return false;
}
+lldb::DataBufferSP MemoryCache::GetL2CacheLine(lldb::addr_t line_base_addr,
+ Status &error) {
+ // This function assumes that the address given is aligned correctly.
+ assert((line_base_addr % m_L2_cache_line_byte_size) == 0);
+
+ std::lock_guard<std::recursive_mutex> guard(m_mutex);
+ auto pos = m_L2_cache.find(line_base_addr);
+ if (pos != m_L2_cache.end())
+ return pos->second;
+
+ auto data_buffer_heap_sp =
+ std::make_shared<DataBufferHeap>(m_L2_cache_line_byte_size, 0);
+ size_t process_bytes_read = m_process.ReadMemoryFromInferior(
+ line_base_addr, data_buffer_heap_sp->GetBytes(),
+ data_buffer_heap_sp->GetByteSize(), error);
+
+ // If we failed a read, not much we can do.
+ if (process_bytes_read == 0)
+ return lldb::DataBufferSP();
+
+ // If we didn't get a complete read, we can still cache what we did get.
+ if (process_bytes_read < m_L2_cache_line_byte_size)
+ data_buffer_heap_sp->SetByteSize(process_bytes_read);
+
+ m_L2_cache[line_base_addr] = data_buffer_heap_sp;
+ return data_buffer_heap_sp;
+}
+
size_t MemoryCache::Read(addr_t addr, void *dst, size_t dst_len,
Status &error) {
- size_t bytes_left = dst_len;
-
- // Check the L1 cache for a range that contain the entire memory read. If we
- // find a range in the L1 cache that does, we use it. Else we fall back to
- // reading memory in m_L2_cache_line_byte_size byte sized chunks. The L1
- // cache contains chunks of memory that are not required to be
- // m_L2_cache_line_byte_size bytes in size, so we don't try anything tricky
- // when reading from them (no partial reads from the L1 cache).
+ if (!dst || dst_len == 0)
+ return 0;
std::lock_guard<std::recursive_mutex> guard(m_mutex);
+ // FIXME: We should do a more thorough check to make sure that we're not
+ // overlapping with any invalid ranges (e.g. Read 0x100 - 0x200 but there's an
+ // invalid range 0x180 - 0x280). `FindEntryThatContains` has an implementation
+ // that takes a range, but it only checks to see if the argument is contained
+ // by an existing invalid range. It cannot check if the argument contains
+ // invalid ranges and cannot check for overlaps.
+ if (m_invalid_ranges.FindEntryThatContains(addr)) {
+ error.SetErrorStringWithFormat("memory read failed for 0x%" PRIx64, addr);
+ return 0;
+ }
+
+ // Check the L1 cache for a range that contains the entire memory read.
+ // L1 cache contains chunks of memory that are not required to be the size of
+ // an L2 cache line. We avoid trying to do partial reads from the L1 cache to
+ // simplify the implementation.
if (!m_L1_cache.empty()) {
AddrRange read_range(addr, dst_len);
BlockMap::iterator pos = m_L1_cache.upper_bound(addr);
}
}
- // If this memory read request is larger than the cache line size, then we
- // (1) try to read as much of it at once as possible, and (2) don't add the
- // data to the memory cache. We don't want to split a big read up into more
- // separate reads than necessary, and with a large memory read request, it is
- // unlikely that the caller function will ask for the next
- // 4 bytes after the large memory read - so there's little benefit to saving
- // it in the cache.
- if (dst && dst_len > m_L2_cache_line_byte_size) {
+ // If the size of the read is greater than the size of an L2 cache line, we'll
+ // just read from the inferior. If that read is successful, we'll cache what
+ // we read in the L1 cache for future use.
+ if (dst_len > m_L2_cache_line_byte_size) {
size_t bytes_read =
m_process.ReadMemoryFromInferior(addr, dst, dst_len, error);
- // Add this non block sized range to the L1 cache if we actually read
- // anything
if (bytes_read > 0)
AddL1CacheData(addr, dst, bytes_read);
return bytes_read;
}
- if (dst && bytes_left > 0) {
- const uint32_t cache_line_byte_size = m_L2_cache_line_byte_size;
- uint8_t *dst_buf = (uint8_t *)dst;
- addr_t curr_addr = addr - (addr % cache_line_byte_size);
- addr_t cache_offset = addr - curr_addr;
-
- while (bytes_left > 0) {
- if (m_invalid_ranges.FindEntryThatContains(curr_addr)) {
- error.SetErrorStringWithFormat("memory read failed for 0x%" PRIx64,
- curr_addr);
- return dst_len - bytes_left;
- }
-
- BlockMap::const_iterator pos = m_L2_cache.find(curr_addr);
- BlockMap::const_iterator end = m_L2_cache.end();
-
- if (pos != end) {
- size_t curr_read_size = cache_line_byte_size - cache_offset;
- if (curr_read_size > bytes_left)
- curr_read_size = bytes_left;
-
- memcpy(dst_buf + dst_len - bytes_left,
- pos->second->GetBytes() + cache_offset, curr_read_size);
-
- bytes_left -= curr_read_size;
- curr_addr += curr_read_size + cache_offset;
- cache_offset = 0;
-
- if (bytes_left > 0) {
- // Get sequential cache page hits
- for (++pos; (pos != end) && (bytes_left > 0); ++pos) {
- assert((curr_addr % cache_line_byte_size) == 0);
-
- if (pos->first != curr_addr)
- break;
-
- curr_read_size = pos->second->GetByteSize();
- if (curr_read_size > bytes_left)
- curr_read_size = bytes_left;
+ // If the size of the read fits inside one L2 cache line, we'll try reading
+ // from the L2 cache. Note that if the range of memory we're reading sits
+ // between two contiguous cache lines, we'll touch two cache lines instead of
+ // just one.
