[Lldb-commits] [lldb] [llvm] [LLDB][Minidump] Add 64b support to LLDB's minidump file builder. (PR #95312)

[Greg Clayton via lldb-commits]

================
@@ -791,26 +807,101 @@ void MinidumpFileBuilder::AddLinuxFileStreams(
       size_t size = memory_buffer->getBufferSize();
       if (size == 0)
         continue;
-      AddDirectory(stream, size);
+      error = AddDirectory(stream, size);
+      if (error.Fail())
+        return error;
       m_data.AppendData(memory_buffer->getBufferStart(), size);
     }
   }
+
+  return error;
 }
 
-Status MinidumpFileBuilder::Dump(lldb::FileUP &core_file) const {
-  constexpr size_t header_size = sizeof(llvm::minidump::Header);
-  constexpr size_t directory_size = sizeof(llvm::minidump::Directory);
+Status MinidumpFileBuilder::AddMemoryList(SaveCoreStyle core_style) {
+  Status error;
+
+  // We first save the thread stacks to ensure they fit in the first UINT32_MAX
+  // bytes of the core file. Thread structures in minidump files can only use
+  // 32 bit memory descriptiors, so we emit them first to ensure the memory is
+  // in accessible with a 32 bit offset.
+  Process::CoreFileMemoryRanges ranges_32;
+  Process::CoreFileMemoryRanges ranges_64;
+  error = m_process_sp->CalculateCoreFileSaveRanges(
+      SaveCoreStyle::eSaveCoreStackOnly, ranges_32);
+  if (error.Fail())
+    return error;
 
+  uint64_t total_size =
+      ranges_32.size() * sizeof(llvm::minidump::MemoryDescriptor);
+  std::unordered_set<addr_t> stack_start_addresses;
+  for (const auto &core_range : ranges_32) {
+    stack_start_addresses.insert(core_range.range.start());
+    total_size += core_range.range.size();
+  }
+
+  if (total_size >= UINT32_MAX) {
+    error.SetErrorStringWithFormat("Unable to write minidump. Stack memory "
+                                   "exceeds 32b limit. (Num Stacks %zu)",
+                                   ranges_32.size());
+    return error;
+  }
+
+  Process::CoreFileMemoryRanges all_core_memory_ranges;
+  if (core_style != SaveCoreStyle::eSaveCoreStackOnly) {
+    error = m_process_sp->CalculateCoreFileSaveRanges(core_style,
+                                                      all_core_memory_ranges);
+    if (error.Fail())
+      return error;
+  }
+
+  // After saving the stacks, we start packing as much as we can into 32b.
+  // We apply a generous padding here so that the Directory, MemoryList and
+  // Memory64List sections all begin in 32b addressable space.
+  // Then anything overflow extends into 64b addressable space.
+  total_size +=
+      256 + (all_core_memory_ranges.size() - stack_start_addresses.size()) *
+                sizeof(llvm::minidump::MemoryDescriptor_64);
----------------
clayborg wrote:

this `total_size` will be wrong if `all_core_memory_ranges` is empty right? If we are saving stacks only, this will be:
```
256 + (0 - stack_start_addresses.size()) * sizeof(llvm::minidump::MemoryDescriptor_64);
```
And we will unsigned underflow but it won't matter because we won't use `total_size`. Best to put a:
```
if (!all_core_memory_ranges.empty()) {
```
around the `total_size` and for loop that iterates over all core ranges to avoid potential issues in the future.

https://github.com/llvm/llvm-project/pull/95312