 kernel
 * mappings, and conditionally installs the PTE values for the EL0 kernel
 * mappings (if alloc_only is false).
 */
static void
arm_vm_prepare_kernel_el0_mappings(bool alloc_only)
{
	pt_entry_t pte = 0;
	vm_offset_t start = ((vm_offset_t)&ExceptionVectorsBase) & ~PAGE_MASK;
	vm_offset_t end = (((vm_offset_t)&ExceptionVectorsEnd) + PAGE_MASK) & ~PAGE_MASK;
	vm_offset_t cur = 0;
	vm_offset_t cur_fixed = 0;

	/* Expand for/map the exceptions vectors in the EL0 kernel mappings. */
	for (cur = start, cur_fixed = ARM_KERNEL_PROTECT_EXCEPTION_START; cur < end; cur += ARM_PGBYTES, cur_fixed += ARM_PGBYTES) {
		/*
		 * We map the exception vectors at a different address than that
		 * of the kernelcache to avoid sharing page table pages with the
		 * kernelcache (as this may cause issues with TLB caching of
		 * page table pages.
		 */
		if (!alloc_only) {
			pte = arm_vm_kernel_pte(cur);
		}

		arm_vm_kernel_el1_map(cur_fixed, pte);
		arm_vm_kernel_el0_map(cur_fixed, pte);
	}

	__builtin_arm_dmb(DMB_ISH);
	__builtin_arm_isb(ISB_SY);

	if (!alloc_only) {
		/*
		 * If we have created the alternate exception vector mappings,
		 * the boot CPU may now switch over to them.
		 */
		set_vbar_el1(ARM_KERNEL_PROTECT_EXCEPTION_START);
		__builtin_arm_isb(ISB_SY);
	}
}

/*
 * arm_vm_populate_kernel_el0_mappings:
 *
 * This function adds all required mappings to the EL0 kernel mappings.
 */
static void
arm_vm_populate_kernel_el0_mappings(void)
{
	arm_vm_prepare_kernel_el0_mappings(FALSE);
}

/*
 * arm_vm_expand_kernel_el0_mappings:
 *
 * This function expands the kernel page tables to accomodate the EL0 kernel
 * mappings.
 */
static void
arm_vm_expand_kernel_el0_mappings(void)
{
	arm_vm_prepare_kernel_el0_mappings(TRUE);
}
#endif /* __ARM_KERNEL_PROTECT__ */

#if defined(KERNEL_INTEGRITY_KTRR)
extern void bootstrap_instructions;

/*
 * arm_replace_identity_map takes the V=P map that we construct in start.s
 * and repurposes it in order to have it map only the page we need in order
 * to turn on the MMU.  This prevents us from running into issues where
 * KTRR will cause us to fault on executable block mappings that cross the
 * KTRR boundary.
 */
static void arm_replace_identity_map(boot_args * args)
{
	vm_offset_t addr;
	pmap_paddr_t paddr;

	pmap_paddr_t l1_ptp_phys = 0;
	tt_entry_t *l1_ptp_virt = NULL;
	tt_entry_t *tte1 = NULL;
	pmap_paddr_t l2_ptp_phys = 0;
	tt_entry_t *l2_ptp_virt = NULL;
	tt_entry_t *tte2 = NULL;
	pmap_paddr_t l3_ptp_phys = 0;
	pt_entry_t *l3_ptp_virt = NULL;
	pt_entry_t *ptep = NULL;

	addr = ((vm_offset_t)&bootstrap_instructions) & ~ARM_PGMASK;
	paddr = kvtophys(addr);

	/*
	 * The V=P page tables (at the time this comment was written) start
	 * after the last bit of kernel data, and consist of 1 L1 page and 1 or
	 * more L2 pages.
	 * Grab references to those pages, and allocate an L3 page.
	 */
	l1_ptp_phys = args->topOfKernelData;
	l1_ptp_virt = (tt_entry_t *)phystokv(l1_ptp_phys);
	tte1 = &l1_ptp_virt[L1_TABLE_INDEX(paddr)];

	l2_ptp_virt = L2_TABLE_VA(tte1);
	l2_ptp_phys = (*tte1) & ARM_TTE_TABLE_MASK;
	tte2 = &l2_ptp_virt[L2_TABLE_INDEX(paddr)];

	l3_ptp_virt = (pt_entry_t *)alloc_ptpage(FALSE);
	l3_ptp_phys = kvtophys((vm_offset_t)l3_ptp_virt);
	ptep = &l3_ptp_virt[L3_TABLE_INDEX(paddr)];

	/*
	 * Replace the large V=P mapping with a mapping that provides only the
	 * mappings needed to turn on the MMU.
	 */

	bzero(l1_ptp_virt, ARM_PGBYTES);
	*tte1 = ARM_TTE_BOOT_TABLE | (l2_ptp_phys & ARM_TTE_TABLE_MASK);

	bzero(l2_ptp_virt, ARM_PGBYTES);
	*tte2 = ARM_TTE_BOOT_TABLE | (l3_ptp_phys & ARM_TTE_TABLE_MASK);

	*ptep = (paddr & ARM_PTE_MASK) |
	        ARM_PTE_TYPE_VALID |
	        ARM_PTE_SH(SH_OUTER_MEMORY) |
	        ARM_PTE_ATTRINDX(CACHE_ATTRINDX_WRITEBACK) |
	        ARM_PTE_AF |
	        ARM_PTE_AP(AP_RONA) |
	        ARM_PTE_NX;
}
#endif /* defined(KERNEL_INTEGRITY_KTRR)*/

tt_entry_t *arm_kva_to_tte(vm_offset_t);

tt_entry_t *
arm_kva_to_tte(vm_offset_t va)
{
	tt_entry_t *tte1, *tte2;
	tte1 = cpu_tte + L1_TABLE_INDEX(va);
	tte2 = L2_TABLE_VA(tte1) + L2_TABLE_INDEX(va);

	return tte2;
}


#define ARM64_GRANULE_ALLOW_BLOCK (1 << 0)
#define ARM64_GRANULE_ALLOW_HINT (1 << 1)

