lldb/source/Target/Memory.cpp

   1 //===-- Memory.cpp --------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "lldb/Target/Memory.h"
  10 #include "lldb/Target/Process.h"
  11 #include "lldb/Utility/DataBufferHeap.h"
  12 #include "lldb/Utility/LLDBLog.h"
  13 #include "lldb/Utility/Log.h"
  14 #include "lldb/Utility/RangeMap.h"
  15 #include "lldb/Utility/State.h"
  16
  17 #include <cinttypes>
  18 #include <memory>
  19
  20 using namespace lldb;
  21 using namespace lldb_private;
  22
  23 // MemoryCache constructor
  24 MemoryCache::MemoryCache(Process &process)
  25     : m_mutex(), m_L1_cache(), m_L2_cache(), m_invalid_ranges(),
  26       m_process(process),
  27       m_L2_cache_line_byte_size(process.GetMemoryCacheLineSize()) {}
  28
  29 // Destructor
  30 MemoryCache::~MemoryCache() = default;
  31
  32 void MemoryCache::Clear(bool clear_invalid_ranges) {
  33   std::lock_guard<std::recursive_mutex> guard(m_mutex);
  34   m_L1_cache.clear();
  35   m_L2_cache.clear();
  36   if (clear_invalid_ranges)
  37     m_invalid_ranges.Clear();
  38   m_L2_cache_line_byte_size = m_process.GetMemoryCacheLineSize();
  39 }
  40
  41 void MemoryCache::AddL1CacheData(lldb::addr_t addr, const void *src,
  42                                  size_t src_len) {
  43   AddL1CacheData(
  44       addr, DataBufferSP(new DataBufferHeap(DataBufferHeap(src, src_len))));
  45 }
  46
  47 void MemoryCache::AddL1CacheData(lldb::addr_t addr,
  48                                  const DataBufferSP &data_buffer_sp) {
  49   std::lock_guard<std::recursive_mutex> guard(m_mutex);
  50   m_L1_cache[addr] = data_buffer_sp;
  51 }
  52
  53 void MemoryCache::Flush(addr_t addr, size_t size) {
  54   if (size == 0)
  55     return;
  56
  57   std::lock_guard<std::recursive_mutex> guard(m_mutex);
  58
  59   // Erase any blocks from the L1 cache that intersect with the flush range
  60   if (!m_L1_cache.empty()) {
  61     AddrRange flush_range(addr, size);
  62     BlockMap::iterator pos = m_L1_cache.upper_bound(addr);
  63     if (pos != m_L1_cache.begin()) {
  64       --pos;
  65     }
  66     while (pos != m_L1_cache.end()) {
  67       AddrRange chunk_range(pos->first, pos->second->GetByteSize());
  68       if (!chunk_range.DoesIntersect(flush_range))
  69         break;
  70       pos = m_L1_cache.erase(pos);
  71     }
  72   }
  73
  74   if (!m_L2_cache.empty()) {
  75     const uint32_t cache_line_byte_size = m_L2_cache_line_byte_size;
  76     const addr_t end_addr = (addr + size - 1);
  77     const addr_t first_cache_line_addr = addr - (addr % cache_line_byte_size);
  78     const addr_t last_cache_line_addr =
  79         end_addr - (end_addr % cache_line_byte_size);
  80     // Watch for overflow where size will cause us to go off the end of the
  81     // 64 bit address space
  82     uint32_t num_cache_lines;
  83     if (last_cache_line_addr >= first_cache_line_addr)
  84       num_cache_lines = ((last_cache_line_addr - first_cache_line_addr) /
  85                          cache_line_byte_size) +
  86                         1;
  87     else
  88       num_cache_lines =
  89           (UINT64_MAX - first_cache_line_addr + 1) / cache_line_byte_size;
  90
  91     uint32_t cache_idx = 0;
  92     for (addr_t curr_addr = first_cache_line_addr; cache_idx < num_cache_lines;
  93          curr_addr += cache_line_byte_size, ++cache_idx) {
  94       BlockMap::iterator pos = m_L2_cache.find(curr_addr);
  95       if (pos != m_L2_cache.end())
