unicorn/qemu/exec.c

/*
 *  Virtual page mapping
 *
 *  Copyright (c) 2003 Fabrice Bellard
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */

#include "qemu/osdep.h"
#include "qemu-common.h"
#include "exec/cpu-defs.h"
#include "cpu.h"

#include "qemu/cutils.h"
#include "exec/exec-all.h"
#include "exec/target_page.h"
#include "tcg/tcg.h"
#include "sysemu/sysemu.h"
#include "sysemu/tcg.h"
#include "qemu/timer.h"
#include "exec/memory.h"
#include "exec/ioport.h"

#ifdef CONFIG_FALLOCATE_PUNCH_HOLE
#include <linux/falloc.h>
#endif

#include "accel/tcg/translate-all.h"

#include "exec/memory-internal.h"
#include "exec/ram_addr.h"

#include "qemu/range.h"
#include "qemu/rcu_queue.h"
#include "uc_priv.h"

typedef struct PhysPageEntry PhysPageEntry;

struct PhysPageEntry {
    /* How many bits skip to next level (in units of L2_SIZE). 0 for a leaf. */
    uint32_t skip : 6;
     /* index into phys_sections (!skip) or phys_map_nodes (skip) */
    uint32_t ptr : 26;
};

#define PHYS_MAP_NODE_NIL (((uint32_t)~0) >> 6)

/* Size of the L2 (and L3, etc) page tables.  */
#define ADDR_SPACE_BITS 64

#define P_L2_BITS 9
#define P_L2_SIZE (1 << P_L2_BITS)

#define P_L2_LEVELS (((ADDR_SPACE_BITS - TARGET_PAGE_BITS - 1) / P_L2_BITS) + 1)

typedef PhysPageEntry Node[P_L2_SIZE];

typedef struct PhysPageMap {
    unsigned sections_nb;
    unsigned sections_nb_alloc;
    unsigned nodes_nb;
    unsigned nodes_nb_alloc;
    Node *nodes;
    MemoryRegionSection *sections;
} PhysPageMap;

struct AddressSpaceDispatch {
    MemoryRegionSection *mru_section;
    /* This is a multi-level map on the physical address space.
     * The bottom level has pointers to MemoryRegionSections.
     */
    PhysPageEntry phys_map;
    PhysPageMap map;
    struct uc_struct *uc;
};

#define SUBPAGE_IDX(addr) ((addr) & ~TARGET_PAGE_MASK)
typedef struct subpage_t {
    MemoryRegion iomem;
    FlatView *fv;
    hwaddr base;
    uint16_t sub_section[];
} subpage_t;

#define PHYS_SECTION_UNASSIGNED 0

static void tcg_commit(MemoryListener *listener);

/**
 * CPUAddressSpace: all the information a CPU needs about an AddressSpace
 * @cpu: the CPU whose AddressSpace this is
 * @as: the AddressSpace itself
 * @memory_dispatch: its dispatch pointer (cached, RCU protected)
 * @tcg_as_listener: listener for tracking changes to the AddressSpace
 */
struct CPUAddressSpace {
    CPUState *cpu;
    AddressSpace *as;
    struct AddressSpaceDispatch *memory_dispatch;
    MemoryListener tcg_as_listener;
};


static void phys_map_node_reserve(AddressSpaceDispatch *d, PhysPageMap *map, unsigned nodes)
{
    if (map->nodes_nb + nodes > map->nodes_nb_alloc) {
        map->nodes_nb_alloc = MAX(d->uc->alloc_hint, map->nodes_nb + nodes);
        map->nodes = g_renew(Node, map->nodes, map->nodes_nb_alloc);
        d->uc->alloc_hint = map->nodes_nb_alloc;
    }
}

static uint32_t phys_map_node_alloc(PhysPageMap *map, bool leaf)
{
    unsigned i;
    uint32_t ret;
    PhysPageEntry e;
    PhysPageEntry *p;

    ret = map->nodes_nb++;
    p = map->nodes[ret];
    assert(ret != PHYS_MAP_NODE_NIL);
    assert(ret != map->nodes_nb_alloc);

    e.skip = leaf ? 0 : 1;
    e.ptr = leaf ? PHYS_SECTION_UNASSIGNED : PHYS_MAP_NODE_NIL;
    for (i = 0; i < P_L2_SIZE; ++i) {
        memcpy(&p[i], &e, sizeof(e));
    }
    return ret;
}

static void phys_page_set_level(PhysPageMap *map, PhysPageEntry *lp,
                                hwaddr *index, uint64_t *nb, uint16_t leaf,
                                int level)
{
    PhysPageEntry *p;
    hwaddr step = (hwaddr)1 << (level * P_L2_BITS);

    if (lp->skip && lp->ptr == PHYS_MAP_NODE_NIL) {
        lp->ptr = phys_map_node_alloc(map, level == 0);
    }
    p = map->nodes[lp->ptr];
    lp = &p[(*index >> (level * P_L2_BITS)) & (P_L2_SIZE - 1)];

    while (*nb && lp < &p[P_L2_SIZE]) {
        if ((*index & (step - 1)) == 0 && *nb >= step) {
            lp->skip = 0;
            lp->ptr = leaf;
            *index += step;
            *nb -= step;
        } else {
            phys_page_set_level(map, lp, index, nb, leaf, level - 1);
        }
        ++lp;
    }
}

static void phys_page_set(AddressSpaceDispatch *d,
                          hwaddr index, uint64_t nb,
                          uint16_t leaf)
{
#ifdef TARGET_ARM
    struct uc_struct *uc = d->uc;
#endif
    /* Wildly overreserve - it doesn't matter much. */
    phys_map_node_reserve(d, &d->map, 3 * P_L2_LEVELS);

    phys_page_set_level(&d->map, &d->phys_map, &index, &nb, leaf, P_L2_LEVELS - 1);
}

/* Compact a non leaf page entry. Simply detect that the entry has a single child,
 * and update our entry so we can skip it and go directly to the destination.
 */
static void phys_page_compact(struct uc_struct *uc, PhysPageEntry *lp, Node *nodes)
{
    unsigned valid_ptr = P_L2_SIZE;
    int valid = 0;
    PhysPageEntry *p;
    int i;

    if (lp->ptr == PHYS_MAP_NODE_NIL) {
        return;
    }

    p = nodes[lp->ptr];
    for (i = 0; i < P_L2_SIZE; i++) {
        if (p[i].ptr == PHYS_MAP_NODE_NIL) {
            continue;
        }

        valid_ptr = i;
        valid++;
        if (p[i].skip) {
            phys_page_compact(uc, &p[i], nodes);
        }
    }

    /* We can only compress if there's only one child. */
    if (valid != 1) {
        return;
    }

    assert(valid_ptr < P_L2_SIZE);

    /* Don't compress if it won't fit in the # of bits we have. */
    if (P_L2_LEVELS >= (1 << 6) &&
        lp->skip + p[valid_ptr].skip >= (1 << 6)) {
        return;
    }

    lp->ptr = p[valid_ptr].ptr;
    if (!p[valid_ptr].skip) {
        /* If our only child is a leaf, make this a leaf. */
        /* By design, we should have made this node a leaf to begin with so we
         * should never reach here.
         * But since it's so simple to handle this, let's do it just in case we
         * change this rule.
         */
        lp->skip = 0;
    } else {
        lp->skip += p[valid_ptr].skip;
    }
}

void address_space_dispatch_compact(AddressSpaceDispatch *d)
{
    if (d->phys_map.skip) {
        phys_page_compact(d->uc, &d->phys_map, d->map.nodes);
    }
}

static inline bool section_covers_addr(const MemoryRegionSection *section,
                                       hwaddr addr)
{
    /* Memory topology clips a memory region to [0, 2^64); size.hi > 0 means
     * the section must cover the entire address space.
     */
    return int128_gethi(section->size) ||
           range_covers_byte(section->offset_within_address_space,
                             int128_getlo(section->size), addr);
}

static MemoryRegionSection *phys_page_find(AddressSpaceDispatch *d, hwaddr addr)
{
#ifdef TARGET_ARM
    struct uc_struct *uc = d->uc;
#endif
    PhysPageEntry lp = d->phys_map, *p;
    Node *nodes = d->map.nodes;
    MemoryRegionSection *sections = d->map.sections;
    hwaddr index = addr >> TARGET_PAGE_BITS;
    int i;

    for (i = P_L2_LEVELS; lp.skip && (i -= lp.skip) >= 0;) {
        if (lp.ptr == PHYS_MAP_NODE_NIL) {
            return &sections[PHYS_SECTION_UNASSIGNED];
        }
        p = nodes[lp.ptr];
        lp = p[(index >> (i * P_L2_BITS)) & (P_L2_SIZE - 1)];
    }

    if (section_covers_addr(&sections[lp.ptr], addr)) {
        return &sections[lp.ptr];
    } else {
        return &sections[PHYS_SECTION_UNASSIGNED];
    }
}

