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/Log.h"
13 #include "lldb/Utility/RangeMap.h"
14 #include "lldb/Utility/State.h"
15 
16 #include <cinttypes>
17 #include <memory>
18 
19 using namespace lldb;
20 using namespace lldb_private;
21 
22 // MemoryCache constructor
23 MemoryCache::MemoryCache(Process &process)
24     : m_mutex(), m_L1_cache(), m_L2_cache(), m_invalid_ranges(),
25       m_process(process),
26       m_L2_cache_line_byte_size(process.GetMemoryCacheLineSize()) {}
27 
28 // Destructor
29 MemoryCache::~MemoryCache() {}
30 
31 void MemoryCache::Clear(bool clear_invalid_ranges) {
32   std::lock_guard<std::recursive_mutex> guard(m_mutex);
33   m_L1_cache.clear();
34   m_L2_cache.clear();
35   if (clear_invalid_ranges)
36     m_invalid_ranges.Clear();
37   m_L2_cache_line_byte_size = m_process.GetMemoryCacheLineSize();
38 }
39 
40 void MemoryCache::AddL1CacheData(lldb::addr_t addr, const void *src,
41                                  size_t src_len) {
42   AddL1CacheData(
43       addr, DataBufferSP(new DataBufferHeap(DataBufferHeap(src, src_len))));
44 }
45 
46 void MemoryCache::AddL1CacheData(lldb::addr_t addr,
47                                  const DataBufferSP &data_buffer_sp) {
48   std::lock_guard<std::recursive_mutex> guard(m_mutex);
49   m_L1_cache[addr] = data_buffer_sp;
50 }
51 
52 void MemoryCache::Flush(addr_t addr, size_t size) {
53   if (size == 0)
54     return;
55 
56   std::lock_guard<std::recursive_mutex> guard(m_mutex);
57 
58   // Erase any blocks from the L1 cache that intersect with the flush range
59   if (!m_L1_cache.empty()) {
60     AddrRange flush_range(addr, size);
61     BlockMap::iterator pos = m_L1_cache.upper_bound(addr);
62     if (pos != m_L1_cache.begin()) {
63       --pos;
64     }
65     while (pos != m_L1_cache.end()) {
66       AddrRange chunk_range(pos->first, pos->second->GetByteSize());
67       if (!chunk_range.DoesIntersect(flush_range))
68         break;
69       pos = m_L1_cache.erase(pos);
70     }
71   }
72 
73   if (!m_L2_cache.empty()) {
74     const uint32_t cache_line_byte_size = m_L2_cache_line_byte_size;
75     const addr_t end_addr = (addr + size - 1);
76     const addr_t first_cache_line_addr = addr - (addr % cache_line_byte_size);
77     const addr_t last_cache_line_addr =
78         end_addr - (end_addr % cache_line_byte_size);
79     // Watch for overflow where size will cause us to go off the end of the
80     // 64 bit address space
81     uint32_t num_cache_lines;
82     if (last_cache_line_addr >= first_cache_line_addr)
83       num_cache_lines = ((last_cache_line_addr - first_cache_line_addr) /
84                          cache_line_byte_size) +
85                         1;
86     else
87       num_cache_lines =
88           (UINT64_MAX - first_cache_line_addr + 1) / cache_line_byte_size;
89 
90     uint32_t cache_idx = 0;
91     for (addr_t curr_addr = first_cache_line_addr; cache_idx < num_cache_lines;
92          curr_addr += cache_line_byte_size, ++cache_idx) {
93       BlockMap::iterator pos = m_L2_cache.find(curr_addr);
94       if (pos != m_L2_cache.end())
95         m_L2_cache.erase(pos);
96     }
97   }
98 }
99 
100 void MemoryCache::AddInvalidRange(lldb::addr_t base_addr,
101                                   lldb::addr_t byte_size) {
102   if (byte_size > 0) {
103     std::lock_guard<std::recursive_mutex> guard(m_mutex);
104     InvalidRanges::Entry range(base_addr, byte_size);
105     m_invalid_ranges.Append(range);
106     m_invalid_ranges.Sort();
107   }
108 }
109 
110 bool MemoryCache::RemoveInvalidRange(lldb::addr_t base_addr,
111                                      lldb::addr_t byte_size) {
112   if (byte_size > 0) {
113     std::lock_guard<std::recursive_mutex> guard(m_mutex);
114     const uint32_t idx = m_invalid_ranges.FindEntryIndexThatContains(base_addr);
115     if (idx != UINT32_MAX) {
116       const InvalidRanges::Entry *entry = m_invalid_ranges.GetEntryAtIndex(idx);
117       if (entry->GetRangeBase() == base_addr &&
118           entry->GetByteSize() == byte_size)
119         return m_invalid_ranges.RemoveEntryAtIndex(idx);
120     }
121   }
122   return false;
123 }
124 
125 size_t MemoryCache::Read(addr_t addr, void *dst, size_t dst_len,
126                          Status &error) {
127   size_t bytes_left = dst_len;
128 
129   // Check the L1 cache for a range that contain the entire memory read. If we
130   // find a range in the L1 cache that does, we use it. Else we fall back to
131   // reading memory in m_L2_cache_line_byte_size byte sized chunks. The L1
132   // cache contains chunks of memory that are not required to be
133   // m_L2_cache_line_byte_size bytes in size, so we don't try anything tricky
134   // when reading from them (no partial reads from the L1 cache).
