Fix which maps to search for globals.
If multiple threads are unwinding at the same time, new maps that contain
the global variables for dex files and jit information are created. This
leads to threads creating more new maps that then get searched, then
more maps, then more searching until virtual address space exhaustion.
Fix this so that we only search maps that have a corresponding rw map that
could contain the global memory.
Small refactor to combine the code to search for global variables into
one class that both classes inherit from.
Modify unit tests for the new pattern checking.
Bug: 117761427
Test: Ran unit tests for libunwindstack/libbacktrace/simpleperf.
Test: Ran art 004-ThreadStress that used to fail.
Change-Id: I837ca6b9d0383100079de090bc7d019598e0cdfe
diff --git a/libunwindstack/DexFiles.cpp b/libunwindstack/DexFiles.cpp
index 17e2526..ac55fee 100644
--- a/libunwindstack/DexFiles.cpp
+++ b/libunwindstack/DexFiles.cpp
@@ -43,10 +43,10 @@
uint64_t dex_file;
};
-DexFiles::DexFiles(std::shared_ptr<Memory>& memory) : memory_(memory) {}
+DexFiles::DexFiles(std::shared_ptr<Memory>& memory) : Global(memory) {}
DexFiles::DexFiles(std::shared_ptr<Memory>& memory, std::vector<std::string>& search_libs)
- : memory_(memory), search_libs_(search_libs) {}
+ : Global(memory, search_libs) {}
DexFiles::~DexFiles() {
for (auto& entry : files_) {
@@ -117,6 +117,11 @@
return true;
}
+bool DexFiles::ReadVariableData(uint64_t ptr_offset) {
+ entry_addr_ = (this->*read_entry_ptr_func_)(ptr_offset);
+ return entry_addr_ != 0;
+}
+
void DexFiles::Init(Maps* maps) {
if (initialized_) {
return;
@@ -124,36 +129,7 @@
initialized_ = true;
entry_addr_ = 0;
- const std::string dex_debug_name("__dex_debug_descriptor");
- for (MapInfo* info : *maps) {
- if (!(info->flags & PROT_READ) || info->offset != 0) {
- continue;
- }
-
- if (!search_libs_.empty()) {
- bool found = false;
- const char* lib = basename(info->name.c_str());
- for (const std::string& name : search_libs_) {
- if (name == lib) {
- found = true;
- break;
- }
- }
- if (!found) {
- continue;
- }
- }
-
- Elf* elf = info->GetElf(memory_, true);
- uint64_t ptr;
- // Find first non-empty list (libart might be loaded multiple times).
- if (elf->GetGlobalVariable(dex_debug_name, &ptr) && ptr != 0) {
- entry_addr_ = (this->*read_entry_ptr_func_)(ptr + info->start);
- if (entry_addr_ != 0) {
- break;
- }
- }
- }
+ FindAndReadVariable(maps, "__dex_debug_descriptor");
}
DexFile* DexFiles::GetDexFile(uint64_t dex_file_offset, MapInfo* info) {