/* Called from RCU critical section */
static MemoryRegionSection *address_space_lookup_region(AddressSpaceDispatch *d,
                                                        hwaddr addr,
                                                        bool resolve_subpage)
{
#ifdef TARGET_ARM
    struct uc_struct *uc = d->uc;
#endif
    MemoryRegionSection *section = d->mru_section;
    subpage_t *subpage;

    if (!section || section == &d->map.sections[PHYS_SECTION_UNASSIGNED] ||
        !section_covers_addr(section, addr)) {
        section = phys_page_find(d, addr);
        d->mru_section = section;
    }
    if (resolve_subpage && section->mr->subpage) {
        subpage = container_of(section->mr, subpage_t, iomem);
        section = &d->map.sections[subpage->sub_section[SUBPAGE_IDX(addr)]];
    }
    return section;
}

/* Called from RCU critical section */
static MemoryRegionSection *
address_space_translate_internal(AddressSpaceDispatch *d, hwaddr addr, hwaddr *xlat,
                                 hwaddr *plen, bool resolve_subpage)
{
    MemoryRegionSection *section;
    MemoryRegion *mr;
    Int128 diff;

    section = address_space_lookup_region(d, addr, resolve_subpage);
    /* Compute offset within MemoryRegionSection */
    addr -= section->offset_within_address_space;

    /* Compute offset within MemoryRegion */
    *xlat = addr + section->offset_within_region;

    mr = section->mr;

    /* MMIO registers can be expected to perform full-width accesses based only
     * on their address, without considering adjacent registers that could
     * decode to completely different MemoryRegions.  When such registers
     * exist (e.g. I/O ports 0xcf8 and 0xcf9 on most PC chipsets), MMIO
     * regions overlap wildly.  For this reason we cannot clamp the accesses
     * here.
     *
     * If the length is small (as is the case for address_space_ldl/stl),
     * everything works fine.  If the incoming length is large, however,
     * the caller really has to do the clamping through memory_access_size.
     */
    if (memory_region_is_ram(mr)) {
        diff = int128_sub(section->size, int128_make64(addr));
        *plen = int128_get64(int128_min(diff, int128_make64(*plen)));
    }
    return section;
}

/**
 * address_space_translate_iommu - translate an address through an IOMMU
 * memory region and then through the target address space.
 *
 * @iommu_mr: the IOMMU memory region that we start the translation from
 * @addr: the address to be translated through the MMU
 * @xlat: the translated address offset within the destination memory region.
 *        It cannot be %NULL.
 * @plen_out: valid read/write length of the translated address. It
 *            cannot be %NULL.
 * @page_mask_out: page mask for the translated address. This
 *            should only be meaningful for IOMMU translated
 *            addresses, since there may be huge pages that this bit
 *            would tell. It can be %NULL if we don't care about it.
 * @is_write: whether the translation operation is for write
 * @is_mmio: whether this can be MMIO, set true if it can
 * @target_as: the address space targeted by the IOMMU
 * @attrs: transaction attributes
 *
 * This function is called from RCU critical section.  It is the common
 * part of flatview_do_translate and address_space_translate_cached.
 */
static MemoryRegionSection address_space_translate_iommu(IOMMUMemoryRegion *iommu_mr,
                                                         hwaddr *xlat,
                                                         hwaddr *plen_out,
                                                         hwaddr *page_mask_out,
                                                         bool is_write,
                                                         bool is_mmio,
                                                         AddressSpace **target_as,
                                                         MemTxAttrs attrs)
{
    MemoryRegionSection *section;
    hwaddr page_mask = (hwaddr)-1;
    MemoryRegion *mr = MEMORY_REGION(iommu_mr);

    do {
        hwaddr addr = *xlat;
        IOMMUMemoryRegionClass *imrc = memory_region_get_iommu_class_nocheck(iommu_mr);
        int iommu_idx = 0;
        IOMMUTLBEntry iotlb;

        if (imrc->attrs_to_index) {
            iommu_idx = imrc->attrs_to_index(iommu_mr, attrs);
        }

        iotlb = imrc->translate(iommu_mr, addr, is_write ?
                                IOMMU_WO : IOMMU_RO, iommu_idx);

        if (!(iotlb.perm & (1 << is_write))) {
            goto unassigned;
        }

        addr = ((iotlb.translated_addr & ~iotlb.addr_mask)
                | (addr & iotlb.addr_mask));
        page_mask &= iotlb.addr_mask;
        *plen_out = MIN(*plen_out, (addr | iotlb.addr_mask) - addr + 1);
        *target_as = iotlb.target_as;

        section = address_space_translate_internal(
                address_space_to_dispatch(iotlb.target_as), addr, xlat,
                plen_out, is_mmio);

        iommu_mr = memory_region_get_iommu(section->mr);
    } while (unlikely(iommu_mr));

    if (page_mask_out) {
        *page_mask_out = page_mask;
    }
    return *section;

unassigned:
    return (MemoryRegionSection) { .mr = &(mr->uc->io_mem_unassigned) };
}

/**
 * flatview_do_translate - translate an address in FlatView
 *
 * @fv: the flat view that we want to translate on
 * @addr: the address to be translated in above address space
 * @xlat: the translated address offset within memory region. It
 *        cannot be @NULL.
 * @plen_out: valid read/write length of the translated address. It
 *            can be @NULL when we don't care about it.
 * @page_mask_out: page mask for the translated address. This
 *            should only be meaningful for IOMMU translated
 *            addresses, since there may be huge pages that this bit
 *            would tell. It can be @NULL if we don't care about it.
 * @is_write: whether the translation operation is for write
 * @is_mmio: whether this can be MMIO, set true if it can
 * @target_as: the address space targeted by the IOMMU
 * @attrs: memory transaction attributes
 *
 * This function is called from RCU critical section
 */
static MemoryRegionSection flatview_do_translate(struct uc_struct *uc, FlatView *fv,
                                                 hwaddr addr,
                                                 hwaddr *xlat,
                                                 hwaddr *plen_out,
                                                 hwaddr *page_mask_out,
                                                 bool is_write,
                                                 bool is_mmio,
                                                 AddressSpace **target_as,
                                                 MemTxAttrs attrs)
{
    MemoryRegionSection *section;
    IOMMUMemoryRegion *iommu_mr;
    hwaddr plen = (hwaddr)(-1);

    if (!plen_out) {
        plen_out = &plen;
    }

    section = address_space_translate_internal(
            flatview_to_dispatch(fv), addr, xlat,
            plen_out, is_mmio);

    iommu_mr = memory_region_get_iommu(section->mr);
    if (unlikely(iommu_mr)) {
        return address_space_translate_iommu(iommu_mr, xlat,
                                             plen_out, page_mask_out,
                                             is_write, is_mmio,
                                             target_as, attrs);
    }
    if (page_mask_out) {
        /* Not behind an IOMMU, use default page size. */
        *page_mask_out = ~TARGET_PAGE_MASK;
    }

    return *section;
}

/* Called from RCU critical section */
MemoryRegion *flatview_translate(struct uc_struct *uc, FlatView *fv, hwaddr addr, hwaddr *xlat,
                                 hwaddr *plen, bool is_write,
                                 MemTxAttrs attrs)
{
    MemoryRegion *mr;
    MemoryRegionSection section;
    AddressSpace *as = NULL;

    /* This can be MMIO, so setup MMIO bit. */
    section = flatview_do_translate(uc, fv, addr, xlat, plen, NULL,
                                    is_write, true, &as, attrs);
    mr = section.mr;

    return mr;
}

/* Called from RCU critical section */
MemoryRegionSection *
address_space_translate_for_iotlb(CPUState *cpu, int asidx, hwaddr addr,
                                  hwaddr *xlat, hwaddr *plen,
                                  MemTxAttrs attrs, int *prot)
{
    MemoryRegionSection *section;
    IOMMUMemoryRegion *iommu_mr;
    IOMMUMemoryRegionClass *imrc;
    IOMMUTLBEntry iotlb;
    int iommu_idx;
    AddressSpaceDispatch *d = cpu->cpu_ases[asidx].memory_dispatch;

    for (;;) {
        section = address_space_translate_internal(d, addr, &addr, plen, false);

        iommu_mr = memory_region_get_iommu(section->mr);
        if (!iommu_mr) {
            break;
        }

        imrc = memory_region_get_iommu_class_nocheck(iommu_mr);

        iommu_idx = imrc->attrs_to_index(iommu_mr, attrs);

        // tcg_register_iommu_notifier(cpu, iommu_mr, iommu_idx);

