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Commit 5ac39278 authored by Peter Collingbourne's avatar Peter Collingbourne
Browse files

Make GetPcAdjustment a free function. 

We're now using it in contexts that don't have all of the registers available,
such as GWP-ASan and soon MTE, so it doesn't make sense to have it be a
member function of Regs.

Bug: 135772972
Change-Id: I18b104ea0adb78588d7e475d0624cefc701ba52c
parent 3ab681c9

debuggerd/libdebuggerd/gwp_asan.cpp

+3 −6
Original line number Diff line number Diff line
@@ -172,15 +172,12 @@ static unwindstack::FrameData BuildFrame(unwindstack::Unwinder* unwinder, uintpt 
    return frame;

  }



  unwindstack::Elf* elf =

      map_info->GetElf(unwinder->GetProcessMemory(), unwindstack::Regs::CurrentArch());

  unwindstack::ArchEnum arch = unwindstack::Regs::CurrentArch();

  unwindstack::Elf* elf = map_info->GetElf(unwinder->GetProcessMemory(), arch);



  uint64_t relative_pc = elf->GetRelPc(pc, map_info);



  // Create registers just to get PC adjustment. Doesn't matter what they point

  // to.

  unwindstack::Regs* regs = unwindstack::Regs::CreateFromLocal();

  uint64_t pc_adjustment = regs->GetPcAdjustment(relative_pc, elf);

  uint64_t pc_adjustment = unwindstack::GetPcAdjustment(relative_pc, elf, arch);

  relative_pc -= pc_adjustment;

  // The debug PC may be different if the PC comes from the JIT.

  uint64_t debug_pc = relative_pc;

libunwindstack/LocalUnwinder.cpp

+1 −1
Original line number Diff line number Diff line
@@ -106,7 +106,7 @@ bool LocalUnwinder::Unwind(std::vector<LocalFrameData>* frame_info, size_t max_f 
    uint64_t step_pc = rel_pc;

    uint64_t pc_adjustment;

    if (adjust_pc) {

      pc_adjustment = regs->GetPcAdjustment(rel_pc, elf);

      pc_adjustment = GetPcAdjustment(rel_pc, elf, arch);

    } else {

      pc_adjustment = 0;

    }

libunwindstack/Regs.cpp

+58 −0
Original line number Diff line number Diff line
@@ -121,4 +121,62 @@ Regs* Regs::CreateFromLocal() { 
  return regs;

}



uint64_t GetPcAdjustment(uint64_t rel_pc, Elf* elf, ArchEnum arch) {

  switch (arch) {

    case ARCH_ARM: {

      if (!elf->valid()) {

        return 2;

      }



      uint64_t load_bias = elf->GetLoadBias();

      if (rel_pc < load_bias) {

        if (rel_pc < 2) {

          return 0;

        }

        return 2;

      }

      uint64_t adjusted_rel_pc = rel_pc - load_bias;

      if (adjusted_rel_pc < 5) {

        if (adjusted_rel_pc < 2) {

          return 0;

        }

        return 2;

      }



      if (adjusted_rel_pc & 1) {

        // This is a thumb instruction, it could be 2 or 4 bytes.

        uint32_t value;

        if (!elf->memory()->ReadFully(adjusted_rel_pc - 5, &value, sizeof(value)) ||

            (value & 0xe000f000) != 0xe000f000) {

          return 2;

        }

      }

      return 4;

    }

  case ARCH_ARM64: {

    if (rel_pc < 4) {

      return 0;

    }

    return 4;

  }

  case ARCH_MIPS:

  case ARCH_MIPS64: {

    if (rel_pc < 8) {

      return 0;

    }

    // For now, just assume no compact branches

    return 8;

  }

  case ARCH_X86:

  case ARCH_X86_64: {

    if (rel_pc == 0) {

      return 0;

    }

    return 1;

  }

  case ARCH_UNKNOWN:

    return 0;

  }

}



}  // namespace unwindstack

libunwindstack/RegsArm.cpp

+0 −31
Original line number Diff line number Diff line
@@ -51,37 +51,6 @@ void RegsArm::set_sp(uint64_t sp) { 
  regs_[ARM_REG_SP] = sp;

}



uint64_t RegsArm::GetPcAdjustment(uint64_t rel_pc, Elf* elf) {

  if (!elf->valid()) {

    return 2;

  }



  uint64_t load_bias = elf->GetLoadBias();

  if (rel_pc < load_bias) {

    if (rel_pc < 2) {

      return 0;

    }

    return 2;

  }

  uint64_t adjusted_rel_pc = rel_pc - load_bias;

  if (adjusted_rel_pc < 5) {

    if (adjusted_rel_pc < 2) {

      return 0;

    }

    return 2;

  }



  if (adjusted_rel_pc & 1) {

    // This is a thumb instruction, it could be 2 or 4 bytes.

    uint32_t value;

    if (!elf->memory()->ReadFully(adjusted_rel_pc - 5, &value, sizeof(value)) ||

        (value & 0xe000f000) != 0xe000f000) {

      return 2;

    }

  }

  return 4;

}



bool RegsArm::SetPcFromReturnAddress(Memory*) {

  uint32_t lr = regs_[ARM_REG_LR];

  if (regs_[ARM_REG_PC] == lr) {

libunwindstack/RegsArm64.cpp

+0 −7
Original line number Diff line number Diff line
@@ -52,13 +52,6 @@ void RegsArm64::set_sp(uint64_t sp) { 
  regs_[ARM64_REG_SP] = sp;

}



uint64_t RegsArm64::GetPcAdjustment(uint64_t rel_pc, Elf*) {

  if (rel_pc < 4) {

    return 0;

  }

  return 4;

}



bool RegsArm64::SetPcFromReturnAddress(Memory*) {

  uint64_t lr = regs_[ARM64_REG_LR];

  if (regs_[ARM64_REG_PC] == lr) {