Ryan Macnak
b0fd6d4a15
TEST=google3 Change-Id: I23236f32d78920388c0b7d2beb738e7cec965226 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/433580 Reviewed-by: Alexander Aprelev <aam@google.com> Commit-Queue: Ryan Macnak <rmacnak@google.com>
2015 lines
74 KiB
C++
2015 lines
74 KiB
C++
// Copyright (c) 2019, the Dart project authors. Please see the AUTHORS file
|
|
// for details. All rights reserved. Use of this source code is governed by a
|
|
// BSD-style license that can be found in the LICENSE file.
|
|
|
|
#include "vm/elf.h"
|
|
|
|
#include "platform/elf.h"
|
|
#include "platform/unwinding_records.h"
|
|
#include "vm/cpu.h"
|
|
#include "vm/dwarf.h"
|
|
#include "vm/dwarf_so_writer.h"
|
|
#include "vm/hash_map.h"
|
|
#include "vm/image_snapshot.h"
|
|
#include "vm/stack_frame.h"
|
|
#include "vm/thread.h"
|
|
#include "vm/unwinding_records.h"
|
|
#include "vm/zone_text_buffer.h"
|
|
|
|
namespace dart {
|
|
|
|
#if defined(DART_PRECOMPILER)
|
|
|
|
class ElfWriteStream : public SharedObjectWriter::DelegatingWriteStream {
|
|
public:
|
|
explicit ElfWriteStream(BaseWriteStream* stream, const ElfWriter& elf)
|
|
: SharedObjectWriter::DelegatingWriteStream(stream, elf), elf_(elf) {}
|
|
|
|
void WriteStringTableIndex();
|
|
|
|
void WriteHalf(uint16_t value) { stream_->WriteFixed(value); }
|
|
void WriteWord(uint32_t value) { stream_->WriteFixed(value); }
|
|
void WriteAddr(compiler::target::uword value) { stream_->WriteFixed(value); }
|
|
void WriteOff(compiler::target::uword value) { stream_->WriteFixed(value); }
|
|
#if defined(TARGET_ARCH_IS_64_BIT)
|
|
void WriteXWord(uint64_t value) { stream_->WriteFixed(value); }
|
|
#endif
|
|
|
|
bool HasValueForLabel(intptr_t label, intptr_t* value) const override;
|
|
|
|
private:
|
|
const ElfWriter& elf_;
|
|
|
|
DISALLOW_COPY_AND_ASSIGN(ElfWriteStream);
|
|
};
|
|
|
|
static constexpr intptr_t kLinearInitValue = -1;
|
|
|
|
#define DEFINE_LINEAR_FIELD_METHODS(name) \
|
|
intptr_t name() const { \
|
|
ASSERT(name##_ != kLinearInitValue); \
|
|
return name##_; \
|
|
} \
|
|
bool name##_is_set() const { \
|
|
return name##_ != kLinearInitValue; \
|
|
} \
|
|
void set_##name(intptr_t value) { \
|
|
ASSERT(value != kLinearInitValue); \
|
|
ASSERT_EQUAL(name##_, kLinearInitValue); \
|
|
name##_ = value; \
|
|
}
|
|
|
|
#define DEFINE_LINEAR_FIELD(name) intptr_t name##_ = kLinearInitValue;
|
|
|
|
// We only allow for dynamic casting to a subset of section types, since
|
|
// these are the only ones we need to distinguish at runtime.
|
|
#define FOR_EACH_SECTION_TYPE(V) \
|
|
V(ReservedSection) \
|
|
V(ElfSymbolTable) \
|
|
V(DynamicTable) \
|
|
V(BitsContainer) \
|
|
V(TextSection) V(DataSection) V(BssSection) V(PseudoSection) V(SectionTable)
|
|
#define DEFINE_TYPE_CHECK_FOR(Type) \
|
|
bool Is##Type() const { \
|
|
return true; \
|
|
}
|
|
|
|
#define DECLARE_SECTION_TYPE_CLASS(Type) class Type;
|
|
FOR_EACH_SECTION_TYPE(DECLARE_SECTION_TYPE_CLASS)
|
|
#undef DECLARE_SECTION_TYPE_CLASS
|
|
|
|
class BitsContainer;
|
|
class Segment;
|
|
class ElfStringTable;
|
|
|
|
// Align note sections and segments to 4 byte boundaries.
|
|
static constexpr intptr_t kNoteAlignment = 4;
|
|
|
|
class ElfSection : public ZoneAllocated {
|
|
public:
|
|
ElfSection(elf::SectionHeaderType t,
|
|
bool allocate,
|
|
bool executable,
|
|
bool writable,
|
|
intptr_t alignment = compiler::target::kWordSize)
|
|
: type(t),
|
|
flags(EncodeFlags(allocate, executable, writable)),
|
|
alignment(alignment),
|
|
// Non-segments will never have a memory offset, here represented by 0.
|
|
memory_offset_(allocate ? kLinearInitValue : 0) {
|
|
// Only SHT_NULL sections (namely, the reserved section) are allowed to have
|
|
// an alignment of 0 (as the written section header entry for the reserved
|
|
// section must be all 0s).
|
|
ASSERT(alignment > 0 || type == elf::SectionHeaderType::SHT_NULL);
|
|
// Non-zero alignments must be a power of 2.
|
|
ASSERT(alignment == 0 || Utils::IsPowerOfTwo(alignment));
|
|
}
|
|
|
|
virtual ~ElfSection() {}
|
|
|
|
const char* ToCString(const ElfStringTable& string_table);
|
|
|
|
// Linker view.
|
|
|
|
const elf::SectionHeaderType type;
|
|
const intptr_t flags;
|
|
const intptr_t alignment;
|
|
|
|
// These are fields that only are not set for most kinds of sections and so we
|
|
// set them to a reasonable default.
|
|
intptr_t link = elf::SHN_UNDEF;
|
|
intptr_t info = 0;
|
|
intptr_t entry_size = 0;
|
|
// This field is set for all sections, but due to reordering, we may set it
|
|
// more than once.
|
|
intptr_t index = elf::SHN_UNDEF;
|
|
|
|
#define FOR_EACH_SECTION_LINEAR_FIELD(M) \
|
|
M(name) \
|
|
M(file_offset)
|
|
|
|
FOR_EACH_SECTION_LINEAR_FIELD(DEFINE_LINEAR_FIELD_METHODS);
|
|
|
|
// Only needs to be overridden for sections that may not be allocated or
|
|
// for allocated sections where MemorySize() and FileSize() may differ.
|
|
virtual intptr_t FileSize() const {
|
|
if (!IsAllocated()) {
|
|
UNREACHABLE();
|
|
}
|
|
return MemorySize();
|
|
}
|
|
|
|
// Loader view.
|
|
|
|
#define FOR_EACH_SEGMENT_LINEAR_FIELD(M) M(memory_offset)
|
|
|
|
FOR_EACH_SEGMENT_LINEAR_FIELD(DEFINE_LINEAR_FIELD_METHODS);
|
|
|
|
// Only needs to be overridden for sections that may be allocated.
|
|
virtual intptr_t MemorySize() const {
|
|
if (IsAllocated()) {
|
|
UNREACHABLE();
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
// Other methods.
|
|
|
|
bool IsAllocated() const {
|
|
return (flags & elf::SHF_ALLOC) == elf::SHF_ALLOC;
|
|
}
|
|
bool IsExecutable() const {
|
|
return (flags & elf::SHF_EXECINSTR) == elf::SHF_EXECINSTR;
|
|
}
|
|
bool IsWritable() const { return (flags & elf::SHF_WRITE) == elf::SHF_WRITE; }
|
|
|
|
// Returns whether the size of a section can change.
|
|
bool HasBeenFinalized() const {
|
|
// Sections can grow or shrink up until ElfWriter::ComputeOffsets has been
|
|
// run, which sets the file (and memory, if applicable) offsets.
|
|
return file_offset_is_set();
|
|
}
|
|
|
|
#define DEFINE_BASE_TYPE_CHECKS(Type) \
|
|
Type* As##Type() { \
|
|
return Is##Type() ? reinterpret_cast<Type*>(this) : nullptr; \
|
|
} \
|
|
const Type* As##Type() const { \
|
|
return const_cast<Type*>(const_cast<ElfSection*>(this)->As##Type()); \
|
|
} \
|
|
virtual bool Is##Type() const { return false; }
|
|
|
|
FOR_EACH_SECTION_TYPE(DEFINE_BASE_TYPE_CHECKS)
|
|
#undef DEFINE_BASE_TYPE_CHECKS
|
|
|
|
// Only some sections support merging.
|
|
virtual bool CanMergeWith(const ElfSection& other) const { return false; }
|
|
virtual void Merge(const ElfSection& other) { UNREACHABLE(); }
|
|
|
|
// Writes the file contents of the section.
|
|
virtual void Write(ElfWriteStream* stream) const { UNREACHABLE(); }
|
|
|
|
virtual void WriteSectionHeader(ElfWriteStream* stream) const {
|
|
#if defined(TARGET_ARCH_IS_32_BIT)
|
|
stream->WriteWord(name());
|
|
stream->WriteWord(static_cast<uint32_t>(type));
|
|
stream->WriteWord(flags);
|
|
stream->WriteAddr(memory_offset());
|
|
stream->WriteOff(file_offset());
|
|
stream->WriteWord(FileSize());
|
|
stream->WriteWord(link);
|
|
stream->WriteWord(info);
|
|
stream->WriteWord(alignment);
|
|
stream->WriteWord(entry_size);
|
|
#else
|
|
stream->WriteWord(name());
|
|
stream->WriteWord(static_cast<uint32_t>(type));
|
|
stream->WriteXWord(flags);
|
|
stream->WriteAddr(memory_offset());
|
|
stream->WriteOff(file_offset());
|
|
stream->WriteXWord(FileSize());
|
|
stream->WriteWord(link);
|
|
stream->WriteWord(info);
|
|
stream->WriteXWord(alignment);
|
|
stream->WriteXWord(entry_size);
|
|
#endif
|
|
}
|
|
|
|
virtual bool IsExcludedFromDebugInfo() const { return false; }
|
|
|
|
private:
|
|
static intptr_t EncodeFlags(bool allocate, bool executable, bool writable) {
|
|
// We currently don't allow sections that are both executable and writable.
|
|
ASSERT(!executable || !writable);
|
|
intptr_t flags = 0;
|
|
if (allocate) flags |= elf::SHF_ALLOC;
|
|
if (executable) flags |= elf::SHF_EXECINSTR;
|
|
if (writable) flags |= elf::SHF_WRITE;
|
|
return flags;
|
|
}
|
|
|
|
FOR_EACH_SECTION_LINEAR_FIELD(DEFINE_LINEAR_FIELD);
|
|
FOR_EACH_SEGMENT_LINEAR_FIELD(DEFINE_LINEAR_FIELD);
|
|
|
|
#undef FOR_EACH_SECTION_LINEAR_FIELD
|
|
#undef FOR_EACH_SEGMENT_LINEAR_FIELD
|
|
};
|
|
|
|
#undef DEFINE_LINEAR_FIELD
|
|
#undef DEFINE_LINEAR_FIELD_METHODS
|
|
|
|
class Segment : public ZoneAllocated {
|
|
public:
|
|
Segment(Zone* zone,
|
|
ElfSection* initial_section,
|
|
elf::ProgramHeaderType segment_type)
|
|
: type(segment_type),
|
|
// Flags for the segment are the same as the initial section.
|
|
flags(EncodeFlags(ASSERT_NOTNULL(initial_section)->IsExecutable(),
|
|
ASSERT_NOTNULL(initial_section)->IsWritable())),
|
|
sections_(zone, 0) {
|
|
// Unlike sections, we don't have a reserved segment with the null type,
|
|
// so we never should pass this value.
