Add extra frame when dex_pc is non-zero.
Use the art dex file library to read the dex data.
Add unit tests for the UnwindDexFile code.
Bug: 72070049
Test: All unit tests continue to pass.
Test: Dumped the backtrace of the 137-cfi test while running in interpreter
Test: mode and verified that the stack trace is correct. Did this on host
Test: and for arm/arm64.
Change-Id: Ia6f343318c5dd6968a954015a7d59fdf101575b0
diff --git a/libbacktrace/UnwindStack.cpp b/libbacktrace/UnwindStack.cpp
index a748d1b..91bcc66 100644
--- a/libbacktrace/UnwindStack.cpp
+++ b/libbacktrace/UnwindStack.cpp
@@ -40,9 +40,67 @@
#include <unwindstack/Unwinder.h>
#include "BacktraceLog.h"
+#ifndef NO_LIBDEXFILE
+#include "UnwindDexFile.h"
+#endif
#include "UnwindStack.h"
#include "UnwindStackMap.h"
+static void FillInDexFrame(UnwindStackMap* stack_map, uint64_t dex_pc,
+ backtrace_frame_data_t* frame) {
+ // The DEX PC points into the .dex section within an ELF file.
+ // However, this is a BBS section manually mmaped to a .vdex file,
+ // so we need to get the following map to find the ELF data.
+ unwindstack::Maps* maps = stack_map->stack_maps();
+ auto it = maps->begin();
+ uint64_t rel_dex_pc;
+ unwindstack::MapInfo* info;
+ for (; it != maps->end(); ++it) {
+ auto entry = *it;
+ if (dex_pc >= entry->start && dex_pc < entry->end) {
+ info = entry;
+ rel_dex_pc = dex_pc - entry->start;
+ frame->map.start = entry->start;
+ frame->map.end = entry->end;
+ frame->map.offset = entry->offset;
+ frame->map.load_bias = entry->load_bias;
+ frame->map.flags = entry->flags;
+ frame->map.name = entry->name;
+ frame->rel_pc = rel_dex_pc;
+ break;
+ }
+ }
+ if (it == maps->end() || ++it == maps->end()) {
+ return;
+ }
+
+ auto entry = *it;
+ auto process_memory = stack_map->process_memory();
+ unwindstack::Elf* elf = entry->GetElf(process_memory, true);
+ if (!elf->valid()) {
+ return;
+ }
+
+ // Adjust the relative dex by the offset.
+ rel_dex_pc += entry->elf_offset;
+
+ uint64_t dex_offset;
+ if (!elf->GetFunctionName(rel_dex_pc, &frame->func_name, &dex_offset)) {
+ return;
+ }
+ frame->func_offset = dex_offset;
+ if (frame->func_name != "$dexfile") {
+ return;
+ }
+
+#ifndef NO_LIBDEXFILE
+ UnwindDexFile* dex_file = stack_map->GetDexFile(dex_pc - dex_offset, info);
+ if (dex_file != nullptr) {
+ dex_file->GetMethodInformation(dex_offset, &frame->func_name, &frame->func_offset);
+ }
+#endif
+}
+
bool Backtrace::Unwind(unwindstack::Regs* regs, BacktraceMap* back_map,
std::vector<backtrace_frame_data_t>* frames, size_t num_ignore_frames,
std::vector<std::string>* skip_names) {
@@ -60,19 +118,25 @@
return true;
}
- frames->resize(unwinder.NumFrames() - num_ignore_frames);
auto unwinder_frames = unwinder.frames();
+ // Get the real number of frames we'll need.
+ size_t total_frames = 0;
+ for (size_t i = num_ignore_frames; i < unwinder.NumFrames(); i++, total_frames++) {
+ if (unwinder_frames[i].dex_pc != 0) {
+ total_frames++;
+ }
+ }
+ frames->resize(total_frames);
size_t cur_frame = 0;
for (size_t i = num_ignore_frames; i < unwinder.NumFrames(); i++, cur_frame++) {
auto frame = &unwinder_frames[i];
backtrace_frame_data_t* back_frame = &frames->at(cur_frame);
- back_frame->num = frame->num - num_ignore_frames;
+ back_frame->num = cur_frame;
back_frame->rel_pc = frame->rel_pc;
back_frame->pc = frame->pc;
back_frame->sp = frame->sp;
- back_frame->dex_pc = frame->dex_pc;
back_frame->func_name = demangle(frame->function_name.c_str());
back_frame->func_offset = frame->function_offset;
@@ -83,6 +147,19 @@
back_frame->map.offset = frame->map_offset;
back_frame->map.load_bias = frame->map_load_bias;
back_frame->map.flags = frame->map_flags;
+
+ // Inject a frame that represents the dex pc data.
+ if (frame->dex_pc != 0) {
+ cur_frame++;
+ backtrace_frame_data_t* dex_frame = &frames->at(cur_frame);
+ dex_frame->num = cur_frame;
+ dex_frame->pc = frame->dex_pc;
+ dex_frame->rel_pc = frame->dex_pc;
+ dex_frame->sp = back_frame->sp;
+ dex_frame->stack_size = 0;
+ dex_frame->func_offset = 0;
+ FillInDexFrame(stack_map, frame->dex_pc, dex_frame);
+ }
}
return true;