ClickHouse/src/Common/Dwarf.h
Azat Khuzhin 4e76629aaf Fixes for -Wshorten-64-to-32
- lots of static_cast
- add safe_cast
- types adjustments
  - config
  - IStorage::read/watch
  - ...
- some TODO's (to convert types in future)

P.S. That was quite a journey...

v2: fixes after rebase
v3: fix conflicts after #42308 merged
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
2022-10-21 13:25:19 +02:00

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#pragma once
#if defined(__ELF__) && !defined(OS_FREEBSD)
/*
* Copyright 2012-present Facebook, Inc.
*
* 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.
*/
/** This file was edited for ClickHouse.
* Original is from folly library.
*/
#include <functional>
#include <memory>
#include <optional>
#include <string>
#include <string_view>
#include <variant>
#include <vector>
namespace DB
{
class Elf;
/**
* DWARF record parser.
*
* We only implement enough DWARF functionality to convert from PC address
* to file and line number information.
*
* This means (although they're not part of the public API of this class), we
* can parse Debug Information Entries (DIEs), abbreviations, attributes (of
* all forms), and we can interpret bytecode for the line number VM.
*
* We can interpret DWARF records of version 2, 3, or 4, although we don't
* actually support many of the version 4 features (such as VLIW, multiple
* operations per instruction)
*
* Note that the DWARF record parser does not allocate heap memory at all.
* This is on purpose: you can use the parser from
* memory-constrained situations (such as an exception handler for
* std::out_of_memory) If it weren't for this requirement, some things would
* be much simpler: the Path class would be unnecessary and would be replaced
* with a std::string; the list of file names in the line number VM would be
* kept as a vector of strings instead of re-executing the program to look for
* DW_LNE_define_file instructions, etc.
*/
class Dwarf final
{
// Note that Dwarf uses (and returns) std::string_view a lot.
// The std::string_view point within sections in the ELF file, and so will
// be live for as long as the passed-in Elf is live.
public:
/** Create a DWARF parser around an ELF file. */
explicit Dwarf(const std::shared_ptr<Elf> & elf);
/**
* More than one location info may exist if current frame is an inline
* function call.
*/
static constexpr uint32_t kMaxInlineLocationInfoPerFrame = 10;
/**
* Represent a file path a s collection of three parts (base directory,
* subdirectory, and file).
*/
class Path
{
public:
Path() = default;
Path(std::string_view baseDir, std::string_view subDir, std::string_view file);
std::string_view baseDir() const { return baseDir_; }
std::string_view subDir() const { return subDir_; }
std::string_view file() const { return file_; }
size_t size() const;
/**
* Copy the Path to a buffer of size bufSize.
*
* toBuffer behaves like snprintf: It will always null-terminate the
* buffer (so it will copy at most bufSize-1 bytes), and it will return
* the number of bytes that would have been written if there had been
* enough room, so, if toBuffer returns a value >= bufSize, the output
* was truncated.
*/
size_t toBuffer(char * buf, size_t bufSize) const;
void toString(std::string & dest) const;
std::string toString() const
{
std::string s;
toString(s);
return s;
}
// TODO(tudorb): Implement operator==, operator!=; not as easy as it
// seems as the same path can be represented in multiple ways
private:
std::string_view baseDir_; /// NOLINT
std::string_view subDir_; /// NOLINT
std::string_view file_; /// NOLINT
};
// Indicates inline function `name` is called at `line@file`.
struct CallLocation
{
Path file = {};
uint64_t line = 0;
std::string_view name;
};
enum class LocationInfoMode
{
// Don't resolve location info.
DISABLED,
// Perform CU lookup using .debug_aranges (might be incomplete).
FAST,
// Scan all CU in .debug_info (slow!) on .debug_aranges lookup failure.
FULL,
// Scan .debug_info (super slower, use with caution) for inline functions in
// addition to FULL.
