gecko-dev/tools/profiler/LulExidxExt.h

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/* libunwind - a platform-independent unwind library
   Copyright 2011 Linaro Limited

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// Copyright (c) 2010, 2011 Google Inc.
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// Derived from libunwind, with extensive modifications.
// This file is derived from the following files in
// toolkit/crashreporter/google-breakpad:
//   src/common/arm_ex_to_module.h
//   src/common/memory_range.h
//   src/common/arm_ex_reader.h

#ifndef LulExidxExt_h
#define LulExidxExt_h

#include "LulMainInt.h"

using lul::LExpr;
using lul::RuleSet;
using lul::SecMap;

namespace lul {

typedef enum extab_cmd {
  ARM_EXIDX_CMD_FINISH,
  ARM_EXIDX_CMD_SUB_FROM_VSP,
  ARM_EXIDX_CMD_ADD_TO_VSP,
  ARM_EXIDX_CMD_REG_POP,
  ARM_EXIDX_CMD_REG_TO_SP,
  ARM_EXIDX_CMD_VFP_POP,
  ARM_EXIDX_CMD_WREG_POP,
  ARM_EXIDX_CMD_WCGR_POP,
  ARM_EXIDX_CMD_RESERVED,
  ARM_EXIDX_CMD_REFUSED,
} extab_cmd_t;

struct exidx_entry {
  uint32_t addr;
  uint32_t data;
};

struct extab_data {
  extab_cmd_t cmd;
  uint32_t data;
};

enum extab_cmd_flags {
  ARM_EXIDX_VFP_SHIFT_16 = 1 << 16,
  ARM_EXIDX_VFP_FSTMD = 1 << 17, // distinguishes FSTMxxD from FSTMxxX
};

// Receives information from arm_ex_reader::ExceptionTableInfo
// and adds it to the SecMap object
// This is in effect the EXIDX summariser.
class ARMExToModule {
 public:
   ARMExToModule(SecMap* smap, void(*log)(const char*)) : smap_(smap)
                                                        , log_(log) { }
  ~ARMExToModule() { }
  void AddStackFrame(uintptr_t addr, size_t size);
  int  ImproveStackFrame(const struct extab_data* edata);
  void DeleteStackFrame();
  void SubmitStackFrame();
 private:
  SecMap* smap_;
  LExpr   vsp_;        // Always appears to be of the form "sp + offset"
  RuleSet curr_rules_; // Also holds the address range being summarised
  // debugging message sink
  void (*log_)(const char*);
  int TranslateCmd(const struct extab_data* edata, LExpr& vsp);
};


// (derived from)
// memory_range.h: Define the google_breakpad::MemoryRange class, which
// is a lightweight wrapper with a pointer and a length to encapsulate
// a contiguous range of memory.

// A lightweight wrapper with a pointer and a length to encapsulate a
// contiguous range of memory. It provides helper methods for checked
// access of a subrange of the memory. Its implemementation does not
// allocate memory or call into libc functions, and is thus safer to use
// in a crashed environment.
class MemoryRange {
 public:

  MemoryRange(const void* data, size_t length) {
    Set(data, length);
  }

  // Sets this memory range to point to |data| and its length to |length|.
  void Set(const void* data, size_t length) {
    data_ = reinterpret_cast<const uint8_t*>(data);
    // Always set |length_| to zero if |data_| is NULL.
    length_ = data ? length : 0;
  }

  // Returns true if this range covers a subrange of |sub_length| bytes
  // at |sub_offset| bytes of this memory range, or false otherwise.
  bool Covers(size_t sub_offset, size_t sub_length) const {
    // The following checks verify that:
    // 1. sub_offset is within [ 0 .. length_ - 1 ]
    // 2. sub_offset + sub_length is within
    //    [ sub_offset .. length_ ]
    return sub_offset < length_ &&
           sub_offset + sub_length >= sub_offset &&
           sub_offset + sub_length <= length_;
  }

  // Returns a pointer to the beginning of this memory range.
  const uint8_t* data() const { return data_; }

  // Returns the length, in bytes, of this memory range.
  size_t length() const { return length_; }

 private:
  // Pointer to the beginning of this memory range.
  const uint8_t* data_;

  // Length, in bytes, of this memory range.
  size_t length_;
};


// This class is a reader for ARM unwind information
// from .ARM.exidx and .ARM.extab sections.
class ExceptionTableInfo {
 public:
  ExceptionTableInfo(const char* exidx_avma, size_t exidx_size,
                     const char* extab_avma, size_t extab_size,
                     uint32_t text_last_avma,
                     lul::ARMExToModule* handler,
                     void (*log)(const char*))
      : mr_exidx_avma_(lul::MemoryRange(exidx_avma, exidx_size)),
        mr_extab_avma_(lul::MemoryRange(extab_avma, extab_size)),
        text_last_avma_(text_last_avma),
        handler_(handler),
        log_(log) { }

  ~ExceptionTableInfo() { }

  // Parses the entries in .ARM.exidx and possibly
  // in .ARM.extab tables, reports what we find to
  // arm_ex_to_module::ARMExToModule.
  void Start();

 private:
  // Memory ranges for the exidx and extab sections in the executing image
  lul::MemoryRange mr_exidx_avma_;
  lul::MemoryRange mr_extab_avma_;
  // Address of the last byte of the text segment in the executing image
  uint32_t text_last_avma_;
  lul::ARMExToModule* handler_;
  // debugging message sink
  void (*log_)(const char*);
  enum ExExtractResult {
    ExSuccess,        // success
    ExInBufOverflow,  // out-of-range while reading .exidx
    ExOutBufOverflow, // output buffer is too small
    ExCantUnwind,     // this function is marked CANT_UNWIND
    ExCantRepresent,  // entry valid, but we can't represent it
    ExInvalid         // entry is invalid
  };
  ExExtractResult
    ExtabEntryExtract(const struct lul::exidx_entry* entry,
                      uint8_t* buf, size_t buf_size,
                      /*OUT*/size_t* buf_used);

  int ExtabEntryDecode(const uint8_t* buf, size_t buf_size);
};

} // namespace lul

#endif // LulExidxExt_h