|
|
ASSERT(segment_type != elf::ProgramHeaderType::PT_NULL);
|
|
// All segments should have at least one section.
|
|
ASSERT(initial_section != nullptr);
|
|
sections_.Add(initial_section);
|
|
}
|
|
|
|
virtual ~Segment() {}
|
|
|
|
const GrowableArray<ElfSection*>& sections() const { return sections_; }
|
|
|
|
intptr_t Alignment() const {
|
|
switch (type) {
|
|
case elf::ProgramHeaderType::PT_LOAD:
|
|
return ElfWriter::kPageSize;
|
|
case elf::ProgramHeaderType::PT_PHDR:
|
|
case elf::ProgramHeaderType::PT_DYNAMIC:
|
|
return compiler::target::kWordSize;
|
|
case elf::ProgramHeaderType::PT_NOTE:
|
|
return kNoteAlignment;
|
|
case elf::ProgramHeaderType::PT_GNU_STACK:
|
|
return 1;
|
|
default:
|
|
UNREACHABLE();
|
|
return 0;
|
|
}
|
|
}
|
|
|
|
bool IsExecutable() const { return (flags & elf::PF_X) == elf::PF_X; }
|
|
bool IsWritable() const { return (flags & elf::PF_W) == elf::PF_W; }
|
|
|
|
void WriteProgramHeader(ElfWriteStream* stream) const {
|
|
#if defined(TARGET_ARCH_IS_32_BIT)
|
|
stream->WriteWord(static_cast<uint32_t>(type));
|
|
stream->WriteOff(FileOffset());
|
|
stream->WriteAddr(MemoryOffset()); // Virtual address.
|
|
stream->WriteAddr(MemoryOffset()); // Physical address.
|
|
stream->WriteWord(FileSize());
|
|
stream->WriteWord(MemorySize());
|
|
stream->WriteWord(flags);
|
|
stream->WriteWord(Alignment());
|
|
#else
|
|
stream->WriteWord(static_cast<uint32_t>(type));
|
|
stream->WriteWord(flags);
|
|
stream->WriteOff(FileOffset());
|
|
stream->WriteAddr(MemoryOffset()); // Virtual address.
|
|
stream->WriteAddr(MemoryOffset()); // Physical address.
|
|
stream->WriteXWord(FileSize());
|
|
stream->WriteXWord(MemorySize());
|
|
stream->WriteXWord(Alignment());
|
|
#endif
|
|
}
|
|
|
|
// Adds a given section to the end of this segment. Returns whether the
|
|
// section was successfully added.
|
|
bool Add(ElfSection* section) {
|
|
ASSERT(section != nullptr);
|
|
// We can't add if memory offsets have already been calculated.
|
|
ASSERT(!section->memory_offset_is_set());
|
|
// We only add additional sections to load segments.
|
|
ASSERT(type == elf::ProgramHeaderType::PT_LOAD);
|
|
// We only add sections with the same executable and writable bits.
|
|
if (IsExecutable() != section->IsExecutable() ||
|
|
IsWritable() != section->IsWritable()) {
|
|
return false;
|
|
}
|
|
sections_.Add(section);
|
|
return true;
|
|
}
|
|
|
|
intptr_t FileOffset() const { return sections_[0]->file_offset(); }
|
|
|
|
intptr_t FileSize() const {
|
|
auto const last = sections_.Last();
|
|
const intptr_t end = last->file_offset() + last->FileSize();
|
|
return end - FileOffset();
|
|
}
|
|
|
|
intptr_t MemoryOffset() const { return sections_[0]->memory_offset(); }
|
|
|
|
intptr_t MemorySize() const {
|
|
auto const last = sections_.Last();
|
|
const intptr_t end = last->memory_offset() + last->MemorySize();
|
|
return end - MemoryOffset();
|
|
}
|
|
|
|
intptr_t MemoryEnd() const { return MemoryOffset() + MemorySize(); }
|
|
|
|
const elf::ProgramHeaderType type;
|
|
const intptr_t flags;
|
|
|
|
private:
|
|
static intptr_t EncodeFlags(bool executable, bool writable) {
|
|
intptr_t flags = elf::PF_R;
|
|
if (executable) flags |= elf::PF_X;
|
|
if (writable) flags |= elf::PF_W;
|
|
return flags;
|
|
}
|
|
|
|
GrowableArray<ElfSection*> sections_;
|
|
};
|
|
|
|
// Represents the first entry in the section table, which should only contain
|
|
// zero values and does not correspond to a memory segment.
|
|
class ReservedSection : public ElfSection {
|
|
public:
|
|
ReservedSection()
|
|
: ElfSection(elf::SectionHeaderType::SHT_NULL,
|
|
/*allocate=*/false,
|
|
/*executable=*/false,
|
|
/*writable=*/false,
|
|
/*alignment=*/0) {
|
|
set_file_offset(0);
|
|
}
|
|
|
|
DEFINE_TYPE_CHECK_FOR(ReservedSection);
|
|
intptr_t FileSize() const { return 0; }
|
|
};
|
|
|
|
// Specifies the permissions used for the stack, notably whether the stack
|
|
// should be executable. If absent, the stack will be executable.
|
|
class GnuStackSection : public ElfSection {
|
|
public:
|
|
GnuStackSection()
|
|
: ElfSection(elf::SectionHeaderType::SHT_NULL,
|
|
/*allocate=*/false,
|
|
/*executable=*/false,
|
|
/*writable=*/true) {
|
|
set_file_offset(0);
|
|
}
|
|
|
|
intptr_t FileSize() const { return 0; }
|
|
};
|
|
|
|
class ElfStringTable : public ElfSection {
|
|
public:
|
|
explicit ElfStringTable(Zone* zone, bool allocate)
|
|
: ElfSection(elf::SectionHeaderType::SHT_STRTAB,
|
|
allocate,
|
|
/*executable=*/false,
|
|
/*writable=*/false),
|
|
dynamic_(allocate),
|
|
text_(zone, 128),
|
|
text_indices_(zone) {
|
|
Add("");
|
|
}
|
|
|
|
intptr_t FileSize() const { return text_.length(); }
|
|
intptr_t MemorySize() const { return dynamic_ ? FileSize() : 0; }
|
|
|
|
void Write(ElfWriteStream* stream) const {
|
|
stream->WriteBytes(text_.buffer(), text_.length());
|
|
}
|
|
|
|
intptr_t Add(const char* str) {
|
|
ASSERT(str != nullptr);
|
|
if (auto const kv = text_indices_.Lookup(str)) {
|
|
return kv->value;
|
|
}
|
|
intptr_t offset = text_.length();
|
|
text_.AddString(str);
|
|
text_.AddChar('\0');
|
|
text_indices_.Insert({str, offset});
|
|
return offset;
|
|
}
|
|
|
|
const char* At(intptr_t index) const {
|
|
if (index >= text_.length()) return nullptr;
|
|
return text_.buffer() + index;
|
|
}
|
|
|
|
static constexpr intptr_t kNotIndexed = CStringIntMapKeyValueTrait::kNoValue;
|
|
|
|
// Returns the index of |str| if it is present in the string table
|
|
// and |kNotIndexed| otherwise.
|
|
intptr_t Lookup(const char* str) const {
|
|
return text_indices_.LookupValue(str);
|
|
}
|
|
|
|
const bool dynamic_;
|
|
ZoneTextBuffer text_;
|
|
CStringIntMap text_indices_;
|
|
};
|
|
|
|
class ElfSymbolTable : public ElfSection {
|
|
public:
|
|
ElfSymbolTable(Zone* zone, ElfStringTable* table, bool dynamic)
|
|
: ElfSection(dynamic ? elf::SectionHeaderType::SHT_DYNSYM
|
|
: elf::SectionHeaderType::SHT_SYMTAB,
|
|
dynamic,
|
|
/*executable=*/false,
|
|
/*writable=*/false),
|
|
zone_(zone),
|
|
table_(table),
|
|
dynamic_(dynamic),
|
|
symbols_(zone, 1),
|
|
by_label_index_(zone) {
|
|
link = table_->index;
|
|
entry_size = sizeof(elf::Symbol);
|
|
// The first symbol table entry is reserved and must be all zeros.
|
|
// (String tables always have the empty string at the 0th index.)
|
|
ASSERT_EQUAL(table_->Lookup(""), 0);
|
|
symbols_.Add({/*name_index=*/0, elf::STB_LOCAL, elf::STT_NOTYPE, /*size=*/0,
|
|
elf::SHN_UNDEF, /*offset=*/0, /*label =*/0});
|
|
// The info field on a symbol table section holds the index of the first
|
|
// non-local symbol, so since there are none yet, it points past the single
|
|
// symbol we do have.
|
|
info = 1;
|
|
}
|
|
|
|
DEFINE_TYPE_CHECK_FOR(ElfSymbolTable)
|
|
const ElfStringTable& strtab() const { return *table_; }
|
|
intptr_t FileSize() const { return symbols_.length() * entry_size; }
|
|
intptr_t MemorySize() const { return dynamic_ ? FileSize() : 0; }
|
|
|
|
struct Symbol {
|
|
void Write(ElfWriteStream* stream) const {
|
|
const intptr_t start = stream->Position();
|
|
ASSERT(section_index == elf::SHN_UNDEF || offset > 0);
|
|
stream->WriteWord(name_index);
|
|
#if defined(TARGET_ARCH_IS_32_BIT)
|
|
stream->WriteAddr(offset);
|
|
stream->WriteWord(size);
|
|
stream->WriteByte(elf::SymbolInfo(binding, type));
|
|
stream->WriteByte(0);
|
|
stream->WriteHalf(section_index);
|
|
#else
|
|
stream->WriteByte(elf::SymbolInfo(binding, type));
|
|
stream->WriteByte(0);
|
|
stream->WriteHalf(section_index);
|
|
stream->WriteAddr(offset);
|
|
stream->WriteXWord(size);
|
|
#endif
|
|
ASSERT_EQUAL(stream->Position() - start, sizeof(elf::Symbol));
|
|
}
|
|
|
|
intptr_t name_index;
|
|
intptr_t binding;
|
|
intptr_t type;
|
|
intptr_t size;
|
|
// Must be updated whenever sections are reordered.
|
|
intptr_t section_index;
|
|
// Initialized to the section-relative offset, must be updated to the
|
|
// snapshot-relative offset before writing.
|
|
intptr_t offset;
|
|
// Only used within the VM and not written as part of the ELF file. If 0,
|
|
// this symbol cannot be looked up via label.
|
|
intptr_t label;
|
|
|
|
private:
|
|
DISALLOW_ALLOCATION();
|
|
};
|
|
|
|
const GrowableArray<Symbol>& symbols() const { return symbols_; }
|
|
|
|
void Initialize(const GrowableArray<ElfSection*>& sections);
|
|
|
|
void Write(ElfWriteStream* stream) const {
|
|
for (const auto& symbol : symbols_) {
|
|
const intptr_t start = stream->Position();
|
|
symbol.Write(stream);
|
|
ASSERT_EQUAL(stream->Position() - start, entry_size);
|
|
}
|
|
}
|
|
|
|
void AddSymbol(const char* name,
|
|
intptr_t binding,
|
|
intptr_t type,
|
|
intptr_t size,
|
|
intptr_t index,
|
|
intptr_t offset,
|
|
intptr_t label) {
|
|
ASSERT(label > 0);
|
|
ASSERT(!table_->HasBeenFinalized());
|
|
auto const name_index = table_->Add(name);
|
|
ASSERT(name_index != 0);
|
|
const intptr_t new_index = symbols_.length();
|
|
symbols_.Add({name_index, binding, type, size, index, offset, label});
|
|
by_label_index_.Insert(label, new_index);
|
|
// The info field on a symbol table section holds the index of the first
|
|
// non-local symbol, so that local symbols can be skipped if desired. Thus,
|
|
// we need to make sure local symbols are before any non-local ones.
