arm/pmap/pmap_data.h

/*
 * Copyright (c) 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
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 * may not be used to create, or enable the creation or redistribution of,
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/**
 * This header file is used to store the types, prototypes, and inline functions
 * that define some of the most important data structures used in the pmap. This
 * header is only meant for sharing types within the pmap; if a type is meant to
 * be used by the rest of the kernel, then put it into osfmk/arm/pmap.h.
 */
#ifndef _ARM_PMAP_PMAP_DATA_H_
#define _ARM_PMAP_PMAP_DATA_H_

#include <stdint.h>

#include <kern/ledger.h>
#include <mach/vm_types.h>
#include <mach_assert.h>
#include <vm/vm_page.h>

#include <arm/cpu_data.h>
#include <arm/machine_routines.h>
#include <arm64/proc_reg.h>

/* Temporary include before moving all ledger functions into pmap_data.c */
#include <os/refcnt.h>

/**
 * These headers are safe to be included in this file since they shouldn't rely
 * on any of the internal pmap header files (so no circular dependencies).
 */
#include <arm/pmap.h>
#include <arm/pmap/pmap_pt_geometry.h>

/**
 * These values represent the first and last kernel-managed physical addresses.
 * We keep track of extra metadata on kernel-managed pages compared to other
 * pages (usually iBoot carved out memory or I/O).
 */
extern pmap_paddr_t vm_first_phys, vm_last_phys;

/**
 * Return whether the given address represents a kernel-managed physical page.
 *
 * Whether a page is considered "kernel-managed" is determined by the BootArgs
 * passed by the bootloader. Typically memory carved out by the bootloader as
 * well as I/O memory should return false.
 *
 * @param pa The physical address to check.
 */
static inline bool
pa_valid(pmap_paddr_t pa)
{
	return (pa >= vm_first_phys) && (pa < vm_last_phys);
}

/**
 * The pmap has a variety of data structures (pv_head_table/pp_attr_table) that
 * contain an entry for every kernel-managed page in the system. These systems
 * are indexed with physical address indices ("pai") generated by this function.
 *
 * The logic is simple since there should be one entry in each of these data
 * structures for each kernel-managed physical page in the system. These data
 * structures are allocated on boot based on the amount of memory available.
 *
 * @note PAIs are defined using the VM page size, which might not be identical
 *       to the underlying hardware page size for an arbitrary address space.
 *       This means that the data structures relying on PAIs will contain one
 *       entry for each VM page, not hardware page.
 *
 * @note This function is only valid for physical addresses that are
 *       kernel-managed.
 */

static inline unsigned int
pa_index(pmap_paddr_t pa)
{
	return (unsigned int)atop(pa - vm_first_phys);
}

/* See the definition of pv_head_table for more information. */
extern pv_entry_t **pv_head_table;

/* Represents a NULL entry in the pv_head_table. */
#define PV_ENTRY_NULL ((pv_entry_t *) 0)

/**
 * Given a physical address index, return the corresponding pv_head_table entry.
 *
 * @note Despite returning a pointer to a pv_entry_t pointer, the entry might
 *       actually be a different type of pointer (pt_entry_t or pt_desc_t)
 *       depending on the type for this entry. Determine the type using
 *       pvh_test_type().
 *
 * @param pai The index returned by pa_index() for the page whose pv_head_table
 *            entry should be retrieved.
 */
static inline pv_entry_t **
pai_to_pvh(unsigned int pai)
{
	return &pv_head_table[pai];
}

/**
 * Each pv_head_table entry can be one of four different types:
 *
 * - PVH_TYPE_NULL: No mappings to the physical page exist outside of the
 *                  physical aperture. Physical aperture mappings are not
 *                  tracked in the pv_head_table.
 *
 * - PVH_TYPE_PVEP: There are multiple mappings to the physical page.
 *                  These entries are linked lists of pv_entry_t objects (which
 *                  each contain a pointer to the associated PTE and a pointer
 *                  to the next entry in the list).
 *
 * - PVH_TYPE_PTEP: There is a single mapping to the physical page. Once more
 *                  mappings are created, this entry will get upgraded to an
 *                  entry of type PVH_TYPE_PVEP. These entries are pointers
 *                  directly to the page table entry that contain the mapping
 *                  (pt_entry_t*).
 *
 * - PVH_TYPE_PTDP: The physical page is being used as a page table. These
 *                  entries are pointers to page table descriptor structures
 *                  (pt_desc_t) which contain metadata related to each page
 *                  table.
 *
 * The type is stored in the bottom two bits of each pv_head_table entry. That
 * type needs to be checked before dereferencing the pointer to determine which
 * pointer type to dereference as.
 */
#define PVH_TYPE_NULL 0x0UL
#define PVH_TYPE_PVEP 0x1UL
#define PVH_TYPE_PTEP 0x2UL
#define PVH_TYPE_PTDP 0x3UL

#define PVH_TYPE_MASK (0x3UL)

#if defined(__arm64__)

/**
 * PV_HEAD_TABLE Flags.
 *
 * All flags listed below are stored in the pv_head_table entry/pointer
 * (per-physical-page) unless otherwise noted.
 *
 * Please update the pv_walk LLDB macro if these flags are changed or added to.
 */

/**
 * This flag is set for every mapping created by an IOMMU.
 *
 * Stored in each PTE pointer (for PVH_TYPE_PVEP lists), or in the pv_head_table
 * entry/pointer for single-PTE entries (PVH_TYPE_PTEP).
 */
#define PVH_FLAG_IOMMU 0x4UL

/**
 * This flag is only valid when PVH_FLAG_IOMMU is set. For an IOMMU mapping, if
 * this bit is set, then the PTE pointer points directly into the IOMMU page
 * table for this mapping. If this bit is cleared, then the "PTE pointer" is
 * actually a pointer to the IOMMU descriptor object that owns this mapping.
 *
 * There are cases where it's not easy to tie an IOMMU mapping directly to a
 * specific page table, so this allows us to at least get a pointer to which
 * IOMMU created this mapping which is useful for debugging purposes.
 *
 * Stored in each PTE pointer (for PVH_TYPE_PVEP lists), or in the pv_head_table
 * entry/pointer for single-PTE entries (PVH_TYPE_PTEP).
 */
#define PVH_FLAG_IOMMU_TABLE (1ULL << 63)

/**
 * This flag is set when the first CPU (non-IOMMU) mapping is created. This is
 * important to keep track of because various accounting statistics are based on
 * the options specified for the first CPU mapping. This flag, and thus the
 * accounting statistics, will persist as long as there *any* mappings of the
 * page (including IOMMU mappings). This works because the accounting for a page
 * should not need to change until the page is recycled by the VM layer, and we
 * double-check that there are no mappings (CPU or IOMMU) when a page is
 * recycled (see: pmap_verify_free()).
 */
#define PVH_FLAG_CPU (1ULL << 62)

/* This bit is used as a lock when modifying a pv_head_table entry. */
#define PVH_LOCK_BIT 61
#define PVH_FLAG_LOCK (1ULL << PVH_LOCK_BIT)

/**
 * This flag is set when there are any executable mappings to this physical
 * page. This is used to prevent any writable mappings from being created at
 * the same time an executable mapping exists.
 */
#define PVH_FLAG_EXEC (1ULL << 60)

/**
 * Marking a pv_head_table entry with this flag denotes that this page is a
 * kernelcache text or data page that shouldn't have dynamically-created
 * mappings.  See PVH_FLAG_LOCKDOWN_MASK for more details.
 */
#define PVH_FLAG_LOCKDOWN_KC (1ULL << 59)

/**
 * This flag is used to mark that a page has been hashed into the hibernation
 * image.
 *
 * The hibernation driver will use this to ensure that all PPL-owned memory is
 * correctly included into the hibernation image (a missing PPL page could be
 * a security concern when coming out of hibernation).
 */
#define PVH_FLAG_HASHED (1ULL << 58)

/**
 * Marking a pv_head_table entry with this flag denotes that this page is a
 * code signature page that shouldn't have dynamically-created mappings.
 * See PVH_FLAG_LOCKDOWN_MASK for more details.
 */
#define PVH_FLAG_LOCKDOWN_CS (1ULL << 57)

/**
 * Marking a pv_head_table entry with this flag denotes that this page is a
 * read-only allocator page that shouldn't have dynamically-created mappings.
 * See PVH_FLAG_LOCKDOWN_MASK for more details.
 */
#define PVH_FLAG_LOCKDOWN_RO (1ULL << 56)

#define PVH_FLAG_RETIRED 0

#define PVH_FLAG_TAGS 0
#define PVH_FLAG_TAGGGED 0

/**
 * Flags which disallow a new mapping to a page.
 */
#define PVH_FLAG_NOMAP_MASK (PVH_FLAG_RETIRED | PVH_FLAG_TAGS)

/**
 * Marking a pv_head_table entry with this flag denotes that this page has
 * been mapped into a non-coherent coprocessor address space and requires a
 * cache flush operation once all mappings have been removed.
 */
#define PVH_FLAG_FLUSH_NEEDED (1ULL << 52)