/*
 * arm_vm_page_granular_helper updates protections at the L3 level.  It will (if
 * neccessary) allocate a page for the L3 table and update the corresponding L2
 * entry.  Then, it will iterate over the L3 table, updating protections as necessary.
 * This expects to be invoked on a L2 entry or sub L2 entry granularity, so this should
 * not be invoked from a context that does not do L2 iteration separately (basically,
 * don't call this except from arm_vm_page_granular_prot).
 *
 * unsigned granule: 0 => force to page granule, or a combination of
 * ARM64_GRANULE_* flags declared above.
 */

static void
arm_vm_page_granular_helper(vm_offset_t start, vm_offset_t _end, vm_offset_t va, pmap_paddr_t pa_offset,
                            int pte_prot_APX, int pte_prot_XN, unsigned granule,
                            pt_entry_t **deferred_pte, pt_entry_t *deferred_ptmp)
{
	if (va & ARM_TT_L2_OFFMASK) { /* ragged edge hanging over a ARM_TT_L2_SIZE  boundary */
		tt_entry_t *tte2;
		tt_entry_t tmplate;
		pmap_paddr_t pa;
		pt_entry_t *ppte, *recursive_pte = NULL, ptmp, recursive_ptmp = 0;
		addr64_t ppte_phys;
		unsigned i;

		va &= ~ARM_TT_L2_OFFMASK;
		pa = va - gVirtBase + gPhysBase - pa_offset;

		if (pa >= real_avail_end)
			return;

		tte2 = arm_kva_to_tte(va);

		assert(_end >= va);
		tmplate = *tte2;

		if (ARM_TTE_TYPE_TABLE == (tmplate & ARM_TTE_TYPE_MASK)) {
			/* pick up the existing page table. */
			ppte = (pt_entry_t *)phystokv((tmplate & ARM_TTE_TABLE_MASK));
		} else {
			// TTE must be reincarnated with page level mappings.
			ppte = (pt_entry_t*)alloc_ptpage(pa_offset == 0);
			bzero(ppte, ARM_PGBYTES);
			ppte_phys = kvtophys((vm_offset_t)ppte);

			*tte2 = pa_to_tte(ppte_phys) | ARM_TTE_TYPE_TABLE | ARM_TTE_VALID;
		}

		vm_offset_t len = _end - va;
		if ((pa + len) > real_avail_end)
			_end -= (pa + len - real_avail_end);
		assert((start - gVirtBase + gPhysBase - pa_offset) >= gPhysBase);

		/* Round up to the nearest PAGE_SIZE boundary when creating mappings:
		 * PAGE_SIZE may be a multiple of ARM_PGBYTES, and we don't want to leave
		 * a ragged non-PAGE_SIZE-aligned edge. */
		vm_offset_t rounded_end = round_page(_end);
		/* Apply the desired protections to the specified page range */
		for (i = 0; i <= (ARM_TT_L3_INDEX_MASK>>ARM_TT_L3_SHIFT); i++) {
			if ((start <= va) && (va < rounded_end)) {

				ptmp = pa | ARM_PTE_AF | ARM_PTE_SH(SH_OUTER_MEMORY) | ARM_PTE_TYPE;
				ptmp = ptmp | ARM_PTE_ATTRINDX(CACHE_ATTRINDX_DEFAULT);
				ptmp = ptmp | ARM_PTE_AP(pte_prot_APX);
				ptmp = ptmp | ARM_PTE_NX;
#if __ARM_KERNEL_PROTECT__
				ptmp = ptmp | ARM_PTE_NG;
#endif /* __ARM_KERNEL_PROTECT__ */

				if (pte_prot_XN) {
					ptmp = ptmp | ARM_PTE_PNX;
				}

				/*
				 * If we can, apply the contiguous hint to this range.  The hint is
				 * applicable if the current address falls within a hint-sized range that will
				 * be fully covered by this mapping request.
				 */
				if ((va >= round_up_pte_hint_address(start)) && (round_up_pte_hint_address(va + 1) <= _end) &&
				    (granule & ARM64_GRANULE_ALLOW_HINT) && use_contiguous_hint) {
					assert((va & ((1 << ARM_PTE_HINT_ADDR_SHIFT) - 1)) == ((pa & ((1 << ARM_PTE_HINT_ADDR_SHIFT) - 1))));
					ptmp |= ARM_PTE_HINT;
					/* Do not attempt to reapply the hint bit to an already-active mapping.
					 * This very likely means we're attempting to change attributes on an already-active mapping,
					 * which violates the requirement of the hint bit.*/
					assert(!kva_active || (ppte[i] == ARM_PTE_TYPE_FAULT));
				}
				/*
				 * Do not change the contiguous bit on an active mapping.  Even in a single-threaded
				 * environment, it's possible for prefetch to produce a TLB conflict by trying to pull in
				 * a hint-sized entry on top of one or more existing page-sized entries.  It's also useful
				 * to make sure we're not trying to unhint a sub-range of a larger hinted range, which
				 * could produce a later TLB conflict.
				 */
				assert(!kva_active || (ppte[i] == ARM_PTE_TYPE_FAULT) || ((ppte[i] & ARM_PTE_HINT) == (ptmp & ARM_PTE_HINT)));

				/*
				 * If we reach an entry that maps the current pte page, delay updating it until the very end.
				 * Otherwise we might end up making the PTE page read-only, leading to a fault later on in
				 * this function if we manage to outrun the TLB.  This can happen on KTRR-enabled devices when
				 * marking segDATACONST read-only.  Mappings for this region may straddle a PT page boundary,
				 * so we must also defer assignment of the following PTE.  We will assume that if the region
				 * were to require one or more full L3 pages, it would instead use L2 blocks where possible,
				 * therefore only requiring at most one L3 page at the beginning and one at the end.
				 */
				if (kva_active && ((pt_entry_t*)(phystokv(pa)) == ppte)) {
					assert(recursive_pte == NULL);
					assert(granule & ARM64_GRANULE_ALLOW_BLOCK);
					recursive_pte = &ppte[i];
					recursive_ptmp = ptmp;
				} else if ((deferred_pte != NULL) && (&ppte[i] == &recursive_pte[1])) {
					assert(*deferred_pte == NULL);
					assert(deferred_ptmp != NULL);
					*deferred_pte = &ppte[i];
					*deferred_ptmp = ptmp;
				} else {
					ppte[i] = ptmp;
				}
			}

			va += ARM_PGBYTES;
			pa += ARM_PGBYTES;
		}
		if (recursive_pte != NULL)
			*recursive_pte = recursive_ptmp;
	}
}