+
+ // We're going to have all of our loads and reads be cache line aligned.
+ addr_t cache_line_offset = addr % m_L2_cache_line_byte_size;
+ addr_t cache_line_base_addr = addr - cache_line_offset;
+ DataBufferSP first_cache_line = GetL2CacheLine(cache_line_base_addr, error);
+ // If we get nothing, then the read to the inferior likely failed. Nothing to
+ // do here.
+ if (!first_cache_line)
+ return 0;
+
+ // If the cache line was not filled out completely and the offset is greater
+ // than what we have available, we can't do anything further here.
+ if (cache_line_offset >= first_cache_line->GetByteSize())
+ return 0;
+
+ uint8_t *dst_buf = (uint8_t *)dst;
+ size_t bytes_left = dst_len;
+ size_t read_size = first_cache_line->GetByteSize() - cache_line_offset;
+ if (read_size > bytes_left)
+ read_size = bytes_left;
+
+ memcpy(dst_buf + dst_len - bytes_left,
+ first_cache_line->GetBytes() + cache_line_offset, read_size);
+ bytes_left -= read_size;
+
+ // If the cache line was not filled out completely and we still have data to
+ // read, we can't do anything further.
+ if (first_cache_line->GetByteSize() < m_L2_cache_line_byte_size &&
+ bytes_left > 0)
+ return dst_len - bytes_left;
+
+ // We'll hit this scenario if our read straddles two cache lines.
+ if (bytes_left > 0) {
+ cache_line_base_addr += m_L2_cache_line_byte_size;
+
+ // FIXME: Until we are able to more thoroughly check for invalid ranges, we
+ // will have to check the second line to see if it is in an invalid range as
+ // well. See the check near the beginning of the function for more details.
+ if (m_invalid_ranges.FindEntryThatContains(cache_line_base_addr)) {
+ error.SetErrorStringWithFormat("memory read failed for 0x%" PRIx64,
+ cache_line_base_addr);
+ return dst_len - bytes_left;
+ }
- memcpy(dst_buf + dst_len - bytes_left, pos->second->GetBytes(),
- curr_read_size);
+ DataBufferSP second_cache_line =
+ GetL2CacheLine(cache_line_base_addr, error);
+ if (!second_cache_line)
+ return dst_len - bytes_left;
- bytes_left -= curr_read_size;
- curr_addr += curr_read_size;
+ read_size = bytes_left;
+ if (read_size > second_cache_line->GetByteSize())
+ read_size = second_cache_line->GetByteSize();
- // We have a cache page that succeeded to read some bytes but not
- // an entire page. If this happens, we must cap off how much data
- // we are able to read...
- if (pos->second->GetByteSize() != cache_line_byte_size)
- return dst_len - bytes_left;
- }
- }
- }
+ memcpy(dst_buf + dst_len - bytes_left, second_cache_line->GetBytes(),
+ read_size);
+ bytes_left -= read_size;
- // We need to read from the process
-
- if (bytes_left > 0) {
- assert((curr_addr % cache_line_byte_size) == 0);
- std::unique_ptr<DataBufferHeap> data_buffer_heap_up(
- new DataBufferHeap(cache_line_byte_size, 0));
- size_t process_bytes_read = m_process.ReadMemoryFromInferior(
- curr_addr, data_buffer_heap_up->GetBytes(),
- data_buffer_heap_up->GetByteSize(), error);
- if (process_bytes_read == 0)
- return dst_len - bytes_left;
-
- if (process_bytes_read != cache_line_byte_size) {
- data_buffer_heap_up->SetByteSize(process_bytes_read);
- if (process_bytes_read < data_buffer_heap_up->GetByteSize()) {
- dst_len -= data_buffer_heap_up->GetByteSize() - process_bytes_read;
- bytes_left = process_bytes_read;
- }
- }
- m_L2_cache[curr_addr] = DataBufferSP(data_buffer_heap_up.release());
- // We have read data and put it into the cache, continue through the
- // loop again to get the data out of the cache...