|
|
if (binding == elf::STB_LOCAL) {
|
|
if (info != new_index) {
|
|
// There are non-local symbols, as otherwise [info] would be the
|
|
// index of the new symbol. Since the order doesn't otherwise matter,
|
|
// swap the new local symbol with the value at index [info], so when
|
|
// [info] is incremented it will point just past the new local symbol.
|
|
ASSERT(symbols_[info].binding != elf::STB_LOCAL);
|
|
symbols_.Swap(info, new_index);
|
|
// Since by_label_index has indices into symbols_, we need to update it.
|
|
by_label_index_.Update({symbols_[info].label, info});
|
|
by_label_index_.Update({symbols_[new_index].label, new_index});
|
|
}
|
|
info += 1;
|
|
}
|
|
}
|
|
|
|
void UpdateSectionIndices(const GrowableArray<intptr_t>& index_map) {
|
|
#if defined(DEBUG)
|
|
const intptr_t map_size = index_map.length();
|
|
// The first entry must be 0 so that symbols with index SHN_UNDEF, like
|
|
// the initial reserved symbol, are unchanged.
|
|
ASSERT_EQUAL(index_map[0], 0);
|
|
for (intptr_t i = 1; i < map_size; i++) {
|
|
ASSERT(index_map[i] != 0);
|
|
ASSERT(index_map[i] < map_size);
|
|
}
|
|
#endif
|
|
for (auto& symbol : symbols_) {
|
|
DEBUG_ASSERT(symbol.section_index < map_size);
|
|
symbol.section_index = index_map[symbol.section_index];
|
|
}
|
|
}
|
|
|
|
void Finalize(const GrowableArray<intptr_t>& address_map) {
|
|
#if defined(DEBUG)
|
|
const intptr_t map_size = address_map.length();
|
|
// The first entry must be 0 so that symbols with index SHN_UNDEF, like
|
|
// the initial reserved symbol, are unchanged.
|
|
ASSERT_EQUAL(address_map[0], 0);
|
|
for (intptr_t i = 1; i < map_size; i++) {
|
|
// No section begins at the start of the snapshot.
|
|
ASSERT(address_map[i] != 0);
|
|
}
|
|
#endif
|
|
for (auto& symbol : symbols_) {
|
|
DEBUG_ASSERT(symbol.section_index < map_size);
|
|
symbol.offset += address_map[symbol.section_index];
|
|
}
|
|
}
|
|
|
|
const Symbol* FindLabel(intptr_t label) const {
|
|
ASSERT(label > 0);
|
|
const intptr_t symbols_index = by_label_index_.Lookup(label);
|
|
if (symbols_index == 0) return nullptr; // Not found.
|
|
return &symbols_[symbols_index];
|
|
}
|
|
|
|
private:
|
|
static intptr_t ElfSymbolType(SharedObjectWriter::SymbolData::Type type) {
|
|
switch (type) {
|
|
case SharedObjectWriter::SymbolData::Type::Section:
|
|
return elf::STT_SECTION;
|
|
case SharedObjectWriter::SymbolData::Type::Function:
|
|
return elf::STT_FUNC;
|
|
case SharedObjectWriter::SymbolData::Type::Object:
|
|
return elf::STT_OBJECT;
|
|
}
|
|
UNREACHABLE();
|
|
}
|
|
|
|
Zone* const zone_;
|
|
ElfStringTable* const table_;
|
|
const bool dynamic_;
|
|
GrowableArray<Symbol> symbols_;
|
|
// Maps positive symbol labels to indexes in symbols_. No entry for the
|
|
// reserved symbol, which has index 0, the same as the IntMap's kNoValue.
|
|
IntMap<intptr_t> by_label_index_;
|
|
};
|
|
|
|
bool ElfWriteStream::HasValueForLabel(intptr_t label, intptr_t* value) const {
|
|
auto* const symbol = elf_.symtab().FindLabel(label);
|
|
if (symbol != nullptr) {
|
|
*value = symbol->offset;
|
|
}
|
|
return symbol != nullptr;
|
|
}
|
|
|
|
class SymbolHashTable : public ElfSection {
|
|
public:
|
|
SymbolHashTable(Zone* zone, ElfSymbolTable* symtab)
|
|
: ElfSection(elf::SectionHeaderType::SHT_HASH,
|
|
/*allocate=*/true,
|
|
/*executable=*/false,
|
|
/*writable=*/false),
|
|
buckets_(zone, 0),
|
|
chains_(zone, 0) {
|
|
link = symtab->index;
|
|
entry_size = sizeof(int32_t);
|
|
|
|
const auto& symbols = symtab->symbols();
|
|
const intptr_t num_symbols = symbols.length();
|
|
buckets_.FillWith(elf::STN_UNDEF, 0, num_symbols);
|
|
chains_.FillWith(elf::STN_UNDEF, 0, num_symbols);
|
|
|
|
for (intptr_t i = 1; i < num_symbols; i++) {
|
|
const auto& symbol = symbols[i];
|
|
uint32_t hash = HashSymbolName(symtab->strtab().At(symbol.name_index));
|
|
uint32_t probe = hash % num_symbols;
|
|
chains_[i] = buckets_[probe]; // next = head
|
|
buckets_[probe] = i; // head = symbol
|
|
}
|
|
}
|
|
|
|
intptr_t MemorySize() const {
|
|
return entry_size * (buckets_.length() + chains_.length() + 2);
|
|
}
|
|
|
|
void Write(ElfWriteStream* stream) const {
|
|
stream->WriteWord(buckets_.length());
|
|
stream->WriteWord(chains_.length());
|
|
for (const int32_t bucket : buckets_) {
|
|
stream->WriteWord(bucket);
|
|
}
|
|
for (const int32_t chain : chains_) {
|
|
stream->WriteWord(chain);
|
|
}
|
|
}
|
|
|
|
static uint32_t HashSymbolName(const void* p) {
|
|
auto* name = reinterpret_cast<const uint8_t*>(p);
|
|
uint32_t h = 0;
|
|
while (*name != '\0') {
|
|
h = (h << 4) + *name++;
|
|
uint32_t g = h & 0xf0000000;
|
|
h ^= g;
|
|
h ^= g >> 24;
|
|
}
|
|
return h;
|
|
}
|
|
|
|
private:
|
|
GrowableArray<int32_t> buckets_; // "Head"
|
|
GrowableArray<int32_t> chains_; // "Next"
|
|
};
|
|
|
|
class DynamicTable : public ElfSection {
|
|
public:
|
|
// .dynamic section is expected to be writable on most Linux systems
|
|
// unless dynamic linker is explicitly built with support for an read-only
|
|
// .dynamic section (DL_RO_DYN_SECTION).
|
|
DynamicTable(Zone* zone, ElfSymbolTable* symtab, SymbolHashTable* hash)
|
|
: ElfSection(elf::SectionHeaderType::SHT_DYNAMIC,
|
|
/*allocate=*/true,
|
|
/*executable=*/false,
|
|
/*writable=*/true),
|
|
symtab_(symtab),
|
|
hash_(hash) {
|
|
link = strtab().index;
|
|
entry_size = sizeof(elf::DynamicEntry);
|
|
|
|
AddEntry(zone, elf::DynamicEntryType::DT_HASH, kInvalidEntry);
|
|
AddEntry(zone, elf::DynamicEntryType::DT_STRTAB, kInvalidEntry);
|
|
AddEntry(zone, elf::DynamicEntryType::DT_STRSZ, kInvalidEntry);
|
|
AddEntry(zone, elf::DynamicEntryType::DT_SYMTAB, kInvalidEntry);
|
|
AddEntry(zone, elf::DynamicEntryType::DT_SYMENT, sizeof(elf::Symbol));
|
|
AddEntry(zone, elf::DynamicEntryType::DT_NULL, 0);
|
|
}
|
|
|
|
static constexpr intptr_t kInvalidEntry = -1;
|
|
|
|
DEFINE_TYPE_CHECK_FOR(DynamicTable)
|
|
const SymbolHashTable& hash() const { return *hash_; }
|
|
const ElfSymbolTable& symtab() const { return *symtab_; }
|
|
const ElfStringTable& strtab() const { return symtab().strtab(); }
|
|
intptr_t MemorySize() const { return entries_.length() * entry_size; }
|
|
|
|
void Write(ElfWriteStream* stream) const {
|
|
for (intptr_t i = 0; i < entries_.length(); i++) {
|
|
entries_[i]->Write(stream);
|
|
}
|
|
}
|
|
|
|
void Finalize() {
|
|
FinalizeEntry(elf::DynamicEntryType::DT_HASH, hash().memory_offset());
|
|
FinalizeEntry(elf::DynamicEntryType::DT_STRTAB, strtab().memory_offset());
|
|
FinalizeEntry(elf::DynamicEntryType::DT_STRSZ, strtab().MemorySize());
|
|
FinalizeEntry(elf::DynamicEntryType::DT_SYMTAB, symtab().memory_offset());
|
|
}
|
|
|
|
private:
|
|
struct Entry : public ZoneAllocated {
|
|
Entry(elf::DynamicEntryType tag, intptr_t value) : tag(tag), value(value) {}
|
|
|
|
void Write(ElfWriteStream* stream) const {
|
|
ASSERT(value != kInvalidEntry);
|
|
const intptr_t start = stream->Position();
|
|
#if defined(TARGET_ARCH_IS_32_BIT)
|
|
stream->WriteWord(static_cast<uint32_t>(tag));
|
|
stream->WriteAddr(value);
|
|
#else
|
|
stream->WriteXWord(static_cast<uint64_t>(tag));
|
|
stream->WriteAddr(value);
|
|
#endif
|
|
ASSERT_EQUAL(stream->Position() - start, sizeof(elf::DynamicEntry));
|
|
}
|
|
|
|
elf::DynamicEntryType tag;
|
|
intptr_t value;
|
|
};
|
|
|
|
void AddEntry(Zone* zone, elf::DynamicEntryType tag, intptr_t value) {
|
|
auto const entry = new (zone) Entry(tag, value);
|
|
entries_.Add(entry);
|
|
}
|
|
|
|
void FinalizeEntry(elf::DynamicEntryType tag, intptr_t value) {
|
|
for (auto* entry : entries_) {
|
|
if (entry->tag == tag) {
|
|
entry->value = value;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
ElfSymbolTable* const symtab_;
|
|
SymbolHashTable* const hash_;
|
|
GrowableArray<Entry*> entries_;
|
|
};
|
|
|
|
class BitsContainer : public ElfSection {
|
|
public:
|
|
// Fully specified BitsContainer information. Unless otherwise specified,
|
|
// BitContainers are aligned on byte boundaries (i.e., no padding is used).
|
|
BitsContainer(elf::SectionHeaderType type,
|
|
bool allocate,
|
|
bool executable,
|
|
bool writable,
|
|
int alignment = 1,
|
|
bool is_excluded_from_debug_info = false)
|
|
: ElfSection(type, allocate, executable, writable, alignment),
|
|
is_excluded_from_debug_info_(is_excluded_from_debug_info) {}
|
|
|
|
// For BitsContainers used only as unallocated sections.