FULL_WITH_INLINE,
};
struct LocationInfo
{
bool has_main_file = false;
Path main_file;
bool has_file_and_line = false;
Path file;
uint64_t line = 0;
};
/**
* Frame information: symbol name and location.
*/
struct SymbolizedFrame
{
bool found = false;
uintptr_t addr = 0;
// Mangled symbol name. Use `folly::demangle()` to demangle it.
const char * name = nullptr;
LocationInfo location;
std::shared_ptr<const Elf> file;
void clear() { *this = SymbolizedFrame(); }
};
/** Find the file and line number information corresponding to address.
* The address must be physical - offset in object file without offset in virtual memory where the object is loaded.
*/
bool findAddress(uintptr_t address, LocationInfo & info, LocationInfoMode mode, std::vector<SymbolizedFrame> & inline_frames) const;
private:
static bool findDebugInfoOffset(uintptr_t address, std::string_view aranges, uint64_t & offset);
std::shared_ptr<const Elf> elf_; /// NOLINT
// DWARF section made up of chunks, each prefixed with a length header.
// The length indicates whether the chunk is DWARF-32 or DWARF-64, which
// guides interpretation of "section offset" records.
// (yes, DWARF-32 and DWARF-64 sections may coexist in the same file)
class Section
{
public:
Section() : is64_bit(false) {}
explicit Section(std::string_view d);
// Return next chunk, if any; the 4- or 12-byte length was already
// parsed and isn't part of the chunk.
bool next(std::string_view & chunk);
// Is the current chunk 64 bit?
bool is64Bit() const { return is64_bit; }
private:
// Yes, 32- and 64- bit sections may coexist. Yikes!
bool is64_bit;
std::string_view data;
};
// Abbreviation for a Debugging Information Entry.
struct DIEAbbreviation
{
uint64_t code = 0;
uint64_t tag = 0;
bool has_children = false;
std::string_view attributes;
};
// Debugging information entry to define a low-level representation of a
// source program. Each debugging information entry consists of an identifying
// tag and a series of attributes. An entry, or group of entries together,
// provide a description of a corresponding entity in the source program.
struct Die
{
bool is64Bit; /// NOLINT
// Offset from start to first attribute
uint8_t attr_offset;
// Offset within debug info.
uint64_t offset;
uint64_t code;
DIEAbbreviation abbr;
};
struct AttributeSpec
{
uint64_t name = 0;
uint64_t form = 0;
int64_t implicitConst = 0; // only set when form=DW_FORM_implicit_const
explicit operator bool() const { return name != 0 || form != 0; }
};
struct Attribute
{
AttributeSpec spec;
const Die & die;
std::variant<uint64_t, std::string_view> attr_value;
};
enum
{
DW_UT_compile = 0x01,
DW_UT_skeleton = 0x04,
};
struct CompilationUnit
{
bool is64Bit = false; /// NOLINT
uint8_t version = 0;
uint8_t unit_type = DW_UT_compile; // DW_UT_compile or DW_UT_skeleton
uint8_t addr_size = 0;
// Offset in .debug_info of this compilation unit.
uint64_t offset = 0;
uint64_t size = 0;
// Offset in .debug_info for the first DIE in this compilation unit.
uint64_t first_die = 0;
uint64_t abbrev_offset = 0;
// The beginning of the CU's contribution to .debug_addr
std::optional<uint64_t> addr_base; // DW_AT_addr_base (DWARF 5)
// The beginning of the offsets table (immediately following the
// header) of the CU's contribution to .debug_loclists
std::optional<uint64_t> loclists_base; // DW_AT_loclists_base (DWARF 5)
// The beginning of the offsets table (immediately following the
// header) of the CU's contribution to .debug_rnglists
std::optional<uint64_t> rnglists_base; // DW_AT_rnglists_base (DWARF 5)
// Points to the first string offset of the compilation units
// contribution to the .debug_str_offsets (or .debug_str_offsets.dwo) section.
std::optional<uint64_t> str_offsets_base; // DW_AT_str_offsets_base (DWARF 5)
// Only the CompilationUnit that contains the caller functions needs this cache.