135 
136   std::lock_guard<std::recursive_mutex> guard(m_mutex);
137   if (!m_L1_cache.empty()) {
138     AddrRange read_range(addr, dst_len);
139     BlockMap::iterator pos = m_L1_cache.upper_bound(addr);
140     if (pos != m_L1_cache.begin()) {
141       --pos;
142     }
143     AddrRange chunk_range(pos->first, pos->second->GetByteSize());
144     if (chunk_range.Contains(read_range)) {
145       memcpy(dst, pos->second->GetBytes() + (addr - chunk_range.GetRangeBase()),
146              dst_len);
147       return dst_len;
148     }
149   }
150 
151   // If this memory read request is larger than the cache line size, then we
152   // (1) try to read as much of it at once as possible, and (2) don't add the
153   // data to the memory cache.  We don't want to split a big read up into more
154   // separate reads than necessary, and with a large memory read request, it is
155   // unlikely that the caller function will ask for the next
156   // 4 bytes after the large memory read - so there's little benefit to saving
157   // it in the cache.
158   if (dst && dst_len > m_L2_cache_line_byte_size) {
159     size_t bytes_read =
160         m_process.ReadMemoryFromInferior(addr, dst, dst_len, error);
161     // Add this non block sized range to the L1 cache if we actually read
162     // anything
163     if (bytes_read > 0)
164       AddL1CacheData(addr, dst, bytes_read);
165     return bytes_read;
166   }
167 
168   if (dst && bytes_left > 0) {
169     const uint32_t cache_line_byte_size = m_L2_cache_line_byte_size;
170     uint8_t *dst_buf = (uint8_t *)dst;
171     addr_t curr_addr = addr - (addr % cache_line_byte_size);
172     addr_t cache_offset = addr - curr_addr;
173 
174     while (bytes_left > 0) {
175       if (m_invalid_ranges.FindEntryThatContains(curr_addr)) {
176         error.SetErrorStringWithFormat("memory read failed for 0x%" PRIx64,
177                                        curr_addr);
178         return dst_len - bytes_left;
179       }
180 
181       BlockMap::const_iterator pos = m_L2_cache.find(curr_addr);
182       BlockMap::const_iterator end = m_L2_cache.end();
183 
184       if (pos != end) {
185         size_t curr_read_size = cache_line_byte_size - cache_offset;
186         if (curr_read_size > bytes_left)
187           curr_read_size = bytes_left;
188 
189         memcpy(dst_buf + dst_len - bytes_left,
190                pos->second->GetBytes() + cache_offset, curr_read_size);
191 
192         bytes_left -= curr_read_size;
193         curr_addr += curr_read_size + cache_offset;
194         cache_offset = 0;
195 
196         if (bytes_left > 0) {
197           // Get sequential cache page hits
198           for (++pos; (pos != end) && (bytes_left > 0); ++pos) {
199             assert((curr_addr % cache_line_byte_size) == 0);
200 
201             if (pos->first != curr_addr)
202               break;
203 
204             curr_read_size = pos->second->GetByteSize();
205             if (curr_read_size > bytes_left)
206               curr_read_size = bytes_left;
207 
208             memcpy(dst_buf + dst_len - bytes_left, pos->second->GetBytes(),
209                    curr_read_size);
210 
211             bytes_left -= curr_read_size;
212             curr_addr += curr_read_size;
213 
214             // We have a cache page that succeeded to read some bytes but not
215             // an entire page. If this happens, we must cap off how much data
216             // we are able to read...