        /* We need all the permissions, so pass IOMMU_NONE so the IOMMU
         * doesn't short-cut its translation table walk.
         */
        iotlb = imrc->translate(iommu_mr, addr, IOMMU_NONE, iommu_idx);
        addr = ((iotlb.translated_addr & ~iotlb.addr_mask)
                | (addr & iotlb.addr_mask));
        /* Update the caller's prot bits to remove permissions the IOMMU
         * is giving us a failure response for. If we get down to no
         * permissions left at all we can give up now.
         */
        if (!(iotlb.perm & IOMMU_RO)) {
            *prot &= ~(PAGE_READ | PAGE_EXEC);
        }
        if (!(iotlb.perm & IOMMU_WO)) {
            *prot &= ~PAGE_WRITE;
        }

        if (!*prot) {
            goto translate_fail;
        }

        d = flatview_to_dispatch(address_space_to_flatview(iotlb.target_as));
    }

    assert(!(memory_region_get_iommu(section->mr) != NULL));
    *xlat = addr;
    // Unicorn:
    //   If there is no memory mapped but still we start emulation, we will get
    //   a default memory region section and it would be marked as an IO memory
    //   in cputlb which prevents further fecthing and execution.
    //
    //   The reason we set prot to 0 here is not to setting protection but to notify
    //   the outer function to add a new **blank** tlb which will never be hitted.
    if (!memory_region_is_ram(section->mr) && section == &d->map.sections[PHYS_SECTION_UNASSIGNED]) {
        *prot = 0;
    }
    return section;

translate_fail:
    return &d->map.sections[PHYS_SECTION_UNASSIGNED];
}

CPUState *qemu_get_cpu(struct uc_struct *uc, int index)
{
    CPUState *cpu = uc->cpu;
    if (cpu->cpu_index == index) {
        return cpu;
    }

    return NULL;
}

void cpu_address_space_init(CPUState *cpu, int asidx, MemoryRegion *mr)
{
    /* Target code should have set num_ases before calling us */
    assert(asidx < cpu->num_ases);

    if (!cpu->cpu_ases) {
        cpu->cpu_ases = g_new0(CPUAddressSpace, cpu->num_ases);
        cpu->cpu_ases[0].cpu = cpu;
        cpu->cpu_ases[0].as = &(cpu->uc->address_space_memory);
        cpu->cpu_ases[0].tcg_as_listener.commit = tcg_commit;
        memory_listener_register(&(cpu->cpu_ases[0].tcg_as_listener), cpu->cpu_ases[0].as);
    }
    /* arm security memory */
    if (asidx > 0) {
        cpu->cpu_ases[asidx].cpu = cpu;
        cpu->cpu_ases[asidx].as = &(cpu->uc->address_space_memory);
        cpu->cpu_ases[asidx].tcg_as_listener.commit = tcg_commit;
        memory_listener_register(&(cpu->cpu_ases[asidx].tcg_as_listener), cpu->cpu_ases[asidx].as);
    }
}

AddressSpace *cpu_get_address_space(CPUState *cpu, int asidx)
{
    /* only one AddressSpace. */
    return cpu->cpu_ases[0].as;
}

void cpu_exec_unrealizefn(CPUState *cpu)
{
}

void cpu_exec_initfn(CPUState *cpu)
{
    cpu->num_ases = 1;
    cpu->as = &(cpu->uc->address_space_memory);
    cpu->memory = cpu->uc->system_memory;
}

void cpu_exec_realizefn(CPUState *cpu)
{
    CPUClass *cc = CPU_GET_CLASS(cpu);

    cc->tcg_initialize(cpu->uc);
    tlb_init(cpu);
}

void tb_invalidate_phys_addr(AddressSpace *as, hwaddr addr, MemTxAttrs attrs)
{
    ram_addr_t ram_addr;
    MemoryRegion *mr;
    hwaddr l = 1;

    mr = address_space_translate(as, addr, &addr, &l, false, attrs);
    if (!memory_region_is_ram(mr)) {
        return;
    }

    ram_addr = memory_region_get_ram_addr(mr) + addr;
    tb_invalidate_phys_page_range(as->uc, ram_addr, ram_addr + 1);
}

static void breakpoint_invalidate(CPUState *cpu, target_ulong pc)
{
    /*
     * There may not be a virtual to physical translation for the pc
     * right now, but there may exist cached TB for this pc.
     * Flush the whole TB cache to force re-translation of such TBs.
     * This is heavyweight, but we're debugging anyway.
     */
    tb_flush(cpu);
}

/* Add a watchpoint.  */
int cpu_watchpoint_insert(CPUState *cpu, vaddr addr, vaddr len,
                          int flags, CPUWatchpoint **watchpoint)
{
#if 0
    CPUWatchpoint *wp;

    /* forbid ranges which are empty or run off the end of the address space */
    if (len == 0 || (addr + len - 1) < addr) {
        error_report("tried to set invalid watchpoint at %"
                     VADDR_PRIx ", len=%" VADDR_PRIu, addr, len);
        return -EINVAL;
    }
    wp = g_malloc(sizeof(*wp));

    wp->vaddr = addr;
    wp->len = len;
    wp->flags = flags;

    /* keep all GDB-injected watchpoints in front */
    if (flags & BP_GDB) {
        QTAILQ_INSERT_HEAD(&cpu->watchpoints, wp, entry);
    } else {
        QTAILQ_INSERT_TAIL(&cpu->watchpoints, wp, entry);
    }

    tlb_flush_page(cpu, addr);

    if (watchpoint)
        *watchpoint = wp;
#endif

    return 0;
}

/* Remove a specific watchpoint by reference.  */
void cpu_watchpoint_remove_by_ref(CPUState *cpu, CPUWatchpoint *watchpoint)
{
#if 0
    QTAILQ_REMOVE(&cpu->watchpoints, watchpoint, entry);

    tlb_flush_page(cpu, watchpoint->vaddr);

    g_free(watchpoint);
#endif
}

/* Remove all matching watchpoints.  */
void cpu_watchpoint_remove_all(CPUState *cpu, int mask)
{
#if 0
    CPUWatchpoint *wp, *next;

    QTAILQ_FOREACH_SAFE(wp, &cpu->watchpoints, entry, next) {
        if (wp->flags & mask) {
            cpu_watchpoint_remove_by_ref(cpu, wp);
        }
    }
#endif
}

/* Return flags for watchpoints that match addr + prot.  */
int cpu_watchpoint_address_matches(CPUState *cpu, vaddr addr, vaddr len)
{
#if 0
    CPUWatchpoint *wp;
    int ret = 0;

    QTAILQ_FOREACH(wp, &cpu->watchpoints, entry) {
        if (watchpoint_address_matches(wp, addr, TARGET_PAGE_SIZE)) {
            ret |= wp->flags;
        }
    }
    return ret;
#endif
    return 0;
}

/* Add a breakpoint.  */
int cpu_breakpoint_insert(CPUState *cpu, vaddr pc, int flags,
                          CPUBreakpoint **breakpoint)
{
    CPUBreakpoint *bp;

    bp = g_malloc(sizeof(*bp));

    bp->pc = pc;
    bp->flags = flags;

    /* keep all GDB-injected breakpoints in front */
    if (flags & BP_GDB) {
        QTAILQ_INSERT_HEAD(&cpu->breakpoints, bp, entry);
    } else {
        QTAILQ_INSERT_TAIL(&cpu->breakpoints, bp, entry);
    }

    breakpoint_invalidate(cpu, pc);

    if (breakpoint) {
        *breakpoint = bp;
    }
    return 0;
}

/* Remove a specific breakpoint.  */
int cpu_breakpoint_remove(CPUState *cpu, vaddr pc, int flags)
{
    CPUBreakpoint *bp;

    QTAILQ_FOREACH(bp, &cpu->breakpoints, entry) {
        if (bp->pc == pc && bp->flags == flags) {
            cpu_breakpoint_remove_by_ref(cpu, bp);
            return 0;
        }
    }
    return -ENOENT;
}

/* Remove a specific breakpoint by reference.  */
void cpu_breakpoint_remove_by_ref(CPUState *cpu, CPUBreakpoint *breakpoint)
{
    QTAILQ_REMOVE(&cpu->breakpoints, breakpoint, entry);

    breakpoint_invalidate(cpu, breakpoint->pc);

    g_free(breakpoint);
}

/* Remove all matching breakpoints. */
void cpu_breakpoint_remove_all(CPUState *cpu, int mask)
{
    CPUBreakpoint *bp, *next;

