Skip to content

[BinaryFormat] Add "SFrame" structures and constants #147264

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 4 commits into from
Jul 15, 2025
Merged
Show file tree
Hide file tree
Changes from all commits
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
165 changes: 165 additions & 0 deletions llvm/include/llvm/BinaryFormat/SFrame.h
Original file line number Diff line number Diff line change
@@ -0,0 +1,165 @@
//===----------------------------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
/// \file
/// This file contains data-structure definitions and constants to support
/// unwinding based on .sframe sections. This only supports SFRAME_VERSION_2
/// as described at https://sourceware.org/binutils/docs/sframe-spec.html
//===----------------------------------------------------------------------===//

#ifndef LLVM_BINARYFORMAT_SFRAME_H
#define LLVM_BINARYFORMAT_SFRAME_H

#include "llvm/ADT/BitmaskEnum.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/Endian.h"

namespace llvm::sframe {

LLVM_ENABLE_BITMASK_ENUMS_IN_NAMESPACE();

constexpr uint16_t Magic = 0xdee2;

enum class Version : uint8_t {
V1 = 1,
V2 = 2,
};

enum class Flags : uint8_t {
FDESorted = 0x01,
FramePointer = 0x02,
FDEFuncStartPCRel = 0x04,
V2AllFlags = FDESorted | FramePointer | FDEFuncStartPCRel,
LLVM_MARK_AS_BITMASK_ENUM(/*LargestValue=*/0xff),
};

enum class ABI : uint8_t {
AArch64EndianBig = 1,
AArch64EndianLittle = 2,
AMD64EndianLittle = 3,
};

/// SFrame FRE Types. Bits 0-3 of FuncDescEntry.Info.
enum class FREType : uint8_t {
Addr1 = 0,
Addr2 = 1,
Addr4 = 2,
};

/// SFrame FDE Types. Bit 4 of FuncDescEntry.Info.
enum class FDEType : uint8_t {
PCInc = 0,
PCMask = 1,
};

/// Speficies key used for signing return addresses. Bit 5 of
/// FuncDescEntry.Info.
enum class AArch64PAuthKey : uint8_t {
A = 0,
B = 1,
};

/// Size of stack offsets. Bits 5-6 of FREInfo.Info.
enum class FREOffset : uint8_t {
B1 = 0,
B2 = 1,
B4 = 2,
};

/// Stack frame base register. Bit 0 of FREInfo.Info.
enum class BaseReg : uint8_t {
FP = 0,
SP = 1,
};

namespace detail {
template <typename T, endianness E>
using packed =
support::detail::packed_endian_specific_integral<T, E, support::unaligned>;
}
Comment on lines +80 to +84
Copy link
Collaborator Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

I'm tempted to add something like packed_endian_t to Support/Endian.h


template <endianness E> struct Preamble {
detail::packed<uint16_t, E> Magic;
detail::packed<enum Version, E> Version;
detail::packed<enum Flags, E> Flags;
};

template <endianness E> struct Header {
struct Preamble<E> Preamble;
detail::packed<ABI, E> ABIArch;
detail::packed<int8_t, E> CFAFixedFPOffset;
detail::packed<int8_t, E> CFAFixedRAOffset;
detail::packed<uint8_t, E> AuxHdrLen;
detail::packed<uint32_t, E> NumFDEs;
detail::packed<uint32_t, E> NumFREs;
detail::packed<uint32_t, E> FRELen;
detail::packed<uint32_t, E> FDEOff;
detail::packed<uint32_t, E> FREOff;
};

template <endianness E> struct FuncDescEntry {
detail::packed<int32_t, E> StartAddress;
detail::packed<uint32_t, E> Size;
detail::packed<uint32_t, E> StartFREOff;
detail::packed<uint32_t, E> NumFREs;
detail::packed<uint8_t, E> Info;
detail::packed<uint8_t, E> RepSize;
detail::packed<uint16_t, E> Padding2;