/*
 * arm_vm_page_granular_prot updates protections by iterating over the L2 entries and
 * changing them.  If a particular chunk necessitates L3 entries (for reasons of
 * alignment or length, or an explicit request that the entry be fully expanded), we
 * hand off to arm_vm_page_granular_helper to deal with the L3 chunk of the logic.
 */
static void
arm_vm_page_granular_prot(vm_offset_t start, unsigned long size, pmap_paddr_t pa_offset,
                          int tte_prot_XN, int pte_prot_APX, int pte_prot_XN,
                          unsigned granule)
{
	pt_entry_t *deferred_pte = NULL, deferred_ptmp = 0;
	vm_offset_t _end = start + size;
	vm_offset_t align_start = (start + ARM_TT_L2_OFFMASK) & ~ARM_TT_L2_OFFMASK;

	if (size == 0x0UL)
		return;

	if (align_start > _end) {
		arm_vm_page_granular_helper(start, _end, start, pa_offset, pte_prot_APX, pte_prot_XN, granule, NULL, NULL);
		return;
	}

	arm_vm_page_granular_helper(start, align_start, start, pa_offset, pte_prot_APX, pte_prot_XN, granule, &deferred_pte, &deferred_ptmp);

	while ((_end - align_start) >= ARM_TT_L2_SIZE) {
		if (!(granule & ARM64_GRANULE_ALLOW_BLOCK)) {
			arm_vm_page_granular_helper(align_start, align_start+ARM_TT_L2_SIZE, align_start + 1, pa_offset,
			                            pte_prot_APX, pte_prot_XN, granule, NULL, NULL);
		} else {
			pmap_paddr_t pa = align_start - gVirtBase + gPhysBase - pa_offset;
			assert((pa & ARM_TT_L2_OFFMASK) == 0);
			tt_entry_t *tte2;
			tt_entry_t tmplate;

			tte2 = arm_kva_to_tte(align_start);

			if ((pa >= gPhysBase) && (pa < real_avail_end)) {
				tmplate = (pa & ARM_TTE_BLOCK_L2_MASK) | ARM_TTE_TYPE_BLOCK
					| ARM_TTE_VALID | ARM_TTE_BLOCK_AF | ARM_TTE_BLOCK_NX
					| ARM_TTE_BLOCK_AP(pte_prot_APX) | ARM_TTE_BLOCK_SH(SH_OUTER_MEMORY)
					| ARM_TTE_BLOCK_ATTRINDX(CACHE_ATTRINDX_WRITEBACK);

#if __ARM_KERNEL_PROTECT__
				tmplate = tmplate | ARM_TTE_BLOCK_NG;
#endif /* __ARM_KERNEL_PROTECT__ */
				if (tte_prot_XN)
					tmplate = tmplate | ARM_TTE_BLOCK_PNX;

				*tte2 = tmplate;
			}
		}
		align_start += ARM_TT_L2_SIZE;
	}

	if (align_start < _end)
		arm_vm_page_granular_helper(align_start, _end, _end, pa_offset, pte_prot_APX, pte_prot_XN, granule, &deferred_pte, &deferred_ptmp);

	if (deferred_pte != NULL)
		*deferred_pte = deferred_ptmp;
}

static inline void
arm_vm_page_granular_RNX(vm_offset_t start, unsigned long size, unsigned granule)
{
	arm_vm_page_granular_prot(start, size, 0, 1, AP_RONA, 1, granule);
}

static inline void
arm_vm_page_granular_ROX(vm_offset_t start, unsigned long size, unsigned granule)
{
	arm_vm_page_granular_prot(start, size, 0, 0, AP_RONA, 0, granule);
}

static inline void
arm_vm_page_granular_RWNX(vm_offset_t start, unsigned long size, unsigned granule)
{
	arm_vm_page_granular_prot(start, size, 0, 1, AP_RWNA, 1, granule);
}

/* used in the chosen/memory-map node, populated by iBoot. */
typedef struct MemoryMapFileInfo {
       vm_offset_t paddr;
       size_t length;
} MemoryMapFileInfo;

void
arm_vm_prot_init(boot_args * args)
{

	segLOWESTTEXT = UINT64_MAX;
	if (segSizePRELINKTEXT  && (segPRELINKTEXTB < segLOWESTTEXT)) segLOWESTTEXT = segPRELINKTEXTB;
	assert(segSizeTEXT);
	if (segTEXTB < segLOWESTTEXT) segLOWESTTEXT = segTEXTB;
	assert(segLOWESTTEXT < UINT64_MAX);

	segEXTRADATA = segLOWESTTEXT;
	segSizeEXTRADATA = 0;

	segLOWEST = segLOWESTTEXT;

	DTEntry memory_map;
	MemoryMapFileInfo *trustCacheRange;
	unsigned int trustCacheRangeSize;
	int err;

	err = DTLookupEntry(NULL, "chosen/memory-map", &memory_map);
	assert(err == kSuccess);

	err = DTGetProperty(memory_map, "TrustCache", (void**)&trustCacheRange, &trustCacheRangeSize);
	if (err == kSuccess) {
		assert(trustCacheRangeSize == sizeof(MemoryMapFileInfo));

		segEXTRADATA = phystokv(trustCacheRange->paddr);
		segSizeEXTRADATA = trustCacheRange->length;

		if (segEXTRADATA <= segLOWEST) {
			segLOWEST = segEXTRADATA;
		}
#if !(DEBUG || DEVELOPMENT)


		else {
			panic("EXTRADATA is in an unexpected place: %#lx > %#lx", segEXTRADATA, segLOWEST);
		}
#endif /* !(DEBUG || DEVELOPMENT) */

		arm_vm_page_granular_RNX(segEXTRADATA, segSizeEXTRADATA, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT);

	}

	/* Map coalesced kext TEXT segment RWNX for now */
	arm_vm_page_granular_RWNX(segPRELINKTEXTB, segSizePRELINKTEXT, ARM64_GRANULE_ALLOW_BLOCK); // Refined in OSKext::readPrelinkedExtensions

	/* Map coalesced kext DATA_CONST segment RWNX (could be empty) */
	arm_vm_page_granular_RWNX(segPLKDATACONSTB, segSizePLKDATACONST, ARM64_GRANULE_ALLOW_BLOCK); // Refined in OSKext::readPrelinkedExtensions

	/* Map coalesced kext TEXT_EXEC segment RX (could be empty) */
	arm_vm_page_granular_ROX(segPLKTEXTEXECB, segSizePLKTEXTEXEC, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT); // Refined in OSKext::readPrelinkedExtensions