    QTAILQ_FOREACH_SAFE(bp, &cpu->breakpoints, entry, next) {
        if (bp->flags & mask) {
            cpu_breakpoint_remove_by_ref(cpu, bp);
        }
    }
}

void cpu_abort(CPUState *cpu, const char *fmt, ...)
{
    abort();
}

/* Called from RCU critical section */
static RAMBlock *qemu_get_ram_block(struct uc_struct *uc, ram_addr_t addr)
{
    RAMBlock *block;

    block = uc->ram_list.mru_block;
    if (block && addr - block->offset < block->max_length) {
        return block;
    }
    RAMBLOCK_FOREACH(block) {
        if (addr - block->offset < block->max_length) {
            goto found;
        }
    }

    fprintf(stderr, "Bad ram offset %" PRIx64 "\n", (uint64_t)addr);
    abort();

found:
    uc->ram_list.mru_block = block;
    return block;
}

/* Note: start and end must be within the same ram block.  */
bool cpu_physical_memory_test_and_clear_dirty(ram_addr_t start,
                                              ram_addr_t length,
                                              unsigned client)
{
    return false;
}

/* Called from RCU critical section */
hwaddr memory_region_section_get_iotlb(CPUState *cpu,
                                       MemoryRegionSection *section)
{
    AddressSpaceDispatch *d = flatview_to_dispatch(section->fv);
    return section - d->map.sections;
}

static int subpage_register(struct uc_struct *uc, subpage_t *mmio, uint32_t start, uint32_t end,
                            uint16_t section);
static subpage_t *subpage_init(struct uc_struct *, FlatView *fv, hwaddr base);

static void *(*phys_mem_alloc)(struct uc_struct *uc, size_t size, uint64_t *align) =
                               qemu_anon_ram_alloc;

static uint16_t phys_section_add(struct uc_struct *uc, PhysPageMap *map,
                                 MemoryRegionSection *section)
{
    /* The physical section number is ORed with a page-aligned
     * pointer to produce the iotlb entries.  Thus it should
     * never overflow into the page-aligned value.
     */
    assert(map->sections_nb < TARGET_PAGE_SIZE);

    if (map->sections_nb == map->sections_nb_alloc) {
        map->sections_nb_alloc = MAX(map->sections_nb_alloc * 2, 16);
        map->sections = g_renew(MemoryRegionSection, map->sections,
                                map->sections_nb_alloc);
    }
    map->sections[map->sections_nb] = *section;
    return map->sections_nb++;
}

static void phys_section_destroy(MemoryRegion *mr)
{
    bool have_sub_page = mr->subpage;

    if (have_sub_page) {
        subpage_t *subpage = container_of(mr, subpage_t, iomem);
        // object_unref(OBJECT(&subpage->iomem));
        g_free(subpage);
    }
}

static void phys_sections_free(PhysPageMap *map)
{
    while (map->sections_nb > 0) {
        MemoryRegionSection *section = &map->sections[--map->sections_nb];
        phys_section_destroy(section->mr);
    }
    g_free(map->sections);
    g_free(map->nodes);
}

static void register_subpage(struct uc_struct *uc, FlatView *fv, MemoryRegionSection *section)
{
    AddressSpaceDispatch *d = flatview_to_dispatch(fv);
    subpage_t *subpage;
    hwaddr base = section->offset_within_address_space
        & TARGET_PAGE_MASK;
    MemoryRegionSection *existing = phys_page_find(d, base);
    MemoryRegionSection subsection = {
        .offset_within_address_space = base,
        .size = int128_make64(TARGET_PAGE_SIZE),
    };
    hwaddr start, end;

    assert(existing->mr->subpage || existing->mr == &(section->mr->uc->io_mem_unassigned));

    if (!(existing->mr->subpage)) {
        subpage = subpage_init(uc, fv, base);
        subsection.fv = fv;
        subsection.mr = &subpage->iomem;
        phys_page_set(d, base >> TARGET_PAGE_BITS, 1,
                      phys_section_add(uc, &d->map, &subsection));
    } else {
        subpage = container_of(existing->mr, subpage_t, iomem);
    }
    start = section->offset_within_address_space & ~TARGET_PAGE_MASK;
    end = start + int128_get64(section->size) - 1;
    subpage_register(uc, subpage, start, end,
                     phys_section_add(uc, &d->map, section));
}


static void register_multipage(struct uc_struct *uc, FlatView *fv,
                               MemoryRegionSection *section)
{
    AddressSpaceDispatch *d = flatview_to_dispatch(fv);
    hwaddr start_addr = section->offset_within_address_space;
    uint16_t section_index = phys_section_add(uc, &d->map, section);
    uint64_t num_pages = int128_get64(int128_rshift(section->size,
                                                    TARGET_PAGE_BITS));

    assert(num_pages);
    phys_page_set(d, start_addr >> TARGET_PAGE_BITS, num_pages, section_index);
}

/*
 * The range in *section* may look like this:
 *
 *      |s|PPPPPPP|s|
 *
 * where s stands for subpage and P for page.
 */
void flatview_add_to_dispatch(struct uc_struct *uc, FlatView *fv, MemoryRegionSection *section)
{
    MemoryRegionSection remain = *section;
    Int128 page_size = int128_make64(TARGET_PAGE_SIZE);

    /* register first subpage */
    if (remain.offset_within_address_space & ~TARGET_PAGE_MASK) {
        uint64_t left = TARGET_PAGE_ALIGN(remain.offset_within_address_space)
                        - remain.offset_within_address_space;

        MemoryRegionSection now = remain;
        now.size = int128_min(int128_make64(left), now.size);
        register_subpage(uc, fv, &now);
        if (int128_eq(remain.size, now.size)) {
            return;
        }
        remain.size = int128_sub(remain.size, now.size);
        remain.offset_within_address_space += int128_get64(now.size);
        remain.offset_within_region += int128_get64(now.size);
    }

    /* register whole pages */
    if (int128_ge(remain.size, page_size)) {
        MemoryRegionSection now = remain;
        now.size = int128_and(now.size, int128_neg(page_size));
        register_multipage(uc, fv, &now);
        if (int128_eq(remain.size, now.size)) {
            return;
        }
        remain.size = int128_sub(remain.size, now.size);
        remain.offset_within_address_space += int128_get64(now.size);
        remain.offset_within_region += int128_get64(now.size);
    }

    /* register last subpage */
    register_subpage(uc, fv, &remain);
}

/* Allocate space within the ram_addr_t space that governs the
 * dirty bitmaps.
 * Called with the ramlist lock held.
 */
static ram_addr_t find_ram_offset(struct uc_struct *uc, ram_addr_t size)
{
    RAMBlock *block, *next_block;
    ram_addr_t offset = RAM_ADDR_MAX, mingap = RAM_ADDR_MAX;

    assert(size != 0); /* it would hand out same offset multiple times */

    if (QLIST_EMPTY_RCU(&uc->ram_list.blocks)) {
        return 0;
    }

    RAMBLOCK_FOREACH(block) {
        ram_addr_t candidate, next = RAM_ADDR_MAX;

        /* Align blocks to start on a 'long' in the bitmap
         * which makes the bitmap sync'ing take the fast path.
         */
        candidate = block->offset + block->max_length;
        candidate = ROUND_UP(candidate, BITS_PER_LONG << TARGET_PAGE_BITS);

        /* Search for the closest following block
         * and find the gap.
         */
        RAMBLOCK_FOREACH(next_block) {
            if (next_block->offset >= candidate) {
                next = MIN(next, next_block->offset);
            }
        }

        /* If it fits remember our place and remember the size
         * of gap, but keep going so that we might find a smaller
         * gap to fill so avoiding fragmentation.
         */
        if (next - candidate >= size && next - candidate < mingap) {
            offset = candidate;
            mingap = next - candidate;
        }
    }

    if (offset == RAM_ADDR_MAX) {
        fprintf(stderr, "Failed to find gap of requested size: %" PRIu64 "\n",
                (uint64_t)size);
        abort();
    }

    return offset;
}

void *qemu_ram_get_host_addr(RAMBlock *rb)
{
    return rb->host;
}

ram_addr_t qemu_ram_get_offset(RAMBlock *rb)
{
    return rb->offset;
}

ram_addr_t qemu_ram_get_used_length(RAMBlock *rb)
{
    return rb->used_length;
}

bool qemu_ram_is_shared(RAMBlock *rb)
{
    return rb->flags & RAM_SHARED;
}

size_t qemu_ram_pagesize(RAMBlock *rb)
{
    return rb->page_size;
}

static void ram_block_add(struct uc_struct *uc, RAMBlock *new_block)
{
    RAMBlock *block;
    RAMBlock *last_block = NULL;

    new_block->offset = find_ram_offset(uc, new_block->max_length);

    if (!new_block->host) {
        new_block->host = phys_mem_alloc(uc, new_block->max_length,
                &new_block->mr->align);
        if (!new_block->host) {
            // mmap fails.
            uc->invalid_error = UC_ERR_NOMEM;
            // error_setg_errno(errp, errno,
            //         "cannot set up guest memory '%s'",
            //         memory_region_name(new_block->mr));
            return;
        }
        // memory_try_enable_merging(new_block->host, new_block->max_length);
    }