// Indexed by (abbr.code - 1) if (abbr.code - 1) < abbrCache.size();
std::vector<DIEAbbreviation> abbr_cache;
};
/** cu must exist during the life cycle of created Die. */
Die getDieAtOffset(const CompilationUnit & cu, uint64_t offset) const;
bool findLocation(
uintptr_t address,
LocationInfoMode mode,
CompilationUnit & cu,
LocationInfo & info,
std::vector<SymbolizedFrame> & inline_frames) const;
/**
* Finds a subprogram debugging info entry that contains a given address among
* children of given die. Depth first search.
*/
void findSubProgramDieForAddress(
const CompilationUnit & cu, const Die & die, uint64_t address, std::optional<uint64_t> base_addr_cu, Die & subprogram) const;
// Interpreter for the line number bytecode VM
class LineNumberVM
{
public:
LineNumberVM(
std::string_view data,
std::string_view compilationDirectory,
std::string_view debugStr,
std::string_view debugLineStr);
bool findAddress(uintptr_t target, Path & file, uint64_t & line);
/** Gets full file name at given index including directory. */
Path getFullFileName(uint64_t index) const;
private:
void init();
void reset();
// Execute until we commit one new row to the line number matrix
bool next(std::string_view & program);
enum StepResult
{
CONTINUE, // Continue feeding opcodes
COMMIT, // Commit new <address, file, line> tuple
END, // End of sequence
};
// Execute one opcode
StepResult step(std::string_view & program);
struct FileName
{
std::string_view relativeName; /// NOLINT
// 0 = current compilation directory
// otherwise, 1-based index in the list of include directories
uint64_t directoryIndex; /// NOLINT
};
// Read one FileName object, remove_prefix program
static bool readFileName(std::string_view & program, FileName & fn);
// Get file name at given index; may be in the initial table
// (fileNames_) or defined using DW_LNE_define_file (and we reexecute
// enough of the program to find it, if so)
FileName getFileName(uint64_t index) const;
// Get include directory at given index
std::string_view getIncludeDirectory(uint64_t index) const;
// Execute opcodes until finding a DW_LNE_define_file and return true;
// return file at the end.
bool nextDefineFile(std::string_view & program, FileName & fn) const;
// Initialization
bool is64Bit_; /// NOLINT
std::string_view data_; /// NOLINT
std::string_view compilationDirectory_; /// NOLINT
std::string_view debugStr_; // needed for DWARF 5 /// NOLINT
std::string_view debugLineStr_; // DWARF 5 /// NOLINT
// Header
uint16_t version_; /// NOLINT
uint8_t minLength_; /// NOLINT
bool defaultIsStmt_; /// NOLINT
int8_t lineBase_; /// NOLINT
uint8_t lineRange_; /// NOLINT
uint8_t opcodeBase_; /// NOLINT
const uint8_t * standardOpcodeLengths_; /// NOLINT
// 6.2.4 The Line Number Program Header.
struct
{
size_t includeDirectoryCount;
std::string_view includeDirectories;
size_t fileNameCount;
std::string_view fileNames;
} v4_;
struct
{
uint8_t directoryEntryFormatCount;
std::string_view directoryEntryFormat;
uint64_t directoriesCount;
std::string_view directories;
uint8_t fileNameEntryFormatCount;
std::string_view fileNameEntryFormat;
uint64_t fileNamesCount;
std::string_view fileNames;
} v5_;
// State machine registers
uint64_t address_; /// NOLINT
uint64_t file_; /// NOLINT
uint64_t line_; /// NOLINT
uint64_t column_; /// NOLINT
bool isStmt_; /// NOLINT
bool basicBlock_; /// NOLINT
bool endSequence_; /// NOLINT
bool prologueEnd_; /// NOLINT
bool epilogueBegin_; /// NOLINT
uint64_t isa_; /// NOLINT
uint64_t discriminator_; /// NOLINT
};
/**
* Finds inlined subroutine DIEs and their caller lines that contains a given
* address among children of given die. Depth first search.