	/* if new segments not present, set space between PRELINK_TEXT and xnu TEXT to RWNX
	 * otherwise we no longer expect any space between the coalesced kext read only segments and xnu rosegments
	 */
	if (!segSizePLKDATACONST && !segSizePLKTEXTEXEC) {
		if (segSizePRELINKTEXT) {
			arm_vm_page_granular_RWNX(segPRELINKTEXTB + segSizePRELINKTEXT, segTEXTB - (segPRELINKTEXTB + segSizePRELINKTEXT),
			    ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT);
		}
	} else {
		/*
		 * If we have the new segments, we should still protect the gap between kext
		 * read-only pages and kernel read-only pages, in the event that this gap
		 * exists.
		 */
		if ((segPLKDATACONSTB + segSizePLKDATACONST) < segTEXTB) {
			arm_vm_page_granular_RWNX(segPLKDATACONSTB + segSizePLKDATACONST, segTEXTB - (segPLKDATACONSTB + segSizePLKDATACONST),
			    ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT);
		}
	}

	/*
	 * Protection on kernel text is loose here to allow shenanigans early on.  These
	 * protections are tightened in arm_vm_prot_finalize().  This is necessary because
	 * we currently patch LowResetVectorBase in cpu.c.
	 *
	 * TEXT segment contains mach headers and other non-executable data. This will become RONX later.
	 */
	arm_vm_page_granular_RNX(segTEXTB, segSizeTEXT, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT);

	/* Can DATACONST start out and stay RNX?
	 * NO, stuff in this segment gets modified during startup (viz. mac_policy_init()/mac_policy_list)
	 * Make RNX in prot_finalize
	 */
	arm_vm_page_granular_RWNX(segDATACONSTB, segSizeDATACONST, ARM64_GRANULE_ALLOW_BLOCK);

	arm_vm_page_granular_ROX(segTEXTEXECB, segSizeTEXTEXEC, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT);


	/* DATA segment will remain RWNX */
	arm_vm_page_granular_RWNX(segDATAB, segSizeDATA, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT);

	arm_vm_page_granular_RWNX(segBOOTDATAB, segSizeBOOTDATA, 0);
	arm_vm_page_granular_RNX((vm_offset_t)&intstack_low_guard, PAGE_MAX_SIZE, 0);
	arm_vm_page_granular_RNX((vm_offset_t)&intstack_high_guard, PAGE_MAX_SIZE, 0);
	arm_vm_page_granular_RNX((vm_offset_t)&excepstack_high_guard, PAGE_MAX_SIZE, 0);

	arm_vm_page_granular_ROX(segKLDB, segSizeKLD, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT);
	arm_vm_page_granular_RWNX(segLINKB, segSizeLINK, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT);
	arm_vm_page_granular_RWNX(segPLKLINKEDITB, segSizePLKLINKEDIT, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT); // Coalesced kext LINKEDIT segment
	arm_vm_page_granular_ROX(segLASTB, segSizeLAST, ARM64_GRANULE_ALLOW_BLOCK); // __LAST may be empty, but we cannot assume this

	arm_vm_page_granular_RWNX(segPRELINKDATAB, segSizePRELINKDATA, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT); // Prelink __DATA for kexts (RW data)

	if (segSizePLKLLVMCOV > 0)
		arm_vm_page_granular_RWNX(segPLKLLVMCOVB, segSizePLKLLVMCOV, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT); // LLVM code coverage data

	arm_vm_page_granular_RWNX(segPRELINKINFOB, segSizePRELINKINFO, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT); /* PreLinkInfoDictionary */

	arm_vm_page_granular_RNX(phystokv(args->topOfKernelData), BOOTSTRAP_TABLE_SIZE, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT); // Boot page tables; they should not be mutable.
}

/*
 * return < 0 for a < b
 *          0 for a == b
 *        > 0 for a > b
 */
typedef int (*cmpfunc_t)(const void *a, const void *b);

extern void
qsort(void *a, size_t n, size_t es, cmpfunc_t cmp);

static int
cmp_ptov_entries(const void *a, const void *b)
{
	const ptov_table_entry *entry_a = a;
	const ptov_table_entry *entry_b = b;
	// Sort in descending order of segment length
	if (entry_a->len < entry_b->len)
		return 1;
	else if (entry_a->len > entry_b->len)
		return -1;
	else
		return 0;
}

SECURITY_READ_ONLY_LATE(static unsigned int) ptov_index = 0;

#define ROUND_TWIG(addr) (((addr) + ARM_TT_TWIG_OFFMASK) & ~(ARM_TT_TWIG_OFFMASK))

static void
arm_vm_physmap_slide(ptov_table_entry *temp_ptov_table, vm_map_address_t physmap_base, vm_map_address_t orig_va, vm_size_t len, int pte_prot_APX, unsigned granule)
{
	pmap_paddr_t pa_offset;

	assert(ptov_index < PTOV_TABLE_SIZE);
	assert((orig_va & ARM_PGMASK) == 0);
	temp_ptov_table[ptov_index].pa = orig_va - gVirtBase + gPhysBase;
	if (ptov_index == 0)
		temp_ptov_table[ptov_index].va = physmap_base;
	else
		temp_ptov_table[ptov_index].va = temp_ptov_table[ptov_index - 1].va + temp_ptov_table[ptov_index - 1].len;
	if (granule & ARM64_GRANULE_ALLOW_BLOCK) {
		vm_map_address_t orig_offset = temp_ptov_table[ptov_index].pa & ARM_TT_TWIG_OFFMASK;
		vm_map_address_t new_offset = temp_ptov_table[ptov_index].va & ARM_TT_TWIG_OFFMASK;
		if (new_offset < orig_offset)
			temp_ptov_table[ptov_index].va += (orig_offset - new_offset);
		else if (new_offset > orig_offset)
			temp_ptov_table[ptov_index].va = ROUND_TWIG(temp_ptov_table[ptov_index].va) + orig_offset;
	}
	assert((temp_ptov_table[ptov_index].va & ARM_PGMASK) == 0);
	temp_ptov_table[ptov_index].len = round_page(len);
	pa_offset = temp_ptov_table[ptov_index].va - orig_va;
	arm_vm_page_granular_prot(temp_ptov_table[ptov_index].va, temp_ptov_table[ptov_index].len, pa_offset, 1, pte_prot_APX, 1, granule);
	++ptov_index;
}


static void
arm_vm_physmap_init(boot_args *args, vm_map_address_t physmap_base, vm_map_address_t dynamic_memory_begin __unused)
{
	ptov_table_entry temp_ptov_table[PTOV_TABLE_SIZE];
	bzero(temp_ptov_table, sizeof(temp_ptov_table));

