Demand read load bias for a map.
Add a static GetLoadBias method to the Elf object that only reads just
enough to get the load bias.
Add a method to MapInfo that gets the load bias. First attempt to get
it if the elf object already exists. If no elf object was created, use
the new static method to get the load bias.
In BacktraceMap, add a custom iterator so that when code dereferences
a map element, that's when the load bias will be retrieved if it hasn't
already been set.
Bug: 69871050
Test: New unit tests, verify tombstones have non-zero load bias values for
Test: libraries with a non-zero load bias.
Change-Id: I125f4abc827589957fce2f0df24b0f25d037d732
diff --git a/libunwindstack/MapInfo.cpp b/libunwindstack/MapInfo.cpp
index 8a7ad9c..51bce8e 100644
--- a/libunwindstack/MapInfo.cpp
+++ b/libunwindstack/MapInfo.cpp
@@ -121,4 +121,23 @@
return elf;
}
+uint64_t MapInfo::GetLoadBias(const std::shared_ptr<Memory>& process_memory) {
+ {
+ // Make sure no other thread is trying to add the elf to this map.
+ std::lock_guard<std::mutex> guard(mutex_);
+ if (elf != nullptr) {
+ if (elf->valid()) {
+ return elf->GetLoadBias();
+ } else {
+ return 0;
+ }
+ }
+ }
+
+ // Call lightweight static function that will only read enough of the
+ // elf data to get the load bias.
+ std::unique_ptr<Memory> memory(CreateMemory(process_memory));
+ return Elf::GetLoadBias(memory.get());
+}
+
} // namespace unwindstack