|
|
explicit BitsContainer(elf::SectionHeaderType type, intptr_t alignment = 1)
|
|
: BitsContainer(type,
|
|
/*allocate=*/false,
|
|
/*executable=*/false,
|
|
/*writable=*/false,
|
|
alignment) {}
|
|
|
|
// For BitsContainers used as segments whose type differ on the type of the
|
|
// ELF file. Creates an elf::SHT_PROGBITS section if type is Snapshot,
|
|
// otherwise creates an elf::SHT_NOBITS section.
|
|
BitsContainer(ElfWriter::Type t,
|
|
bool executable,
|
|
bool writable,
|
|
intptr_t alignment = 1)
|
|
: BitsContainer(t == ElfWriter::Type::Snapshot
|
|
? elf::SectionHeaderType::SHT_PROGBITS
|
|
: elf::SectionHeaderType::SHT_NOBITS,
|
|
/*allocate=*/true,
|
|
executable,
|
|
writable,
|
|
alignment,
|
|
/*is_excluded_from_debug_info=*/true) {}
|
|
|
|
DEFINE_TYPE_CHECK_FOR(BitsContainer)
|
|
|
|
bool IsNoBits() const { return type == elf::SectionHeaderType::SHT_NOBITS; }
|
|
bool HasBytes() const {
|
|
return portions_.length() != 0 && portions_[0].bytes != nullptr;
|
|
}
|
|
|
|
struct Portion {
|
|
void Write(ElfWriteStream* stream, intptr_t section_start) const {
|
|
ASSERT(bytes != nullptr);
|
|
if (relocations != nullptr) {
|
|
const intptr_t address = section_start + offset;
|
|
stream->WriteBytesWithRelocations(bytes, size, address, *relocations);
|
|
} else {
|
|
stream->WriteBytes(bytes, size);
|
|
}
|
|
}
|
|
|
|
intptr_t offset;
|
|
const char* symbol_name;
|
|
intptr_t label;
|
|
const uint8_t* bytes;
|
|
intptr_t size;
|
|
const SharedObjectWriter::RelocationArray* relocations;
|
|
const SharedObjectWriter::SymbolDataArray* symbols;
|
|
|
|
private:
|
|
DISALLOW_ALLOCATION();
|
|
};
|
|
|
|
const GrowableArray<Portion>& portions() const { return portions_; }
|
|
|
|
const Portion& AddPortion(
|
|
const uint8_t* bytes,
|
|
intptr_t size,
|
|
const SharedObjectWriter::RelocationArray* relocations = nullptr,
|
|
const SharedObjectWriter::SymbolDataArray* symbols = nullptr,
|
|
const char* symbol_name = nullptr,
|
|
intptr_t label = 0) {
|
|
// Any named portion should also have a valid symbol label.
|
|
ASSERT(symbol_name == nullptr || label > 0);
|
|
ASSERT(IsNoBits() || bytes != nullptr);
|
|
ASSERT(bytes != nullptr || relocations == nullptr);
|
|
// Make sure all portions are consistent in containing bytes.
|
|
ASSERT(portions_.is_empty() || HasBytes() == (bytes != nullptr));
|
|
const intptr_t offset = Utils::RoundUp(total_size_, alignment);
|
|
portions_.Add(
|
|
{offset, symbol_name, label, bytes, size, relocations, symbols});
|
|
const Portion& portion = portions_.Last();
|
|
total_size_ = offset + size;
|
|
return portion;
|
|
}
|
|
|
|
void Write(ElfWriteStream* stream) const {
|
|
if (type == elf::SectionHeaderType::SHT_NOBITS) return;
|
|
intptr_t start_position = stream->Position(); // Used for checks.
|
|
for (const auto& portion : portions_) {
|
|
stream->Align(alignment);
|
|
ASSERT_EQUAL(stream->Position(), start_position + portion.offset);
|
|
portion.Write(stream, memory_offset());
|
|
}
|
|
ASSERT_EQUAL(stream->Position(), start_position + total_size_);
|
|
}
|
|
|
|
// Returns the hash for the portion corresponding to symbol_name.
|
|
// Returns 0 if the portion has no bytes or no portions have that name.
|
|
uint32_t Hash(const char* symbol_name) const {
|
|
for (const auto& portion : portions_) {
|
|
if (strcmp(symbol_name, portion.symbol_name) == 0) {
|
|
if (portion.bytes == nullptr) return 0;
|
|
const uint32_t hash = Utils::StringHash(portion.bytes, portion.size);
|
|
// Ensure a non-zero return.
|
|
return hash == 0 ? 1 : hash;
|
|
}
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
intptr_t FileSize() const { return IsNoBits() ? 0 : total_size_; }
|
|
intptr_t MemorySize() const { return IsAllocated() ? total_size_ : 0; }
|
|
|
|
virtual bool IsExcludedFromDebugInfo() const {
|
|
return is_excluded_from_debug_info_;
|
|
}
|
|
|
|
private:
|
|
const bool is_excluded_from_debug_info_;
|
|
GrowableArray<Portion> portions_;
|
|
intptr_t total_size_ = 0;
|
|
};
|
|
|
|
class NoteSection : public BitsContainer {
|
|
public:
|
|
NoteSection()
|
|
: BitsContainer(elf::SectionHeaderType::SHT_NOTE,
|
|
/*allocate=*/true,
|
|
/*executable=*/false,
|
|
/*writable=*/false,
|
|
kNoteAlignment) {}
|
|
};
|
|
|
|
// Abstract bits container that allows merging by just appending the portion
|
|
// information (with properly adjusted offsets) of the other to this one.
|
|
class ConcatenableBitsContainer : public BitsContainer {
|
|
public:
|
|
ConcatenableBitsContainer(ElfWriter::Type type,
|
|
bool executable,
|
|
bool writable,
|
|
intptr_t alignment)
|
|
: BitsContainer(type, executable, writable, alignment) {}
|
|
|
|
virtual bool CanMergeWith(const ElfSection& other) const = 0;
|
|
virtual void Merge(const ElfSection& other) {
|
|
ASSERT(other.IsBitsContainer());
|
|
ASSERT(CanMergeWith(other));
|
|
for (const auto& portion : other.AsBitsContainer()->portions()) {
|
|
AddPortion(portion.bytes, portion.size, portion.relocations,
|
|
portion.symbols, portion.symbol_name, portion.label);
|
|
}
|
|
}
|
|
};
|
|
|
|
class TextSection : public ConcatenableBitsContainer {
|
|
public:
|
|
explicit TextSection(ElfWriter::Type t)
|
|
: ConcatenableBitsContainer(t,
|
|
/*executable=*/true,
|
|
/*writable=*/false,
|
|
ImageWriter::kTextAlignment) {}
|
|
|
|
DEFINE_TYPE_CHECK_FOR(TextSection);
|
|
|
|
virtual bool CanMergeWith(const ElfSection& other) const {
|
|
return other.IsTextSection();
|
|
}
|
|
};
|
|
|
|
class DataSection : public ConcatenableBitsContainer {
|
|
public:
|
|
explicit DataSection(ElfWriter::Type t)
|
|
: ConcatenableBitsContainer(t,
|
|
/*executable=*/false,
|
|
/*writable=*/false,
|
|
ImageWriter::kRODataAlignment) {}
|
|
|
|
DEFINE_TYPE_CHECK_FOR(DataSection);
|
|
|
|
virtual bool CanMergeWith(const ElfSection& other) const {
|
|
return other.IsDataSection();
|
|
}
|
|
};
|
|
|
|
class BssSection : public ConcatenableBitsContainer {
|
|
public:
|
|
explicit BssSection(ElfWriter::Type t)
|
|
: ConcatenableBitsContainer(t,
|
|
/*executable=*/false,
|
|
/*writable=*/true,
|
|
ImageWriter::kBssAlignment) {}
|
|
|
|
DEFINE_TYPE_CHECK_FOR(BssSection);
|
|
|
|
virtual bool CanMergeWith(const ElfSection& other) const {
|
|
return other.IsBssSection();
|
|
}
|
|
};
|
|
|
|
// Represents portions of the file/memory space which do not correspond to
|
|
// sections from the section header. Should never be added to the section table,
|
|
// but may be added to segments.
|
|
class PseudoSection : public ElfSection {
|
|
public:
|
|
// All PseudoSections are aligned to target word size.
|
|
static constexpr intptr_t kAlignment = compiler::target::kWordSize;
|
|
|
|
PseudoSection(bool allocate, bool executable, bool writable)
|
|
: ElfSection(elf::SectionHeaderType::SHT_NULL,
|
|
allocate,
|
|
executable,
|
|
writable,
|
|
kAlignment) {}
|
|
|
|
DEFINE_TYPE_CHECK_FOR(PseudoSection)
|
|
|
|
void Write(ElfWriteStream* stream) const = 0;
|
|
};
|
|
|
|
class ProgramTable : public PseudoSection {
|
|
public:
|
|
explicit ProgramTable(Zone* zone)
|
|
: PseudoSection(/*allocate=*/true,
|
|
/*executable=*/false,
|
|
/*writable=*/false),
|
|
segments_(zone, 0) {
|
|
entry_size = sizeof(elf::ProgramHeader);
|
|
}
|
|
|
|
const GrowableArray<Segment*>& segments() const { return segments_; }
|
|
intptr_t SegmentCount() const { return segments_.length(); }
|
|
intptr_t MemorySize() const {
|
|
return segments_.length() * sizeof(elf::ProgramHeader);
|
|
}
|
|
|
|
void Add(Segment* segment) {
|
|
ASSERT(segment != nullptr);
|
|
segments_.Add(segment);
|
|
}
|
|
|
|
void Write(ElfWriteStream* stream) const;
|
|
|
|
private:
|
|
GrowableArray<Segment*> segments_;
|
|
};
|
|
|
|
// This particular PseudoSection should not appear in segments either (hence
|
|
// being marked non-allocated), but is directly held by the Elf object.
|
|
class SectionTable : public PseudoSection {
|
|
public:
|
|
explicit SectionTable(Zone* zone)
|
|
: PseudoSection(/*allocate=*/false,
|
|
/*executable=*/false,
|
|
/*writable=*/false),
|
|
zone_(zone),
|
|
sections_(zone_, 2),
|
|
shstrtab_(zone_, /*allocate=*/false) {
|
|
entry_size = sizeof(elf::SectionHeader);
|
|
// The section at index 0 (elf::SHN_UNDEF) must be all 0s.
|
|
ASSERT_EQUAL(shstrtab_.Lookup(""), 0);
|
|
Add(new (zone_) ReservedSection(), "");
|
|
Add(&shstrtab_, ".shstrtab");
|
|
}
|
|
|
|
const GrowableArray<ElfSection*>& sections() const { return sections_; }
|
|
intptr_t SectionCount() const { return sections_.length(); }
|
|
intptr_t StringTableIndex() const { return shstrtab_.index; }
|
|
|
|
const ElfStringTable& shstrtab() const { return shstrtab_; }
|
|
|
|
bool HasSectionNamed(const char* name) {
|
|
return shstrtab_.Lookup(name) != ElfStringTable::kNotIndexed;
|
|
}
|
|
|
|
void Add(ElfSection* section, const char* name = nullptr) {
|
|
ASSERT(!section->IsPseudoSection());
|
|
ASSERT(name != nullptr || section->name_is_set());
|
|
if (name != nullptr) {
|
|
// First, check for an existing section with the same table name.
|
|
if (auto* const old_section = Find(name)) {
|
|
ASSERT(old_section->CanMergeWith(*section));
|
|
old_section->Merge(*section);
|
|
return;
|
|
}
|
|
// No existing section with this name.