  96         m_L2_cache.erase(pos);
  97     }
  98   }
  99 }
 100
 101 void MemoryCache::AddInvalidRange(lldb::addr_t base_addr,
 102                                   lldb::addr_t byte_size) {
 103   if (byte_size > 0) {
 104     std::lock_guard<std::recursive_mutex> guard(m_mutex);
 105     InvalidRanges::Entry range(base_addr, byte_size);
 106     m_invalid_ranges.Append(range);
 107     m_invalid_ranges.Sort();
 108   }
 109 }
 110
 111 bool MemoryCache::RemoveInvalidRange(lldb::addr_t base_addr,
 112                                      lldb::addr_t byte_size) {
 113   if (byte_size > 0) {
 114     std::lock_guard<std::recursive_mutex> guard(m_mutex);
 115     const uint32_t idx = m_invalid_ranges.FindEntryIndexThatContains(base_addr);
 116     if (idx != UINT32_MAX) {
 117       const InvalidRanges::Entry *entry = m_invalid_ranges.GetEntryAtIndex(idx);
 118       if (entry->GetRangeBase() == base_addr &&
 119           entry->GetByteSize() == byte_size)
 120         return m_invalid_ranges.RemoveEntryAtIndex(idx);
 121     }
 122   }
 123   return false;
 124 }
 125
 126 lldb::DataBufferSP MemoryCache::GetL2CacheLine(lldb::addr_t line_base_addr,
 127                                                Status &error) {
 128   // This function assumes that the address given is aligned correctly.
 129   assert((line_base_addr % m_L2_cache_line_byte_size) == 0);
 130
 131   std::lock_guard<std::recursive_mutex> guard(m_mutex);
 132   auto pos = m_L2_cache.find(line_base_addr);
 133   if (pos != m_L2_cache.end())
 134     return pos->second;
 135
 136   auto data_buffer_heap_sp =
 137       std::make_shared<DataBufferHeap>(m_L2_cache_line_byte_size, 0);
 138   size_t process_bytes_read = m_process.ReadMemoryFromInferior(
 139       line_base_addr, data_buffer_heap_sp->GetBytes(),
 140       data_buffer_heap_sp->GetByteSize(), error);
 141
 142   // If we failed a read, not much we can do.
 143   if (process_bytes_read == 0)
 144     return lldb::DataBufferSP();
 145
 146   // If we didn't get a complete read, we can still cache what we did get.
 147   if (process_bytes_read < m_L2_cache_line_byte_size)
 148     data_buffer_heap_sp->SetByteSize(process_bytes_read);
 149
 150   m_L2_cache[line_base_addr] = data_buffer_heap_sp;
 151   return data_buffer_heap_sp;
 152 }
 153
 154 size_t MemoryCache::Read(addr_t addr, void *dst, size_t dst_len,
 155                          Status &error) {
 156   if (!dst || dst_len == 0)
 157     return 0;
 158
 159   std::lock_guard<std::recursive_mutex> guard(m_mutex);
 160   // FIXME: We should do a more thorough check to make sure that we're not
 161   // overlapping with any invalid ranges (e.g. Read 0x100 - 0x200 but there's an
 162   // invalid range 0x180 - 0x280). `FindEntryThatContains` has an implementation
 163   // that takes a range, but it only checks to see if the argument is contained
 164   // by an existing invalid range. It cannot check if the argument contains
 165   // invalid ranges and cannot check for overlaps.
 166   if (m_invalid_ranges.FindEntryThatContains(addr)) {
 167     error.SetErrorStringWithFormat("memory read failed for 0x%" PRIx64, addr);
 168     return 0;
 169   }
 170
 171   // Check the L1 cache for a range that contains the entire memory read.
 172   // L1 cache contains chunks of memory that are not required to be the size of
 173   // an L2 cache line. We avoid trying to do partial reads from the L1 cache to
 174   // simplify the implementation.
