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Commit 92acaac8 authored by Christopher Ferris's avatar Christopher Ferris
Browse files

Refactor the DwarfSection classes. 

Modify the code for the no header sections because it turns out that
it is not okay to assume that the fdes are non-overlapping. It's necessary
to read the fdes in order and match as you go.

Modify the code so that it only reads until it finds the given pc rather than
reading all of the cie/fde entries at once.

Rewrote the tests to verify the new behavior.

Bug: 68998033
Bug: 110235461

Test: Ran libbacktrace/libunwindstack unit tests.
Test: Unwind the mediaserver process on a walleye and verify it
Test: unwinds properly.

Change-Id: I7bb59d1db72c13fa34caa9735ec34c1a60e20ed2
parent fc1cf907

libunwindstack/DwarfDebugFrame.h

+2 −2
Original line number Diff line number Diff line
@@ -26,9 +26,9 @@ 
namespace unwindstack {



template <typename AddressType>

class DwarfDebugFrame : public DwarfSectionImpl<AddressType> {

class DwarfDebugFrame : public DwarfSectionImplNoHdr<AddressType> {

 public:

  DwarfDebugFrame(Memory* memory) : DwarfSectionImpl<AddressType>(memory) {

  DwarfDebugFrame(Memory* memory) : DwarfSectionImplNoHdr<AddressType>(memory) {

    this->cie32_value_ = static_cast<uint32_t>(-1);

    this->cie64_value_ = static_cast<uint64_t>(-1);

  }

libunwindstack/DwarfEhFrame.h

+2 −2
Original line number Diff line number Diff line
@@ -25,9 +25,9 @@ 
namespace unwindstack {



template <typename AddressType>

class DwarfEhFrame : public DwarfSectionImpl<AddressType> {

class DwarfEhFrame : public DwarfSectionImplNoHdr<AddressType> {

 public:

  DwarfEhFrame(Memory* memory) : DwarfSectionImpl<AddressType>(memory) {}

  DwarfEhFrame(Memory* memory) : DwarfSectionImplNoHdr<AddressType>(memory) {}

  virtual ~DwarfEhFrame() = default;



  uint64_t GetCieOffsetFromFde32(uint32_t pointer) override {

libunwindstack/DwarfEhFrameWithHdr.cpp

+30 −4
Original line number Diff line number Diff line
@@ -39,6 +39,7 @@ bool DwarfEhFrameWithHdr<AddressType>::Init(uint64_t offset, uint64_t size, uint 
  memory_.clear_text_offset();

  memory_.set_data_offset(offset);

  memory_.set_cur_offset(offset);

  pc_offset_ = offset;



  // Read the first four bytes all at once.

  uint8_t data[4];
@@ -88,12 +89,22 @@ bool DwarfEhFrameWithHdr<AddressType>::Init(uint64_t offset, uint64_t size, uint 
}



template <typename AddressType>

const DwarfFde* DwarfEhFrameWithHdr<AddressType>::GetFdeFromIndex(size_t index) {

  const FdeInfo* info = GetFdeInfoFromIndex(index);

  if (info == nullptr) {

const DwarfFde* DwarfEhFrameWithHdr<AddressType>::GetFdeFromPc(uint64_t pc) {

  uint64_t fde_offset;

  if (!GetFdeOffsetFromPc(pc, &fde_offset)) {

    return nullptr;

  }

  return this->GetFdeFromOffset(info->offset);

  const DwarfFde* fde = this->GetFdeFromOffset(fde_offset);

  if (fde == nullptr) {

    return nullptr;

  }



  // Guaranteed pc >= pc_start, need to check pc in the fde range.

  if (pc < fde->pc_end) {

    return fde;

  }

  last_error_.code = DWARF_ERROR_ILLEGAL_STATE;

  return nullptr;

}



template <typename AddressType>
@@ -241,6 +252,21 @@ bool DwarfEhFrameWithHdr<AddressType>::GetFdeOffsetFromPc(uint64_t pc, uint64_t* 
  }