    /* Keep the list sorted from biggest to smallest block.  Unlike QTAILQ,
     * QLIST (which has an RCU-friendly variant) does not have insertion at
     * tail, so save the last element in last_block.
     */
    RAMBLOCK_FOREACH(block) {
        last_block = block;
        if (block->max_length < new_block->max_length) {
            break;
        }
    }
    if (block) {
        QLIST_INSERT_BEFORE_RCU(block, new_block, next);
    } else if (last_block) {
        QLIST_INSERT_AFTER_RCU(last_block, new_block, next);
    } else { /* list is empty */
        QLIST_INSERT_HEAD_RCU(&uc->ram_list.blocks, new_block, next);
    }
    uc->ram_list.mru_block = NULL;

    /* Write list before version */
    //smp_wmb();

    cpu_physical_memory_set_dirty_range(new_block->offset,
                                        new_block->used_length,
                                        DIRTY_CLIENTS_ALL);

}

RAMBlock *qemu_ram_alloc_from_ptr(struct uc_struct *uc, ram_addr_t size, void *host,
                                   MemoryRegion *mr)
{
    RAMBlock *new_block;
    ram_addr_t max_size = size;

    size = HOST_PAGE_ALIGN(uc, size);
    max_size = HOST_PAGE_ALIGN(uc, max_size);
    new_block = g_malloc0(sizeof(*new_block));
    if (new_block == NULL)
        return NULL;
    new_block->mr = mr;
    new_block->used_length = size;
    new_block->max_length = max_size;
    assert(max_size >= size);
    new_block->page_size = uc->qemu_real_host_page_size;
    new_block->host = host;
    if (host) {
        new_block->flags |= RAM_PREALLOC;
    }

    uc->invalid_addr = UC_ERR_OK;
    ram_block_add(mr->uc, new_block);

    if (uc->invalid_error != UC_ERR_OK) {
        g_free(new_block);
        return NULL;
    }

    return new_block;
}

RAMBlock *qemu_ram_alloc(struct uc_struct *uc, ram_addr_t size, MemoryRegion *mr)
{
    return qemu_ram_alloc_from_ptr(uc, size, NULL, mr);
}

static void reclaim_ramblock(struct uc_struct *uc, RAMBlock *block)
{
    if (block->flags & RAM_PREALLOC) {
        ;
    } else if (false) {
    } else {
        qemu_anon_ram_free(uc, block->host, block->max_length);
    }
    g_free(block);
}

void qemu_ram_free(struct uc_struct *uc, RAMBlock *block)
{
    if (!block) {
        return;
    }

    //if (block->host) {
    //    ram_block_notify_remove(block->host, block->max_length);
    //}

    QLIST_REMOVE_RCU(block, next);
    uc->ram_list.mru_block = NULL;
    /* Write list before version */
    //smp_wmb();
    // call_rcu(block, reclaim_ramblock, rcu);
    reclaim_ramblock(uc, block);
}

/* Return a host pointer to ram allocated with qemu_ram_alloc.
 * This should not be used for general purpose DMA.  Use address_space_map
 * or address_space_rw instead. For local memory (e.g. video ram) that the
 * device owns, use memory_region_get_ram_ptr.
 *
 * Called within RCU critical section.
 */
void *qemu_map_ram_ptr(struct uc_struct *uc, RAMBlock *ram_block, ram_addr_t addr)
{
    RAMBlock *block = ram_block;

    if (block == NULL) {
        block = qemu_get_ram_block(uc, addr);
        addr -= block->offset;
    }

    return ramblock_ptr(block, addr);
}

/* Return a host pointer to guest's ram. Similar to qemu_map_ram_ptr
 * but takes a size argument.
 *
 * Called within RCU critical section.
 */
static void *qemu_ram_ptr_length(struct uc_struct *uc, RAMBlock *ram_block, ram_addr_t addr,
                                 hwaddr *size, bool lock)
{
    RAMBlock *block = ram_block;
    if (*size == 0) {
        return NULL;
    }

    if (block == NULL) {
        block = qemu_get_ram_block(uc, addr);
        addr -= block->offset;
    }
    *size = MIN(*size, block->max_length - addr);

    return ramblock_ptr(block, addr);
}

/* Return the offset of a hostpointer within a ramblock */
ram_addr_t qemu_ram_block_host_offset(RAMBlock *rb, void *host)
{
    ram_addr_t res = (uint8_t *)host - (uint8_t *)rb->host;
    assert((uintptr_t)host >= (uintptr_t)rb->host);
    assert(res < rb->max_length);

    return res;
}

/*
 * Translates a host ptr back to a RAMBlock, a ram_addr and an offset
 * in that RAMBlock.
 *
 * ptr: Host pointer to look up
 * round_offset: If true round the result offset down to a page boundary
 * *ram_addr: set to result ram_addr
 * *offset: set to result offset within the RAMBlock
 *
 * Returns: RAMBlock (or NULL if not found)
 *
 * By the time this function returns, the returned pointer is not protected
 * by RCU anymore.  If the caller is not within an RCU critical section and
 * does not hold the iothread lock, it must have other means of protecting the
 * pointer, such as a reference to the region that includes the incoming
 * ram_addr_t.
 */
RAMBlock *qemu_ram_block_from_host(struct uc_struct *uc, void *ptr,
                                   bool round_offset, ram_addr_t *offset)
{
    RAMBlock *block;
    uint8_t *host = ptr;

    block = uc->ram_list.mru_block;
    if (block && block->host && host - block->host < block->max_length) {
        goto found;
    }

    RAMBLOCK_FOREACH(block) {
        /* This case append when the block is not mapped. */
        if (block->host == NULL) {
            continue;
        }
        if (host - block->host < block->max_length) {
            goto found;
        }
    }

    return NULL;

found:
    *offset = (host - block->host);
    if (round_offset) {
        *offset &= TARGET_PAGE_MASK;
    }
    return block;
}

/* Some of the softmmu routines need to translate from a host pointer
   (typically a TLB entry) back to a ram offset.  */
ram_addr_t qemu_ram_addr_from_host(struct uc_struct *uc, void *ptr)
{
    RAMBlock *block;
    ram_addr_t offset;

    block = qemu_ram_block_from_host(uc, ptr, false, &offset);
    if (!block) {
        return RAM_ADDR_INVALID;
    }

    return block->offset + offset;
}

/* Generate a debug exception if a watchpoint has been hit.  */
void cpu_check_watchpoint(CPUState *cpu, vaddr addr, vaddr len,
                          MemTxAttrs attrs, int flags, uintptr_t ra)
{
}

static MemTxResult flatview_read(struct uc_struct *uc, FlatView *fv, hwaddr addr,
                                 MemTxAttrs attrs, void *buf, hwaddr len);
static MemTxResult flatview_write(struct uc_struct *, FlatView *fv, hwaddr addr, MemTxAttrs attrs,
                                  const void *buf, hwaddr len);
static bool flatview_access_valid(struct uc_struct *uc, FlatView *fv, hwaddr addr, hwaddr len,
                                  bool is_write, MemTxAttrs attrs);

static MemTxResult subpage_read(struct uc_struct *uc, void *opaque, hwaddr addr, uint64_t *data,
                                unsigned len, MemTxAttrs attrs)
{
    subpage_t *subpage = opaque;
    uint8_t buf[8];
    MemTxResult res;

#if defined(DEBUG_SUBPAGE)
    printf("%s: subpage %p len %u addr " TARGET_FMT_plx "\n", __func__,
           subpage, len, addr);
#endif
    res = flatview_read(uc, subpage->fv, addr + subpage->base, attrs, buf, len);
    if (res) {
        return res;
    }
    *data = ldn_p(buf, len);
    return MEMTX_OK;
}

static MemTxResult subpage_write(struct uc_struct *uc, void *opaque, hwaddr addr,
                                 uint64_t value, unsigned len, MemTxAttrs attrs)
{
    subpage_t *subpage = opaque;
    uint8_t buf[8];