217             if (pos->second->GetByteSize() != cache_line_byte_size)
218               return dst_len - bytes_left;
219           }
220         }
221       }
222 
223       // We need to read from the process
224 
225       if (bytes_left > 0) {
226         assert((curr_addr % cache_line_byte_size) == 0);
227         std::unique_ptr<DataBufferHeap> data_buffer_heap_up(
228             new DataBufferHeap(cache_line_byte_size, 0));
229         size_t process_bytes_read = m_process.ReadMemoryFromInferior(
230             curr_addr, data_buffer_heap_up->GetBytes(),
231             data_buffer_heap_up->GetByteSize(), error);
232         if (process_bytes_read == 0)
233           return dst_len - bytes_left;
234 
235         if (process_bytes_read != cache_line_byte_size) {
236           if (process_bytes_read < data_buffer_heap_up->GetByteSize()) {
237             dst_len -= data_buffer_heap_up->GetByteSize() - process_bytes_read;
238             bytes_left = process_bytes_read;
239           }
240           data_buffer_heap_up->SetByteSize(process_bytes_read);
241         }
242         m_L2_cache[curr_addr] = DataBufferSP(data_buffer_heap_up.release());
243         // We have read data and put it into the cache, continue through the
244         // loop again to get the data out of the cache...
245       }
246     }
247   }
248 
249   return dst_len - bytes_left;
250 }
251 
252 AllocatedBlock::AllocatedBlock(lldb::addr_t addr, uint32_t byte_size,
253                                uint32_t permissions, uint32_t chunk_size)
254     : m_range(addr, byte_size), m_permissions(permissions),
255       m_chunk_size(chunk_size)
256 {
257   // The entire address range is free to start with.
258   m_free_blocks.Append(m_range);
259   assert(byte_size > chunk_size);
260 }
261 
262 AllocatedBlock::~AllocatedBlock() {}
263 
264 lldb::addr_t AllocatedBlock::ReserveBlock(uint32_t size) {
265   // We must return something valid for zero bytes.
266   if (size == 0)
267     size = 1;
268   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS));
269 
270   const size_t free_count = m_free_blocks.GetSize();
271   for (size_t i=0; i<free_count; ++i)
272   {
273     auto &free_block = m_free_blocks.GetEntryRef(i);
274     const lldb::addr_t range_size = free_block.GetByteSize();
275     if (range_size >= size)
276     {
277       // We found a free block that is big enough for our data. Figure out how
278       // many chunks we will need and calculate the resulting block size we
279       // will reserve.
280       addr_t addr = free_block.GetRangeBase();
281       size_t num_chunks = CalculateChunksNeededForSize(size);
282       lldb::addr_t block_size = num_chunks * m_chunk_size;
283       lldb::addr_t bytes_left = range_size - block_size;
284       if (bytes_left == 0)
285       {
286         // The newly allocated block will take all of the bytes in this
287         // available block, so we can just add it to the allocated ranges and
288         // remove the range from the free ranges.
289         m_reserved_blocks.Insert(free_block, false);
290         m_free_blocks.RemoveEntryAtIndex(i);
291       }
292       else
293       {
294         // Make the new allocated range and add it to the allocated ranges.
295         Range<lldb::addr_t, uint32_t> reserved_block(free_block);
296         reserved_block.SetByteSize(block_size);
297         // Insert the reserved range and don't combine it with other blocks in
298         // the reserved blocks list.
299         m_reserved_blocks.Insert(reserved_block, false);
300         // Adjust the free range in place since we won't change the sorted
301         // ordering of the m_free_blocks list.