- }
- }
+ return dst_len - bytes_left;
}
- return dst_len - bytes_left;
+ return dst_len;
}
AllocatedBlock::AllocatedBlock(lldb::addr_t addr, uint32_t byte_size,
--- /dev/null
+//===-- MemoryTest.cpp ----------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "lldb/Target/Memory.h"
+#include "Plugins/Platform/MacOSX/PlatformMacOSX.h"
+#include "Plugins/Platform/MacOSX/PlatformRemoteMacOSX.h"
+#include "lldb/Core/Debugger.h"
+#include "lldb/Host/FileSystem.h"
+#include "lldb/Host/HostInfo.h"
+#include "lldb/Target/Process.h"
+#include "lldb/Target/Target.h"
+#include "lldb/Utility/ArchSpec.h"
+#include "lldb/Utility/DataBufferHeap.h"
+#include "gtest/gtest.h"
+
+using namespace lldb_private;
+using namespace lldb_private::repro;
+using namespace lldb;
+
+namespace {
+class MemoryTest : public ::testing::Test {
+public:
+ void SetUp() override {
+ FileSystem::Initialize();
+ HostInfo::Initialize();
+ PlatformMacOSX::Initialize();
+ }
+ void TearDown() override {
+ PlatformMacOSX::Terminate();
+ HostInfo::Terminate();
+ FileSystem::Terminate();
+ }
+};
+
+class DummyProcess : public Process {
+public:
+ DummyProcess(lldb::TargetSP target_sp, lldb::ListenerSP listener_sp)
+ : Process(target_sp, listener_sp), m_bytes_left(0) {}
+
+ // Required overrides
+ bool CanDebug(lldb::TargetSP target, bool plugin_specified_by_name) override {
+ return true;
+ }
+ Status DoDestroy() override { return {}; }
+ void RefreshStateAfterStop() override {}
+ size_t DoReadMemory(lldb::addr_t vm_addr, void *buf, size_t size,
+ Status &error) override {
+ if (m_bytes_left == 0)
+ return 0;
+
+ size_t num_bytes_to_write = size;
+ if (m_bytes_left < size) {
+ num_bytes_to_write = m_bytes_left;
+ m_bytes_left = 0;
+ } else {
+ m_bytes_left -= size;
+ }
+
+ memset(buf, 'B', num_bytes_to_write);
+ return num_bytes_to_write;
+ }
+ bool DoUpdateThreadList(ThreadList &old_thread_list,
+ ThreadList &new_thread_list) override {
+ return false;
+ }
+ llvm::StringRef GetPluginName() override { return "Dummy"; }
+
+ // Test-specific additions
+ size_t m_bytes_left;
+ MemoryCache &GetMemoryCache() { return m_memory_cache; }
+ void SetMaxReadSize(size_t size) { m_bytes_left = size; }
+};
+} // namespace
+
+TargetSP CreateTarget(DebuggerSP &debugger_sp, ArchSpec &arch) {
+ PlatformSP platform_sp;
+ TargetSP target_sp;
+ debugger_sp->GetTargetList().CreateTarget(
+ *debugger_sp, "", arch, eLoadDependentsNo, platform_sp, target_sp);
+ return target_sp;
+}
+
+TEST_F(MemoryTest, TesetMemoryCacheRead) {
+ ArchSpec arch("x86_64-apple-macosx-");
+
+ Platform::SetHostPlatform(PlatformRemoteMacOSX::CreateInstance(true, &arch));
+
+ DebuggerSP debugger_sp = Debugger::CreateInstance();
+ ASSERT_TRUE(debugger_sp);
+
+ TargetSP target_sp = CreateTarget(debugger_sp, arch);
+ ASSERT_TRUE(target_sp);
+
+ ListenerSP listener_sp(Listener::MakeListener("dummy"));
+ ProcessSP process_sp = std::make_shared<DummyProcess>(target_sp, listener_sp);
+ ASSERT_TRUE(process_sp);
+
+ DummyProcess *process = static_cast<DummyProcess *>(process_sp.get());
+ MemoryCache &mem_cache = process->GetMemoryCache();
+ const uint64_t l2_cache_size = process->GetMemoryCacheLineSize();
+ Status error;
+ auto data_sp = std::make_shared<DataBufferHeap>(l2_cache_size * 2, '\0');
+ size_t bytes_read = 0;
+
+ // Cache empty, memory read fails, size > l2 cache size
+ process->SetMaxReadSize(0);
+ bytes_read = mem_cache.Read(0x1000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == 0);
+
+ // Cache empty, memory read fails, size <= l2 cache size
+ data_sp->SetByteSize(l2_cache_size);
+ bytes_read = mem_cache.Read(0x1000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == 0);
+
+ // Cache empty, memory read succeeds, size > l2 cache size
+ process->SetMaxReadSize(l2_cache_size * 4);
+ data_sp->SetByteSize(l2_cache_size * 2);
+ bytes_read = mem_cache.Read(0x1000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == data_sp->GetByteSize());
+ ASSERT_TRUE(process->m_bytes_left == l2_cache_size * 2);
+
+ // Reading data previously cached (not in L2 cache).