#if defined(DEBUG_SUBPAGE)
    printf("%s: subpage %p len %u addr " TARGET_FMT_plx
           " value %"PRIx64"\n",
           __func__, subpage, len, addr, value);
#endif
    stn_p(buf, len, value);
    return flatview_write(uc, subpage->fv, addr + subpage->base, attrs, buf, len);
}

static bool subpage_accepts(struct uc_struct *uc, void *opaque, hwaddr addr,
                            unsigned len, bool is_write,
                            MemTxAttrs attrs)
{
    subpage_t *subpage = opaque;
#if defined(DEBUG_SUBPAGE)
    printf("%s: subpage %p %c len %u addr " TARGET_FMT_plx "\n",
           __func__, subpage, is_write ? 'w' : 'r', len, addr);
#endif

    return flatview_access_valid(uc, subpage->fv, addr + subpage->base,
                                 len, is_write, attrs);
}

static const MemoryRegionOps subpage_ops = {
    .read_with_attrs = subpage_read,
    .write_with_attrs = subpage_write,
    .impl.min_access_size = 1,
    .impl.max_access_size = 8,
    .valid.min_access_size = 1,
    .valid.max_access_size = 8,
    .valid.accepts = subpage_accepts,
    .endianness = DEVICE_NATIVE_ENDIAN,
};

static int subpage_register(struct uc_struct *uc, subpage_t *mmio, uint32_t start, uint32_t end,
                            uint16_t section)
{
    int idx, eidx;

    if (start >= TARGET_PAGE_SIZE || end >= TARGET_PAGE_SIZE)
        return -1;
    idx = SUBPAGE_IDX(start);
    eidx = SUBPAGE_IDX(end);
#if defined(DEBUG_SUBPAGE)
    printf("%s: %p start %08x end %08x idx %08x eidx %08x section %d\n",
           __func__, mmio, start, end, idx, eidx, section);
#endif
    for (; idx <= eidx; idx++) {
        mmio->sub_section[idx] = section;
    }

    return 0;
}

static subpage_t *subpage_init(struct uc_struct *uc, FlatView *fv, hwaddr base)
{
    subpage_t *mmio;

    /* mmio->sub_section is set to PHYS_SECTION_UNASSIGNED with g_malloc0 */
    mmio = g_malloc0(sizeof(subpage_t) + TARGET_PAGE_SIZE * sizeof(uint16_t));
    mmio->fv = fv;
    mmio->base = base;
    memory_region_init_io(fv->root->uc, &mmio->iomem, &subpage_ops, mmio,
                          TARGET_PAGE_SIZE);
    mmio->iomem.subpage = true;
#if defined(DEBUG_SUBPAGE)
    printf("%s: %p base " TARGET_FMT_plx " len %08x\n", __func__,
           mmio, base, TARGET_PAGE_SIZE);
#endif

    return mmio;
}

static uint16_t dummy_section(struct uc_struct *uc, PhysPageMap *map, FlatView *fv, MemoryRegion *mr)
{
    assert(fv);
    MemoryRegionSection section = {
        .fv = fv,
        .mr = mr,
        .offset_within_address_space = 0,
        .offset_within_region = 0,
        .size = int128_2_64(),
    };

    return phys_section_add(uc, map, &section);
}

MemoryRegionSection *iotlb_to_section(CPUState *cpu,
                                      hwaddr index, MemTxAttrs attrs)
{
#ifdef TARGET_ARM
    struct uc_struct *uc = cpu->uc;
#endif
    int asidx = cpu_asidx_from_attrs(cpu, attrs);
    CPUAddressSpace *cpuas = &cpu->cpu_ases[asidx];
    AddressSpaceDispatch *d = cpuas->memory_dispatch;
    MemoryRegionSection *sections = d->map.sections;

    return &sections[index & ~TARGET_PAGE_MASK];
}

static void io_mem_init(struct uc_struct *uc)
{
    memory_region_init_io(uc, &uc->io_mem_unassigned, &unassigned_mem_ops, NULL,
                          UINT64_MAX);
}

AddressSpaceDispatch *address_space_dispatch_new(struct uc_struct *uc, FlatView *fv)
{
    AddressSpaceDispatch *d = g_new0(AddressSpaceDispatch, 1);
#ifndef NDEBUG
    uint16_t n;

    n = dummy_section(uc, &d->map, fv, &(uc->io_mem_unassigned));
    assert(n == PHYS_SECTION_UNASSIGNED);
#else
    dummy_section(uc, &d->map, fv, &(uc->io_mem_unassigned));
#endif

    d->phys_map  = (PhysPageEntry) { .ptr = PHYS_MAP_NODE_NIL, .skip = 1 };
    d->uc = uc;

    return d;
}

void address_space_dispatch_free(AddressSpaceDispatch *d)
{
    phys_sections_free(&d->map);
    g_free(d);
}

static void tcg_commit(MemoryListener *listener)
{
    CPUAddressSpace *cpuas;
    AddressSpaceDispatch *d;

    /* since each CPU stores ram addresses in its TLB cache, we must
       reset the modified entries */
    cpuas = container_of(listener, CPUAddressSpace, tcg_as_listener);
    cpu_reloading_memory_map();
    /* The CPU and TLB are protected by the iothread lock.
     * We reload the dispatch pointer now because cpu_reloading_memory_map()
     * may have split the RCU critical section.
     */
    d = address_space_to_dispatch(cpuas->as);
    cpuas->memory_dispatch = d;
    tlb_flush(cpuas->cpu);
}

static uint64_t unassigned_io_read(struct uc_struct *uc, void* opaque, hwaddr addr, unsigned size)
{
#ifdef _MSC_VER
    return (uint64_t)0xffffffffffffffffULL;
#else
    return (uint64_t)-1ULL;
#endif
}

static void unassigned_io_write(struct uc_struct *uc, void* opaque, hwaddr addr, uint64_t data, unsigned size)
{
}

static const MemoryRegionOps unassigned_io_ops = {
    .read = unassigned_io_read,
    .write = unassigned_io_write,
    .endianness = DEVICE_NATIVE_ENDIAN,
};

static void memory_map_init(struct uc_struct *uc)
{
    uc->system_memory = g_malloc(sizeof(*(uc->system_memory)));
    memory_region_init(uc, uc->system_memory, UINT64_MAX);
    address_space_init(uc, &uc->address_space_memory, uc->system_memory);

    uc->system_io = g_malloc(sizeof(*(uc->system_io)));
    memory_region_init_io(uc, uc->system_io, &unassigned_io_ops, NULL, 65536);
    address_space_init(uc, &uc->address_space_io, uc->system_io);
}

/* physical memory access (slow version, mainly for debug) */
static void invalidate_and_set_dirty(MemoryRegion *mr, hwaddr addr,
                                     hwaddr length)
{
}

static int memory_access_size(MemoryRegion *mr, unsigned l, hwaddr addr)
{
    unsigned access_size_max = mr->ops->valid.max_access_size;

    /* Regions are assumed to support 1-4 byte accesses unless
       otherwise specified.  */
    if (access_size_max == 0) {
        access_size_max = 4;
    }

    /* Bound the maximum access by the alignment of the address.  */
    if (!mr->ops->impl.unaligned) {
#ifdef _MSC_VER
        unsigned align_size_max = addr & (0ULL - addr);
#else
        unsigned align_size_max = addr & -addr;
#endif
        if (align_size_max != 0 && align_size_max < access_size_max) {
            access_size_max = align_size_max;
        }
    }

    /* Don't attempt accesses larger than the maximum.  */
    if (l > access_size_max) {
        l = access_size_max;
    }
    l = pow2floor(l);

    return l;
}

static bool prepare_mmio_access(MemoryRegion *mr)
{
    return true;
}

/* Called within RCU critical section.  */
static MemTxResult flatview_write_continue(struct uc_struct *uc, FlatView *fv, hwaddr addr,
                                           MemTxAttrs attrs,
                                           const void *ptr,
                                           hwaddr len, hwaddr addr1,
                                           hwaddr l, MemoryRegion *mr)
{
    uint8_t *ram_ptr;
    uint64_t val;
    MemTxResult result = MEMTX_OK;
    bool release_lock = false;
    const uint8_t *buf = ptr;

    for (;;) {
        if (!memory_access_is_direct(mr, true)) {
            release_lock |= prepare_mmio_access(mr);
            l = memory_access_size(mr, l, addr1);
            /* XXX: could force current_cpu to NULL to avoid
               potential bugs */
            val = ldn_he_p(buf, l);
            result |= memory_region_dispatch_write(uc, mr, addr1, val,
                                                   size_memop(l), attrs);
        } else {
            /* RAM case */
            ram_ptr = qemu_ram_ptr_length(fv->root->uc, mr->ram_block, addr1, &l, false);
            memcpy(ram_ptr, buf, l);
        }

        if (release_lock) {
            release_lock = false;
        }

        len -= l;
        buf += l;
        addr += l;

        if (!len) {
            break;
        }

        l = len;
        mr = flatview_translate(uc, fv, addr, &addr1, &l, true, attrs);
    }

    return result;
}

/* Called from RCU critical section.  */
static MemTxResult flatview_write(struct uc_struct *uc, FlatView *fv, hwaddr addr, MemTxAttrs attrs,
                                  const void *buf, hwaddr len)
{
    hwaddr l;
    hwaddr addr1;
    MemoryRegion *mr;
    MemTxResult result = MEMTX_OK;