 175   if (!m_L1_cache.empty()) {
 176     AddrRange read_range(addr, dst_len);
 177     BlockMap::iterator pos = m_L1_cache.upper_bound(addr);
 178     if (pos != m_L1_cache.begin()) {
 179       --pos;
 180     }
 181     AddrRange chunk_range(pos->first, pos->second->GetByteSize());
 182     if (chunk_range.Contains(read_range)) {
 183       memcpy(dst, pos->second->GetBytes() + (addr - chunk_range.GetRangeBase()),
 184              dst_len);
 185       return dst_len;
 186     }
 187   }
 188
 189   // If the size of the read is greater than the size of an L2 cache line, we'll
 190   // just read from the inferior. If that read is successful, we'll cache what
 191   // we read in the L1 cache for future use.
 192   if (dst_len > m_L2_cache_line_byte_size) {
 193     size_t bytes_read =
 194         m_process.ReadMemoryFromInferior(addr, dst, dst_len, error);
 195     if (bytes_read > 0)
 196       AddL1CacheData(addr, dst, bytes_read);
 197     return bytes_read;
 198   }
 199
 200   // If the size of the read fits inside one L2 cache line, we'll try reading
 201   // from the L2 cache. Note that if the range of memory we're reading sits
 202   // between two contiguous cache lines, we'll touch two cache lines instead of
 203   // just one.
 204
 205   // We're going to have all of our loads and reads be cache line aligned.
 206   addr_t cache_line_offset = addr % m_L2_cache_line_byte_size;
 207   addr_t cache_line_base_addr = addr - cache_line_offset;
 208   DataBufferSP first_cache_line = GetL2CacheLine(cache_line_base_addr, error);
 209   // If we get nothing, then the read to the inferior likely failed. Nothing to
 210   // do here.
 211   if (!first_cache_line)
 212     return 0;
 213
 214   // If the cache line was not filled out completely and the offset is greater
 215   // than what we have available, we can't do anything further here.
 216   if (cache_line_offset >= first_cache_line->GetByteSize())
 217     return 0;
 218
 219   uint8_t *dst_buf = (uint8_t *)dst;
 220   size_t bytes_left = dst_len;
 221   size_t read_size = first_cache_line->GetByteSize() - cache_line_offset;
 222   if (read_size > bytes_left)
 223     read_size = bytes_left;
 224
 225   memcpy(dst_buf + dst_len - bytes_left,
 226          first_cache_line->GetBytes() + cache_line_offset, read_size);
 227   bytes_left -= read_size;
 228
 229   // If the cache line was not filled out completely and we still have data to
 230   // read, we can't do anything further.
 231   if (first_cache_line->GetByteSize() < m_L2_cache_line_byte_size &&
 232       bytes_left > 0)
 233     return dst_len - bytes_left;
 234
 235   // We'll hit this scenario if our read straddles two cache lines.
 236   if (bytes_left > 0) {
 237     cache_line_base_addr += m_L2_cache_line_byte_size;
 238
 239     // FIXME: Until we are able to more thoroughly check for invalid ranges, we
 240     // will have to check the second line to see if it is in an invalid range as
 241     // well. See the check near the beginning of the function for more details.
 242     if (m_invalid_ranges.FindEntryThatContains(cache_line_base_addr)) {
 243       error.SetErrorStringWithFormat("memory read failed for 0x%" PRIx64,
 244                                      cache_line_base_addr);
 245       return dst_len - bytes_left;
 246     }
 247
 248     DataBufferSP second_cache_line =
 249         GetL2CacheLine(cache_line_base_addr, error);
 250     if (!second_cache_line)
 251       return dst_len - bytes_left;
 252
 253     read_size = bytes_left;
 254     if (read_size > second_cache_line->GetByteSize())
 255       read_size = second_cache_line->GetByteSize();
 256
 257     memcpy(dst_buf + dst_len - bytes_left, second_cache_line->GetBytes(),
 258            read_size);
 259     bytes_left -= read_size;
 260
 261     return dst_len - bytes_left;
 262   }
 263
 264   return dst_len;
 265 }
 266
 267 AllocatedBlock::AllocatedBlock(lldb::addr_t addr, uint32_t byte_size,
 268                                uint32_t permissions, uint32_t chunk_size)
 269     : m_range(addr, byte_size), m_permissions(permissions),
 270       m_chunk_size(chunk_size)
 271 {
 272   // The entire address range is free to start with.