/**
 * Marking a pv_head_table entry with any bit in this mask denotes that this page
 * has been locked down by the PPL.  Locked down pages can't have new mappings
 * created or existing mappings removed, and all existing mappings will have been
 * converted to read-only.  This essentially makes the page immutable.
 */
#define PVH_FLAG_LOCKDOWN_MASK (PVH_FLAG_LOCKDOWN_KC | PVH_FLAG_LOCKDOWN_CS | PVH_FLAG_LOCKDOWN_RO)


/**
 * These bits need to be set to safely dereference a pv_head_table
 * entry/pointer.
 *
 * Any change to this #define should also update the copy located in the pmap.py
 * LLDB macros file.
 */

#define PVH_HIGH_FLAGS (PVH_FLAG_CPU | PVH_FLAG_LOCK | PVH_FLAG_EXEC | PVH_FLAG_LOCKDOWN_MASK | \
    PVH_FLAG_HASHED | PVH_FLAG_FLUSH_NEEDED | PVH_FLAG_RETIRED)


#endif /* defined(__arm64__) */

/* Mask used to clear out the TYPE bits from a pv_head_table entry/pointer. */
#define PVH_LIST_MASK (~PVH_TYPE_MASK)

/* Which 32-bit word in each pv_head_table entry/pointer contains the LOCK bit. */
#if defined(__arm64__)
#define PVH_LOCK_WORD 1 /* Assumes little-endian */
#endif /* defined(__arm64__) */

/**
 * Assert that a pv_head_table entry is locked. Will panic if the lock isn't
 * acquired.
 *
 * @param index The physical address index to check.
 */
static inline void
pvh_assert_locked(__assert_only unsigned int index)
{
	assert((vm_offset_t)(pv_head_table[index]) & PVH_FLAG_LOCK);
}


/**
 * Lock a pv_head_table entry.
 *
 * @param index The physical address index of the pv_head_table entry to lock.
 */
static inline void
pvh_lock(unsigned int index)
{
	pmap_lock_bit((uint32_t*)(&pv_head_table[index]) + PVH_LOCK_WORD,
	    PVH_LOCK_BIT - (PVH_LOCK_WORD * 32));
}

/**
 * Unlock a pv_head_table entry.
 *
 * @param index The physical address index of the pv_head_table entry to unlock.
 */
static inline void
pvh_unlock(unsigned int index)
{
	pvh_assert_locked(index);

	pmap_unlock_bit((uint32_t*)(&pv_head_table[index]) + PVH_LOCK_WORD,
	    PVH_LOCK_BIT - (PVH_LOCK_WORD * 32));
}

/**
 * Check that a pv_head_table entry/pointer is a specific type.
 *
 * @param pvh The pv_head_table entry/pointer to check.
 * @param type The type to check for.
 *
 * @return True if the pv_head_table entry is of the passed in type, false
 *         otherwise.
 */
static inline bool
pvh_test_type(pv_entry_t **pvh, vm_offset_t type)
{
	return ((*(vm_offset_t *)pvh) & PVH_TYPE_MASK) == type;
}

/**
 * Convert a pv_head_table entry/pointer into a page table entry pointer. This
 * should only be done if the type of this entry is PVH_TYPE_PTEP.
 *
 * @param pvh The pv_head_table entry/pointer to convert into a pt_entry_t*.
 *
 * @return Return back a safe to derefence pointer to the single mapping of this
 *         physical page by masking off the TYPE bits and adding any missing
 *         flags to the upper portion of the pointer.
 */
static inline pt_entry_t*
pvh_ptep(pv_entry_t **pvh)
{
	return (pt_entry_t *)(((*(vm_offset_t *)pvh) & PVH_LIST_MASK) | PVH_HIGH_FLAGS);
}

/**
 * Convert a pv_head_table entry/pointer into a PVE list pointer. This
 * should only be done if the type of this entry is PVH_TYPE_PVEP.
 *
 * @param pvh The pv_head_table entry/pointer to convert into a safe to
 *            dereference pv_entry_t*.
 *
 * @return Return back a safe to derefence pointer to the first mapping of this
 *         physical page by masking off the TYPE bits and adding any missing
 *         flags to the upper portion of the pointer.
 */
static inline pv_entry_t*
pvh_pve_list(pv_entry_t **pvh)
{
	return (pv_entry_t *)(((*(vm_offset_t *)pvh) & PVH_LIST_MASK) | PVH_HIGH_FLAGS);
}

/**
 * Return the flags associated with a pv_head_table entry/pointer.
 *
 * @param pvh The pv_head_table entry whose flags to get.
 */
static inline vm_offset_t
pvh_get_flags(pv_entry_t **pvh)
{
	return (*(vm_offset_t *)pvh) & PVH_HIGH_FLAGS;
}

/**
 * Atomically set the flags associated with a pv_head_table entry/pointer.
 *
 * @param pvh The pv_head_table entry whose flags are getting set.
 */
static inline void
pvh_set_flags(pv_entry_t **pvh, vm_offset_t flags)
{
	os_atomic_store((vm_offset_t *)pvh, ((*(vm_offset_t *)pvh) & ~PVH_HIGH_FLAGS) | flags, relaxed);
}

/**
 * Update a pv_head_table entry/pointer to be a different type and/or point to
 * a different object.
 *
 * @note The pv_head_table entry MUST already be locked.
 *
 * @note This function will clobber any existing flags stored in the PVH pointer
 *       (except PVH_FLAG_LOCK). It's up to the caller to preserve flags if that
 *       functionality is needed (either by ensuring `pvep` contains those
 *       flags, or by manually setting the flags after this call).
 *
 * @param pvh The pv_head_table entry/pointer to update.
 * @param pvep The new entry to use. This could be either a pt_entry_t*,
 *             pv_entry_t*, or pt_desc_t* depending on the type.
 * @param type The type of the new entry.
 */
static inline void
pvh_update_head(pv_entry_t **pvh, void *pvep, unsigned int type)
{
	assert((*(vm_offset_t *)pvh) & PVH_FLAG_LOCK);
	os_atomic_store((vm_offset_t *)pvh, (vm_offset_t)pvep | type | PVH_FLAG_LOCK, relaxed);
}

/**
 * Update a pv_head_table entry/pointer to be a different type and/or point to
 * a different object.
 *
 * @note The pv_head_table entry CAN'T already be locked.
 *
 * @note This function will clobber any existing flags stored in the PVH
 *       pointer. It's up to the caller to preserve flags if that functionality
 *       is needed (either by ensuring `pvep` contains those flags, or by
 *       manually setting the flags after this call).
 *
 * @param pvh The pv_head_table entry/pointer to update.
 * @param pvep The new entry to use. This could be either a pt_entry_t*,
 *             pv_entry_t*, or pt_desc_t* depending on the type.
 * @param type The type of the new entry.
 */
static inline void
pvh_update_head_unlocked(pv_entry_t **pvh, void *pvep, unsigned int type)
{
	assert(!((*(vm_offset_t *)pvh) & PVH_FLAG_LOCK));
	*(vm_offset_t *)pvh = ((vm_offset_t)pvep | type) & ~PVH_FLAG_LOCK;
}

/**
 * Given a page table entry pointer retrieved from the pv_head_table (from an
 * entry of type PVH_TYPE_PTEP or PVH_TYPE_PVEP), return back whether the PTE is
 * an IOMMU mapping.
 *
 * @note The way this function determines whether the passed in pointer is
 *       pointing to an IOMMU PTE, is by checking for a special flag stored in
 *       the lower bits of the pointer. This flag is only set on pointers stored
 *       in the pv_head_table, and as such, this function will only work on
 *       pointers retrieved from the pv_head_table. If a pointer to a PTE was
 *       directly retrieved from an IOMMU's page tables, this function would
 *       always return false despite actually being an IOMMU PTE.
 *
 * @param ptep A PTE pointer obtained from the pv_head_table to check.
 *
 * @return True if the entry is an IOMMU mapping, false otherwise.
 */
static inline bool
pvh_ptep_is_iommu(const pt_entry_t *ptep)
{
#ifdef PVH_FLAG_IOMMU
	return (vm_offset_t)ptep & PVH_FLAG_IOMMU;
#else /* PVH_FLAG_IOMMU */
	#pragma unused(ptep)
	return false;
#endif /* PVH_FLAG_IOMMU */
}

/**
 * Sometimes the PTE pointers retrieved from the pv_head_table (from an entry of
 * type PVH_TYPE_PTEP or PVH_TYPE_PVEP) contain flags themselves. This function
 * strips out those flags and returns back a dereferencable pointer.
 *
 * @param ptep The PTE pointer to strip out the unwanted flags.
 *
 * @return A valid dereferencable pointer to the page table entry.
 */
static inline const pt_entry_t*
pvh_strip_ptep(const pt_entry_t *ptep)
{
#ifdef PVH_FLAG_IOMMU
	const vm_offset_t pte_va = (vm_offset_t)ptep;
	return (const pt_entry_t*)((pte_va & ~PVH_FLAG_IOMMU) | PVH_FLAG_IOMMU_TABLE);
#else /* PVH_FLAG_IOMMU */
	return ptep;
#endif /* PVH_FLAG_IOMMU */
}