uint8_t getPAuthKey() const { return (Info >> 5) & 1; }
FDEType getFDEType() const { return static_cast<FDEType>((Info >> 4) & 1); }
FREType getFREType() const { return static_cast<FREType>(Info & 0xf); }
void setPAuthKey(uint8_t P) { setFuncInfo(P, getFDEType(), getFREType()); }
void setFDEType(FDEType D) { setFuncInfo(getPAuthKey(), D, getFREType()); }
void setFREType(FREType R) { setFuncInfo(getPAuthKey(), getFDEType(), R); }
void setFuncInfo(uint8_t PAuthKey, FDEType FDE, FREType FRE) {
Info = ((PAuthKey & 1) << 5) | ((static_cast<uint8_t>(FDE) & 1) << 4) |
(static_cast<uint8_t>(FRE) & 0xf);
}
};

template <endianness E> struct FREInfo {
detail::packed<uint8_t, E> Info;
Comment on lines +126 to +127
Copy link
Collaborator Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Technically, this (and all of the other 1-byte values) don't need to be templated, but I thought I'd do it anyway for consistency.


bool isReturnAddressSigned() const { return Info >> 7; }
FREOffset getOffsetSize() const {
return static_cast<FREOffset>((Info >> 5) & 3);
}
uint8_t getOffsetCount() const { return (Info >> 1) & 0xf; }
BaseReg getBaseRegister() const { return static_cast<BaseReg>(Info & 1); }
void setReturnAddressSigned(bool RA) {
setFREInfo(RA, getOffsetSize(), getOffsetCount(), getBaseRegister());
}
void setOffsetSize(FREOffset Sz) {
setFREInfo(isReturnAddressSigned(), Sz, getOffsetCount(),
getBaseRegister());
}
void setOffsetCount(uint8_t N) {
setFREInfo(isReturnAddressSigned(), getOffsetSize(), N, getBaseRegister());
}
void setBaseRegister(BaseReg Reg) {
setFREInfo(isReturnAddressSigned(), getOffsetSize(), getOffsetCount(), Reg);
}
void setFREInfo(bool RA, FREOffset Sz, uint8_t N, BaseReg Reg) {
Info = ((RA & 1) << 7) | ((static_cast<uint8_t>(Sz) & 3) << 5) |
((N & 0xf) << 1) | (static_cast<uint8_t>(Reg) & 1);
}
};

template <typename T, endianness E> struct FrameRowEntry {
detail::packed<T, E> StartAddress;
FREInfo<E> Info;
};

template <endianness E> using FrameRowEntryAddr1 = FrameRowEntry<uint8_t, E>;
template <endianness E> using FrameRowEntryAddr2 = FrameRowEntry<uint16_t, E>;
template <endianness E> using FrameRowEntryAddr4 = FrameRowEntry<uint32_t, E>;

} // namespace llvm::sframe

#endif // LLVM_BINARYFORMAT_SFRAME_H
1 change: 1 addition & 0 deletions llvm/unittests/BinaryFormat/CMakeLists.txt
Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@ add_llvm_unittest(BinaryFormatTests
MsgPackDocumentTest.cpp
MsgPackReaderTest.cpp
MsgPackWriterTest.cpp
SFrameTest.cpp
TestFileMagic.cpp
)

118 changes: 118 additions & 0 deletions llvm/unittests/BinaryFormat/SFrameTest.cpp
Original file line number Diff line number Diff line change
@@ -0,0 +1,118 @@
//===- SFrameTest.cpp -----------------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//

#include "llvm/BinaryFormat/SFrame.h"
#include "gtest/gtest.h"
#include <type_traits>

using namespace llvm;
using namespace llvm::sframe;

namespace {

template <typename EndianT> class SFrameTest : public testing::Test {
protected:
static constexpr endianness Endian = EndianT::value;

// Test structure sizes and triviality.
static_assert(std::is_trivial_v<Preamble<Endian>>);
static_assert(sizeof(Preamble<Endian>) == 4);

static_assert(std::is_trivial_v<Header<Endian>>);
static_assert(sizeof(Header<Endian>) == 28);

static_assert(std::is_trivial_v<FuncDescEntry<Endian>>);
static_assert(sizeof(FuncDescEntry<Endian>) == 20);

static_assert(std::is_trivial_v<FrameRowEntryAddr1<Endian>>);
static_assert(sizeof(FrameRowEntryAddr1<Endian>) == 2);