+ data_sp->SetByteSize(l2_cache_size + 1);
+ bytes_read = mem_cache.Read(0x1000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == data_sp->GetByteSize());
+ ASSERT_TRUE(process->m_bytes_left == l2_cache_size * 2); // Verify we didn't
+ // read from the
+ // inferior.
+
+ // Read from a different address, but make the size == l2 cache size.
+ // This should fill in a the L2 cache.
+ data_sp->SetByteSize(l2_cache_size);
+ bytes_read = mem_cache.Read(0x2000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == data_sp->GetByteSize());
+ ASSERT_TRUE(process->m_bytes_left == l2_cache_size);
+
+ // Read from that L2 cache entry but read less than size of the cache line.
+ // Additionally, read from an offset.
+ data_sp->SetByteSize(l2_cache_size - 5);
+ bytes_read = mem_cache.Read(0x2001, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == data_sp->GetByteSize());
+ ASSERT_TRUE(process->m_bytes_left == l2_cache_size); // Verify we didn't read
+ // from the inferior.
+
+ // What happens if we try to populate an L2 cache line but the read gives less
+ // than the size of a cache line?
+ process->SetMaxReadSize(l2_cache_size - 10);
+ data_sp->SetByteSize(l2_cache_size - 5);
+ bytes_read = mem_cache.Read(0x3000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == l2_cache_size - 10);
+ ASSERT_TRUE(process->m_bytes_left == 0);
+
+ // What happens if we have a partial L2 cache line filled in and we try to
+ // read the part that isn't filled in?
+ data_sp->SetByteSize(10);
+ bytes_read = mem_cache.Read(0x3000 + l2_cache_size - 10, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == 0); // The last 10 bytes from this line are
+ // missing and we should be reading nothing
+ // here.
+
+ // What happens when we try to straddle 2 cache lines?
+ process->SetMaxReadSize(l2_cache_size * 2);
+ data_sp->SetByteSize(l2_cache_size);
+ bytes_read = mem_cache.Read(0x4001, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == l2_cache_size);
+ ASSERT_TRUE(process->m_bytes_left == 0);
+
+ // What happens when we try to straddle 2 cache lines where the first one is
+ // only partially filled?
+ process->SetMaxReadSize(l2_cache_size - 1);
+ data_sp->SetByteSize(l2_cache_size);
+ bytes_read = mem_cache.Read(0x5005, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == l2_cache_size - 6); // Ignoring the first 5 bytes,
+ // missing the last byte
+ ASSERT_TRUE(process->m_bytes_left == 0);
+
+ // What happens if we add an invalid range and try to do a read larger than
+ // a cache line?
+ mem_cache.AddInvalidRange(0x6000, l2_cache_size * 2);
+ process->SetMaxReadSize(l2_cache_size * 2);
+ data_sp->SetByteSize(l2_cache_size * 2);
+ bytes_read = mem_cache.Read(0x6000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == 0);
+ ASSERT_TRUE(process->m_bytes_left == l2_cache_size * 2);
+
+ // What happens if we add an invalid range and try to do a read lt/eq a
+ // cache line?
+ mem_cache.AddInvalidRange(0x7000, l2_cache_size);
+ process->SetMaxReadSize(l2_cache_size);
+ data_sp->SetByteSize(l2_cache_size);
+ bytes_read = mem_cache.Read(0x7000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == 0);
+ ASSERT_TRUE(process->m_bytes_left == l2_cache_size);
+
+ // What happens if we remove the invalid range and read again?
+ mem_cache.RemoveInvalidRange(0x7000, l2_cache_size);
+ bytes_read = mem_cache.Read(0x7000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == l2_cache_size);
+ ASSERT_TRUE(process->m_bytes_left == 0);
+
+ // What happens if we flush and read again?
+ process->SetMaxReadSize(l2_cache_size * 2);
+ mem_cache.Flush(0x7000, l2_cache_size);
+ bytes_read = mem_cache.Read(0x7000, data_sp->GetBytes(),
+ data_sp->GetByteSize(), error);
+ ASSERT_TRUE(bytes_read == l2_cache_size);
+ ASSERT_TRUE(process->m_bytes_left == l2_cache_size); // Verify that we re-read
+ // instead of using an
+ // old cache
+}