/**
 * PVH_TYPE_PVEP Helper Functions.
 *
 * The following are methods used to manipulate PVE lists. This is the type of
 * pv_head_table entry used when there are multiple mappings to a single
 * physical page.
 */

/**
 * Whether a physical page is using "alternate accounting" (ALTACCT) for its
 * ledger statistics is something that needs to be tracked on a per-mapping
 * basis, not on a per-physical-page basis. Because of that, it's tracked
 * differently depending on whether there's a single mapping to a page
 * (PVH_TYPE_PTEP) or multiple (PVH_TYPE_PVEP). For single mappings, the bit is
 * tracked in the pp_attr_table. But when there are multiple mappings, the least
 * significant bit of the corresponding "pve_pte" pointer in each pv_entry object
 * is used as a marker for pages using alternate accounting.
 *
 * @note See the definition for PP_ATTR_ALTACCT for a more detailed description
 *       of what "alternate accounting" actually means in respect to the
 *       footprint ledger.
 *
 * Since some code (KernelDiskImages, e.g.) might map a phsyical page as
 * "device" memory (i.e. external) while it's also being used as regular
 * "anonymous" memory (i.e. internal) in user space, we have to manage the
 * "internal" attribute per mapping rather than per physical page.
 * When there are multiple mappings, we use the next least significant bit of
 * the corresponding "pve_pte" pointer for that.
 */
#define PVE_PTEP_ALTACCT ((uintptr_t) 0x1)
#define PVE_PTEP_INTERNAL ((uintptr_t) 0x2)
#define PVE_PTEP_FLAGS (PVE_PTEP_ALTACCT | PVE_PTEP_INTERNAL)

/**
 * Set the ALTACCT bit for a specific PTE pointer.
 *
 * @param pvep A pointer to the current pv_entry mapping in the linked list of
 *             mappings.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline void
pve_set_altacct(pv_entry_t *pvep, unsigned idx)
{
	assert(idx < PTE_PER_PVE);
	pvep->pve_ptep[idx] = (pt_entry_t *)((uintptr_t)pvep->pve_ptep[idx] | PVE_PTEP_ALTACCT);
}
/**
 * Set the INTERNAL bit for a specific PTE pointer.
 *
 * @param pvep A pointer to the current pv_entry mapping in the linked list of
 *             mappings.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline void
pve_set_internal(pv_entry_t *pvep, unsigned idx)
{
	assert(idx < PTE_PER_PVE);
	pvep->pve_ptep[idx] = (pt_entry_t *)((uintptr_t)pvep->pve_ptep[idx] | PVE_PTEP_INTERNAL);
}

/**
 * Clear the ALTACCT bit for a specific PTE pointer.
 *
 * @param pvep A pointer to the current pv_entry mapping in the linked list of
 *             mappings.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline void
pve_clr_altacct(pv_entry_t *pvep, unsigned idx)
{
	assert(idx < PTE_PER_PVE);
	pvep->pve_ptep[idx] = (pt_entry_t *)((uintptr_t)pvep->pve_ptep[idx] & ~PVE_PTEP_ALTACCT);
}
/**
 * Clear the INTERNAL bit for a specific PTE pointer.
 *
 * @param pvep A pointer to the current pv_entry mapping in the linked list of
 *             mappings.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline void
pve_clr_internal(pv_entry_t *pvep, unsigned idx)
{
	assert(idx < PTE_PER_PVE);
	pvep->pve_ptep[idx] = (pt_entry_t *)((uintptr_t)pvep->pve_ptep[idx] & ~PVE_PTEP_INTERNAL);
}

/**
 * Return the ALTACCT bit for a specific PTE pointer.
 *
 * @param pvep A pointer to the current pv_entry mapping in the linked list of
 *             mappings.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline bool
pve_get_altacct(pv_entry_t *pvep, unsigned idx)
{
	assert(idx < PTE_PER_PVE);
	return (uintptr_t)pvep->pve_ptep[idx] & PVE_PTEP_ALTACCT;
}
/**
 * Return the INTERNAL bit for a specific PTE pointer.
 *
 * @param pvep A pointer to the current pv_entry mapping in the linked list of
 *             mappings.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline bool
pve_get_internal(pv_entry_t *pvep, unsigned idx)
{
	assert(idx < PTE_PER_PVE);
	return (uintptr_t)pvep->pve_ptep[idx] & PVE_PTEP_INTERNAL;
}

/**
 * Return the next mapping (pv_entry) in a linked list of mappings. This applies
 * to pv_head_table entries of type PVH_TYPE_PVEP.
 *
 * @param pvep A pointer to the current pv_entry mapping in the linked list of
 *             mappings.
 *
 * @return The next virtual mapping for a physical page, or PV_ENTRY_NULL if the
 *         end of the list has been reached.
 */
static inline pv_entry_t *
pve_next(pv_entry_t *pvep)
{
	return pvep->pve_next;
}

/**
 * Return a pointer to the pve_next field in a pv_entry. This value is used
 * when adding and removing entries to a PVE list.
 *
 * @param pvep The pv_entry whose pve_next field is being accessed.
 *
 * @return Pointer to the pve_next field.
 */
static inline pv_entry_t **
pve_next_ptr(pv_entry_t *pvep)
{
	return &pvep->pve_next;
}

/**
 * Return a pointer to the page table entry for this mapping.
 *
 * @param pvep The pv_entry whose pve_ptep field is to be returned.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 *
 * @return Pointer to the page table entry.
 */
static inline pt_entry_t *
pve_get_ptep(pv_entry_t *pvep, unsigned idx)
{
	assert(idx < PTE_PER_PVE);
	return (pt_entry_t *)((uintptr_t)pvep->pve_ptep[idx] & ~PVE_PTEP_FLAGS);
}

/**
 * Update the page table entry for a specific physical to virtual mapping.
 *
 * @param pvep The pv_entry to update.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 * @param ptep_new The new page table entry.
 */
static inline void
pve_set_ptep(pv_entry_t *pvep, unsigned idx, pt_entry_t *ptep_new)
{
	assert(idx < PTE_PER_PVE);
	pvep->pve_ptep[idx] = ptep_new;
}

/**
 * Initialize all fields in a PVE to NULL.
 *
 * @param pvep The pv_entry to initialize.
 */
static inline void
pve_init(pv_entry_t *pvep)
{
	pvep->pve_next = PV_ENTRY_NULL;
	for (int i = 0; i < PTE_PER_PVE; i++) {
		pvep->pve_ptep[i] = PT_ENTRY_NULL;
	}
}

/**
 * Find PTE pointer in PVE and return its index.
 *
 * @param pvep The PVE to search.
 * @param ptep PTE to search for.
 *
 * @return Index of the found entry, or -1 if no entry exists.
 */
static inline int
pve_find_ptep_index(pv_entry_t *pvep, pt_entry_t *ptep)
{
	for (unsigned int i = 0; i < PTE_PER_PVE; i++) {
		if (pve_get_ptep(pvep, i) == ptep) {
			return (int)i;
		}
	}

	return -1;
}

/**
 * Checks if no PTEs are currently associated with this PVE.
 *
 * @param pvep The PVE to search.
 *
 * @return True if no PTEs are currently associated with this PVE, or false.
 */
static inline bool
pve_is_empty(pv_entry_t *pvep)
{
	for (unsigned int i = 0; i < PTE_PER_PVE; i++) {
		if (pve_get_ptep(pvep, i) != PT_ENTRY_NULL) {
			return false;
		}
	}

	return true;
}

/**
 * Prepend a new pv_entry node to a PVE list.
 *
 * @note This function will clobber any existing flags stored in the PVH
 *       pointer. It's up to the caller to preserve flags if that functionality
 *       is needed (either by ensuring `pvep` contains those flags, or by
 *       manually setting the flags after this call).
 *
 * @param pvh The linked list of mappings to update.
 * @param pvep The new mapping to add to the linked list.
 */
static inline void
pve_add(pv_entry_t **pvh, pv_entry_t *pvep)
{
	assert(pvh_test_type(pvh, PVH_TYPE_PVEP));

	pvep->pve_next = pvh_pve_list(pvh);
	pvh_update_head(pvh, pvep, PVH_TYPE_PVEP);
}