    l = len;
    mr = flatview_translate(uc, fv, addr, &addr1, &l, true, attrs);
    result = flatview_write_continue(uc, fv, addr, attrs, buf, len,
                                     addr1, l, mr);

    return result;
}

/* Called within RCU critical section.  */
MemTxResult flatview_read_continue(struct uc_struct *uc, FlatView *fv, hwaddr addr,
                                   MemTxAttrs attrs, void *ptr,
                                   hwaddr len, hwaddr addr1, hwaddr l,
                                   MemoryRegion *mr)
{
    uint8_t *ram_ptr;
    uint64_t val;
    MemTxResult result = MEMTX_OK;
    bool release_lock = false;
    uint8_t *buf = ptr;

    for (;;) {
        if (!memory_access_is_direct(mr, false)) {
            /* I/O case */
            release_lock |= prepare_mmio_access(mr);
            l = memory_access_size(mr, l, addr1);
            result |= memory_region_dispatch_read(uc, mr, addr1, &val,
                                                  size_memop(l), attrs);
            stn_he_p(buf, l, val);
        } else {
            /* RAM case */
            ram_ptr = qemu_ram_ptr_length(fv->root->uc, mr->ram_block, addr1, &l, false);
            memcpy(buf, ram_ptr, l);
        }

        if (release_lock) {
            release_lock = false;
        }

        len -= l;
        buf += l;
        addr += l;

        if (!len) {
            break;
        }

        l = len;
        mr = flatview_translate(uc, fv, addr, &addr1, &l, false, attrs);
    }

    return result;
}

/* Called from RCU critical section.  */
static MemTxResult flatview_read(struct uc_struct *uc, FlatView *fv, hwaddr addr,
                                 MemTxAttrs attrs, void *buf, hwaddr len)
{
    hwaddr l;
    hwaddr addr1;
    MemoryRegion *mr;

    l = len;
    mr = flatview_translate(uc, fv, addr, &addr1, &l, false, attrs);
    return flatview_read_continue(uc, fv, addr, attrs, buf, len,
                                  addr1, l, mr);
}

MemTxResult address_space_read_full(AddressSpace *as, hwaddr addr,
                                    MemTxAttrs attrs, void *buf, hwaddr len)
{
    MemTxResult result = MEMTX_OK;
    FlatView *fv;

    if (len > 0) {
        fv = address_space_to_flatview(as);
        result = flatview_read(as->uc, fv, addr, attrs, buf, len);
    }

    return result;
}

MemTxResult address_space_write(AddressSpace *as, hwaddr addr,
                                MemTxAttrs attrs,
                                const void *buf, hwaddr len)
{
    MemTxResult result = MEMTX_OK;
    FlatView *fv;

    if (len > 0) {
        fv = address_space_to_flatview(as);
        result = flatview_write(as->uc, fv, addr, attrs, buf, len);
    }

    return result;
}

MemTxResult address_space_rw(AddressSpace *as, hwaddr addr, MemTxAttrs attrs,
                             void *buf, hwaddr len, bool is_write)
{
    if (is_write) {
        return address_space_write(as, addr, attrs, buf, len);
    } else {
        return address_space_read_full(as, addr, attrs, buf, len);
    }
}

bool cpu_physical_memory_rw(AddressSpace *as, hwaddr addr, void *buf,
                            hwaddr len, bool is_write)
{
    MemTxResult result = address_space_rw(as, addr, MEMTXATTRS_UNSPECIFIED,
                     buf, len, is_write);
    if (result == MEMTX_OK) {
        return true;
    } else {
        return false;
    }
}

enum write_rom_type {
    WRITE_DATA,
    FLUSH_CACHE,
};

static inline MemTxResult address_space_write_rom_internal(AddressSpace *as,
                                                           hwaddr addr,
                                                           MemTxAttrs attrs,
                                                           const void *ptr,
                                                           hwaddr len,
                                                           enum write_rom_type type)
{
    hwaddr l;
    uint8_t *ram_ptr;
    hwaddr addr1;
    MemoryRegion *mr;
    const uint8_t *buf = ptr;

    while (len > 0) {
        l = len;
        mr = address_space_translate(as, addr, &addr1, &l, true, attrs);

        if (!memory_region_is_ram(mr)) {
            l = memory_access_size(mr, l, addr1);
        } else {
            /* ROM/RAM case */
            ram_ptr = qemu_map_ram_ptr(as->uc, mr->ram_block, addr1);
            switch (type) {
            case WRITE_DATA:
                memcpy(ram_ptr, buf, l);
                break;
            case FLUSH_CACHE:
                flush_icache_range((uintptr_t)ram_ptr, (uintptr_t)ram_ptr + l);
                break;
            }
        }
        len -= l;
        buf += l;
        addr += l;
    }
    return MEMTX_OK;
}

/* used for ROM loading : can write in RAM and ROM */
MemTxResult address_space_write_rom(AddressSpace *as, hwaddr addr,
                                    MemTxAttrs attrs,
                                    const void *buf, hwaddr len)
{
    return address_space_write_rom_internal(as, addr, attrs,
                                            buf, len, WRITE_DATA);
}

void cpu_flush_icache_range(AddressSpace *as, hwaddr start, hwaddr len)
{
}

void cpu_exec_init_all(struct uc_struct *uc)
{
    /* The data structures we set up here depend on knowing the page size,
     * so no more changes can be made after this point.
     * In an ideal world, nothing we did before we had finished the
     * machine setup would care about the target page size, and we could
     * do this much later, rather than requiring board models to state
     * up front what their requirements are.
     */
    finalize_target_page_bits(uc);
    memory_map_init(uc);
    io_mem_init(uc);
}

static bool flatview_access_valid(struct uc_struct *uc, FlatView *fv, hwaddr addr, hwaddr len,
                                  bool is_write, MemTxAttrs attrs)
{
    MemoryRegion *mr;
    hwaddr l, xlat;

    while (len > 0) {
        l = len;
        mr = flatview_translate(uc, fv, addr, &xlat, &l, is_write, attrs);
        if (!memory_access_is_direct(mr, is_write)) {
            l = memory_access_size(mr, l, addr);
            if (!memory_region_access_valid(uc, mr, xlat, l, is_write, attrs)) {
                return false;
            }
        }

        len -= l;
        addr += l;
    }
    return true;
}

bool address_space_access_valid(AddressSpace *as, hwaddr addr,
                                hwaddr len, bool is_write,
                                MemTxAttrs attrs)
{
    FlatView *fv;
    bool result;

    fv = address_space_to_flatview(as);
    result = flatview_access_valid(as->uc, fv, addr, len, is_write, attrs);
    return result;
}

static hwaddr
flatview_extend_translation(struct uc_struct *uc, FlatView *fv, hwaddr addr,
                            hwaddr target_len,
                            MemoryRegion *mr, hwaddr base, hwaddr len,
                            bool is_write, MemTxAttrs attrs)
{
    hwaddr done = 0;
    hwaddr xlat;
    MemoryRegion *this_mr;

    for (;;) {
        target_len -= len;
        addr += len;
        done += len;
        if (target_len == 0) {
            return done;
        }

        len = target_len;
        this_mr = flatview_translate(uc, fv, addr, &xlat,
                                     &len, is_write, attrs);
        if (this_mr != mr || xlat != base + done) {
            return done;
        }
    }
}

/* Map a physical memory region into a host virtual address.
 * May map a subset of the requested range, given by and returned in *plen.
 * May return NULL if resources needed to perform the mapping are exhausted.
 * Use only for reads OR writes - not for read-modify-write operations.
 * Use cpu_register_map_client() to know when retrying the map operation is
 * likely to succeed.
 */
void *address_space_map(AddressSpace *as,
                        hwaddr addr,
                        hwaddr *plen,
                        bool is_write,
                        MemTxAttrs attrs)
{
    hwaddr len = *plen;
    hwaddr l, xlat;
    MemoryRegion *mr;
    void *ptr;
    FlatView *fv;
    struct uc_struct *uc = as->uc;

    if (len == 0) {
        return NULL;
    }

    l = len;
    fv = address_space_to_flatview(as);
    mr = flatview_translate(uc, fv, addr, &xlat, &l, is_write, attrs);

    if (!memory_access_is_direct(mr, is_write)) {
        /* Avoid unbounded allocations */
        l = MIN(l, TARGET_PAGE_SIZE);
        mr->uc->bounce.buffer = qemu_memalign(TARGET_PAGE_SIZE, l);
        mr->uc->bounce.addr = addr;
        mr->uc->bounce.len = l;

        mr->uc->bounce.mr = mr;
        if (!is_write) {
            flatview_read(as->uc, fv, addr, MEMTXATTRS_UNSPECIFIED,
                               mr->uc->bounce.buffer, l);
        }