 273   m_free_blocks.Append(m_range);
 274   assert(byte_size > chunk_size);
 275 }
 276
 277 AllocatedBlock::~AllocatedBlock() = default;
 278
 279 lldb::addr_t AllocatedBlock::ReserveBlock(uint32_t size) {
 280   // We must return something valid for zero bytes.
 281   if (size == 0)
 282     size = 1;
 283   Log *log = GetLog(LLDBLog::Process);
 284
 285   const size_t free_count = m_free_blocks.GetSize();
 286   for (size_t i=0; i<free_count; ++i)
 287   {
 288     auto &free_block = m_free_blocks.GetEntryRef(i);
 289     const lldb::addr_t range_size = free_block.GetByteSize();
 290     if (range_size >= size)
 291     {
 292       // We found a free block that is big enough for our data. Figure out how
 293       // many chunks we will need and calculate the resulting block size we
 294       // will reserve.
 295       addr_t addr = free_block.GetRangeBase();
 296       size_t num_chunks = CalculateChunksNeededForSize(size);
 297       lldb::addr_t block_size = num_chunks * m_chunk_size;
 298       lldb::addr_t bytes_left = range_size - block_size;
 299       if (bytes_left == 0)
 300       {
 301         // The newly allocated block will take all of the bytes in this
 302         // available block, so we can just add it to the allocated ranges and
 303         // remove the range from the free ranges.
 304         m_reserved_blocks.Insert(free_block, false);
 305         m_free_blocks.RemoveEntryAtIndex(i);
 306       }
 307       else
 308       {
 309         // Make the new allocated range and add it to the allocated ranges.
 310         Range<lldb::addr_t, uint32_t> reserved_block(free_block);
 311         reserved_block.SetByteSize(block_size);
 312         // Insert the reserved range and don't combine it with other blocks in
 313         // the reserved blocks list.
 314         m_reserved_blocks.Insert(reserved_block, false);
 315         // Adjust the free range in place since we won't change the sorted
 316         // ordering of the m_free_blocks list.
 317         free_block.SetRangeBase(reserved_block.GetRangeEnd());
 318         free_block.SetByteSize(bytes_left);
 319       }
 320       LLDB_LOGV(log, "({0}) (size = {1} ({1:x})) => {2:x}", this, size, addr);
 321       return addr;
 322     }
 323   }
 324
 325   LLDB_LOGV(log, "({0}) (size = {1} ({1:x})) => {2:x}", this, size,
 326             LLDB_INVALID_ADDRESS);
 327   return LLDB_INVALID_ADDRESS;
 328 }
 329
 330 bool AllocatedBlock::FreeBlock(addr_t addr) {
 331   bool success = false;
 332   auto entry_idx = m_reserved_blocks.FindEntryIndexThatContains(addr);
 333   if (entry_idx != UINT32_MAX)
 334   {
 335     m_free_blocks.Insert(m_reserved_blocks.GetEntryRef(entry_idx), true);
 336     m_reserved_blocks.RemoveEntryAtIndex(entry_idx);
 337     success = true;
 338   }
 339   Log *log = GetLog(LLDBLog::Process);
 340   LLDB_LOGV(log, "({0}) (addr = {1:x}) => {2}", this, addr, success);
 341   return success;
 342 }
 343
 344 AllocatedMemoryCache::AllocatedMemoryCache(Process &process)
 345     : m_process(process), m_mutex(), m_memory_map() {}
 346
 347 AllocatedMemoryCache::~AllocatedMemoryCache() = default;
 348
 349 void AllocatedMemoryCache::Clear(bool deallocate_memory) {
 350   std::lock_guard<std::recursive_mutex> guard(m_mutex);
 351   if (m_process.IsAlive() && deallocate_memory) {