/**
 * Remove an entry from a PVE list of mappings.
 *
 * @note This function will clobber any existing flags stored in the PVH
 *       pointer. It's up to the caller to preserve flags if that functionality
 *       is needed.
 *
 * @param pvh The pv_head_table entry of the PVE list to remove a mapping from.
 *            This is the first entry in the list of pv_entry_t mappings.
 * @param pvepp A pointer to the pv_entry_t* that's being removed. If this entry
 *              is the first in the linked list of mappings, then this should be
 *              identical to the pv_head_table entry. If the mapping isn't the
 *              first, then this is a pointer to the pve_next field in the
 *              previous mapping.
 * @param pvep The entry that should be removed. Should be identical to a
 *             dereference of the pvepp parameter (unless it's the pv_head_table
 *             entry).
 */
static inline void
pve_remove(pv_entry_t **pvh, pv_entry_t **pvepp, pv_entry_t *pvep)
{
	assert(pvh_test_type(pvh, PVH_TYPE_PVEP));

	if (pvepp == pvh) {
		if (pve_next(pvep) == PV_ENTRY_NULL) {
			/* The last mapping to this page is being removed. */
			pvh_update_head(pvh, PV_ENTRY_NULL, PVH_TYPE_NULL);
		} else {
			/**
			 * There are still mappings left, make the next one the new head of
			 * the list. This effectively removes the first entry from the list.
			 */
			pvh_update_head(pvh, pve_next(pvep), PVH_TYPE_PVEP);
		}
	} else {
		/**
		 * Move the previous entry's next field to the entry after the one being
		 * removed. This will clobber the ALTACCT and INTERNAL bits.
		 */
		*pvepp = pve_next(pvep);
	}
}

/**
 * PVH_TYPE_PTDP Types and Helper Functions.
 *
 * The following are types and methods used to manipulate page table descriptor
 * (PTD) objects. This is the type of pv_head_table entry used when a page is
 * being used as a page table.
 */

/**
 * When the pmap layer allocates memory, it always does so in chunks of the VM
 * page size (which are represented by the PAGE_SIZE/PAGE_SHIFT macros). The VM
 * page size might not match up with the hardware page size for a given address
 * space (this is especially true on systems that support more than one page
 * size).
 *
 * The pv_head_table is allocated to have one entry per VM page, not hardware
 * page (which can change depending on the address space). Because of that, a
 * single VM-page-sized region (single pv_head_table entry) can potentially hold
 * up to four page tables. Only one page table descriptor (PTD) is allocated per
 * pv_head_table entry (per VM page), so on some systems, one PTD might have to
 * keep track of up to four different page tables.
 */

#if __ARM_MIXED_PAGE_SIZE__
#define PT_INDEX_MAX (ARM_PGBYTES / 4096)
#elif (ARM_PGSHIFT == 14)
#define PT_INDEX_MAX 1
#elif (ARM_PGSHIFT == 12)
#define PT_INDEX_MAX 4
#else
#error Unsupported ARM_PGSHIFT
#endif /* __ARM_MIXED_PAGE_SIZE__ || ARM_PGSHIFT == 14 || ARM_PGSHIFT == 12 */


/**
 * Page table descriptor (PTD) info structure.
 *
 * Contains information about a page table. These pieces of data are separate
 * from the PTD itself because in address spaces where the VM page size doesn't
 * match the underlying hardware page size, one PTD could represent multiple
 * page tables (and so will need multiple PTD info structures).
 *
 * These fields are also in their own struct so that they can be allocated
 * separately from the associated pt_desc_t object. This allows us to allocate
 * the counts in this structure in a way that ensures they don't fall within the
 * same cache line as the main pt_desc_t object. This is important because the
 * fields in this structure are atomically updated which could cause false
 * sharing cache performance issues with the "va" field in pt_desc_t if all of
 * the fields were within the same structure.
 */
typedef struct {
	/**
	 * Pre-defined sentinel values for ptd_info_t.refcnt. If these refcnt values
	 * change, make sure to update the showpte LLDB macro to reflect the
	 * changes.
	 */
	#define PT_DESC_REFCOUNT                0x4000U
	#define PT_DESC_IOMMU_GRANTED_REFCOUNT  0x8000U
	#define PT_DESC_IOMMU_ACCEPTED_REFCOUNT 0x8001U

	/*
	 * For non-leaf pagetables, should always be PT_DESC_REFCOUNT.
	 * For leaf pagetables, should reflect the number of non-empty PTEs.
	 * For IOMMU pages, should always be either PT_DESC_IOMMU_GRANTED_REFCOUNT
	 * or PT_DESC_IOMMU_ACCEPTED_REFCOUNT.
	 */
	unsigned short refcnt;

	/*
	 * For non-leaf pagetables, should be 0.
	 * For leaf pagetables, should reflect the number of wired entries.
	 * For IOMMU pages, may optionally reflect a driver-defined refcount (IOMMU
	 * operations are implicitly wired).
	 */
	unsigned short wiredcnt;
} ptd_info_t;

/**
 * Page Table Descriptor (PTD).
 *
 * Provides a per-table data structure and a way of keeping track of all page
 * tables in the system.
 *
 * This structure is also used as a convenient way of keeping track of IOMMU
 * pages (which may or may not be used as page tables). In that case the "iommu"
 * field will point to the owner of the page, ptd_info[0].refcnt will be
 * PT_DESC_IOMMU_GRANTED_REFCOUNT or PT_DESC_IOMMU_ACCEPTED_REFCOUNT, and
 * ptd_info[0].wiredcnt can be used as an arbitrary refcnt controlled by the
 * IOMMU driver.
 */
typedef struct pt_desc {
	/**
	 * This queue chain provides a mechanism for keeping a list of pages
	 * being used as page tables. This is used to potentially reclaim userspace
	 * page tables as a fast way of "allocating" a page.
	 *
	 * Refer to osfmk/kern/queue.h for more information about queue chains.
	 */
	queue_chain_t pt_page;

	/* Each page table is either owned by a pmap or a specific IOMMU. */
	union {
		struct pmap *pmap;
	};

	/**
	 * The following fields contain per-page-table properties, and as such,
	 * might have multiple elements each. This is due to a single PTD
	 * potentially representing multiple page tables (in address spaces where
	 * the VM page size differs from the hardware page size). Use the
	 * ptd_get_index() function to get the correct index for a specific page
	 * table.
	 */

	/**
	 * The first address of the virtual address space this page table is
	 * translating for, or a value set by an IOMMU driver if this PTD is being
	 * used to track an IOMMU page.
	 */
	vm_offset_t va[PT_INDEX_MAX];

	/**
	 * ptd_info_t's are allocated separately so as to reduce false sharing
	 * with the va field. This is desirable because ptd_info_t's are updated
	 * atomically from all CPUs.
	 */
	ptd_info_t *ptd_info;
} pt_desc_t;

/**
 * Convert a pv_head_table entry/pointer into a page table descriptor pointer.
 * This should only be done if the type of this entry is PVH_TYPE_PTDP.
 *
 * @param pvh The pv_head_table entry/pointer to convert into a safe to
 *            dereference pt_desc_t*.
 *
 * @return Return back a safe to derefence pointer to the page table descriptor
 *         for this physical page by masking off the TYPE bits and adding any
 *         missing flags to the upper portion of the pointer.
 */
static inline pt_desc_t*
pvh_ptd(pv_entry_t **pvh)
{
	return (pt_desc_t *)(((*(vm_offset_t *)pvh) & PVH_LIST_MASK) | PVH_HIGH_FLAGS);
}

/**
 * Given an arbitrary page table entry, return back the page table descriptor
 * (PTD) object for the page table that contains that entry.
 *
 * @param ptep Pointer to a PTE whose page table descriptor object to return.
 *
 * @return The PTD object for the passed in page table.
 */
static inline pt_desc_t *
ptep_get_ptd(const pt_entry_t *ptep)
{
	assert(ptep != NULL);

	const vm_offset_t pt_base_va = (vm_offset_t)ptep;
	pv_entry_t **pvh = pai_to_pvh(pa_index(ml_static_vtop(pt_base_va)));

	if (__improbable(!pvh_test_type(pvh, PVH_TYPE_PTDP))) {
		panic("%s: invalid PV head 0x%llx for PTE %p", __func__, (uint64_t)(*pvh), ptep);
	}

	return pvh_ptd(pvh);
}

/**
 * Given an arbitrary page table entry, return back the pmap that owns that
 * page table.
 *
 * @note This won't work correctly for page tables owned by IOMMUs, because
 *       those table aren't owned by any specific pmap.
 *
 * @param ptep Pointer to a page table entry whose owner we're trying to return.
 *
 * @return The pmap that owns the given page table entry.
 */
static inline struct pmap *
ptep_get_pmap(const pt_entry_t *ptep)
{
	return ptep_get_ptd(ptep)->pmap;
}