	// Will be handed back to VM layer through ml_static_mfree() in arm_vm_prot_finalize()
	arm_vm_physmap_slide(temp_ptov_table, physmap_base, gVirtBase, segLOWEST - gVirtBase, AP_RWNA,
	    ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT);

	arm_vm_page_granular_RWNX(end_kern, phystokv(args->topOfKernelData) - end_kern,
	    ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT); /* Device Tree, RAM Disk (if present), bootArgs */

	arm_vm_physmap_slide(temp_ptov_table, physmap_base, (args->topOfKernelData + BOOTSTRAP_TABLE_SIZE - gPhysBase + gVirtBase),
	    real_avail_end - (args->topOfKernelData + BOOTSTRAP_TABLE_SIZE), AP_RWNA, ARM64_GRANULE_ALLOW_BLOCK | ARM64_GRANULE_ALLOW_HINT); // rest of physmem

	assert((temp_ptov_table[ptov_index - 1].va + temp_ptov_table[ptov_index - 1].len) <= dynamic_memory_begin);

	// Sort in descending order of segment length.  LUT traversal is linear, so largest (most likely used)
	// segments should be placed earliest in the table to optimize lookup performance.
	qsort(temp_ptov_table, PTOV_TABLE_SIZE, sizeof(temp_ptov_table[0]), cmp_ptov_entries);

	memcpy(ptov_table, temp_ptov_table, sizeof(ptov_table));
}


void
arm_vm_prot_finalize(boot_args * args __unused)
{
	/*
	 * At this point, we are far enough along in the boot process that it will be
	 * safe to free up all of the memory preceeding the kernel.  It may in fact
	 * be safe to do this earlier.
	 *
	 * This keeps the memory in the V-to-P mapping, but advertises it to the VM
	 * as usable.
	 */

	/*
	 * if old style PRELINK segment exists, free memory before it, and after it before XNU text
	 * otherwise we're dealing with a new style kernel cache, so we should just free the
	 * memory before PRELINK_TEXT segment, since the rest of the KEXT read only data segments
	 * should be immediately followed by XNU's TEXT segment
	 */

	ml_static_mfree(phystokv(gPhysBase), segLOWEST - gVirtBase);

	/*
	 * KTRR support means we will be mucking with these pages and trying to
	 * protect them; we cannot free the pages to the VM if we do this.
	 */
	if (!segSizePLKDATACONST && !segSizePLKTEXTEXEC && segSizePRELINKTEXT) {
		/* If new segments not present, PRELINK_TEXT is not dynamically sized, free DRAM between it and xnu TEXT */
		ml_static_mfree(segPRELINKTEXTB + segSizePRELINKTEXT, segTEXTB - (segPRELINKTEXTB + segSizePRELINKTEXT));
	}

	/* tighten permissions on kext read only data and code */
	arm_vm_page_granular_RNX(segPRELINKTEXTB, segSizePRELINKTEXT, ARM64_GRANULE_ALLOW_BLOCK);
	arm_vm_page_granular_RNX(segPLKDATACONSTB, segSizePLKDATACONST, ARM64_GRANULE_ALLOW_BLOCK);

	cpu_stack_alloc(&BootCpuData);
	arm64_replace_bootstack(&BootCpuData);
	ml_static_mfree(phystokv(segBOOTDATAB - gVirtBase + gPhysBase), segSizeBOOTDATA);

#if __ARM_KERNEL_PROTECT__
	arm_vm_populate_kernel_el0_mappings();
#endif /* __ARM_KERNEL_PROTECT__ */


#if defined(KERNEL_INTEGRITY_KTRR)
	/*
	 * __LAST,__pinst should no longer be executable.
	 */
	arm_vm_page_granular_RNX(segLASTB, segSizeLAST, ARM64_GRANULE_ALLOW_BLOCK);

	/*
	 * Must wait until all other region permissions are set before locking down DATA_CONST
	 * as the kernel static page tables live in DATA_CONST on KTRR enabled systems
	 * and will become immutable.
	 */
#endif

	arm_vm_page_granular_RNX(segDATACONSTB, segSizeDATACONST, ARM64_GRANULE_ALLOW_BLOCK);

	__builtin_arm_dsb(DSB_ISH);
	flush_mmu_tlb();
}

#define TBI_USER 0x1
#define TBI_KERNEL 0x2

boolean_t user_tbi = TRUE;

/*
 * TBI (top-byte ignore) is an ARMv8 feature for ignoring the top 8 bits of
 * address accesses. It can be enabled separately for TTBR0 (user) and
 * TTBR1 (kernel). We enable it by default for user only, but allow both
 * to be controlled by the 'tbi' boot-arg.
 */
static void
set_tbi(void)
{
#if !__ARM_KERNEL_PROTECT__
	/* If we are not built with __ARM_KERNEL_PROTECT__, TBI can be turned
	 * off with a boot-arg.
	 */
	uint64_t old_tcr, new_tcr;
	int tbi = 0;

	if (PE_parse_boot_argn("tbi", &tbi, sizeof(tbi)))
		user_tbi = ((tbi & TBI_USER) == TBI_USER);
	old_tcr = new_tcr = get_tcr();
	new_tcr |= (user_tbi) ? TCR_TBI0_TOPBYTE_IGNORED : 0;

#if !defined(HAS_APPLE_PAC)
	/*
	 * arm_vm_init() runs after rebase_threaded_starts(), so enabling TBI1
	 * at this point will break the computed pointer signatures.  TBID1
	 * could help mitigate this problem, but for now we'll just disable
	 * kernel TBI if PAC is being used.
	 */
	new_tcr |= (tbi & TBI_KERNEL) ? TCR_TBI1_TOPBYTE_IGNORED : 0;
#endif

	if (old_tcr != new_tcr) {
		set_tcr(new_tcr);
		sysreg_restore.tcr_el1 = new_tcr;
	}
#endif /* !__ARM_KERNEL_PROTECT__ */
}

#define ARM64_PHYSMAP_SLIDE_RANGE (1ULL << 30) // 1 GB
#define ARM64_PHYSMAP_SLIDE_MASK  (ARM64_PHYSMAP_SLIDE_RANGE - 1)

void
arm_vm_init(uint64_t memory_size, boot_args * args)
{
	vm_map_address_t va_l1, va_l1_end;
	tt_entry_t       *cpu_l1_tte;
	vm_map_address_t va_l2, va_l2_end;
	tt_entry_t       *cpu_l2_tte;
	pmap_paddr_t     boot_ttep;
	tt_entry_t       *boot_tte;
	uint64_t         mem_segments;
	vm_offset_t      ptpage_vaddr;
	vm_map_address_t dynamic_memory_begin;
	vm_map_address_t physmap_base;


