Add proper support for embedded elf files.
- Add a method to get the max size of an elf file by reading the
section header offset + size. This will properly map an elf
file embedded into an apk, instead of just mapping in what is done
by the dynamic linker. It does assume that the section headers are
at the end of the elf file.
- Add new tests for the above functionality.
- Update the unwind_symbols tool to take an address for finding a
function instead of dumping the entire symbol table.
Bug: 23762183
Test: Unit tests pass, unwind through the camera process and verify
Test: the GoogleCamera.apk shows some function names.
Change-Id: I00c021680fe1d43b60d652bf91bbf6667d9617be
diff --git a/libunwindstack/MapInfo.cpp b/libunwindstack/MapInfo.cpp
index d0e1216..3272215 100644
--- a/libunwindstack/MapInfo.cpp
+++ b/libunwindstack/MapInfo.cpp
@@ -27,6 +27,55 @@
namespace unwindstack {
+Memory* MapInfo::GetFileMemory() {
+ std::unique_ptr<MemoryFileAtOffset> memory(new MemoryFileAtOffset);
+ if (offset == 0) {
+ if (memory->Init(name, 0)) {
+ return memory.release();
+ }
+ return nullptr;
+ }
+
+ // There are two possibilities when the offset is non-zero.
+ // - There is an elf file embedded in a file.
+ // - The whole file is an elf file, and the offset needs to be saved.
+ //
+ // Map in just the part of the file for the map. If this is not
+ // a valid elf, then reinit as if the whole file is an elf file.
+ // If the offset is a valid elf, then determine the size of the map
+ // and reinit to that size. This is needed because the dynamic linker
+ // only maps in a portion of the original elf, and never the symbol
+ // file data.
+ uint64_t map_size = end - start;
+ if (!memory->Init(name, offset, map_size)) {
+ return nullptr;
+ }
+
+ bool valid;
+ uint64_t max_size;
+ Elf::GetInfo(memory.get(), &valid, &max_size);
+ if (!valid) {
+ // Init as if the whole file is an elf.
+ if (memory->Init(name, 0)) {
+ elf_offset = offset;
+ return memory.release();
+ }
+ return nullptr;
+ }
+
+ if (max_size > map_size) {
+ if (memory->Init(name, offset, max_size)) {
+ return memory.release();
+ }
+ // Try to reinit using the default map_size.
+ if (memory->Init(name, offset, map_size)) {
+ return memory.release();
+ }
+ return nullptr;
+ }
+ return memory.release();
+}
+
Memory* MapInfo::CreateMemory(pid_t pid) {
if (end <= start) {
return nullptr;
@@ -40,33 +89,13 @@
if (flags & MAPS_FLAGS_DEVICE_MAP) {
return nullptr;
}
-
- std::unique_ptr<MemoryFileAtOffset> file_memory(new MemoryFileAtOffset);
- uint64_t map_size;
- if (offset != 0) {
- // Only map in a piece of the file.
- map_size = end - start;
- } else {
- map_size = UINT64_MAX;
- }
- if (file_memory->Init(name, offset, map_size)) {
- // It's possible that a non-zero offset might not be pointing to
- // valid elf data. Check if this is a valid elf, and if not assume
- // that this was meant to incorporate the entire file.
- if (offset != 0 && !Elf::IsValidElf(file_memory.get())) {
- // Don't bother checking the validity that will happen on the elf init.
- if (file_memory->Init(name, 0)) {
- elf_offset = offset;
- return file_memory.release();
- }
- // Fall through if the init fails.
- } else {
- return file_memory.release();
- }
+ Memory* memory = GetFileMemory();
+ if (memory != nullptr) {
+ return memory;
}
}
- Memory* memory = nullptr;
+ Memory* memory;
if (pid == getpid()) {
memory = new MemoryLocal();
} else {