static_assert(std::is_trivial_v<FrameRowEntryAddr2<Endian>>);
static_assert(sizeof(FrameRowEntryAddr2<Endian>) == 3);

static_assert(std::is_trivial_v<FrameRowEntryAddr4<Endian>>);
static_assert(sizeof(FrameRowEntryAddr4<Endian>) == 5);
};

struct NameGenerator {
template <typename T> static constexpr const char *GetName(int) {
if constexpr (T::value == endianness::little)
return "little";
if constexpr (T::value == endianness::big)
return "big";
}
};
using Types =
testing::Types<std::integral_constant<endianness, endianness::little>,
std::integral_constant<endianness, endianness::big>>;
TYPED_TEST_SUITE(SFrameTest, Types, NameGenerator);

TYPED_TEST(SFrameTest, FDEFlags) {
FuncDescEntry<TestFixture::Endian> FDE = {};
EXPECT_EQ(FDE.Info, 0u);
EXPECT_EQ(FDE.getPAuthKey(), 0);
EXPECT_EQ(FDE.getFDEType(), FDEType::PCInc);
EXPECT_EQ(FDE.getFREType(), FREType::Addr1);

FDE.setPAuthKey(1);
EXPECT_EQ(FDE.Info, 0x20u);
EXPECT_EQ(FDE.getPAuthKey(), 1);
EXPECT_EQ(FDE.getFDEType(), FDEType::PCInc);
EXPECT_EQ(FDE.getFREType(), FREType::Addr1);

FDE.setFDEType(FDEType::PCMask);
EXPECT_EQ(FDE.Info, 0x30u);
EXPECT_EQ(FDE.getPAuthKey(), 1);
EXPECT_EQ(FDE.getFDEType(), FDEType::PCMask);
EXPECT_EQ(FDE.getFREType(), FREType::Addr1);

FDE.setFREType(FREType::Addr4);
EXPECT_EQ(FDE.Info, 0x32u);
EXPECT_EQ(FDE.getPAuthKey(), 1);
EXPECT_EQ(FDE.getFDEType(), FDEType::PCMask);
EXPECT_EQ(FDE.getFREType(), FREType::Addr4);
}

TYPED_TEST(SFrameTest, FREFlags) {
FREInfo<TestFixture::Endian> Info = {};
EXPECT_EQ(Info.Info, 0u);
EXPECT_FALSE(Info.isReturnAddressSigned());
EXPECT_EQ(Info.getOffsetSize(), FREOffset::B1);
EXPECT_EQ(Info.getOffsetCount(), 0u);
EXPECT_EQ(Info.getBaseRegister(), BaseReg::FP);

Info.setReturnAddressSigned(true);
EXPECT_EQ(Info.Info, 0x80u);
EXPECT_TRUE(Info.isReturnAddressSigned());
EXPECT_EQ(Info.getOffsetSize(), FREOffset::B1);
EXPECT_EQ(Info.getOffsetCount(), 0u);
EXPECT_EQ(Info.getBaseRegister(), BaseReg::FP);

Info.setOffsetSize(FREOffset::B4);
EXPECT_EQ(Info.Info, 0xc0u);
EXPECT_TRUE(Info.isReturnAddressSigned());
EXPECT_EQ(Info.getOffsetSize(), FREOffset::B4);
EXPECT_EQ(Info.getOffsetCount(), 0u);
EXPECT_EQ(Info.getBaseRegister(), BaseReg::FP);

Info.setOffsetCount(3);
EXPECT_EQ(Info.Info, 0xc6u);
EXPECT_TRUE(Info.isReturnAddressSigned());
EXPECT_EQ(Info.getOffsetSize(), FREOffset::B4);
EXPECT_EQ(Info.getOffsetCount(), 3u);
EXPECT_EQ(Info.getBaseRegister(), BaseReg::FP);

Info.setBaseRegister(BaseReg::SP);
EXPECT_EQ(Info.Info, 0xc7u);
EXPECT_TRUE(Info.isReturnAddressSigned());
EXPECT_EQ(Info.getOffsetSize(), FREOffset::B4);
EXPECT_EQ(Info.getOffsetCount(), 3u);
EXPECT_EQ(Info.getBaseRegister(), BaseReg::SP);
}

} // namespace
Loading