/**
 * Given an arbitrary translation table entry, get the page table descriptor
 * (PTD) object for the page table pointed to by the TTE.
 *
 * @param tte The translation table entry to parse. For instance, if this is an
 *            L2 TTE, then the PTD for the L3 table this entry points to will be
 *            returned.
 *
 * @return The page table descriptor (PTD) for the page table pointed to by this
 *         TTE.
 */
static inline pt_desc_t *
tte_get_ptd(const tt_entry_t tte)
{
	const vm_offset_t pt_base_va = (vm_offset_t)(tte & ~((tt_entry_t)PAGE_MASK));
	pv_entry_t **pvh = pai_to_pvh(pa_index(pt_base_va));

	if (__improbable(!pvh_test_type(pvh, PVH_TYPE_PTDP))) {
		panic("%s: invalid PV head 0x%llx for TTE 0x%llx", __func__, (uint64_t)(*pvh), (uint64_t)tte);
	}

	return pvh_ptd(pvh);
}

/**
 * In address spaces where the VM page size doesn't match the underlying
 * hardware page size, one PTD could represent multiple page tables. This
 * function returns the correct index value depending on which page table is
 * being accessed. That index value can then be used to access the
 * per-page-table properties stored within a PTD.
 *
 * @note See the description above the PT_INDEX_MAX definition for a more
 *       detailed explanation of why multiple page tables can be represented
 *       by a single PTD object in the pv_head_table.
 *
 * @param ptd The page table descriptor that's being accessed.
 * @param ttep Pointer to the translation table entry that's being accessed.
 *
 * @return The correct index value for a specific, hardware-sized page
 *         table.
 */
static inline unsigned
ptd_get_index(__unused const pt_desc_t *ptd, __unused const tt_entry_t *ttep)
{
#if PT_INDEX_MAX == 1
	return 0;
#else
	assert(ptd != NULL);

	const uint64_t pmap_page_shift = pt_attr_leaf_shift(pmap_get_pt_attr(ptd->pmap));
	const vm_offset_t ttep_page = (vm_offset_t)ttep >> pmap_page_shift;

	/**
	 * Use the difference between the VM page shift and the hardware page shift
	 * to get the index of the correct page table. In practice, this equates to
	 * masking out the bottom two bits of the L3 table index in address spaces
	 * where the VM page size is greater than the hardware page size. In address
	 * spaces where they're identical, the index will always be zero.
	 */
	const unsigned int ttep_index = ttep_page & ((1U << (PAGE_SHIFT - pmap_page_shift)) - 1);
	assert(ttep_index < PT_INDEX_MAX);

	return ttep_index;
#endif
}

/**
 * In address spaces where the VM page size doesn't match the underlying
 * hardware page size, one PTD could represent multiple page tables. This
 * function returns the correct ptd_info_t structure depending on which page
 * table is being accessed.
 *
 * @note See the description above the PT_INDEX_MAX definition for a more
 *       detailed explanation of why multiple page tables can be represented
 *       by a single PTD object in the pv_head_table.
 *
 * @param ptd The page table descriptor that's being accessed.
 * @param ttep Pointer to the translation table entry that's being accessed.
 *
 * @return The correct ptd_info_t structure for a specific, hardware-sized page
 *         table.
 */
static inline ptd_info_t *
ptd_get_info(pt_desc_t *ptd, const tt_entry_t *ttep)
{
	assert((ptd != NULL) && (ptd->ptd_info[0].refcnt < PT_DESC_IOMMU_GRANTED_REFCOUNT));

	return &ptd->ptd_info[ptd_get_index(ptd, ttep)];
}

/**
 * Given a pointer to a page table entry, return back the ptd_info structure
 * for the page table that contains that entry.
 *
 * @param ptep Pointer to a PTE whose ptd_info object to return.
 *
 * @return The ptd_info object for the page table that contains the passed in
 *         page table entry.
 */
static inline ptd_info_t *
ptep_get_info(const pt_entry_t *ptep)
{
	return ptd_get_info(ptep_get_ptd(ptep), ptep);
}

/**
 * Return the virtual address mapped by the passed in leaf page table entry,
 * using an already-retrieved pagetable descriptor.
 *
 * @param ptdp pointer to the descriptor for the pagetable containing ptep
 * @param ptep Pointer to a PTE to parse
 */
static inline vm_map_address_t
ptd_get_va(const pt_desc_t *ptdp, const pt_entry_t *ptep)
{
	const pt_attr_t * const pt_attr = pmap_get_pt_attr(ptdp->pmap);

	vm_map_address_t va = ptdp->va[ptd_get_index(ptdp, ptep)];
	vm_offset_t ptep_index = ((vm_offset_t)ptep & pt_attr_leaf_offmask(pt_attr)) / sizeof(*ptep);

	va += (ptep_index << pt_attr_leaf_shift(pt_attr));

	return va;
}

/**
 * Return the virtual address that is being mapped by the passed in leaf page
 * table entry.
 *
 * @param ptep Pointer to a PTE to parse.
 */
static inline vm_map_address_t
ptep_get_va(const pt_entry_t *ptep)
{
	return ptd_get_va(ptep_get_ptd(ptep), ptep);
}

/**
 * Physical Page Attribute Table (pp_attr_table) defines and helper functions.
 */

/* How many bits to use for flags on a per-VM-page basis. */
typedef uint16_t pp_attr_t;

/* See the definition of pp_attr_table for more information. */
extern volatile pp_attr_t* pp_attr_table;

/**
 * Flags stored in the pp_attr_table on a per-physical-page basis.
 *
 * Please update the pv_walk LLDB macro if these flags are changed or added to.
 */

/**
 * The bottom 6-bits are used to store the default WIMG (cacheability and memory
 * type) setting for this physical page. This can be changed by calling
 * pmap_set_cache_attributes().
 *
 * If a default WIMG setting isn't set for a page, then the default is Normal,
 * Cached memory (VM_WIMG_DEFAULT).
 */
#define PP_ATTR_WIMG_MASK 0x003F
#define PP_ATTR_WIMG(x) ((x) & PP_ATTR_WIMG_MASK)

/**
 * The reference and modify bits keep track of whether a page has been accessed
 * or modified since the last time the bits were cleared. These bits are used to
 * enforce policy decisions in the VM layer.
 */
#define PP_ATTR_REFERENCED 0x0040
#define PP_ATTR_MODIFIED   0x0080

/**
 * This physical page is being used as anonymous memory that's internally
 * managed by the VM and is not connected to an external pager. This flag is
 * only set/cleared on the first CPU mapping of a page (see PVH_FLAG_CPU). Any
 * subsequent mappings won't set/clear this flag until all mappings are removed
 * and a new CPU mapping is added.
 */
#define PP_ATTR_INTERNAL 0x0100

/**
 * This flag is used to keep track of pages that are still resident but are not
 * considered dirty and can be reclaimed under memory pressure. These pages do
 * not count as a part of the memory footprint, so the footprint ledger does not
 * need to be updated for these pages. This is hinted to the VM by the
 * `madvise(MADV_FREE_REUSABLE)` system call.
 */
#define PP_ATTR_REUSABLE 0x0200

/**
 * This flag denotes that a page is utilizing "alternate accounting". This means
 * that the pmap doesn't need to keep track of these pages with regards to the
 * footprint ledger because the VM is already accounting for them in a different
 * way. These include IOKit mappings (VM adds their entire virtual size to the
 * footprint), and purgeable pages (VM counts them only when non-volatile and
 * only for one "owner"), among others.
 *
 * Note that alternate accounting status is tracked on a per-mapping basis (not
 * per-page). Because of that the ALTACCT flag in the pp_attr_table is only used
 * when there's a single mapping to a page. When there are multiple mappings,
 * the status of this flag is tracked in the pv_head_table (see PVE_PTEP_ALTACCT
 * above).
 */
#define PP_ATTR_ALTACCT 0x0400

/**
 * This bit was originally used on x86 to keep track of what pages to not
 * encrypt during the hibernation process as a performance optimization when
 * encryption was done in software. This doesn't apply to the ARM
 * hibernation process because all pages are automatically encrypted using
 * hardware acceleration. Despite that, the pmap still keeps track of this flag
 * as a debugging aid on internal builds.
 *
 * TODO: This bit can probably be reclaimed:
 * rdar://70740650 (PMAP Cleanup: Potentially reclaim the PP_ATTR_NOENCRYPT bit on ARM)
 */
#define PP_ATTR_NOENCRYPT 0x0800

/**
 * These bits denote that a physical page is expecting the next access or
 * modification to set the PP_ATTR_REFERENCED and PP_ATTR_MODIFIED flags
 * respectively.
 */
#define PP_ATTR_REFFAULT 0x1000
#define PP_ATTR_MODFAULT 0x2000

#if XNU_MONITOR
/**
 * Denotes that a page is owned by the PPL. This is modified/checked with the
 * PVH lock held, to avoid ownership related races. This does not need to be a
 * PP_ATTR bit (as we have the lock), but for now this is a convenient place to
 * put the bit.
 */
#define PP_ATTR_MONITOR 0x4000

/**
 * Denotes that a page *cannot* be owned by the PPL. This is required in order
 * to temporarily 'pin' kernel pages that are used to store PPL output
 * parameters. Otherwise a malicious or buggy caller could pass PPL-owned memory
 * for these parameters and in so doing stage a write gadget against the PPL.
 */
#define PP_ATTR_NO_MONITOR 0x8000