|
|
const intptr_t name_index = shstrtab_.Add(name);
|
|
section->set_name(name_index);
|
|
}
|
|
section->index = sections_.length();
|
|
sections_.Add(section);
|
|
}
|
|
|
|
ElfSection* Find(const char* name) const {
|
|
const intptr_t name_index = shstrtab_.Lookup(name);
|
|
if (name_index == ElfStringTable::kNotIndexed) {
|
|
// We're guaranteed that no section with this name has been added yet.
|
|
return nullptr;
|
|
}
|
|
// We check walk all sections to check for uniqueness in DEBUG mode.
|
|
ElfSection* result = nullptr;
|
|
for (ElfSection* const section : sections_) {
|
|
if (section->name() == name_index) {
|
|
#if defined(DEBUG)
|
|
ASSERT(result == nullptr);
|
|
result = section;
|
|
#else
|
|
return section;
|
|
#endif
|
|
}
|
|
}
|
|
return result;
|
|
}
|
|
|
|
TextSection* FindTextSection() const {
|
|
if (auto section = Find(ElfWriter::kTextName)) {
|
|
return section->AsTextSection();
|
|
}
|
|
return nullptr;
|
|
}
|
|
|
|
intptr_t FileSize() const {
|
|
return sections_.length() * sizeof(elf::SectionHeader);
|
|
}
|
|
|
|
void Write(ElfWriteStream* stream) const;
|
|
|
|
// Reorders the sections for creating a minimal amount of segments and
|
|
// creates and returns an appropriate program table.
|
|
//
|
|
// Also takes and adjusts section indices in the static symbol table, since it
|
|
// is not recorded in sections_ for stripped outputs.
|
|
ProgramTable* CreateProgramTable(ElfSymbolTable* symtab);
|
|
|
|
private:
|
|
Zone* const zone_;
|
|
GrowableArray<ElfSection*> sections_;
|
|
ElfStringTable shstrtab_;
|
|
};
|
|
|
|
void ElfWriteStream::WriteStringTableIndex() {
|
|
return WriteHalf(elf_.section_table().StringTableIndex());
|
|
}
|
|
|
|
class ElfHeader : public PseudoSection {
|
|
public:
|
|
ElfHeader(const ProgramTable& program_table,
|
|
const SectionTable& section_table)
|
|
: PseudoSection(/*allocate=*/true,
|
|
/*executable=*/false,
|
|
/*writable=*/false),
|
|
program_table_(program_table),
|
|
section_table_(section_table) {}
|
|
|
|
intptr_t MemorySize() const { return sizeof(elf::ElfHeader); }
|
|
|
|
void Write(ElfWriteStream* stream) const;
|
|
|
|
private:
|
|
const ProgramTable& program_table_;
|
|
const SectionTable& section_table_;
|
|
};
|
|
|
|
#undef DEFINE_TYPE_CHECK_FOR
|
|
#undef FOR_EACH_SECTION_TYPE
|
|
|
|
ElfWriter::ElfWriter(Zone* zone,
|
|
BaseWriteStream* stream,
|
|
Type type,
|
|
Dwarf* dwarf)
|
|
: SharedObjectWriter(zone, stream, type, dwarf),
|
|
section_table_(new (zone) SectionTable(zone)) {}
|
|
|
|
void ElfWriter::AddText(const char* name,
|
|
intptr_t label,
|
|
const uint8_t* bytes,
|
|
intptr_t size,
|
|
const SharedObjectWriter::RelocationArray* relocations,
|
|
const SharedObjectWriter::SymbolDataArray* symbols) {
|
|
auto* const container = new (zone_) TextSection(type_);
|
|
container->AddPortion(bytes, size, relocations, symbols, name, label);
|
|
section_table_->Add(container, kTextName);
|
|
}
|
|
|
|
void ElfWriter::CreateBSS() {
|
|
// Not idempotent.
|
|
ASSERT(section_table_->Find(kBssName) == nullptr);
|
|
// No text section means no BSS section.
|
|
auto* const text_section = section_table_->Find(kTextName);
|
|
if (text_section == nullptr) return;
|
|
ASSERT(text_section->IsTextSection());
|
|
|
|
auto* const bss_container = new (zone_) BssSection(type_);
|
|
for (const auto& portion : text_section->AsBitsContainer()->portions()) {
|
|
size_t size;
|
|
const char* symbol_name;
|
|
intptr_t label;
|
|
// First determine whether this is the VM's text portion or the isolate's.
|
|
if (strcmp(portion.symbol_name, kVmSnapshotInstructionsAsmSymbol) == 0) {
|
|
size = BSS::kVmEntryCount * compiler::target::kWordSize;
|
|
symbol_name = kVmSnapshotBssAsmSymbol;
|
|
label = kVmBssLabel;
|
|
} else if (strcmp(portion.symbol_name,
|
|
kIsolateSnapshotInstructionsAsmSymbol) == 0) {
|
|
size = BSS::kIsolateGroupEntryCount * compiler::target::kWordSize;
|
|
symbol_name = kIsolateSnapshotBssAsmSymbol;
|
|
label = kIsolateBssLabel;
|
|
} else {
|
|
// Not VM or isolate text.
|
|
UNREACHABLE();
|
|
}
|
|
|
|
uint8_t* bytes = nullptr;
|
|
if (type_ == Type::Snapshot) {
|
|
// Ideally the BSS segment would take no space in the object, but
|
|
// Android's "strip" utility truncates the memory-size of our segments to
|
|
// their file-size.
|
|
//
|
|
// Therefore we must insert zero-filled data for the BSS.
|
|
bytes = zone_->Alloc<uint8_t>(size);
|
|
memset(bytes, 0, size);
|
|
}
|
|
// For the BSS section, we add the section symbols as local symbols in the
|
|
// static symbol table, as these addresses are only used for relocation.
|
|
// (This matches the behavior in the assembly output.)
|
|
auto* symbols = new (zone_) SharedObjectWriter::SymbolDataArray();
|
|
symbols->Add({symbol_name, SymbolData::Type::Section, 0, size, label});
|
|
bss_container->AddPortion(bytes, size, /*relocations=*/nullptr, symbols);
|
|
}
|
|
|
|
section_table_->Add(bss_container, kBssName);
|
|
}
|
|
|
|
void ElfWriter::AddROData(
|
|
const char* name,
|
|
intptr_t label,
|
|
const uint8_t* bytes,
|
|
intptr_t size,
|
|
const SharedObjectWriter::RelocationArray* relocations,
|
|
const SharedObjectWriter::SymbolDataArray* symbols) {
|
|
auto* const container = new (zone_) DataSection(type_);
|
|
container->AddPortion(bytes, size, relocations, symbols, name, label);
|
|
section_table_->Add(container, kDataName);
|
|
}
|
|
|
|
void ElfSymbolTable::Initialize(const GrowableArray<ElfSection*>& sections) {
|
|
for (auto* const section : sections) {
|
|
// The values of all added symbols are memory addresses.
|
|
if (!section->IsAllocated()) continue;
|
|
if (auto* const bits = section->AsBitsContainer()) {
|
|
for (const auto& portion : section->AsBitsContainer()->portions()) {
|
|
if (portion.symbol_name != nullptr) {
|
|
// Global dynamic symbols for the content of a given section, which is
|
|
// always a single structured element (and thus we use STT_OBJECT).
|
|
const intptr_t binding = elf::STB_GLOBAL;
|
|
const intptr_t type = elf::STT_OBJECT;
|
|
// Some tools assume the static symbol table is a superset of the
|
|
// dynamic symbol table when it exists and only use it, so put all
|
|
// dynamic symbols there also. (see dartbug.com/41783).
|
|
AddSymbol(portion.symbol_name, binding, type, portion.size,
|
|
section->index, portion.offset, portion.label);
|
|
}
|
|
if (!dynamic_ && portion.symbols != nullptr) {
|
|
for (const auto& symbol_data : *portion.symbols) {
|
|
const intptr_t type = ElfSymbolType(symbol_data.type);
|
|
// Local static-only symbols, e.g., code payloads or RO objects.
|
|
AddSymbol(symbol_data.name, elf::STB_LOCAL, type, symbol_data.size,
|
|
section->index, portion.offset + symbol_data.offset,
|
|
symbol_data.label);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
void ElfWriter::InitializeSymbolTables() {
|
|
// Not idempotent.
|
|
ASSERT(symtab_ == nullptr);
|
|
|
|
// Create static and dynamic symbol tables.
|
|
auto* const dynstrtab = new (zone_) ElfStringTable(zone_, /*allocate=*/true);
|
|
section_table_->Add(dynstrtab, ".dynstr");
|
|
auto* const dynsym =
|
|
new (zone_) ElfSymbolTable(zone_, dynstrtab, /*dynamic=*/true);
|
|
section_table_->Add(dynsym, ".dynsym");
|
|
dynsym->Initialize(section_table_->sections());
|
|
// Now the dynamic symbol table is populated, set up the hash table and
|
|
// dynamic table.
|
|
auto* const hash = new (zone_) SymbolHashTable(zone_, dynsym);
|
|
section_table_->Add(hash, ".hash");
|
|
auto* const dynamic = new (zone_) DynamicTable(zone_, dynsym, hash);
|
|
section_table_->Add(dynamic, kDynamicTableName);
|
|
|
|
// We only add the static string and symbol tables to the section table if
|
|
// this is an unstripped output, but we always create them as they are used
|
|
// to resolve relocations.
|
|
auto* const strtab = new (zone_) ElfStringTable(zone_, /*allocate=*/false);
|
|
if (!IsStripped()) {
|
|
section_table_->Add(strtab, ".strtab");
|
|
}
|
|
symtab_ = new (zone_) ElfSymbolTable(zone_, strtab, /*dynamic=*/false);
|
|
if (!IsStripped()) {
|
|
section_table_->Add(symtab_, ".symtab");
|
|
}
|
|
symtab_->Initialize(section_table_->sections());
|
|
}
|
|
|
|
void ElfWriter::FinalizeEhFrame() {
|
|
#if !defined(TARGET_ARCH_IA32)
|
|
auto text_section = section_table_->FindTextSection();
|
|
// No text section added means no .eh_frame.
|
|
if (text_section == nullptr) return;
|
|
|
|
GrowableArray<Dwarf::FrameDescriptionEntry> fdes(zone_, 0);
|
|
for (const auto& portion : text_section->portions()) {
|
|
ASSERT(portion.label != 0);
|
|
fdes.Add({portion.label, portion.size});
|
|
}
|
|
|
|
ZoneWriteStream stream(zone(), DwarfSharedObjectStream::kInitialBufferSize);
|
|
DwarfSharedObjectStream dwarf_stream(zone_, &stream);
|
|
Dwarf::WriteCallFrameInformationRecords(&dwarf_stream, fdes);
|
|
|
|
auto* const eh_frame = new (zone_)
|
|
BitsContainer(type_, /*executable=*/false, /*writable=*/false);
|
|
eh_frame->AddPortion(dwarf_stream.buffer(), dwarf_stream.bytes_written(),
|
|
dwarf_stream.relocations());
|
|
section_table_->Add(eh_frame, ".eh_frame");
|
|
|
|
#if defined(DART_TARGET_OS_WINDOWS) && defined(TARGET_ARCH_IS_64_BIT)
|
|
// Append Windows unwinding instructions to the end of .text section.