	/*
	 * Get the virtual and physical memory base from boot_args.
	 */
	gVirtBase = args->virtBase;
	gPhysBase = args->physBase;
#if KASAN
	real_phys_size = args->memSize + (shadow_ptop - shadow_pbase);
#else
	real_phys_size = args->memSize;
#endif
	/*
	 * Ensure the physical region we specify for the VM to manage ends on a
	 * software page boundary.  Note that the software page size (PAGE_SIZE)
	 * may be a multiple of the hardware page size specified in ARM_PGBYTES.
	 * We must round the reported memory size down to the nearest PAGE_SIZE
	 * boundary to ensure the VM does not try to manage a page it does not
	 * completely own.  The KASAN shadow region, if present, is managed entirely
	 * in units of the hardware page size and should not need similar treatment.
	 */
	gPhysSize = mem_size = ((gPhysBase + args->memSize) & ~PAGE_MASK) - gPhysBase;

	if ((memory_size != 0) && (mem_size > memory_size))
		mem_size = memory_size;
	if (mem_size >= ((VM_MAX_KERNEL_ADDRESS - VM_MIN_KERNEL_ADDRESS) / 4))
		panic("Unsupported memory configuration %lx\n", mem_size);

	physmap_base = phystokv(args->topOfKernelData) + BOOTSTRAP_TABLE_SIZE;

	// Slide the physical aperture to a random page-aligned location within the slide range
	uint64_t physmap_slide = early_random() & ARM64_PHYSMAP_SLIDE_MASK & ~((uint64_t)PAGE_MASK);
	assert(physmap_slide < ARM64_PHYSMAP_SLIDE_RANGE);

	physmap_base += physmap_slide;

	static_memory_end = physmap_base + mem_size + (PTOV_TABLE_SIZE * ARM_TT_TWIG_SIZE); // worst possible case for block alignment
#if KASAN
	/* add the KASAN stolen memory to the physmap */
	dynamic_memory_begin = static_memory_end + (shadow_ptop - shadow_pbase);
#else
	dynamic_memory_begin = static_memory_end;
#endif
	if (dynamic_memory_begin > VM_MAX_KERNEL_ADDRESS)
		panic("Unsupported memory configuration %lx\n", mem_size);

	boot_ttep = args->topOfKernelData;
	boot_tte = (tt_entry_t *) phystokv(boot_ttep);

#if DEVELOPMENT || DEBUG
	/* Sanity check - assert that BOOTSTRAP_TABLE_SIZE is sufficiently-large to
	 * hold our bootstrap mappings for any possible slide */
	size_t bytes_mapped = dynamic_memory_begin - gVirtBase;
	size_t l1_entries = 1 + ((bytes_mapped + ARM_TT_L1_SIZE - 1) / ARM_TT_L1_SIZE);
	/* 1 L1 each for V=P and KVA, plus 1 page for each L2 */
	size_t pages_used = 2 * (l1_entries + 1);
	if (pages_used > BOOTSTRAP_TABLE_SIZE) {
		panic("BOOTSTRAP_TABLE_SIZE too small for memory config\n");
	}
#endif

	/*
	 *  TTBR0 L1, TTBR0 L2 - 1:1 bootstrap mapping.
	 *  TTBR1 L1, TTBR1 L2 - kernel mapping
	 */
	avail_start = boot_ttep + BOOTSTRAP_TABLE_SIZE;

#if defined(KERNEL_INTEGRITY_KTRR)
	arm_replace_identity_map(args);
#endif

	/* Initialize invalid tte page */
	invalid_tte = (tt_entry_t *)alloc_ptpage(TRUE);
	invalid_ttep = kvtophys((vm_offset_t)invalid_tte);
	bzero(invalid_tte, ARM_PGBYTES);

	/*
	 * Initialize l1 page table page
	 */
	cpu_tte = (tt_entry_t *)alloc_ptpage(TRUE);
	cpu_ttep = kvtophys((vm_offset_t)cpu_tte);
	bzero(cpu_tte, ARM_PGBYTES);
	avail_end = gPhysBase + mem_size;
	assert(!(avail_end & PAGE_MASK));

#if KASAN
	real_avail_end = gPhysBase + real_phys_size;
#else
	real_avail_end = avail_end;
#endif

	/*
	 * Initialize l1 and l2 page table pages :
	 *   map physical memory at the kernel base virtual address
	 *   cover the kernel dynamic address range section
	 *
	 *   the so called physical aperture should be statically mapped
	 */
	va_l1 = gVirtBase;
	va_l1_end = dynamic_memory_begin;
	cpu_l1_tte = cpu_tte + ((va_l1 & ARM_TT_L1_INDEX_MASK) >> ARM_TT_L1_SHIFT);

	while (va_l1 < va_l1_end) {
		if (*cpu_l1_tte == ARM_TTE_EMPTY) {
			/* Allocate a page and setup L1 Table TTE in L1 */
			ptpage_vaddr = alloc_ptpage(TRUE);
			*cpu_l1_tte = (kvtophys(ptpage_vaddr) & ARM_TTE_TABLE_MASK) | ARM_TTE_TYPE_TABLE | ARM_TTE_VALID;
			bzero((void *)ptpage_vaddr, ARM_PGBYTES);
		}

		if ((va_l1 + ARM_TT_L1_SIZE) < va_l1) {
			/* If this is the last L1 entry, it must cover the last mapping. */
			break;
		}

		va_l1 += ARM_TT_L1_SIZE;
		cpu_l1_tte++;
	}

#if __ARM_KERNEL_PROTECT__
	/* Expand the page tables to prepare for the EL0 mappings. */
	arm_vm_expand_kernel_el0_mappings();
#endif /* __ARM_KERNEL_PROTECT__ */

	/*
	 * Now retrieve addresses for end, edata, and etext from MACH-O headers
	 */
	segPRELINKTEXTB  = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__PRELINK_TEXT", &segSizePRELINKTEXT);
	segPLKDATACONSTB = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__PLK_DATA_CONST", &segSizePLKDATACONST);
	segPLKTEXTEXECB  = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__PLK_TEXT_EXEC", &segSizePLKTEXTEXEC);
	segTEXTB         = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__TEXT", &segSizeTEXT);
	segDATACONSTB    = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__DATA_CONST", &segSizeDATACONST);
	segTEXTEXECB     = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__TEXT_EXEC", &segSizeTEXTEXEC);
	segDATAB         = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__DATA", &segSizeDATA);

	segBOOTDATAB    = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__BOOTDATA", &segSizeBOOTDATA);
	segLINKB         = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__LINKEDIT", &segSizeLINK);
	segKLDB          = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__KLD", &segSizeKLD);
	segPRELINKDATAB  = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__PRELINK_DATA", &segSizePRELINKDATA);
	segPRELINKINFOB  = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__PRELINK_INFO", &segSizePRELINKINFO);
	segPLKLLVMCOVB   = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__PLK_LLVM_COV", &segSizePLKLLVMCOV);
	segPLKLINKEDITB  = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__PLK_LINKEDIT", &segSizePLKLINKEDIT);
	segLASTB         = (vm_offset_t) getsegdatafromheader(&_mh_execute_header, "__LAST", &segSizeLAST);

