llvm-project/lldb/tools/debugserver/source/MacOSX/MachVMMemory.cpp

//===-- MachVMMemory.cpp ----------------------------------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
//  Created by Greg Clayton on 6/26/07.
//
//===----------------------------------------------------------------------===//

#include "MachVMMemory.h"
#include "MachVMRegion.h"
#include "DNBLog.h"
#include <mach/mach_vm.h>

MachVMMemory::MachVMMemory() :
    m_page_size    (kInvalidPageSize),
    m_err        (0)
{
}

MachVMMemory::~MachVMMemory()
{
}

nub_size_t
MachVMMemory::PageSize()
{
    if (m_page_size == kInvalidPageSize)
    {
        m_err = ::host_page_size( ::mach_host_self(), &m_page_size);
        if (m_err.Fail())
            m_page_size = 0;
    }
    return m_page_size;
}

nub_size_t
MachVMMemory::MaxBytesLeftInPage(nub_addr_t addr, nub_size_t count)
{
    const nub_size_t page_size = PageSize();
    if (page_size > 0)
    {
        nub_size_t page_offset = (addr % page_size);
        nub_size_t bytes_left_in_page = page_size - page_offset;
        if (count > bytes_left_in_page)
            count = bytes_left_in_page;
    }
    return count;
}

nub_bool_t
MachVMMemory::GetMemoryRegionInfo(task_t task, nub_addr_t address, DNBRegionInfo *region_info)
{
    MachVMRegion vmRegion(task);

    if (vmRegion.GetRegionForAddress(address))
    {
        region_info->addr = vmRegion.StartAddress();
        region_info->size = vmRegion.GetByteSize();
        region_info->permissions = vmRegion.GetDNBPermissions();
    }
    else
    {
        region_info->addr = address;
        region_info->size = 0;
        if (vmRegion.GetError().Success())
        {
            // vmRegion.GetRegionForAddress() return false, indicating that "address"
            // wasn't in a valid region, but the "vmRegion" info was successfully 
            // read from the task which means the info describes the next valid
            // region from which we can infer the size of this invalid region
            mach_vm_address_t start_addr = vmRegion.StartAddress();
            if (address < start_addr)
                region_info->size = start_addr - address;
        }
        // If we can't get any infor about the size from the next region, just fill
        // 1 in as the byte size
        if (region_info->size == 0)
            region_info->size = 1;

        // Not readable, writeable or executable
        region_info->permissions = 0;
    }
    return true;
}

nub_size_t
MachVMMemory::Read(task_t task, nub_addr_t address, void *data, nub_size_t data_count)
{
    if (data == NULL || data_count == 0)
        return 0;

    nub_size_t total_bytes_read = 0;
    nub_addr_t curr_addr = address;
    uint8_t *curr_data = (uint8_t*)data;
    while (total_bytes_read < data_count)
    {
        mach_vm_size_t curr_size = MaxBytesLeftInPage(curr_addr, data_count - total_bytes_read);
        mach_msg_type_number_t curr_bytes_read = 0;
        vm_offset_t vm_memory = NULL;
        m_err = ::mach_vm_read (task, curr_addr, curr_size, &vm_memory, &curr_bytes_read);
        
        // We end up being asked to read memory at 0x0 a lot without that being a real error, so that ends up just
        // causing a lot of useless log spam.  Only complain on failing reads if the address is not 0x0.
        if (DNBLogCheckLogBit(LOG_MEMORY) || (m_err.Fail() && curr_addr != 0))
            m_err.LogThreaded("::mach_vm_read ( task = 0x%4.4x, addr = 0x%8.8llx, size = %llu, data => %8.8p, dataCnt => %i )", task, (uint64_t)curr_addr, (uint64_t)curr_size, vm_memory, curr_bytes_read);