/**
 * All of the bits owned by the PPL; kernel requests to set or clear these bits
 * are illegal.
 */
#define PP_ATTR_PPL_OWNED_BITS (PP_ATTR_MONITOR | PP_ATTR_NO_MONITOR)
#endif /* XNU_MONITOR */

/**
 * Atomically set some flags in a pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 * @param bits The flags to set in the entry.
 */
static inline void
ppattr_set_bits(unsigned int pai, pp_attr_t bits)
{
	volatile pp_attr_t *ppattr = &pp_attr_table[pai];
	os_atomic_or(ppattr, bits, acq_rel);
}

/**
 * Atomically clear some flags in a pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 * @param bits The flags to clear in the entry.
 */
static inline void
ppattr_clear_bits(unsigned int pai, pp_attr_t bits)
{
	volatile pp_attr_t *ppattr = &pp_attr_table[pai];
	os_atomic_andnot(ppattr, bits, acq_rel);
}

/**
 * Return true if the pp_attr_table entry contains the passed in bits.
 *
 * @param pai The physical address index for the entry to test.
 * @param bits The flags to check for.
 */
static inline bool
ppattr_test_bits(unsigned int pai, pp_attr_t bits)
{
	const volatile pp_attr_t *ppattr = &pp_attr_table[pai];
	return (*ppattr & bits) == bits;
}

/**
 * Only set some flags in a pp_attr_table entry if the passed in physical
 * address is a kernel-managed address.
 *
 * @param pa The physical address for the entry to update.
 * @param bits The flags to set in the entry.
 */
static inline void
ppattr_pa_set_bits(pmap_paddr_t pa, pp_attr_t bits)
{
	if (pa_valid(pa)) {
		ppattr_set_bits(pa_index(pa), bits);
	}
}

/**
 * Only clear some flags in a pp_attr_table entry if the passed in physical
 * address is a kernel-managed address.
 *
 * @param pa The physical address for the entry to update.
 * @param bits The flags to clear in the entry.
 */
static inline void
ppattr_pa_clear_bits(pmap_paddr_t pa, pp_attr_t bits)
{
	if (pa_valid(pa)) {
		ppattr_clear_bits(pa_index(pa), bits);
	}
}

/**
 * Only test flags in a pp_attr_table entry if the passed in physical address
 * is a kernel-managed page.
 *
 * @param pa The physical address for the entry to test.
 * @param bits The flags to check for.
 *
 * @return False if the PA isn't a kernel-managed page, otherwise true/false
 *         depending on whether the bits are set.
 */
static inline bool
ppattr_pa_test_bits(pmap_paddr_t pa, pp_attr_t bits)
{
	return pa_valid(pa) ? ppattr_test_bits(pa_index(pa), bits) : false;
}

/**
 * Set the PP_ATTR_MODIFIED flag on a specific pp_attr_table entry if the passed
 * in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to update.
 */
static inline void
ppattr_pa_set_modify(pmap_paddr_t pa)
{
	ppattr_pa_set_bits(pa, PP_ATTR_MODIFIED);
}

/**
 * Clear the PP_ATTR_MODIFIED flag on a specific pp_attr_table entry if the
 * passed in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to update.
 */
static inline void
ppattr_pa_clear_modify(pmap_paddr_t pa)
{
	ppattr_pa_clear_bits(pa, PP_ATTR_MODIFIED);
}

/**
 * Set the PP_ATTR_REFERENCED flag on a specific pp_attr_table entry if the
 * passed in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to update.
 */
static inline void
ppattr_pa_set_reference(pmap_paddr_t pa)
{
	ppattr_pa_set_bits(pa, PP_ATTR_REFERENCED);
}

/**
 * Clear the PP_ATTR_REFERENCED flag on a specific pp_attr_table entry if the
 * passed in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to update.
 */
static inline void
ppattr_pa_clear_reference(pmap_paddr_t pa)
{
	ppattr_pa_clear_bits(pa, PP_ATTR_REFERENCED);
}

#if XNU_MONITOR

/**
 * Set the PP_ATTR_MONITOR flag on a specific pp_attr_table entry if the passed
 * in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to update.
 */
static inline void
ppattr_pa_set_monitor(pmap_paddr_t pa)
{
	ppattr_pa_set_bits(pa, PP_ATTR_MONITOR);
}

/**
 * Clear the PP_ATTR_MONITOR flag on a specific pp_attr_table entry if the
 * passed in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to update.
 */
static inline void
ppattr_pa_clear_monitor(pmap_paddr_t pa)
{
	ppattr_pa_clear_bits(pa, PP_ATTR_MONITOR);
}

/**
 * Only test for the PP_ATTR_MONITOR flag in a pp_attr_table entry if the passed
 * in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to test.
 *
 * @return False if the PA isn't a kernel-managed page, otherwise true/false
 *         depending on whether the PP_ATTR_MONITOR is set.
 */
static inline bool
ppattr_pa_test_monitor(pmap_paddr_t pa)
{
	return ppattr_pa_test_bits(pa, PP_ATTR_MONITOR);
}

/**
 * Set the PP_ATTR_NO_MONITOR flag on a specific pp_attr_table entry if the
 * passed in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to update.
 */
static inline void
ppattr_pa_set_no_monitor(pmap_paddr_t pa)
{
	ppattr_pa_set_bits(pa, PP_ATTR_NO_MONITOR);
}

/**
 * Clear the PP_ATTR_NO_MONITOR flag on a specific pp_attr_table entry if the
 * passed in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to update.
 */
static inline void
ppattr_pa_clear_no_monitor(pmap_paddr_t pa)
{
	ppattr_pa_clear_bits(pa, PP_ATTR_NO_MONITOR);
}

/**
 * Only test for the PP_ATTR_NO_MONITOR flag in a pp_attr_table entry if the
 * passed in physical address is a kernel-managed page.
 *
 * @param pa The physical address for the entry to test.
 *
 * @return False if the PA isn't a kernel-managed page, otherwise true/false
 *         depending on whether the PP_ATTR_NO_MONITOR is set.
 */
static inline bool
ppattr_pa_test_no_monitor(pmap_paddr_t pa)
{
	return ppattr_pa_test_bits(pa, PP_ATTR_NO_MONITOR);
}

#endif /* XNU_MONITOR */

/**
 * Set the PP_ATTR_INTERNAL flag on a specific pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_set_internal(unsigned int pai)
{
	ppattr_set_bits(pai, PP_ATTR_INTERNAL);
}

/**
 * Clear the PP_ATTR_INTERNAL flag on a specific pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_clear_internal(unsigned int pai)
{
	ppattr_clear_bits(pai, PP_ATTR_INTERNAL);
}

/**
 * Return true if the pp_attr_table entry has the PP_ATTR_INTERNAL flag set.
 *
 * @param pai The physical address index for the entry to test.
 */
static inline bool
ppattr_test_internal(unsigned int pai)
{
	return ppattr_test_bits(pai, PP_ATTR_INTERNAL);
}

/**
 * Set the PP_ATTR_REUSABLE flag on a specific pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_set_reusable(unsigned int pai)
{
	ppattr_set_bits(pai, PP_ATTR_REUSABLE);
}

/**
 * Clear the PP_ATTR_REUSABLE flag on a specific pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_clear_reusable(unsigned int pai)
{
	ppattr_clear_bits(pai, PP_ATTR_REUSABLE);
}

/**
 * Return true if the pp_attr_table entry has the PP_ATTR_REUSABLE flag set.
 *
 * @param pai The physical address index for the entry to test.
 */
static inline bool
ppattr_test_reusable(unsigned int pai)
{
	return ppattr_test_bits(pai, PP_ATTR_REUSABLE);
}

/**
 * Set the PP_ATTR_ALTACCT flag on a specific pp_attr_table entry.
 *
 * @note This is only valid when the ALTACCT flag is being tracked using the
 *       pp_attr_table. See the descriptions above the PVE_PTEP_ALTACCT and
 *       PP_ATTR_ALTACCT definitions for more information.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_set_altacct(unsigned int pai)
{
	ppattr_set_bits(pai, PP_ATTR_ALTACCT);
}

/**
 * Clear the PP_ATTR_ALTACCT flag on a specific pp_attr_table entry.
 *
 * @note This is only valid when the ALTACCT flag is being tracked using the
 *       pp_attr_table. See the descriptions above the PVE_PTEP_ALTACCT and
 *       PP_ATTR_ALTACCT definitions for more information.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_clear_altacct(unsigned int pai)
{
	ppattr_clear_bits(pai, PP_ATTR_ALTACCT);
}