        *plen = l;
        return mr->uc->bounce.buffer;
    }


    *plen = flatview_extend_translation(as->uc, fv, addr, len, mr, xlat,
                                        l, is_write, attrs);
    ptr = qemu_ram_ptr_length(as->uc, mr->ram_block, xlat, plen, true);

    return ptr;
}

/* Unmaps a memory region previously mapped by address_space_map().
 * Will also mark the memory as dirty if is_write is true.  access_len gives
 * the amount of memory that was actually read or written by the caller.
 */
void address_space_unmap(AddressSpace *as, void *buffer, hwaddr len,
                         bool is_write, hwaddr access_len)
{
    if (buffer != as->uc->bounce.buffer) {
        MemoryRegion *mr;
        ram_addr_t addr1;

        mr = memory_region_from_host(as->uc, buffer, &addr1);
        assert(mr != NULL);
        if (is_write) {
            invalidate_and_set_dirty(mr, addr1, access_len);
        }
        return;
    }
    if (is_write) {
        address_space_write(as, as->uc->bounce.addr, MEMTXATTRS_UNSPECIFIED,
                            as->uc->bounce.buffer, access_len);
    }
    qemu_vfree(as->uc->bounce.buffer);
    as->uc->bounce.buffer = NULL;
}

void *cpu_physical_memory_map(AddressSpace *as, hwaddr addr,
                              hwaddr *plen,
                              bool is_write)
{
    return address_space_map(as, addr, plen, is_write,
                             MEMTXATTRS_UNSPECIFIED);
}

void cpu_physical_memory_unmap(AddressSpace *as, void *buffer, hwaddr len,
                               bool is_write, hwaddr access_len)
{
    address_space_unmap(as, buffer, len, is_write, access_len);
}

#define ARG1_DECL                AddressSpace *as
#define ARG1                     as
#ifdef UNICORN_ARCH_POSTFIX
#define SUFFIX UNICORN_ARCH_POSTFIX
#else
#define SUFFIX
#endif
#define TRANSLATE(...)           address_space_translate(as, __VA_ARGS__)
#include "memory_ldst.inc.c"

/* Called from RCU critical section.  This function has the same
 * semantics as address_space_translate, but it only works on a
 * predefined range of a MemoryRegion that was mapped with
 * address_space_cache_init.
 */
static inline MemoryRegion *address_space_translate_cached(
    MemoryRegionCache *cache, hwaddr addr, hwaddr *xlat,
    hwaddr *plen, bool is_write, MemTxAttrs attrs)
{
    MemoryRegionSection section;
    MemoryRegion *mr;
    IOMMUMemoryRegion *iommu_mr;
    AddressSpace *target_as;

    assert(!cache->ptr);
    *xlat = addr + cache->xlat;

    mr = cache->mrs.mr;
    iommu_mr = memory_region_get_iommu(mr);
    if (!iommu_mr) {
        /* MMIO region.  */
        return mr;
    }

    section = address_space_translate_iommu(iommu_mr, xlat, plen,
                                            NULL, is_write, true,
                                            &target_as, attrs);
    return section.mr;
}

#define ARG1_DECL                MemoryRegionCache *cache
#define ARG1                     cache
#ifdef UNICORN_ARCH_POSTFIX
#define SUFFIX                   glue(_cached_slow, UNICORN_ARCH_POSTFIX)
#else
#define SUFFIX                   _cached_slow
#endif
#define TRANSLATE(...)           address_space_translate_cached(cache, __VA_ARGS__)
#include "memory_ldst.inc.c"

/* virtual memory access for debug (includes writing to ROM) */
int cpu_memory_rw_debug(CPUState *cpu, target_ulong addr,
                        void *ptr, target_ulong len, bool is_write)
{
#ifdef TARGET_ARM
    struct uc_struct *uc = cpu->uc;
#endif
    hwaddr phys_addr;
    target_ulong l, page;
    uint8_t *buf = ptr;

    while (len > 0) {
        int asidx;
        MemTxAttrs attrs;

        page = addr & TARGET_PAGE_MASK;
        phys_addr = cpu_get_phys_page_attrs_debug(cpu, page, &attrs);
        asidx = cpu_asidx_from_attrs(cpu, attrs);
        /* if no physical page mapped, return an error */
        if (phys_addr == -1)
            return -1;
        l = (page + TARGET_PAGE_SIZE) - addr;
        if (l > len)
            l = len;
        phys_addr += (addr & ~TARGET_PAGE_MASK);
        if (is_write) {
            address_space_write_rom(cpu->cpu_ases[asidx].as, phys_addr,
                                    attrs, buf, l);
        } else {
            address_space_read(cpu->cpu_ases[asidx].as, phys_addr, attrs, buf,
                               l);
        }
        len -= l;
        buf += l;
        addr += l;
    }
    return 0;
}

/*
 * Allows code that needs to deal with migration bitmaps etc to still be built
 * target independent.
 */
size_t qemu_target_page_size(struct uc_struct *uc)
{
    return TARGET_PAGE_SIZE;
}

int qemu_target_page_bits(struct uc_struct *uc)
{
    return TARGET_PAGE_BITS;
}

int qemu_target_page_bits_min(void)
{
    return TARGET_PAGE_BITS_MIN;
}

bool target_words_bigendian(void)
{
#if defined(TARGET_WORDS_BIGENDIAN)
    return true;
#else
    return false;
#endif
}

bool cpu_physical_memory_is_io(AddressSpace *as, hwaddr phys_addr)
{
    MemoryRegion*mr;
    hwaddr l = 1;
    bool res;

    mr = address_space_translate(as,
                                 phys_addr, &phys_addr, &l, false,
                                 MEMTXATTRS_UNSPECIFIED);

    res = !memory_region_is_ram(mr);
    return res;
}

/*
 * Unmap pages of memory from start to start+length such that
 * they a) read as 0, b) Trigger whatever fault mechanism
 * the OS provides for postcopy.
 * The pages must be unmapped by the end of the function.
 * Returns: 0 on success, none-0 on failure
 *
 */
int ram_block_discard_range(struct uc_struct *uc, RAMBlock *rb, uint64_t start, size_t length)
{
    int ret = -1;

    uint8_t *host_startaddr = rb->host + start;

    if (!QEMU_PTR_IS_ALIGNED(host_startaddr, rb->page_size)) {
        //error_report("ram_block_discard_range: Unaligned start address: %p",
        //             host_startaddr);
        goto err;
    }

    if ((start + length) <= rb->used_length) {
        bool need_madvise;
        if (!QEMU_IS_ALIGNED(length, rb->page_size)) {
            //error_report("ram_block_discard_range: Unaligned length: %zx",
            //             length);
            goto err;
        }

        errno = ENOTSUP; /* If we are missing MADVISE etc */

        /* The logic here is messy;
         *    madvise DONTNEED fails for hugepages
         *    fallocate works on hugepages and shmem
         */
        need_madvise = (rb->page_size == uc->qemu_host_page_size);
        if (need_madvise) {
            /* For normal RAM this causes it to be unmapped,
             * for shared memory it causes the local mapping to disappear
             * and to fall back on the file contents (which we just
             * fallocate'd away).
             */
#if defined(CONFIG_MADVISE)
            ret =  madvise(host_startaddr, length, MADV_DONTNEED);
            if (ret) {
                ret = -errno;
                //error_report("ram_block_discard_range: Failed to discard range "
                //             "%s:%" PRIx64 " +%zx (%d)",
                //             rb->idstr, start, length, ret);
                goto err;
            }
#else
            ret = -ENOSYS;
            //error_report("ram_block_discard_range: MADVISE not available"
            //             "%s:%" PRIx64 " +%zx (%d)",
            //             rb->idstr, start, length, ret);
            goto err;
#endif
        }
    } else {
        //error_report("ram_block_discard_range: Overrun block '%s' (%" PRIu64
        //             "/%zx/" RAM_ADDR_FMT")",
        //             rb->idstr, start, length, rb->used_length);
    }

err:
    return ret;
}

bool ramblock_is_pmem(RAMBlock *rb)
{
    return rb->flags & RAM_PMEM;
}

void page_size_init(struct uc_struct *uc)
{
    /* NOTE: we can always suppose that qemu_host_page_size >=
       TARGET_PAGE_SIZE */
    if (uc->qemu_host_page_size == 0) {
        uc->qemu_host_page_size = uc->qemu_real_host_page_size;
    }
    if (uc->qemu_host_page_size < TARGET_PAGE_SIZE) {
        uc->qemu_host_page_size = TARGET_PAGE_SIZE;
    }
}