}



template <typename AddressType>

void DwarfEhFrameWithHdr<AddressType>::GetFdes(std::vector<const DwarfFde*>* fdes) {

  for (size_t i = 0; i < fde_count_; i++) {

    const FdeInfo* info = GetFdeInfoFromIndex(i);

    if (info == nullptr) {

      break;

    }

    const DwarfFde* fde = this->GetFdeFromOffset(info->offset);

    if (fde == nullptr) {

      break;

    }

    fdes->push_back(fde);

  }

}



// Explicitly instantiate DwarfEhFrameWithHdr

template class DwarfEhFrameWithHdr<uint32_t>;

template class DwarfEhFrameWithHdr<uint64_t>;

libunwindstack/DwarfEhFrameWithHdr.h

+22 −6
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ 


#include <unordered_map>



#include "DwarfEhFrame.h"

#include <unwindstack/DwarfSection.h>



namespace unwindstack {
@@ -29,12 +29,12 @@ namespace unwindstack { 
class Memory;



template <typename AddressType>

class DwarfEhFrameWithHdr : public DwarfEhFrame<AddressType> {

class DwarfEhFrameWithHdr : public DwarfSectionImpl<AddressType> {

 public:

  // Add these so that the protected members of DwarfSectionImpl

  // can be accessed without needing a this->.

  using DwarfSectionImpl<AddressType>::memory_;

  using DwarfSectionImpl<AddressType>::fde_count_;

  using DwarfSectionImpl<AddressType>::pc_offset_;

  using DwarfSectionImpl<AddressType>::entries_offset_;

  using DwarfSectionImpl<AddressType>::entries_end_;

  using DwarfSectionImpl<AddressType>::last_error_;
@@ -45,14 +45,27 @@ class DwarfEhFrameWithHdr : public DwarfEhFrame<AddressType> { 
    uint64_t offset;

  };



  DwarfEhFrameWithHdr(Memory* memory) : DwarfEhFrame<AddressType>(memory) {}

  DwarfEhFrameWithHdr(Memory* memory) : DwarfSectionImpl<AddressType>(memory) {}

  virtual ~DwarfEhFrameWithHdr() = default;



  uint64_t GetCieOffsetFromFde32(uint32_t pointer) override {

    return this->memory_.cur_offset() - pointer - 4;

  }



  uint64_t GetCieOffsetFromFde64(uint64_t pointer) override {

    return this->memory_.cur_offset() - pointer - 8;

  }



  uint64_t AdjustPcFromFde(uint64_t pc) override {

    // The eh_frame uses relative pcs.

    return pc + this->memory_.cur_offset() - 4;

  }



  bool Init(uint64_t offset, uint64_t size, uint64_t load_bias) override;



  bool GetFdeOffsetFromPc(uint64_t pc, uint64_t* fde_offset) override;

  const DwarfFde* GetFdeFromPc(uint64_t pc) override;



  const DwarfFde* GetFdeFromIndex(size_t index) override;

  bool GetFdeOffsetFromPc(uint64_t pc, uint64_t* fde_offset);



  const FdeInfo* GetFdeInfoFromIndex(size_t index);
@@ -60,6 +73,8 @@ class DwarfEhFrameWithHdr : public DwarfEhFrame<AddressType> { 


  bool GetFdeOffsetBinary(uint64_t pc, uint64_t* fde_offset, uint64_t total_entries);



  void GetFdes(std::vector<const DwarfFde*>* fdes) override;



 protected:

  uint8_t version_;

  uint8_t ptr_encoding_;
@@ -71,6 +86,7 @@ class DwarfEhFrameWithHdr : public DwarfEhFrame<AddressType> { 
  uint64_t entries_data_offset_;

  uint64_t cur_entries_offset_ = 0;



  uint64_t fde_count_;

  std::unordered_map<uint64_t, FdeInfo> fde_info_;

};

libunwindstack/DwarfSection.cpp

+371 −466

File changed.

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