        if (m_err.Success())
        {
            if (curr_bytes_read != curr_size)
            {
                if (DNBLogCheckLogBit(LOG_MEMORY))
                    m_err.LogThreaded("::mach_vm_read ( task = 0x%4.4x, addr = 0x%8.8llx, size = %llu, data => %8.8p, dataCnt=>%i ) only read %u of %llu bytes", task, (uint64_t)curr_addr, (uint64_t)curr_size, vm_memory, curr_bytes_read, curr_bytes_read, (uint64_t)curr_size);
            }
            ::memcpy (curr_data, (void *)vm_memory, curr_bytes_read);
            ::vm_deallocate (mach_task_self (), vm_memory, curr_bytes_read);
            total_bytes_read += curr_bytes_read;
            curr_addr += curr_bytes_read;
            curr_data += curr_bytes_read;
        }
        else
        {
            break;
        }
    }
    return total_bytes_read;
}


nub_size_t
MachVMMemory::Write(task_t task, nub_addr_t address, const void *data, nub_size_t data_count)
{
    MachVMRegion vmRegion(task);

    nub_size_t total_bytes_written = 0;
    nub_addr_t curr_addr = address;
    const uint8_t *curr_data = (const uint8_t*)data;


    while (total_bytes_written < data_count)
    {
        if (vmRegion.GetRegionForAddress(curr_addr))
        {
            mach_vm_size_t curr_data_count = data_count - total_bytes_written;
            mach_vm_size_t region_bytes_left = vmRegion.BytesRemaining(curr_addr);
            if (region_bytes_left == 0)
            {
                break;
            }
            if (curr_data_count > region_bytes_left)
                curr_data_count = region_bytes_left;

            if (vmRegion.SetProtections(curr_addr, curr_data_count, VM_PROT_READ | VM_PROT_WRITE))
            {
                nub_size_t bytes_written = WriteRegion(task, curr_addr, curr_data, curr_data_count);
                if (bytes_written <= 0)
                {
                    // Error should have already be posted by WriteRegion...
                    break;
                }
                else
                {
                    total_bytes_written += bytes_written;
                    curr_addr += bytes_written;
                    curr_data += bytes_written;
                }
            }
            else
            {
                DNBLogThreadedIf(LOG_MEMORY_PROTECTIONS, "Failed to set read/write protections on region for address: [0x%8.8llx-0x%8.8llx)", (uint64_t)curr_addr, (uint64_t)(curr_addr + curr_data_count));
                break;
            }
        }
        else
        {
            DNBLogThreadedIf(LOG_MEMORY_PROTECTIONS, "Failed to get region for address: 0x%8.8llx", (uint64_t)address);
            break;
        }
    }

    return total_bytes_written;
}


nub_size_t
MachVMMemory::WriteRegion(task_t task, const nub_addr_t address, const void *data, const nub_size_t data_count)
{
    if (data == NULL || data_count == 0)
        return 0;

    nub_size_t total_bytes_written = 0;
    nub_addr_t curr_addr = address;
    const uint8_t *curr_data = (const uint8_t*)data;
    while (total_bytes_written < data_count)
    {
        mach_msg_type_number_t curr_data_count = MaxBytesLeftInPage(curr_addr, data_count - total_bytes_written);
        m_err = ::mach_vm_write (task, curr_addr, (pointer_t) curr_data, curr_data_count);
        if (DNBLogCheckLogBit(LOG_MEMORY) || m_err.Fail())
            m_err.LogThreaded("::mach_vm_write ( task = 0x%4.4x, addr = 0x%8.8llx, data = %8.8p, dataCnt = %u )", task, (uint64_t)curr_addr, curr_data, curr_data_count);

#if !defined (__i386__) && !defined (__x86_64__)
        vm_machine_attribute_val_t mattr_value = MATTR_VAL_CACHE_FLUSH;

        m_err = ::vm_machine_attribute (task, curr_addr, curr_data_count, MATTR_CACHE, &mattr_value);
        if (DNBLogCheckLogBit(LOG_MEMORY) || m_err.Fail())
            m_err.LogThreaded("::vm_machine_attribute ( task = 0x%4.4x, addr = 0x%8.8llx, size = %u, attr = MATTR_CACHE, mattr_value => MATTR_VAL_CACHE_FLUSH )", task, (uint64_t)curr_addr, curr_data_count);
#endif

        if (m_err.Success())
        {
            total_bytes_written += curr_data_count;
            curr_addr += curr_data_count;
            curr_data += curr_data_count;
        }
        else
        {
            break;
        }
    }
    return total_bytes_written;
}