	(void) PE_parse_boot_argn("use_contiguous_hint", &use_contiguous_hint, sizeof(use_contiguous_hint));
	assert(segSizePRELINKTEXT < 0x03000000); /* 23355738 */

	/* if one of the new segments is present, the other one better be as well */
	if (segSizePLKDATACONST || segSizePLKTEXTEXEC) {
		assert(segSizePLKDATACONST && segSizePLKTEXTEXEC);
	}

	etext = (vm_offset_t) segTEXTB + segSizeTEXT;
	sdata = (vm_offset_t) segDATAB;
	edata = (vm_offset_t) segDATAB + segSizeDATA;
	end_kern = round_page(getlastaddr());      /* Force end to next page */

	vm_set_page_size();

	vm_kernel_base = segTEXTB;
	vm_kernel_top = (vm_offset_t) &last_kernel_symbol;
	vm_kext_base = segPRELINKTEXTB;
	vm_kext_top = vm_kext_base + segSizePRELINKTEXT;

	vm_prelink_stext = segPRELINKTEXTB;
	if (!segSizePLKTEXTEXEC && !segSizePLKDATACONST) {
		vm_prelink_etext = segPRELINKTEXTB + segSizePRELINKTEXT;
	} else {
		vm_prelink_etext = segPRELINKTEXTB + segSizePRELINKTEXT + segSizePLKDATACONST + segSizePLKTEXTEXEC;
	}
	vm_prelink_sinfo = segPRELINKINFOB;
	vm_prelink_einfo = segPRELINKINFOB + segSizePRELINKINFO;
	vm_slinkedit = segLINKB;
	vm_elinkedit = segLINKB + segSizeLINK;

	vm_prelink_sdata = segPRELINKDATAB;
	vm_prelink_edata = segPRELINKDATAB + segSizePRELINKDATA;

	arm_vm_prot_init(args);


	/*
	 * Initialize the page tables for the low globals:
	 *   cover this address range:
	 *     LOW_GLOBAL_BASE_ADDRESS + 2MB
	 */
	va_l1 = va_l2 = LOW_GLOBAL_BASE_ADDRESS;
	cpu_l1_tte = cpu_tte + ((va_l1 & ARM_TT_L1_INDEX_MASK) >> ARM_TT_L1_SHIFT);
	cpu_l2_tte = ((tt_entry_t *) phystokv(((*cpu_l1_tte) & ARM_TTE_TABLE_MASK))) + ((va_l2 & ARM_TT_L2_INDEX_MASK) >> ARM_TT_L2_SHIFT);
	ptpage_vaddr = alloc_ptpage(TRUE);
	*cpu_l2_tte = (kvtophys(ptpage_vaddr) & ARM_TTE_TABLE_MASK) | ARM_TTE_TYPE_TABLE | ARM_TTE_VALID | ARM_TTE_TABLE_PXN | ARM_TTE_TABLE_XN;
	bzero((void *)ptpage_vaddr, ARM_PGBYTES);

	/*
	 * Initialize l2 page table pages :
	 *   cover this address range:
	 *    KERNEL_DYNAMIC_ADDR - VM_MAX_KERNEL_ADDRESS
	 */
	va_l1 = dynamic_memory_begin;
	va_l1_end = VM_MAX_KERNEL_ADDRESS;
	cpu_l1_tte = cpu_tte + ((va_l1 & ARM_TT_L1_INDEX_MASK) >> ARM_TT_L1_SHIFT);

	while (va_l1 < va_l1_end) {
		if (*cpu_l1_tte == ARM_TTE_EMPTY) {
			/* Allocate a page and setup L1 Table TTE in L1 */
			ptpage_vaddr = alloc_ptpage(TRUE);
			*cpu_l1_tte = (kvtophys(ptpage_vaddr) & ARM_TTE_TABLE_MASK) | ARM_TTE_TYPE_TABLE | ARM_TTE_VALID | ARM_DYNAMIC_TABLE_XN;
			bzero((void *)ptpage_vaddr, ARM_PGBYTES);
		}

		if ((va_l1 + ARM_TT_L1_SIZE) < va_l1) {
			/* If this is the last L1 entry, it must cover the last mapping. */
			break;
		}

		va_l1 += ARM_TT_L1_SIZE;
		cpu_l1_tte++;
	}

#if KASAN
	/* record the extent of the physmap */
	physmap_vbase = physmap_base;
	physmap_vtop = static_memory_end;
	kasan_init();
#endif /* KASAN */

#if MONOTONIC
	mt_early_init();
#endif /* MONOTONIC */

	set_tbi();

	arm_vm_physmap_init(args, physmap_base, dynamic_memory_begin);
	set_mmu_ttb_alternate(cpu_ttep & TTBR_BADDR_MASK);


	set_mmu_ttb(invalid_ttep & TTBR_BADDR_MASK);

	flush_mmu_tlb();
	kva_active = TRUE;
	// global table pointers may need to be different due to physical aperture remapping
	cpu_tte = (tt_entry_t*)(phystokv(cpu_ttep));
	invalid_tte = (tt_entry_t*)(phystokv(invalid_ttep));

	sane_size = mem_size - (avail_start - gPhysBase);
	max_mem = mem_size;
	vm_kernel_slid_base = segLOWESTTEXT;
	vm_kernel_slid_top = vm_prelink_einfo;
	vm_kernel_slide = segTEXTB-VM_KERNEL_LINK_ADDRESS;
	vm_kernel_stext = segTEXTB;
	assert(segDATACONSTB == segTEXTB + segSizeTEXT);
	assert(segTEXTEXECB == segDATACONSTB + segSizeDATACONST);
	vm_kernel_etext = segTEXTB + segSizeTEXT + segSizeDATACONST + segSizeTEXTEXEC;

	dynamic_memory_begin = ROUND_TWIG(dynamic_memory_begin);
	pmap_bootstrap(dynamic_memory_begin);

	disable_preemption();