*/
void findInlinedSubroutineDieForAddress(
const CompilationUnit & cu,
const Die & die,
const LineNumberVM & line_vm,
uint64_t address,
std::optional<uint64_t> base_addr_cu,
std::vector<CallLocation> & locations,
size_t max_size) const;
// Read an abbreviation from a std::string_view, return true if at end; remove_prefix section
static bool readAbbreviation(std::string_view & section, DIEAbbreviation & abbr);
static void readCompilationUnitAbbrs(std::string_view abbrev, CompilationUnit & cu);
/**
* Iterates over all children of a debugging info entry, calling the given
* callable for each. Iteration is stopped early if any of the calls return
* false. Returns the offset of next DIE after iterations.
*/
size_t forEachChild(const CompilationUnit & cu, const Die & die, std::function<bool(const Die & die)> f) const;
// Get abbreviation corresponding to a code, in the chunk starting at
// offset in the .debug_abbrev section
DIEAbbreviation getAbbreviation(uint64_t code, uint64_t offset) const;
/**
* Iterates over all attributes of a debugging info entry, calling the given
* callable for each. If all attributes are visited, then return the offset of
* next DIE, or else iteration is stopped early and return size_t(-1) if any
* of the calls return false.
*/
size_t forEachAttribute(const CompilationUnit & cu, const Die & die, std::function<bool(const Attribute & die)> f) const;
Attribute readAttribute(
const CompilationUnit & cu,
const Die & die,
AttributeSpec spec,
std::string_view & info) const;
// Read one attribute <name, form> pair, remove_prefix sp; returns <0, 0> at end.
static AttributeSpec readAttributeSpec(std::string_view & sp);
// Read one attribute value, remove_prefix sp
using AttributeValue = std::variant<uint64_t, std::string_view>;
AttributeValue readAttributeValue(std::string_view & sp, uint64_t form, bool is64_bit) const;
// Get an ELF section by name, return true if found
std::string_view getSection(const char * name) const;
CompilationUnit getCompilationUnit(uint64_t offset) const;
// Finds the Compilation Unit starting at offset.
CompilationUnit findCompilationUnit(uint64_t targetOffset) const;
template <class T>
std::optional<T> getAttribute(const CompilationUnit & cu, const Die & die, uint64_t attr_name) const
{
std::optional<T> result;
forEachAttribute(cu, die, [&](const Attribute & attr)
{
if (attr.spec.name == attr_name)
{
result = std::get<T>(attr.attr_value);
return false;
}
return true;
});
return result;
}
// Check if the given address is in the range list at the given offset in .debug_ranges.
bool isAddrInRangeList(
const CompilationUnit & cu,
uint64_t address,
std::optional<uint64_t> base_addr,
size_t offset,
uint8_t addr_size) const;
std::string_view abbrev_; // .debug_abbrev /// NOLINT
std::string_view addr_; // .debug_addr (DWARF 5) /// NOLINT
std::string_view aranges_; // .debug_aranges /// NOLINT
std::string_view info_; // .debug_info /// NOLINT
std::string_view line_; // .debug_line /// NOLINT
std::string_view line_str_; // .debug_line_str (DWARF 5) /// NOLINT
std::string_view loclists_; // .debug_loclists (DWARF 5) /// NOLINT
std::string_view ranges_; // .debug_ranges /// NOLINT
std::string_view rnglists_; // .debug_rnglists (DWARF 5) /// NOLINT
std::string_view str_; // .debug_str /// NOLINT
std::string_view str_offsets_; // .debug_str_offsets (DWARF 5) /// NOLINT
};
}
#endif