|
|
{ // NOLINT
|
|
auto* const unwinding_instructions_frame = new (zone_) TextSection(type_);
|
|
ZoneWriteStream stream(
|
|
zone(),
|
|
/*initial_size=*/UnwindingRecordsPlatform::SizeInBytes());
|
|
uint8_t* unwinding_instructions =
|
|
zone()->Alloc<uint8_t>(UnwindingRecordsPlatform::SizeInBytes());
|
|
|
|
intptr_t start_offset =
|
|
Utils::RoundUp(text_section->FileSize(), text_section->alignment);
|
|
stream.WriteBytes(UnwindingRecords::GenerateRecordsInto(
|
|
start_offset, unwinding_instructions),
|
|
UnwindingRecordsPlatform::SizeInBytes());
|
|
|
|
unwinding_instructions_frame->AddPortion(stream.buffer(),
|
|
stream.bytes_written());
|
|
section_table_->Add(unwinding_instructions_frame, kTextName);
|
|
}
|
|
#endif
|
|
#endif // !defined(TARGET_ARCH_IA32)
|
|
}
|
|
|
|
void ElfWriter::FinalizeDwarfSections() {
|
|
if (dwarf_ == nullptr) return;
|
|
|
|
// Currently we only output DWARF information involving code.
|
|
ASSERT(section_table_->HasSectionNamed(kTextName));
|
|
|
|
auto add_debug = [&](const char* name,
|
|
const DwarfSharedObjectStream& stream) {
|
|
auto const container =
|
|
new (zone_) BitsContainer(elf::SectionHeaderType::SHT_PROGBITS);
|
|
container->AddPortion(stream.buffer(), stream.bytes_written(),
|
|
stream.relocations());
|
|
section_table_->Add(container, name);
|
|
};
|
|
{
|
|
ZoneWriteStream stream(zone(), DwarfSharedObjectStream::kInitialBufferSize);
|
|
DwarfSharedObjectStream dwarf_stream(zone_, &stream);
|
|
dwarf_->WriteAbbreviations(&dwarf_stream);
|
|
add_debug(".debug_abbrev", dwarf_stream);
|
|
}
|
|
|
|
{
|
|
ZoneWriteStream stream(zone(), DwarfSharedObjectStream::kInitialBufferSize);
|
|
DwarfSharedObjectStream dwarf_stream(zone_, &stream);
|
|
dwarf_->WriteDebugInfo(&dwarf_stream);
|
|
add_debug(".debug_info", dwarf_stream);
|
|
}
|
|
|
|
{
|
|
ZoneWriteStream stream(zone(), DwarfSharedObjectStream::kInitialBufferSize);
|
|
DwarfSharedObjectStream dwarf_stream(zone_, &stream);
|
|
dwarf_->WriteLineNumberProgram(&dwarf_stream);
|
|
add_debug(".debug_line", dwarf_stream);
|
|
}
|
|
}
|
|
|
|
ProgramTable* SectionTable::CreateProgramTable(ElfSymbolTable* symtab) {
|
|
const intptr_t num_sections = sections_.length();
|
|
// Should have at least the reserved entry in sections_.
|
|
ASSERT(!sections_.is_empty());
|
|
ASSERT_EQUAL(sections_[0]->alignment, 0);
|
|
|
|
// The new program table that collects the segments for allocated sections
|
|
// and a few special segments.
|
|
auto* const program_table = new (zone_) ProgramTable(zone_);
|
|
|
|
GrowableArray<ElfSection*> reordered_sections(zone_, num_sections);
|
|
// Maps the old indices of sections to the new ones.
|
|
GrowableArray<intptr_t> index_map(zone_, num_sections);
|
|
index_map.FillWith(0, 0, num_sections);
|
|
|
|
Segment* current_segment = nullptr;
|
|
// Only called for sections in the section table (i.e., not special sections
|
|
// appearing in segments only or the section table itself).
|
|
auto add_to_reordered_sections = [&](ElfSection* section) {
|
|
intptr_t new_index = reordered_sections.length();
|
|
index_map[section->index] = new_index;
|
|
section->index = new_index;
|
|
reordered_sections.Add(section);
|
|
if (section->IsAllocated()) {
|
|
ASSERT(current_segment != nullptr);
|
|
if (!current_segment->Add(section)) {
|
|
// The current segment is incompatible for the current section, so
|
|
// create a new one.
|
|
current_segment = new (zone_)
|
|
Segment(zone_, section, elf::ProgramHeaderType::PT_LOAD);
|
|
program_table->Add(current_segment);
|
|
}
|
|
}
|
|
};
|
|
|
|
// The first section in the section header table is always a reserved
|
|
// entry containing only 0 values, so copy it over from sections_.
|
|
add_to_reordered_sections(sections_[0]);
|
|
|
|
// There are few important invariants originating from Android idiosyncrasies
|
|
// we are trying to maintain when ordering sections:
|
|
//
|
|
// - Android requires the program header table be in the first load segment,
|
|
// so create PseudoSections representing the ELF header and program header
|
|
// table to initialize that segment.
|
|
//
|
|
// - The Android dynamic linker in Jelly Bean incorrectly assumes that all
|
|
// non-writable segments are contiguous. Thus we write them all together.
|
|
// The bug is here: https://github.com/aosp-mirror/platform_bionic/blob/94963af28e445384e19775a838a29e6a71708179/linker/linker.c#L1991-L2001
|
|
//
|
|
// - On Android native libraries can be mapped directly from an APK
|
|
// they are stored uncompressed in it. In such situations the name
|
|
// of the mapping no longer provides enough information for libunwindstack
|
|
// to find the original ELF file and instead it has to rely on heuristics
|
|
// to locate program header table. These heuristics currently assume that
|
|
// program header table will be located in the RO mapping which precedes
|
|
// RX mapping.
|
|
//
|
|
// These invariants imply the following order of segments: RO (program
|
|
// header, .note.gnu.build-id, .dynstr, .dynsym, .hash, .rodata
|
|
// and .eh_frame), RX (.text), RW (.dynamic and .bss).
|
|
//
|
|
auto* const elf_header = new (zone_) ElfHeader(*program_table, *this);
|
|
|
|
// Self-reference to program header table. Required by Android but not by
|
|
// Linux. Must appear before any PT_LOAD entries.
|
|
program_table->Add(new (zone_) Segment(zone_, program_table,
|
|
elf::ProgramHeaderType::PT_PHDR));
|
|
|
|
// Create the initial load segment which contains the ELF header and program
|
|
// table.
|
|
current_segment =
|
|
new (zone_) Segment(zone_, elf_header, elf::ProgramHeaderType::PT_LOAD);
|
|
program_table->Add(current_segment);
|
|
current_segment->Add(program_table);
|
|
|
|
// We now do several passes over the collected sections to reorder them in
|
|
// a way that minimizes segments (and thus padding) in the resulting snapshot.
|
|
|
|
auto add_sections_matching =
|
|
[&](const std::function<bool(ElfSection*)>& should_add) {
|
|
// We emit section in the following order:
|
|
//
|
|
// * all non-NOBITS and non-PROGBITS sections;
|
|
// * all PROGBITS sections which don't get excluded from debug info;
|
|
// * all sections which get excluded from debug info (these are all
|
|
// either PROGBITS or NOBITS depending on the snapshot type);
|
|
// * all NOBITS sections which don't get excluded from debug info;
|
|
//
|
|
// This order guarantees that NOBITS sections are all grouped together
|
|
// at the end of the segment and the order of sections is the same
|
|
// for both snapshot ELF and debug info ELF (in other words it does not
|
|
// change when a section switches its type from PROGBITS to NOBITS).
|
|
//
|
|
// Consistent order is important because different sections have
|
|
// different alignment requirements, which means order might
|
|
// affect memory offset of section. This might cascade down to the
|
|
// text section and create inconsistency between snapshot and debug
|
|
// info.
|
|
//
|
|
// See also ElfWriter::AssertConsistency.
|
|
for (auto* const section : sections_) {
|
|
if (section->type != elf::SectionHeaderType::SHT_NOBITS &&
|
|
section->type != elf::SectionHeaderType::SHT_PROGBITS) {
|
|
if (should_add(section)) {
|
|
add_to_reordered_sections(section);
|
|
}
|
|
}
|
|
}
|
|
for (auto* const section : sections_) {
|
|
if (section->type == elf::SectionHeaderType::SHT_PROGBITS &&
|
|
!section->IsExcludedFromDebugInfo() && should_add(section)) {
|
|
add_to_reordered_sections(section);
|
|
}
|
|
}
|
|
for (auto* const section : sections_) {
|
|
if (section->IsExcludedFromDebugInfo() && should_add(section)) {
|
|
add_to_reordered_sections(section);
|
|
}
|
|
}
|
|
for (auto* const section : sections_) {
|
|
if (section->type == elf::SectionHeaderType::SHT_NOBITS &&
|
|
!section->IsExcludedFromDebugInfo() && should_add(section)) {
|
|
add_to_reordered_sections(section);
|
|
}
|
|
}
|
|
};
|
|
|
|
// If a build ID was created, we put it right after the program table so it
|
|
// can be read with a minimum number of bytes from the ELF file.
|
|
auto* const build_id = Find(ElfWriter::kBuildIdNoteName);
|
|
if (build_id != nullptr) {
|
|
ASSERT(build_id->type == elf::SectionHeaderType::SHT_NOTE);
|
|
add_to_reordered_sections(build_id);
|
|
}
|
|
|
|
// Now add the other non-writable, non-executable allocated sections.
|
|
add_sections_matching([&](ElfSection* section) -> bool {
|
|
if (section == build_id) return false; // Already added.
|
|
return section->IsAllocated() && !section->IsWritable() &&
|
|
!section->IsExecutable();
|
|
});
|
|
|
|
// Now add the executable sections in a new segment.
|
|
add_sections_matching([](ElfSection* section) -> bool {
|
|
return section->IsExecutable(); // Implies IsAllocated() && !IsWritable()
|
|
});
|
|
|
|
// Now add all the writable sections.
|
|
add_sections_matching([](ElfSection* section) -> bool {
|
|
return section->IsWritable(); // Implies IsAllocated() && !IsExecutable()
|
|
});
|
|
|
|
// We put all non-reserved unallocated sections last. Otherwise, they would
|
|
// affect the file offset but not the memory offset of any following allocated
|
|
// sections. Doing it in this order makes it easier to keep file and memory
|
|
// offsets page-aligned with respect to each other, which is required for
|
|
// some loaders.
|
|
add_sections_matching([](ElfSection* section) -> bool {
|
|
// Don't re-add the initial reserved section.
|
|
return !section->IsReservedSection() && !section->IsAllocated();
|
|
});
|
|
|
|
// All sections should have been accounted for in the loops above.
|
|
ASSERT_EQUAL(sections_.length(), reordered_sections.length());
|
|
// Replace the content of sections_ with the reordered sections.
|
|
sections_.Clear();
|
|
sections_.AddArray(reordered_sections);
|
|
|
|
// This must be true for uses of the map to be correct.
|
|
ASSERT_EQUAL(index_map[elf::SHN_UNDEF], elf::SHN_UNDEF);
|
|
|
|
// Since the section indices have been updated, change links to match
|
|
// and update the indexes of symbols in any symbol tables.
|
|
for (auto* const section : sections_) {
|
|
// SHN_UNDEF maps to SHN_UNDEF, so no need to check for it.
|
|
section->link = index_map[section->link];
|
|
if (auto* const table = section->AsElfSymbolTable()) {
|
|
table->UpdateSectionIndices(index_map);
|
|
}
|
|
}
|
|
if (symtab->index == elf::SHN_UNDEF) {
|
|
// The output is stripped, so this wasn't finalized during the loop above.
|
|
symtab->UpdateSectionIndices(index_map);
|
|
}
|
|
|
|
// Add any special non-load segments.
|
|
if (build_id != nullptr) {
|
|
// Add a PT_NOTE segment for the build ID.