302         free_block.SetRangeBase(reserved_block.GetRangeEnd());
303         free_block.SetByteSize(bytes_left);
304       }
305       LLDB_LOGV(log, "({0}) (size = {1} ({1:x})) => {2:x}", this, size, addr);
306       return addr;
307     }
308   }
309 
310   LLDB_LOGV(log, "({0}) (size = {1} ({1:x})) => {2:x}", this, size,
311             LLDB_INVALID_ADDRESS);
312   return LLDB_INVALID_ADDRESS;
313 }
314 
315 bool AllocatedBlock::FreeBlock(addr_t addr) {
316   bool success = false;
317   auto entry_idx = m_reserved_blocks.FindEntryIndexThatContains(addr);
318   if (entry_idx != UINT32_MAX)
319   {
320     m_free_blocks.Insert(m_reserved_blocks.GetEntryRef(entry_idx), true);
321     m_reserved_blocks.RemoveEntryAtIndex(entry_idx);
322     success = true;
323   }
324   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS));
325   LLDB_LOGV(log, "({0}) (addr = {1:x}) => {2}", this, addr, success);
326   return success;
327 }
328 
329 AllocatedMemoryCache::AllocatedMemoryCache(Process &process)
330     : m_process(process), m_mutex(), m_memory_map() {}
331 
332 AllocatedMemoryCache::~AllocatedMemoryCache() {}
333 
334 void AllocatedMemoryCache::Clear() {
335   std::lock_guard<std::recursive_mutex> guard(m_mutex);
336   if (m_process.IsAlive()) {
337     PermissionsToBlockMap::iterator pos, end = m_memory_map.end();
338     for (pos = m_memory_map.begin(); pos != end; ++pos)
339       m_process.DoDeallocateMemory(pos->second->GetBaseAddress());
340   }
341   m_memory_map.clear();
342 }
343 
344 AllocatedMemoryCache::AllocatedBlockSP
345 AllocatedMemoryCache::AllocatePage(uint32_t byte_size, uint32_t permissions,
346                                    uint32_t chunk_size, Status &error) {
347   AllocatedBlockSP block_sp;
348   const size_t page_size = 4096;
349   const size_t num_pages = (byte_size + page_size - 1) / page_size;
350   const size_t page_byte_size = num_pages * page_size;
351 
352   addr_t addr = m_process.DoAllocateMemory(page_byte_size, permissions, error);
353 
354   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS));
355   if (log) {
356     LLDB_LOGF(log,
357               "Process::DoAllocateMemory (byte_size = 0x%8.8" PRIx32
358               ", permissions = %s) => 0x%16.16" PRIx64,
359               (uint32_t)page_byte_size, GetPermissionsAsCString(permissions),
360               (uint64_t)addr);
361   }
362 
363   if (addr != LLDB_INVALID_ADDRESS) {
364     block_sp = std::make_shared<AllocatedBlock>(addr, page_byte_size,
365                                                 permissions, chunk_size);
366     m_memory_map.insert(std::make_pair(permissions, block_sp));
367   }
368   return block_sp;
369 }
370 
371 lldb::addr_t AllocatedMemoryCache::AllocateMemory(size_t byte_size,
372                                                   uint32_t permissions,
373                                                   Status &error) {
374   std::lock_guard<std::recursive_mutex> guard(m_mutex);
375 
376   addr_t addr = LLDB_INVALID_ADDRESS;
377   std::pair<PermissionsToBlockMap::iterator, PermissionsToBlockMap::iterator>
378       range = m_memory_map.equal_range(permissions);
379 
380   for (PermissionsToBlockMap::iterator pos = range.first; pos != range.second;
381        ++pos) {
382     addr = (*pos).second->ReserveBlock(byte_size);
383     if (addr != LLDB_INVALID_ADDRESS)
384       break;
385   }
386 
387   if (addr == LLDB_INVALID_ADDRESS) {
388     AllocatedBlockSP block_sp(AllocatePage(byte_size, permissions, 16, error));
389 
390     if (block_sp)
391       addr = block_sp->ReserveBlock(byte_size);
392   }
393   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS));
394   LLDB_LOGF(log,
395             "AllocatedMemoryCache::AllocateMemory (byte_size = 0x%8.8" PRIx32
396             ", permissions = %s) => 0x%16.16" PRIx64,
397             (uint32_t)byte_size, GetPermissionsAsCString(permissions),
398             (uint64_t)addr);
399   return addr;
400 }
401 
402 bool AllocatedMemoryCache::DeallocateMemory(lldb::addr_t addr) {
403   std::lock_guard<std::recursive_mutex> guard(m_mutex);
404 
405   PermissionsToBlockMap::iterator pos, end = m_memory_map.end();
406   bool success = false;
407   for (pos = m_memory_map.begin(); pos != end; ++pos) {
408     if (pos->second->Contains(addr)) {
409       success = pos->second->FreeBlock(addr);
410       break;
411     }
412   }
413   Log *log(GetLogIfAllCategoriesSet(LIBLLDB_LOG_PROCESS));
414   LLDB_LOGF(log,
415             "AllocatedMemoryCache::DeallocateMemory (addr = 0x%16.16" PRIx64
416             ") => %i",
417             (uint64_t)addr, success);
418   return success;
419 }
420