Pavel Labath 1211baa51c Breakpad: Generate unwind plans from STACK CFI records
Summary:
This patch implements the GetUnwindPlan interface (added in the previous
patch) for SymbolFileBreakpad, and uses it to generate unwind plans from
STACK CFI records in breakpad files.

We first perform a light-weight parse of the breakpad in order to build
up a map of regions covered by the unwind info so that we can later jump
to the right record when we need to unwind a specific function.

The actual parsing is relatively straight-forward, as the STACK CFI records
are just another (text) form of the eh_frame unwind instructions, and
the same goes for lldb's UnwindPlans. The newly-introduced
PostfixExpression API is used to convert the breakpad postfix
expressions into DWARF. The generated dwarf expressions are stored in a
BumpPtrAllocator, as the UnwindPlan does not take ownership of the
expression data it references (usually this is static data in an object
file, so special ownership is needed).

At this moment the generated unwind plans aren't used in the actual
unwind machinery (only in the image show-unwind command), but that is
coming in a separate patch.

Reviewers: amccarth, clayborg, markmentovai

Subscribers: aprantl, jasonmolenda, lldb-commits

Differential Revision: https://reviews.llvm.org/D61733

llvm-svn: 360574
2019-05-13 11:25:35 +00:00

223 lines
7.7 KiB
C++

//===-- SymbolFileBreakpad.h ------------------------------------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#ifndef LLDB_PLUGINS_SYMBOLFILE_BREAKPAD_SYMBOLFILEBREAKPAD_H
#define LLDB_PLUGINS_SYMBOLFILE_BREAKPAD_SYMBOLFILEBREAKPAD_H
#include "Plugins/ObjectFile/Breakpad/BreakpadRecords.h"
#include "lldb/Core/FileSpecList.h"
#include "lldb/Symbol/LineTable.h"
#include "lldb/Symbol/SymbolFile.h"
#include "lldb/Symbol/UnwindPlan.h"
namespace lldb_private {
namespace breakpad {
class SymbolFileBreakpad : public SymbolFile {
public:
// Static Functions
static void Initialize();
static void Terminate();
static void DebuggerInitialize(Debugger &debugger) {}
static ConstString GetPluginNameStatic();
static const char *GetPluginDescriptionStatic() {
return "Breakpad debug symbol file reader.";
}
static SymbolFile *CreateInstance(ObjectFile *obj_file) {
return new SymbolFileBreakpad(obj_file);
}
// Constructors and Destructors
SymbolFileBreakpad(ObjectFile *object_file) : SymbolFile(object_file) {}
~SymbolFileBreakpad() override {}
uint32_t CalculateAbilities() override;
void InitializeObject() override {}
// Compile Unit function calls
uint32_t GetNumCompileUnits() override;
lldb::CompUnitSP ParseCompileUnitAtIndex(uint32_t index) override;
lldb::LanguageType ParseLanguage(CompileUnit &comp_unit) override {
return lldb::eLanguageTypeUnknown;
}
size_t ParseFunctions(CompileUnit &comp_unit) override;
bool ParseLineTable(CompileUnit &comp_unit) override;
bool ParseDebugMacros(CompileUnit &comp_unit) override { return false; }
bool ParseSupportFiles(CompileUnit &comp_unit,
FileSpecList &support_files) override;
size_t ParseTypes(CompileUnit &cu) override { return 0; }
bool ParseImportedModules(
const SymbolContext &sc,
std::vector<lldb_private::SourceModule> &imported_modules) override {
return false;
}
size_t ParseBlocksRecursive(Function &func) override { return 0; }
uint32_t FindGlobalVariables(ConstString name,
const CompilerDeclContext *parent_decl_ctx,
uint32_t max_matches,
VariableList &variables) override {
return 0;
}
size_t ParseVariablesForContext(const SymbolContext &sc) override {
return 0;
}
Type *ResolveTypeUID(lldb::user_id_t type_uid) override { return nullptr; }
llvm::Optional<ArrayInfo> GetDynamicArrayInfoForUID(
lldb::user_id_t type_uid,
const lldb_private::ExecutionContext *exe_ctx) override {
return llvm::None;
}
bool CompleteType(CompilerType &compiler_type) override { return false; }
uint32_t ResolveSymbolContext(const Address &so_addr,
lldb::SymbolContextItem resolve_scope,
SymbolContext &sc) override;
uint32_t ResolveSymbolContext(const FileSpec &file_spec, uint32_t line,