|
|
program_table->Add(
|
|
new (zone_) Segment(zone_, build_id, elf::ProgramHeaderType::PT_NOTE));
|
|
}
|
|
|
|
// Add a PT_DYNAMIC segment for the dynamic symbol table.
|
|
ASSERT(HasSectionNamed(ElfWriter::kDynamicTableName));
|
|
auto* const dynamic = Find(ElfWriter::kDynamicTableName)->AsDynamicTable();
|
|
program_table->Add(
|
|
new (zone_) Segment(zone_, dynamic, elf::ProgramHeaderType::PT_DYNAMIC));
|
|
|
|
// Add a PT_GNU_STACK segment to prevent the loading of our snapshot from
|
|
// switch the stack to be executable.
|
|
auto* const gnu_stack = new (zone_) GnuStackSection();
|
|
program_table->Add(new (zone_) Segment(zone_, gnu_stack,
|
|
elf::ProgramHeaderType::PT_GNU_STACK));
|
|
|
|
return program_table;
|
|
}
|
|
|
|
void ElfWriter::Finalize() {
|
|
// Generate the build ID now that we have all user-provided sections.
|
|
GenerateBuildId();
|
|
|
|
// We add a BSS section in all cases, even to the separate debugging
|
|
// information, to ensure that relocated addresses are consistent between ELF
|
|
// snapshots and the corresponding separate debugging information.
|
|
CreateBSS();
|
|
|
|
FinalizeEhFrame();
|
|
FinalizeDwarfSections();
|
|
|
|
// Create and initialize the dynamic and static symbol tables and any
|
|
// other associated sections now that all other sections have been added.
|
|
InitializeSymbolTables();
|
|
// Creates an appropriate program table containing load segments for allocated
|
|
// sections and any other segments needed. May reorder sections to minimize
|
|
// the number of load segments, so also takes the static symbol table so
|
|
// symbol section indices can be adjusted if needed.
|
|
program_table_ = section_table_->CreateProgramTable(symtab_);
|
|
// Calculate file and memory offsets, and finalizes symbol values in any
|
|
// symbol tables.
|
|
ComputeOffsets();
|
|
|
|
#if defined(DEBUG)
|
|
if (type_ == Type::Snapshot) {
|
|
// For files that will be dynamically loaded, ensure the file offsets
|
|
// of allocated sections are page aligned to the memory offsets.
|
|
for (auto* const segment : program_table_->segments()) {
|
|
for (auto* const section : segment->sections()) {
|
|
ASSERT_EQUAL(section->file_offset() % ElfWriter::kPageSize,
|
|
section->memory_offset() % ElfWriter::kPageSize);
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
|
|
// Finally, write the ELF file contents.
|
|
ElfWriteStream wrapped(unwrapped_stream_, *this);
|
|
|
|
auto write_section = [&](const ElfSection* section) {
|
|
wrapped.Align(section->alignment);
|
|
ASSERT_EQUAL(wrapped.Position(), section->file_offset());
|
|
section->Write(&wrapped);
|
|
ASSERT_EQUAL(wrapped.Position(),
|
|
section->file_offset() + section->FileSize());
|
|
};
|
|
|
|
// To match ComputeOffsets, first we write allocated sections and then
|
|
// unallocated sections. We access the allocated sections via the load
|
|
// segments so we can properly align the stream for each entered segment.
|
|
intptr_t section_index = 1; // We don't visit the reserved section.
|
|
for (auto* const segment : program_table_->segments()) {
|
|
if (segment->type != elf::ProgramHeaderType::PT_LOAD) continue;
|
|
wrapped.Align(segment->Alignment());
|
|
for (auto* const section : segment->sections()) {
|
|
ASSERT(section->IsAllocated());
|
|
write_section(section);
|
|
if (!section->IsPseudoSection()) {
|
|
ASSERT_EQUAL(section->index, section_index);
|
|
section_index++;
|
|
}
|
|
}
|
|
}
|
|
const auto& sections = section_table_->sections();
|
|
for (; section_index < sections.length(); section_index++) {
|
|
auto* const section = sections[section_index];
|
|
ASSERT(!section->IsAllocated());
|
|
write_section(section);
|
|
}
|
|
// Finally, write the section table.
|
|
write_section(section_table_);
|
|
}
|
|
|
|
void ElfWriter::AssertConsistency(const ElfWriter* snapshot,
|
|
const ElfWriter* debug_info) {
|
|
// We do not care about consistency if there is no .text section.
|
|
if (snapshot->section_table_->FindTextSection() == nullptr &&
|
|
debug_info->section_table_->FindTextSection() == nullptr) {
|
|
return;
|
|
}
|
|
|
|
// Sections emitted before .text must go in the same order and end up
|
|
// at the same memory offsets. The reason for this rigid check is to
|
|
// guarantee that text section ends up at the same memory offset in
|
|
// both snapshot and debug info ELF files. If we allow sections to be
|
|
// reordered that might influence memory offset because sections have
|
|
// different alignment requirements and thus they might pack more
|
|
// tight in some orderings.
|
|
//
|
|
// See reordering algorithm in SectionTable::CreateProgramTable (specifically
|
|
// add_sections_matching helper).
|
|
const auto& snapshot_sections = snapshot->section_table_->sections();
|
|
const auto& debug_info_sections = debug_info->section_table_->sections();
|
|
const auto& snapshot_shstrtab = snapshot->section_table_->shstrtab();
|
|
const auto& debug_info_shstrtab = debug_info->section_table_->shstrtab();
|
|
|
|
bool failed = false;
|
|
for (intptr_t i = 0; i < snapshot_sections.length(); i++) {
|
|
if (i >= debug_info_sections.length()) {
|
|
OS::PrintErr(
|
|
"mismatch snapshot and debug-info ELF section tables: "
|
|
"not enough sections in debug info\n");
|
|
failed = true;
|
|
break;
|
|
}
|
|
|
|
auto snapshot_section = snapshot_sections.At(i);
|
|
auto debug_info_section = debug_info_sections.At(i);
|
|
|
|
auto snapshot_section_name = snapshot_shstrtab.At(snapshot_section->name());
|
|
if (!(snapshot_section->type == debug_info_section->type ||
|
|
(snapshot_section->type == elf::SectionHeaderType::SHT_PROGBITS &&
|
|
debug_info_section->type == elf::SectionHeaderType::SHT_NOBITS)) ||
|
|
snapshot_section->memory_offset() !=
|
|
debug_info_section->memory_offset() ||
|
|
strcmp(snapshot_section_name,
|
|
debug_info_shstrtab.At(debug_info_section->name())) != 0) {
|
|
OS::PrintErr("mismatch in section table at index %" Pd
|
|
": snapshot has %s, debug info has %s\n",
|
|
i, snapshot_section->ToCString(snapshot_shstrtab),
|
|
debug_info_section->ToCString(debug_info_shstrtab));
|
|
failed = true;
|
|
break;
|
|
}
|
|
|
|
if (strcmp(snapshot_section_name, ElfWriter::kTextName) == 0) {
|
|
break;
|
|
}
|
|
}
|
|
|
|
if (!failed) {
|
|
return;
|
|
}
|
|
|
|
const auto dump_sections = [](const GrowableArray<ElfSection*>& sections,
|
|
const ElfStringTable& shstrtab) {
|
|
for (intptr_t i = 0; i < sections.length(); i++) {
|
|
OS::PrintErr("[% 2" Pd "] %s\n", i, sections[i]->ToCString(shstrtab));
|
|
}
|
|
};
|
|
|
|
OS::PrintErr("Snapshot ELF sections:\n");
|
|
dump_sections(snapshot_sections, snapshot_shstrtab);
|
|
OS::PrintErr("Debug info ELF sections:\n");
|
|
dump_sections(debug_info_sections, debug_info_shstrtab);
|
|
FATAL("Mismatch between snapshot and debug info ELF was detected");
|
|
}
|
|
|
|
// For the build ID, we generate a 128-bit hash, where each 32 bits is a hash of
|
|
// the contents of the following segments in order:
|
|
//
|
|
// .text(VM) | .text(Isolate) | .rodata(VM) | .rodata(Isolate)
|
|
static constexpr const char* kBuildIdSegmentNames[]{
|
|
kVmSnapshotInstructionsAsmSymbol,
|
|
kIsolateSnapshotInstructionsAsmSymbol,
|
|
kVmSnapshotDataAsmSymbol,
|
|
kIsolateSnapshotDataAsmSymbol,
|
|
};
|
|
static constexpr intptr_t kBuildIdSegmentNamesLength =
|
|
ARRAY_SIZE(kBuildIdSegmentNames);
|
|
// Includes the note name, but not the description.
|
|
static constexpr intptr_t kBuildIdHeaderSize =
|
|
sizeof(elf::Note) + sizeof(elf::ELF_NOTE_GNU);
|
|
|
|
void ElfWriter::GenerateBuildId() {
|
|
// Not idempotent.
|
|
ASSERT(section_table_->Find(kBuildIdNoteName) == nullptr);
|
|
uint32_t hashes[kBuildIdSegmentNamesLength];
|
|
// Currently, we construct the build ID out of data from two different
|
|
// sections: the .text section and the .rodata section.
|
|
//
|
|
// TODO(dartbug.com/43274): Generate build IDs for separate debugging
|
|
// information for assembly snapshots.
|
|
auto* const text_section = section_table_->Find(kTextName);
|
|
if (text_section == nullptr) return;
|
|
ASSERT(text_section->IsTextSection());
|
|
auto* const text_bits = text_section->AsBitsContainer();
|
|
auto* const data_section = section_table_->Find(kDataName);
|
|
ASSERT(data_section == nullptr || data_section->IsDataSection());
|
|
// Hash each component by first hashing the associated text section and, if
|
|
// there's not one, hashing the associated data section (if any).
|
|
//
|
|
// Any component of the build ID which does not have an associated section
|
|
// in the result is kept as 0.
|
|
bool has_any_text = false;
|
|
for (intptr_t i = 0; i < kBuildIdSegmentNamesLength; i++) {
|
|
auto* const name = kBuildIdSegmentNames[i];
|
|
hashes[i] = text_bits->Hash(name);
|
|
if (hashes[i] != 0) {
|
|
has_any_text = true;
|
|
} else if (data_section != nullptr) {
|
|
hashes[i] = data_section->AsBitsContainer()->Hash(name);
|
|
}
|
|
}
|
|
// If none of the sections in the hash were text sections, then we don't need
|
|
// a build ID, as it is only used to symbolicize non-symbolic stack traces.
|
|
if (!has_any_text) return;
|
|
auto const description_bytes = reinterpret_cast<uint8_t*>(hashes);
|
|
const size_t description_length = sizeof(hashes);
|
|
// Now that we have the description field contents, create the section.
|
|
ZoneWriteStream stream(zone(), kBuildIdHeaderSize + description_length);
|
|
stream.WriteFixed<decltype(elf::Note::name_size)>(sizeof(elf::ELF_NOTE_GNU));
|
|
stream.WriteFixed<decltype(elf::Note::description_size)>(description_length);
|
|
stream.WriteFixed<decltype(elf::Note::type)>(elf::NoteType::NT_GNU_BUILD_ID);
|
|
ASSERT_EQUAL(stream.Position(), sizeof(elf::Note));
|
|
stream.WriteBytes(elf::ELF_NOTE_GNU, sizeof(elf::ELF_NOTE_GNU));
|
|
ASSERT_EQUAL(stream.bytes_written(), kBuildIdHeaderSize);
|
|
stream.WriteBytes(description_bytes, description_length);
|
|
auto* const container = new (zone_) NoteSection();
|
|
container->AddPortion(stream.buffer(), stream.bytes_written(),
|
|
/*relocations=*/nullptr, /*symbols=*/nullptr,
|
|
kSnapshotBuildIdAsmSymbol, kBuildIdLabel);
|
|
section_table_->Add(container, kBuildIdNoteName);
|
|
}
|
|
|
|
void ElfWriter::ComputeOffsets() {
|
|
intptr_t file_offset = 0;
|
|
intptr_t memory_offset = 0;
|
|
|
|
// Maps indices of allocated sections in the section table to memory offsets.