/**
 * Get the PP_ATTR_ALTACCT flag on a specific pp_attr_table entry.
 *
 * @note This is only valid when the ALTACCT flag is being tracked using the
 *       pp_attr_table. See the descriptions above the PVE_PTEP_ALTACCT and
 *       PP_ATTR_ALTACCT definitions for more information.
 *
 * @param pai The physical address index for the entry to test.
 *
 * @return True if the passed in page uses alternate accounting, false
 *         otherwise.
 */
static inline bool
ppattr_is_altacct(unsigned int pai)
{
	return ppattr_test_bits(pai, PP_ATTR_ALTACCT);
}
/**
 * Get the PP_ATTR_INTERNAL flag on a specific pp_attr_table entry.
 *
 * @note This is only valid when the INTERNAL flag is being tracked using the
 *       pp_attr_table. See the descriptions above the PVE_PTEP_INTERNAL and
 *       PP_ATTR_INTERNAL definitions for more information.
 *
 * @param pai The physical address index for the entry to test.
 *
 * @return True if the passed in page is accounted for as "internal", false
 *         otherwise.
 */
static inline bool
ppattr_is_internal(unsigned int pai)
{
	return ppattr_test_bits(pai, PP_ATTR_INTERNAL);
}

/**
 * The "alternate accounting" (ALTACCT) status for a page is tracked differently
 * depending on whether there are one or multiple mappings to a page. This
 * function abstracts out the difference between single and multiple mappings to
 * a page and provides a single function for determining whether alternate
 * accounting is set for a mapping.
 *
 * @note See the descriptions above the PVE_PTEP_ALTACCT and PP_ATTR_ALTACCT
 *       definitions for more information.
 *
 * @param pai The physical address index for the entry to test.
 * @param pvep Pointer to the pv_entry_t object containing that mapping.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 *
 * @return True if the passed in page uses alternate accounting, false
 *         otherwise.
 */
static inline bool
ppattr_pve_is_altacct(unsigned int pai, pv_entry_t *pvep, unsigned idx)
{
	return (pvep == PV_ENTRY_NULL) ? ppattr_is_altacct(pai) : pve_get_altacct(pvep, idx);
}
/**
 * The "internal" (INTERNAL) status for a page is tracked differently
 * depending on whether there are one or multiple mappings to a page. This
 * function abstracts out the difference between single and multiple mappings to
 * a page and provides a single function for determining whether "internal"
 * is set for a mapping.
 *
 * @note See the descriptions above the PVE_PTEP_INTERNAL and PP_ATTR_INTERNAL
 *       definitions for more information.
 *
 * @param pai The physical address index for the entry to test.
 * @param pvep Pointer to the pv_entry_t object containing that mapping.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 *
 * @return True if the passed in page is "internal", false otherwise.
 */
static inline bool
ppattr_pve_is_internal(unsigned int pai, pv_entry_t *pvep, unsigned idx)
{
	return (pvep == PV_ENTRY_NULL) ? ppattr_is_internal(pai) : pve_get_internal(pvep, idx);
}

/**
 * The "alternate accounting" (ALTACCT) status for a page is tracked differently
 * depending on whether there are one or multiple mappings to a page. This
 * function abstracts out the difference between single and multiple mappings to
 * a page and provides a single function for setting the alternate accounting status
 * for a mapping.
 *
 * @note See the descriptions above the PVE_PTEP_ALTACCT and PP_ATTR_ALTACCT
 *       definitions for more information.
 *
 * @param pai The physical address index for the entry to update.
 * @param pvep Pointer to the pv_entry_t object containing that mapping.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline void
ppattr_pve_set_altacct(unsigned int pai, pv_entry_t *pvep, unsigned idx)
{
	if (pvep == PV_ENTRY_NULL) {
		ppattr_set_altacct(pai);
	} else {
		pve_set_altacct(pvep, idx);
	}
}
/**
 * The "internal" (INTERNAL) status for a page is tracked differently
 * depending on whether there are one or multiple mappings to a page. This
 * function abstracts out the difference between single and multiple mappings to
 * a page and provides a single function for setting the "internal" status
 * for a mapping.
 *
 * @note See the descriptions above the PVE_PTEP_INTERNAL and PP_ATTR_INTERNAL
 *       definitions for more information.
 *
 * @param pai The physical address index for the entry to update.
 * @param pvep Pointer to the pv_entry_t object containing that mapping.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline void
ppattr_pve_set_internal(unsigned int pai, pv_entry_t *pvep, unsigned idx)
{
	if (pvep == PV_ENTRY_NULL) {
		ppattr_set_internal(pai);
	} else {
		pve_set_internal(pvep, idx);
	}
}

/**
 * The "alternate accounting" (ALTACCT) status for a page is tracked differently
 * depending on whether there are one or multiple mappings to a page. This
 * function abstracts out the difference between single and multiple mappings to
 * a page and provides a single function for clearing the alternate accounting status
 * for a mapping.
 *
 * @note See the descriptions above the PVE_PTEP_ALTACCT and PP_ATTR_ALTACCT
 *       definitions for more information.
 *
 * @param pai The physical address index for the entry to update.
 * @param pvep Pointer to the pv_entry_t object containing that mapping.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline void
ppattr_pve_clr_altacct(unsigned int pai, pv_entry_t *pvep, unsigned idx)
{
	if (pvep == PV_ENTRY_NULL) {
		ppattr_clear_altacct(pai);
	} else {
		pve_clr_altacct(pvep, idx);
	}
}
/**
 * The "internal" (INTERNAL) status for a page is tracked differently
 * depending on whether there are one or multiple mappings to a page. This
 * function abstracts out the difference between single and multiple mappings to
 * a page and provides a single function for clearing the "internal" status
 * for a mapping.
 *
 * @note See the descriptions above the PVE_PTEP_INTERNAL and PP_ATTR_INTERNAL
 *       definitions for more information.
 *
 * @param pai The physical address index for the entry to update.
 * @param pvep Pointer to the pv_entry_t object containing that mapping.
 * @param idx Index of the chosen PTE pointer inside the PVE.
 */
static inline void
ppattr_pve_clr_internal(unsigned int pai, pv_entry_t *pvep, unsigned idx)
{
	if (pvep == PV_ENTRY_NULL) {
		ppattr_clear_internal(pai);
	} else {
		pve_clr_internal(pvep, idx);
	}
}

/**
 * Set the PP_ATTR_REFFAULT flag on a specific pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_set_reffault(unsigned int pai)
{
	ppattr_set_bits(pai, PP_ATTR_REFFAULT);
}

/**
 * Clear the PP_ATTR_REFFAULT flag on a specific pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_clear_reffault(unsigned int pai)
{
	ppattr_clear_bits(pai, PP_ATTR_REFFAULT);
}

/**
 * Return true if the pp_attr_table entry has the PP_ATTR_REFFAULT flag set.
 *
 * @param pai The physical address index for the entry to test.
 */
static inline bool
ppattr_test_reffault(unsigned int pai)
{
	return ppattr_test_bits(pai, PP_ATTR_REFFAULT);
}

/**
 * Set the PP_ATTR_MODFAULT flag on a specific pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_set_modfault(unsigned int pai)
{
	ppattr_set_bits(pai, PP_ATTR_MODFAULT);
}

/**
 * Clear the PP_ATTR_MODFAULT flag on a specific pp_attr_table entry.
 *
 * @param pai The physical address index for the entry to update.
 */
static inline void
ppattr_clear_modfault(unsigned int pai)
{
	ppattr_clear_bits(pai, PP_ATTR_MODFAULT);
}

/**
 * Return true if the pp_attr_table entry has the PP_ATTR_MODFAULT flag set.
 *
 * @param pai The physical address index for the entry to test.
 */
static inline bool
ppattr_test_modfault(unsigned int pai)
{
	return ppattr_test_bits(pai, PP_ATTR_MODFAULT);
}

static inline boolean_t
pmap_is_preemptible(void)
{
	return preemption_enabled() || (startup_phase < STARTUP_SUB_EARLY_BOOT);
}

/**
 * This helper function ensures that potentially-long-running batched PPL operations are
 * called in preemptible context before entering the PPL, so that the PPL call may
 * periodically exit to allow pending urgent ASTs to be taken.
 */
static inline void
pmap_verify_preemptible(void)
{
	assert(pmap_is_preemptible());
}

/**
 * The minimum number of pages to keep in the PPL page free list.
 *
 * We define our target as 8 pages: enough for 2 page table pages, a PTD page,
 * and a PV page; in essence, twice as many pages as may be necessary to satisfy
 * a single pmap_enter request.
 */
#define PMAP_MIN_FREE_PPL_PAGES 8

/**
 * Flags passed to various page allocation functions, usually accessed through
 * the pmap_pages_alloc_zeroed() API. Each function that can take these flags as
 * a part of its option field, will describe these flags in its function header.
 */

/**
 * Instruct the allocation function to return immediately if no pages are
 * current available. Without this flag, the function will spin and wait for a
 * page to become available. This flag can be required in some circumstances
 * (for instance, when allocating pages from within the PPL).
 */
#define PMAP_PAGES_ALLOCATE_NOWAIT 0x1

