Elf interface for new unwinder.
This cl includes the code to read arm unwind information from a shared
library.
Bug: 23762183
Test: Passes all unit tests. I can dump the arm unwind information
Test: for an arm shared library.
Change-Id: I43501ea2eab843b81de8bd5128401dd1971af8d3
diff --git a/libunwindstack/ElfInterfaceArm.cpp b/libunwindstack/ElfInterfaceArm.cpp
new file mode 100644
index 0000000..e157320
--- /dev/null
+++ b/libunwindstack/ElfInterfaceArm.cpp
@@ -0,0 +1,127 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <elf.h>
+#include <stdint.h>
+
+#include "ArmExidx.h"
+#include "ElfInterface.h"
+#include "ElfInterfaceArm.h"
+#include "Machine.h"
+#include "Memory.h"
+#include "Regs.h"
+
+bool ElfInterfaceArm::FindEntry(uint32_t pc, uint64_t* entry_offset) {
+ if (start_offset_ == 0 || total_entries_ == 0) {
+ return false;
+ }
+
+ // Need to subtract the load_bias from the pc.
+ if (pc < load_bias_) {
+ return false;
+ }
+ pc -= load_bias_;
+
+ size_t first = 0;
+ size_t last = total_entries_;
+ while (first < last) {
+ size_t current = (first + last) / 2;
+ uint32_t addr = addrs_[current];
+ if (addr == 0) {
+ if (!GetPrel31Addr(start_offset_ + current * 8, &addr)) {
+ return false;
+ }
+ addrs_[current] = addr;
+ }
+ if (pc == addr) {
+ *entry_offset = start_offset_ + current * 8;
+ return true;
+ }
+ if (pc < addr) {
+ last = current;
+ } else {
+ first = current + 1;
+ }
+ }
+ if (last != 0) {
+ *entry_offset = start_offset_ + (last - 1) * 8;
+ return true;
+ }
+ return false;
+}
+
+bool ElfInterfaceArm::GetPrel31Addr(uint32_t offset, uint32_t* addr) {
+ uint32_t data;
+ if (!memory_->Read32(offset, &data)) {
+ return false;
+ }
+
+ // Sign extend the value if necessary.
+ int32_t value = (static_cast<int32_t>(data) << 1) >> 1;
+ *addr = offset + value;
+ return true;
+}
+
+#if !defined(PT_ARM_EXIDX)
+#define PT_ARM_EXIDX 0x70000001
+#endif
+
+bool ElfInterfaceArm::HandleType(uint64_t offset, uint32_t type) {
+ if (type != PT_ARM_EXIDX) {
+ return false;
+ }
+
+ Elf32_Phdr phdr;
+ if (!memory_->Read(offset, &phdr, &phdr.p_vaddr, sizeof(phdr.p_vaddr))) {
+ return true;
+ }
+ if (!memory_->Read(offset, &phdr, &phdr.p_memsz, sizeof(phdr.p_memsz))) {
+ return true;
+ }
+ // The load_bias_ should always be set by this time.
+ start_offset_ = phdr.p_vaddr - load_bias_;
+ total_entries_ = phdr.p_memsz / 8;
+ return true;
+}
+
+bool ElfInterfaceArm::Step(uint64_t pc, Regs* regs, Memory* process_memory) {
+ return StepExidx(pc, regs, process_memory) ||
+ ElfInterface32::Step(pc, regs, process_memory);
+}
+
+bool ElfInterfaceArm::StepExidx(uint64_t pc, Regs* regs, Memory* process_memory) {
+ RegsArm* regs_arm = reinterpret_cast<RegsArm*>(regs);
+ // First try arm, then try dwarf.
+ uint64_t entry_offset;
+ if (!FindEntry(pc, &entry_offset)) {
+ return false;
+ }
+ ArmExidx arm(regs_arm, memory_, process_memory);
+ arm.set_cfa(regs_arm->sp());
+ if (arm.ExtractEntryData(entry_offset) && arm.Eval()) {
+ // If the pc was not set, then use the LR registers for the PC.
+ if (!arm.pc_set()) {
+ regs_arm->set_pc((*regs_arm)[ARM_REG_LR]);
+ (*regs_arm)[ARM_REG_PC] = regs_arm->pc();
+ } else {
+ regs_arm->set_pc((*regs_arm)[ARM_REG_PC]);
+ }
+ regs_arm->set_sp(arm.cfa());
+ (*regs_arm)[ARM_REG_SP] = regs_arm->sp();
+ return true;
+ }
+ return false;
+}