bool check_inlines,
lldb::SymbolContextItem resolve_scope,
SymbolContextList &sc_list) override;
size_t GetTypes(SymbolContextScope *sc_scope, lldb::TypeClass type_mask,
TypeList &type_list) override {
return 0;
}
uint32_t FindFunctions(ConstString name,
const CompilerDeclContext *parent_decl_ctx,
lldb::FunctionNameType name_type_mask,
bool include_inlines, bool append,
SymbolContextList &sc_list) override;
uint32_t FindFunctions(const RegularExpression &regex, bool include_inlines,
bool append, SymbolContextList &sc_list) override;
uint32_t FindTypes(ConstString name,
const CompilerDeclContext *parent_decl_ctx, bool append,
uint32_t max_matches,
llvm::DenseSet<SymbolFile *> &searched_symbol_files,
TypeMap &types) override;
size_t FindTypes(const std::vector<CompilerContext> &context, bool append,
TypeMap &types) override;
TypeSystem *GetTypeSystemForLanguage(lldb::LanguageType language) override {
return nullptr;
}
CompilerDeclContext
FindNamespace(ConstString name,
const CompilerDeclContext *parent_decl_ctx) override {
return CompilerDeclContext();
}
void AddSymbols(Symtab &symtab) override;
lldb::UnwindPlanSP
GetUnwindPlan(const Address &address,
const RegisterInfoResolver &resolver) override;
ConstString GetPluginName() override { return GetPluginNameStatic(); }
uint32_t GetPluginVersion() override { return 1; }
private:
// A class representing a position in the breakpad file. Useful for
// remembering the position so we can go back to it later and parse more data.
// Can be converted to/from a LineIterator, but it has a much smaller memory
// footprint.
struct Bookmark {
uint32_t section;
size_t offset;
friend bool operator<(const Bookmark &lhs, const Bookmark &rhs) {
return std::tie(lhs.section, lhs.offset) <
std::tie(rhs.section, rhs.offset);
}
};
// At iterator class for simplifying algorithms reading data from the breakpad
// file. It iterates over all records (lines) in the sections of a given type.
// It also supports saving a specific position (via the GetBookmark() method)
// and then resuming from it afterwards.
class LineIterator;
// Return an iterator range for all records in the given object file of the
// given type.
llvm::iterator_range<LineIterator> lines(Record::Kind section_type);
// Breakpad files do not contain sufficient information to correctly
// reconstruct compile units. The approach chosen here is to treat each
// function as a compile unit. The compile unit name is the name if the first
// line entry belonging to this function.
// This class is our internal representation of a compile unit. It stores the
// CompileUnit object and a bookmark pointing to the FUNC record of the
// compile unit function. It also lazily construct the list of support files
// and line table entries for the compile unit, when these are needed.
class CompUnitData {
public:
CompUnitData(Bookmark bookmark) : bookmark(bookmark) {}
CompUnitData() = default;
CompUnitData(const CompUnitData &rhs) : bookmark(rhs.bookmark) {}
CompUnitData &operator=(const CompUnitData &rhs) {
bookmark = rhs.bookmark;
support_files.reset();
line_table_up.reset();
return *this;
}
friend bool operator<(const CompUnitData &lhs, const CompUnitData &rhs) {
return lhs.bookmark < rhs.bookmark;
}
Bookmark bookmark;
llvm::Optional<FileSpecList> support_files;
std::unique_ptr<LineTable> line_table_up;
};
SymbolVendor &GetSymbolVendor();
lldb::addr_t GetBaseFileAddress();
void ParseFileRecords();
void ParseCUData();
void ParseLineTableAndSupportFiles(CompileUnit &cu, CompUnitData &data);
void ParseUnwindData();
bool ParseUnwindRow(llvm::StringRef unwind_rules,
const RegisterInfoResolver &resolver,
UnwindPlan::Row &row);
using CompUnitMap = RangeDataVector<lldb::addr_t, lldb::addr_t, CompUnitData>;
llvm::Optional<std::vector<FileSpec>> m_files;
llvm::Optional<CompUnitMap> m_cu_data;
using UnwindMap = RangeDataVector<lldb::addr_t, lldb::addr_t, Bookmark>;
llvm::Optional<UnwindMap> m_unwind_data;
llvm::BumpPtrAllocator m_allocator;
};
} // namespace breakpad
} // namespace lldb_private
#endif