/**
 * Instructs an allocation function to fallback to reclaiming a userspace page
 * table if it failed to allocate a page from the free lists. This can be useful
 * when allocating from within the PPL because refilling the free lists requires
 * exiting and re-entering the PPL (which incurs extra latency).
 *
 * This is a quick way of allocating a page at the expense of having to
 * reallocate the table the next time one of its mappings is accessed.
 */
#define PMAP_PAGE_RECLAIM_NOWAIT 0x2

/**
 * Global variables exported to the rest of the internal pmap implementation.
 */
#if XNU_MONITOR
extern uint64_t pmap_ppl_free_page_count;
extern pmap_paddr_t pmap_stacks_start_pa;
extern pmap_paddr_t pmap_stacks_end_pa;
extern pmap_paddr_t ppl_cpu_save_area_start;
extern pmap_paddr_t ppl_cpu_save_area_end;
#endif /* XNU_MONITOR */
extern unsigned int inuse_pmap_pages_count;
extern vm_object_t pmap_object;
extern uint32_t pv_alloc_initial_target;
extern uint32_t pv_kern_alloc_initial_target;

/**
 * Functions exported to the rest of the internal pmap implementation.
 */
extern void pmap_data_bootstrap(void);
extern void pmap_enqueue_pages(vm_page_t);
extern kern_return_t pmap_pages_alloc_zeroed(pmap_paddr_t *, unsigned, unsigned);
extern void pmap_pages_free(pmap_paddr_t, unsigned);

#if XNU_MONITOR

extern void pmap_mark_page_as_ppl_page_internal(pmap_paddr_t, bool);
extern void pmap_mark_page_as_ppl_page(pmap_paddr_t);
extern void pmap_mark_page_as_kernel_page(pmap_paddr_t);
extern pmap_paddr_t pmap_alloc_page_for_kern(unsigned int);
extern void pmap_alloc_page_for_ppl(unsigned int);
extern uint64_t pmap_release_ppl_pages_to_kernel(void);

extern uint64_t pmap_ledger_validate(const volatile void *);
void pmap_ledger_retain(ledger_t ledger);
void pmap_ledger_release(ledger_t ledger);
extern void pmap_ledger_check_balance(pmap_t pmap);

kern_return_t pmap_alloc_pmap(pmap_t *pmap);
void pmap_free_pmap(pmap_t pmap);

#endif /* XNU_MONITOR */

/**
 * The modes in which a pmap lock can be acquired. Note that shared access
 * doesn't necessarily mean "read-only". As long as data is atomically updated
 * correctly (to account for multi-cpu accesses) data can still get written with
 * a shared lock held. Care just needs to be taken so as to not introduce any
 * race conditions when there are multiple writers.
 *
 * This is here in pmap_data.h because it's a needed parameter for pv_alloc()
 * and pmap_enter_pv(). This header is always included in pmap_internal.h before
 * the rest of the pmap locking code is defined so there shouldn't be any issues
 * with missing types.
 */
OS_ENUM(pmap_lock_mode, uint8_t,
    PMAP_LOCK_SHARED,
    PMAP_LOCK_EXCLUSIVE);

/**
 * Possible return values for pv_alloc(). See the pv_alloc() function header for
 * a description of each of these values.
 */
typedef enum {
	PV_ALLOC_SUCCESS,
	PV_ALLOC_RETRY,
	PV_ALLOC_FAIL
} pv_alloc_return_t;

extern pv_alloc_return_t pv_alloc(
	pmap_t, unsigned int, pmap_lock_mode_t, unsigned int, pv_entry_t **);
extern void pv_free(pv_entry_t *);
extern void pv_list_free(pv_entry_t *, pv_entry_t *, int);
extern void pmap_compute_pv_targets(void);
extern pv_alloc_return_t pmap_enter_pv(
	pmap_t, pt_entry_t *, int, unsigned int, pmap_lock_mode_t, pv_entry_t **, int *new_pve_ptep_idx);
extern void pmap_remove_pv(pmap_t, pt_entry_t *, int, bool, bool *, bool *);

extern void ptd_bootstrap(pt_desc_t *, unsigned int);
extern pt_desc_t *ptd_alloc_unlinked(void);
extern pt_desc_t *ptd_alloc(pmap_t);
extern void ptd_deallocate(pt_desc_t *);
extern void ptd_info_init(
	pt_desc_t *, pmap_t, vm_map_address_t, unsigned int, pt_entry_t *);

extern kern_return_t pmap_ledger_credit(pmap_t, int, ledger_amount_t);
extern kern_return_t pmap_ledger_debit(pmap_t, int, ledger_amount_t);

extern void validate_pmap_internal(const volatile struct pmap *, const char *);
extern void validate_pmap_mutable_internal(const volatile struct pmap *, const char *);

/**
 * Macro function wrappers around pmap validation so that the calling function
 * can be printed in the panic strings for easier validation failure debugging.
 */
#define validate_pmap(x) validate_pmap_internal(x, __func__)
#define validate_pmap_mutable(x) validate_pmap_mutable_internal(x, __func__)

/**
 * This structure describes a PPL-owned I/O range.
 *
 * @note This doesn't necessarily have to represent "I/O" only, this can also
 *       represent non-kernel-managed DRAM (e.g., iBoot carveouts). Any physical
 *       address region that isn't considered "kernel-managed" is fair game.
 *
 * @note The layout of this structure needs to map 1-to-1 with the pmap-io-range
 *       device tree nodes. Astris (through the LowGlobals) also depends on the
 *       consistency of this structure.
 */
typedef struct pmap_io_range {
	/* Physical address of the PPL-owned I/O range. */
	uint64_t addr;

	/**
	 * Length (in bytes) of the PPL-owned I/O range. Has to be the size
	 * of a page if the range will be refered to by pmap_io_filter_entries.
	 */
	uint64_t len;

	/* Strong DSB required for pages in this range. */
	#define PMAP_IO_RANGE_STRONG_SYNC (1UL << 31)

	/* Corresponds to memory carved out by bootloader. */
	#define PMAP_IO_RANGE_CARVEOUT (1UL << 30)

	/* Pages in this range need to be included in the hibernation image */
	#define PMAP_IO_RANGE_NEEDS_HIBERNATING (1UL << 29)

	/* Mark the range as 'owned' by a given subsystem */
	#define PMAP_IO_RANGE_OWNED (1UL << 28)

	/**
	 * Lower 16 bits treated as pp_attr_t, upper 16 bits contain additional
	 * mapping flags (defined above).
	 */
	uint32_t wimg;

	/**
	 * 4 Character Code (4CC) describing what this range is.
	 *
	 * This has to be unique for each "type" of pages, meaning pages sharing
	 * the same register layout, if it is used for the I/O filter descriptors
	 * below. Otherwise it doesn't matter.
	 */
	uint32_t signature;
} pmap_io_range_t;

/* Reminder: be sure to change all relevant device trees if you change the layout of pmap_io_range_t */
_Static_assert(sizeof(pmap_io_range_t) == 24, "unexpected size for pmap_io_range_t");

extern pmap_io_range_t* pmap_find_io_attr(pmap_paddr_t);

/**
 * This structure describes a sub-page-size I/O region owned by PPL but the kernel can write to.
 *
 * @note I/O filter software will use a collection of such data structures to determine access
 *       permissions to a page owned by PPL.
 *
 * @note The {signature, offset} key is used to index a collection of such data structures to
 *       optimize for space in the case where one page layout is repeated for many devices, such
 *       as the memory controller channels.
 */
typedef struct pmap_io_filter_entry {
	/* 4 Character Code (4CC) describing what this range (page) is. */
	uint32_t signature;

	/* Offset within the page. It has to be within [0, PAGE_SIZE). */
	uint16_t offset;

	/* Length of the range, and (offset + length) has to be within [0, PAGE_SIZE). */
	uint16_t length;
} pmap_io_filter_entry_t;

_Static_assert(sizeof(pmap_io_filter_entry_t) == 8, "unexpected size for pmap_io_filter_entry_t");

extern pmap_io_filter_entry_t *pmap_find_io_filter_entry(pmap_paddr_t, uint64_t, const pmap_io_range_t **);

extern void pmap_cpu_data_init_internal(unsigned int);

/**
 * Flush a single 16K page from noncoherent coprocessor caches.
 *
 * @note Nonocoherent cache flushes are only guaranteed to work if the participating coprocessor(s)
 *       do not have any active VA translations for the page being flushed.  Since coprocessor
 *       mappings should always be controlled by some PPL IOMMU extension, they should always
 *       have PV list entries.  This flush should therefore be performed at a point when the PV
 *       list is known to be either empty or at least to not contain any IOMMU entries.  For
 *       the purposes of our security model, it is sufficient to wait for the PV list to become
 *       empty, as we really want to protect PPL-sensitive pages from malicious/accidental
 *       coprocessor cacheline evictions, and the PV list must be empty before a page can be
 *       handed to the PPL.
 *
 * @param paddr The base physical address of the page to flush.
 */
extern void pmap_flush_noncoherent_page(pmap_paddr_t paddr);

#endif /* _ARM_PMAP_PMAP_DATA_H_ */