From 395f42d36d37a81ce1c11918bfded0a2afaa6195 Mon Sep 17 00:00:00 2001
From: Christopher Ferris <cferris@google.com>
Date: Wed, 20 Dec 2017 18:49:01 -0800
Subject: Add ability to read jit gdb data.

Changes:
- New JitDebug class to handle all of the jit gdb interface.
- Add unit tests for all, along with new offline test using debug data.
- Add new Memory type called MemoryOfflineParts that has multiple
  MemoryOffline objects to support the offline test.
- Update the tools to use the JitDebug object.
- Modify libbacktrace to use the JitDebug, but only looking in libart.so
  and libartd.so.
- Change the Format32Bits to Is32Bit since it's more accurate and I use
  it in a different context where original name didn't make sense.
- Add a new function to find global variables in an elf file
  (GetGlobalVariable).
- Add a new function to determine if a pc is valid for this elf (IsValidPc).

Bug: 68396769

Test: Ran new unit tests. Added new offline test that uses jit debug data.
Test: Ran art test that generates jit data and verified a crash unwinds
Test: through the jit data.
Change-Id: I6e7ee2f5bab2242028a06feece156dff21c0a974
---
 libunwindstack/Elf.cpp | 48 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)

(limited to 'libunwindstack/Elf.cpp')

diff --git a/libunwindstack/Elf.cpp b/libunwindstack/Elf.cpp
index 5ec4a3d..220e549 100644
--- a/libunwindstack/Elf.cpp
+++ b/libunwindstack/Elf.cpp
@@ -103,6 +103,37 @@ bool Elf::GetFunctionName(uint64_t addr, std::string* name, uint64_t* func_offse
                                                      addr, load_bias_, name, func_offset)));
 }
 
+bool Elf::GetGlobalVariable(const std::string& name, uint64_t* memory_address) {
+  if (!valid_) {
+    return false;
+  }
+
+  if (!interface_->GetGlobalVariable(name, memory_address) &&
+      (gnu_debugdata_interface_ == nullptr ||
+       !gnu_debugdata_interface_->GetGlobalVariable(name, memory_address))) {
+    return false;
+  }
+
+  // Adjust by the load bias.
+  if (*memory_address < load_bias_) {
+    return false;
+  }
+
+  *memory_address -= load_bias_;
+
+  // If this winds up in the dynamic section, then we might need to adjust
+  // the address.
+  uint64_t dynamic_end = interface_->dynamic_vaddr() + interface_->dynamic_size();
+  if (*memory_address >= interface_->dynamic_vaddr() && *memory_address < dynamic_end) {
+    if (interface_->dynamic_vaddr() > interface_->dynamic_offset()) {
+      *memory_address -= interface_->dynamic_vaddr() - interface_->dynamic_offset();
+    } else {
+      *memory_address += interface_->dynamic_offset() - interface_->dynamic_vaddr();
+    }
+  }
+  return true;
+}
+
 // The relative pc is always relative to the start of the map from which it comes.
 bool Elf::Step(uint64_t rel_pc, uint64_t adjusted_rel_pc, uint64_t elf_offset, Regs* regs,
                Memory* process_memory, bool* finished) {
@@ -160,6 +191,23 @@ void Elf::GetInfo(Memory* memory, bool* valid, uint64_t* size) {
   }
 }
 
+bool Elf::IsValidPc(uint64_t pc) {
+  if (!valid_ || pc < load_bias_) {
+    return false;
+  }
+  pc -= load_bias_;
+
+  if (interface_->IsValidPc(pc)) {
+    return true;
+  }
+
+  if (gnu_debugdata_interface_ != nullptr && gnu_debugdata_interface_->IsValidPc(pc)) {
+    return true;
+  }
+
+  return false;
+}
+
 ElfInterface* Elf::CreateInterfaceFromMemory(Memory* memory) {
   if (!IsValidElf(memory)) {
     return nullptr;
-- 
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