	/*
	 * Initialize l3 page table pages :
	 *   cover this address range:
	 *    2MB + FrameBuffer size + 10MB for each 256MB segment
	 */

	mem_segments = (mem_size + 0x0FFFFFFF) >> 28;

	va_l1 = dynamic_memory_begin;
	va_l1_end = va_l1 + ((2 + (mem_segments * 10)) << 20);
	va_l1_end += round_page(args->Video.v_height * args->Video.v_rowBytes);
	va_l1_end = (va_l1_end + 0x00000000007FFFFFULL) & 0xFFFFFFFFFF800000ULL;

	cpu_l1_tte = cpu_tte + ((va_l1 & ARM_TT_L1_INDEX_MASK) >> ARM_TT_L1_SHIFT);

	while (va_l1 < va_l1_end) {

		va_l2 = va_l1;

		if (((va_l1 & ~ARM_TT_L1_OFFMASK)+ARM_TT_L1_SIZE) < va_l1) {
			/* If this is the last L1 entry, it must cover the last mapping. */
			va_l2_end = va_l1_end;
		} else {
			va_l2_end = MIN((va_l1 & ~ARM_TT_L1_OFFMASK)+ARM_TT_L1_SIZE, va_l1_end);
		}

		cpu_l2_tte = ((tt_entry_t *) phystokv(((*cpu_l1_tte) & ARM_TTE_TABLE_MASK))) + ((va_l2 & ARM_TT_L2_INDEX_MASK) >> ARM_TT_L2_SHIFT);

		while (va_l2 < va_l2_end) {
			pt_entry_t *    ptp;
			pmap_paddr_t    ptp_phys;

			/* Allocate a page and setup L3 Table TTE in L2 */
			ptp = (pt_entry_t *) alloc_ptpage(FALSE);
			ptp_phys = (pmap_paddr_t)kvtophys((vm_offset_t)ptp);

			pmap_init_pte_page(kernel_pmap, ptp, va_l2, 3, TRUE, TRUE);

			*cpu_l2_tte = (pa_to_tte (ptp_phys)) | ARM_TTE_TYPE_TABLE | ARM_TTE_VALID | ARM_DYNAMIC_TABLE_XN;

			va_l2 += ARM_TT_L2_SIZE;
			cpu_l2_tte++;
		};

		va_l1 = va_l2_end;
		cpu_l1_tte++;
	}

	/*
	 * Initialize l3 page table pages :
	 *   cover this address range:
	 *   (VM_MAX_KERNEL_ADDRESS & CPUWINDOWS_BASE_MASK) - VM_MAX_KERNEL_ADDRESS
	 */
	va_l1 = VM_MAX_KERNEL_ADDRESS & CPUWINDOWS_BASE_MASK;
	va_l1_end = VM_MAX_KERNEL_ADDRESS;

	cpu_l1_tte = cpu_tte + ((va_l1 & ARM_TT_L1_INDEX_MASK) >> ARM_TT_L1_SHIFT);

	while (va_l1 < va_l1_end) {

		va_l2 = va_l1;

		if (((va_l1 & ~ARM_TT_L1_OFFMASK)+ARM_TT_L1_SIZE) < va_l1) {
			/* If this is the last L1 entry, it must cover the last mapping. */
			va_l2_end = va_l1_end;
		} else {
			va_l2_end = MIN((va_l1 & ~ARM_TT_L1_OFFMASK)+ARM_TT_L1_SIZE, va_l1_end);
		}

		cpu_l2_tte = ((tt_entry_t *) phystokv(((*cpu_l1_tte) & ARM_TTE_TABLE_MASK))) + ((va_l2 & ARM_TT_L2_INDEX_MASK) >> ARM_TT_L2_SHIFT);

		while (va_l2 < va_l2_end) {
			pt_entry_t *    ptp;
			pmap_paddr_t    ptp_phys;

			/* Allocate a page and setup L3 Table TTE in L2 */
			ptp = (pt_entry_t *) alloc_ptpage(FALSE);
			ptp_phys = (pmap_paddr_t)kvtophys((vm_offset_t)ptp);

			pmap_init_pte_page(kernel_pmap, ptp, va_l2, 3, TRUE, TRUE);

			*cpu_l2_tte = (pa_to_tte (ptp_phys)) | ARM_TTE_TYPE_TABLE | ARM_TTE_VALID | ARM_DYNAMIC_TABLE_XN;

			va_l2 += ARM_TT_L2_SIZE;
			cpu_l2_tte++;
		};

		va_l1 = va_l2_end;
		cpu_l1_tte++;
	}

#if __ARM64_PMAP_SUBPAGE_L1__ && __ARM_16K_PG__
	/*
	 * In this configuration, the bootstrap mappings (arm_vm_init) and
	 * the heap mappings occupy separate L1 regions.  Explicitly set up
	 * the heap L1 allocations here.
	 */
	va_l1 = VM_MIN_KERNEL_ADDRESS & ~ARM_TT_L1_OFFMASK;
	cpu_l1_tte = cpu_tte + ((va_l1 & ARM_TT_L1_INDEX_MASK) >> ARM_TT_L1_SHIFT);

	while ((va_l1 >= (VM_MIN_KERNEL_ADDRESS & ~ARM_TT_L1_OFFMASK)) && (va_l1 < VM_MAX_KERNEL_ADDRESS)) {
		/*
		 * If the L1 entry has not yet been allocated, allocate it
		 * now and treat it as a heap table.
		 */
		if (*cpu_l1_tte == ARM_TTE_EMPTY) {
			tt_entry_t *new_tte = (tt_entry_t*)alloc_ptpage(FALSE);
			bzero(new_tte, ARM_PGBYTES);
			*cpu_l1_tte = (kvtophys((vm_offset_t)new_tte) & ARM_TTE_TABLE_MASK)  | ARM_TTE_TYPE_TABLE | ARM_TTE_VALID | ARM_DYNAMIC_TABLE_XN;
		}

		cpu_l1_tte++;
		va_l1 += ARM_TT_L1_SIZE;
	}
#endif

	/*
	 * Adjust avail_start so that the range that the VM owns
	 * starts on a PAGE_SIZE aligned boundary.
	 */
	avail_start = (avail_start + PAGE_MASK) & ~PAGE_MASK;

	first_avail = avail_start;
	patch_low_glo_static_region(args->topOfKernelData, avail_start - args->topOfKernelData);
	enable_preemption();
}