 352     PermissionsToBlockMap::iterator pos, end = m_memory_map.end();
 353     for (pos = m_memory_map.begin(); pos != end; ++pos)
 354       m_process.DoDeallocateMemory(pos->second->GetBaseAddress());
 355   }
 356   m_memory_map.clear();
 357 }
 358
 359 AllocatedMemoryCache::AllocatedBlockSP
 360 AllocatedMemoryCache::AllocatePage(uint32_t byte_size, uint32_t permissions,
 361                                    uint32_t chunk_size, Status &error) {
 362   AllocatedBlockSP block_sp;
 363   const size_t page_size = 4096;
 364   const size_t num_pages = (byte_size + page_size - 1) / page_size;
 365   const size_t page_byte_size = num_pages * page_size;
 366
 367   addr_t addr = m_process.DoAllocateMemory(page_byte_size, permissions, error);
 368
 369   Log *log = GetLog(LLDBLog::Process);
 370   if (log) {
 371     LLDB_LOGF(log,
 372               "Process::DoAllocateMemory (byte_size = 0x%8.8" PRIx32
 373               ", permissions = %s) => 0x%16.16" PRIx64,
 374               (uint32_t)page_byte_size, GetPermissionsAsCString(permissions),
 375               (uint64_t)addr);
 376   }
 377
 378   if (addr != LLDB_INVALID_ADDRESS) {
 379     block_sp = std::make_shared<AllocatedBlock>(addr, page_byte_size,
 380                                                 permissions, chunk_size);
 381     m_memory_map.insert(std::make_pair(permissions, block_sp));
 382   }
 383   return block_sp;
 384 }
 385
 386 lldb::addr_t AllocatedMemoryCache::AllocateMemory(size_t byte_size,
 387                                                   uint32_t permissions,
 388                                                   Status &error) {
 389   std::lock_guard<std::recursive_mutex> guard(m_mutex);
 390
 391   addr_t addr = LLDB_INVALID_ADDRESS;
 392   std::pair<PermissionsToBlockMap::iterator, PermissionsToBlockMap::iterator>
 393       range = m_memory_map.equal_range(permissions);
 394
 395   for (PermissionsToBlockMap::iterator pos = range.first; pos != range.second;
 396        ++pos) {
 397     addr = (*pos).second->ReserveBlock(byte_size);
 398     if (addr != LLDB_INVALID_ADDRESS)
 399       break;
 400   }
 401
 402   if (addr == LLDB_INVALID_ADDRESS) {
 403     AllocatedBlockSP block_sp(AllocatePage(byte_size, permissions, 16, error));
 404
 405     if (block_sp)
 406       addr = block_sp->ReserveBlock(byte_size);
 407   }
 408   Log *log = GetLog(LLDBLog::Process);
 409   LLDB_LOGF(log,
 410             "AllocatedMemoryCache::AllocateMemory (byte_size = 0x%8.8" PRIx32
 411             ", permissions = %s) => 0x%16.16" PRIx64,
 412             (uint32_t)byte_size, GetPermissionsAsCString(permissions),
 413             (uint64_t)addr);
 414   return addr;
 415 }
 416
 417 bool AllocatedMemoryCache::DeallocateMemory(lldb::addr_t addr) {
 418   std::lock_guard<std::recursive_mutex> guard(m_mutex);
 419
 420   PermissionsToBlockMap::iterator pos, end = m_memory_map.end();
 421   bool success = false;
 422   for (pos = m_memory_map.begin(); pos != end; ++pos) {
 423     if (pos->second->Contains(addr)) {
 424       success = pos->second->FreeBlock(addr);
 425       break;
 426     }
 427   }
 428   Log *log = GetLog(LLDBLog::Process);
 429   LLDB_LOGF(log,
 430             "AllocatedMemoryCache::DeallocateMemory (addr = 0x%16.16" PRIx64
 431             ") => %i",
 432             (uint64_t)addr, success);
 433   return success;
 434 }