|
|
const intptr_t num_sections = section_table_->SectionCount();
|
|
GrowableArray<intptr_t> address_map(zone_, num_sections);
|
|
address_map.Add(0); // Don't adjust offsets for symbols with index SHN_UNDEF.
|
|
|
|
auto calculate_section_offsets = [&](ElfSection* section) {
|
|
file_offset = Utils::RoundUp(file_offset, section->alignment);
|
|
section->set_file_offset(file_offset);
|
|
file_offset += section->FileSize();
|
|
if (section->IsAllocated()) {
|
|
memory_offset = Utils::RoundUp(memory_offset, section->alignment);
|
|
section->set_memory_offset(memory_offset);
|
|
memory_offset += section->MemorySize();
|
|
}
|
|
};
|
|
|
|
intptr_t section_index = 1; // We don't visit the reserved section.
|
|
for (auto* const segment : program_table_->segments()) {
|
|
if (segment->type != elf::ProgramHeaderType::PT_LOAD) continue;
|
|
// Adjust file and memory offsets for segment alignment on entry.
|
|
file_offset = Utils::RoundUp(file_offset, segment->Alignment());
|
|
memory_offset = Utils::RoundUp(memory_offset, segment->Alignment());
|
|
for (auto* const section : segment->sections()) {
|
|
ASSERT(section->IsAllocated());
|
|
calculate_section_offsets(section);
|
|
if (!section->IsPseudoSection()) {
|
|
// Note: this assumes that the sections in the section header has all
|
|
// allocated sections before all (non-reserved) unallocated sections and
|
|
// in the same order as the load segments in in the program table.
|
|
address_map.Add(section->memory_offset());
|
|
ASSERT_EQUAL(section->index, section_index);
|
|
section_index++;
|
|
}
|
|
}
|
|
}
|
|
|
|
const auto& sections = section_table_->sections();
|
|
for (; section_index < sections.length(); section_index++) {
|
|
auto* const section = sections[section_index];
|
|
ASSERT(!section->IsAllocated());
|
|
calculate_section_offsets(section);
|
|
}
|
|
|
|
ASSERT_EQUAL(section_index, sections.length());
|
|
// Now that all sections have been handled, set the file offset for the
|
|
// section table, as it will be written after the last section.
|
|
calculate_section_offsets(section_table_);
|
|
|
|
#if defined(DEBUG)
|
|
// Double check that segment starts are aligned as expected.
|
|
for (auto* const segment : program_table_->segments()) {
|
|
ASSERT(Utils::IsAligned(segment->MemoryOffset(), segment->Alignment()));
|
|
}
|
|
#endif
|
|
|
|
// This must be true for uses of the map to be correct.
|
|
ASSERT_EQUAL(address_map[elf::SHN_UNDEF], 0);
|
|
// Adjust addresses in symbol tables as we now have section memory offsets.
|
|
// Also finalize the entries of the dynamic table, as some are memory offsets.
|
|
for (auto* const section : sections) {
|
|
if (auto* const table = section->AsElfSymbolTable()) {
|
|
table->Finalize(address_map);
|
|
} else if (auto* const dynamic = section->AsDynamicTable()) {
|
|
dynamic->Finalize();
|
|
}
|
|
}
|
|
// Also adjust addresses in symtab for stripped snapshots.
|
|
if (IsStripped()) {
|
|
ASSERT_EQUAL(symtab_->index, elf::SHN_UNDEF);
|
|
symtab_->Finalize(address_map);
|
|
}
|
|
}
|
|
|
|
void ElfHeader::Write(ElfWriteStream* stream) const {
|
|
ASSERT_EQUAL(file_offset(), 0);
|
|
ASSERT_EQUAL(memory_offset(), 0);
|
|
#if defined(TARGET_ARCH_IS_32_BIT)
|
|
uint8_t size = elf::ELFCLASS32;
|
|
#else
|
|
uint8_t size = elf::ELFCLASS64;
|
|
#endif
|
|
uint8_t e_ident[16] = {0x7f,
|
|
'E',
|
|
'L',
|
|
'F',
|
|
size,
|
|
elf::ELFDATA2LSB,
|
|
elf::EV_CURRENT,
|
|
elf::ELFOSABI_SYSV,
|
|
0,
|
|
0,
|
|
0,
|
|
0,
|
|
0,
|
|
0,
|
|
0,
|
|
0};
|
|
stream->WriteBytes(e_ident, 16);
|
|
|
|
stream->WriteHalf(elf::ET_DYN); // Shared library.
|
|
|
|
#if defined(TARGET_ARCH_IA32)
|
|
stream->WriteHalf(elf::EM_386);
|
|
#elif defined(TARGET_ARCH_X64)
|
|
stream->WriteHalf(elf::EM_X86_64);
|
|
#elif defined(TARGET_ARCH_ARM)
|
|
stream->WriteHalf(elf::EM_ARM);
|
|
#elif defined(TARGET_ARCH_ARM64)
|
|
stream->WriteHalf(elf::EM_AARCH64);
|
|
#elif defined(TARGET_ARCH_RISCV32) || defined(TARGET_ARCH_RISCV64)
|
|
stream->WriteHalf(elf::EM_RISCV);
|
|
#else
|
|
FATAL("Unknown ELF architecture");
|
|
#endif
|
|
|
|
stream->WriteWord(elf::EV_CURRENT); // Version
|
|
stream->WriteAddr(0); // "Entry point"
|
|
stream->WriteOff(program_table_.file_offset());
|
|
stream->WriteOff(section_table_.file_offset());
|
|
|
|
#if defined(TARGET_ARCH_ARM)
|
|
uword flags = elf::EF_ARM_ABI | (TargetCPUFeatures::hardfp_supported()
|
|
? elf::EF_ARM_ABI_FLOAT_HARD
|
|
: elf::EF_ARM_ABI_FLOAT_SOFT);
|
|
#elif defined(TARGET_ARCH_RISCV32) || defined(TARGET_ARCH_RISCV64)
|
|
uword flags = elf::EF_RISCV_RVC | elf::EF_RISCV_FLOAT_ABI_DOUBLE;
|
|
#else
|
|
uword flags = 0;
|
|
#endif
|
|
stream->WriteWord(flags);
|
|
|
|
stream->WriteHalf(sizeof(elf::ElfHeader));
|
|
stream->WriteHalf(program_table_.entry_size);
|
|
stream->WriteHalf(program_table_.SegmentCount());
|
|
stream->WriteHalf(section_table_.entry_size);
|
|
stream->WriteHalf(section_table_.SectionCount());
|
|
stream->WriteStringTableIndex();
|
|
}
|
|
|
|
void ProgramTable::Write(ElfWriteStream* stream) const {
|
|
ASSERT(segments_.length() > 0);
|
|
// Make sure all relevant segments were created by checking the type of the
|
|
// first.
|
|
ASSERT(segments_[0]->type == elf::ProgramHeaderType::PT_PHDR);
|
|
const intptr_t start = stream->Position();
|
|
// Should be immediately following the ELF header.
|
|
ASSERT_EQUAL(start, sizeof(elf::ElfHeader));
|
|
#if defined(DEBUG)
|
|
// Here, we count the number of times that a PT_LOAD writable segment is
|
|
// followed by a non-writable segment. We initialize last_writable to true
|
|
// so that we catch the case where the first segment is non-writable.
|
|
bool last_writable = true;
|
|
int non_writable_groups = 0;
|
|
#endif
|
|
for (intptr_t i = 0; i < segments_.length(); i++) {
|
|
const Segment* const segment = segments_[i];
|
|
ASSERT(segment->type != elf::ProgramHeaderType::PT_NULL);
|
|
ASSERT_EQUAL(i == 0, segment->type == elf::ProgramHeaderType::PT_PHDR);
|
|
#if defined(DEBUG)
|
|
if (segment->type == elf::ProgramHeaderType::PT_LOAD) {
|
|
if (last_writable && !segment->IsWritable()) {
|
|
non_writable_groups++;
|
|
}
|
|
last_writable = segment->IsWritable();
|
|
}
|
|
#endif
|
|
const intptr_t start = stream->Position();
|
|
segment->WriteProgramHeader(stream);
|
|
const intptr_t end = stream->Position();
|
|
ASSERT_EQUAL(end - start, entry_size);
|
|
}
|
|
#if defined(DEBUG)
|
|
// All PT_LOAD non-writable segments must be contiguous. If not, some older
|
|
// Android dynamic linkers fail to handle writable segments between
|
|
// non-writable ones. See https://github.com/flutter/flutter/issues/43259.
|
|
ASSERT(non_writable_groups <= 1);
|
|
#endif
|
|
}
|
|
|
|
void SectionTable::Write(ElfWriteStream* stream) const {
|
|
for (intptr_t i = 0; i < sections_.length(); i++) {
|
|
const ElfSection* const section = sections_[i];
|
|
ASSERT_EQUAL(i == 0, section->IsReservedSection());
|
|
ASSERT_EQUAL(section->index, i);
|
|
ASSERT(section->link < sections_.length());
|
|
const intptr_t start = stream->Position();
|
|
section->WriteSectionHeader(stream);
|
|
const intptr_t end = stream->Position();
|
|
ASSERT_EQUAL(end - start, entry_size);
|
|
}
|
|
}
|
|
|
|
static const char* SectionHeaderTypeToString(elf::SectionHeaderType type) {
|
|
switch (type) {
|
|
case elf::SectionHeaderType::SHT_NULL:
|
|
return "SHT_NULL";
|
|
case elf::SectionHeaderType::SHT_PROGBITS:
|
|
return "SHT_PROGBITS";
|
|
case elf::SectionHeaderType::SHT_SYMTAB:
|
|
return "SHT_SYMTAB";
|
|
case elf::SectionHeaderType::SHT_STRTAB:
|
|
return "SHT_STRTAB";
|
|
case elf::SectionHeaderType::SHT_HASH:
|
|
return "SHT_HASH";
|
|
case elf::SectionHeaderType::SHT_NOTE:
|
|
return "SHT_NOTE";
|
|
case elf::SectionHeaderType::SHT_NOBITS:
|
|
return "SHT_NOBITS";
|
|
case elf::SectionHeaderType::SHT_DYNAMIC:
|
|
return "SHT_DYNAMIC";
|
|
case elf::SectionHeaderType::SHT_DYNSYM:
|
|
return "SHT_DYNSYM";
|
|
default:
|
|
return "Unknown";
|
|
}
|
|
}
|
|
|
|
const char* ElfSection::ToCString(const ElfStringTable& string_table) {
|
|
return Thread::Current()->zone()->PrintToString(
|
|
"ElfSection [%s]{type=%s, align=%" Pd ", flags=%s%s%s, fsz=%" Px
|
|
", msz=%" Px ", foffs=%" Px ", moffs=%" Px "}",
|
|
string_table.At(name()), SectionHeaderTypeToString(type), alignment,
|
|
IsAllocated() ? "A" : "", IsWritable() ? "W" : "",
|
|
IsExecutable() ? "X" : "", IsAllocated() ? FileSize() : -1,
|
|
IsAllocated() ? MemorySize() : -1, file_offset_, memory_offset_);
|
|
}
|
|
|
|
#endif // DART_PRECOMPILER
|
|
|
|
} // namespace dart
|