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//===- BTFDebug.cpp - BTF Generator ---------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing BTF debug info.
//
//===----------------------------------------------------------------------===//
#include "BTFDebug.h"
#include "BPF.h"
#include "BPFCORE.h"
#include "MCTargetDesc/BPFMCTargetDesc.h"
#include "llvm/BinaryFormat/ELF.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineOperand.h"
#include "llvm/MC/MCContext.h"
#include "llvm/MC/MCObjectFileInfo.h"
#include "llvm/MC/MCSectionELF.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Support/LineIterator.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include <optional>
using namespace llvm;
static const char *BTFKindStr[] = {
#define HANDLE_BTF_KIND(ID, NAME) "BTF_KIND_" #NAME,
#include "llvm/DebugInfo/BTF/BTF.def"
};
/// Emit a BTF common type.
void BTFTypeBase::emitType(MCStreamer &OS) {
OS.AddComment(std::string(BTFKindStr[Kind]) + "(id = " + std::to_string(Id) +
")");
OS.emitInt32(BTFType.NameOff);
OS.AddComment("0x" + Twine::utohexstr(BTFType.Info));
OS.emitInt32(BTFType.Info);
OS.emitInt32(BTFType.Size);
}
BTFTypeDerived::BTFTypeDerived(const DIDerivedType *DTy, unsigned Tag,
bool NeedsFixup)
: DTy(DTy), NeedsFixup(NeedsFixup), Name(DTy->getName()) {
switch (Tag) {
case dwarf::DW_TAG_pointer_type:
Kind = BTF::BTF_KIND_PTR;
break;
case dwarf::DW_TAG_const_type:
Kind = BTF::BTF_KIND_CONST;
break;
case dwarf::DW_TAG_volatile_type:
Kind = BTF::BTF_KIND_VOLATILE;
break;
case dwarf::DW_TAG_typedef:
Kind = BTF::BTF_KIND_TYPEDEF;
break;
case dwarf::DW_TAG_restrict_type:
Kind = BTF::BTF_KIND_RESTRICT;
break;
default:
llvm_unreachable("Unknown DIDerivedType Tag");
}
BTFType.Info = Kind << 24;
}
/// Used by DW_TAG_pointer_type only.
BTFTypeDerived::BTFTypeDerived(unsigned NextTypeId, unsigned Tag,
StringRef Name)
: DTy(nullptr), NeedsFixup(false), Name(Name) {
Kind = BTF::BTF_KIND_PTR;
BTFType.Info = Kind << 24;
BTFType.Type = NextTypeId;
}
void BTFTypeDerived::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(Name);
if (NeedsFixup || !DTy)
return;
// The base type for PTR/CONST/VOLATILE could be void.
const DIType *ResolvedType = DTy->getBaseType();
if (!ResolvedType) {
assert((Kind == BTF::BTF_KIND_PTR || Kind == BTF::BTF_KIND_CONST ||
Kind == BTF::BTF_KIND_VOLATILE) &&
"Invalid null basetype");
BTFType.Type = 0;
} else {
BTFType.Type = BDebug.getTypeId(ResolvedType);
}
}
void BTFTypeDerived::emitType(MCStreamer &OS) { BTFTypeBase::emitType(OS); }
void BTFTypeDerived::setPointeeType(uint32_t PointeeType) {
BTFType.Type = PointeeType;
}
/// Represent a struct/union forward declaration.
BTFTypeFwd::BTFTypeFwd(StringRef Name, bool IsUnion) : Name(Name) {
Kind = BTF::BTF_KIND_FWD;
BTFType.Info = IsUnion << 31 | Kind << 24;
BTFType.Type = 0;
}
void BTFTypeFwd::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(Name);
}
void BTFTypeFwd::emitType(MCStreamer &OS) { BTFTypeBase::emitType(OS); }
BTFTypeInt::BTFTypeInt(uint32_t Encoding, uint32_t SizeInBits,
uint32_t OffsetInBits, StringRef TypeName)
: Name(TypeName) {
// Translate IR int encoding to BTF int encoding.
uint8_t BTFEncoding;
switch (Encoding) {
case dwarf::DW_ATE_boolean:
BTFEncoding = BTF::INT_BOOL;
break;
case dwarf::DW_ATE_signed:
case dwarf::DW_ATE_signed_char:
BTFEncoding = BTF::INT_SIGNED;
break;
case dwarf::DW_ATE_unsigned:
case dwarf::DW_ATE_unsigned_char:
BTFEncoding = 0;
break;
default:
llvm_unreachable("Unknown BTFTypeInt Encoding");
}
Kind = BTF::BTF_KIND_INT;
BTFType.Info = Kind << 24;
BTFType.Size = roundupToBytes(SizeInBits);
IntVal = (BTFEncoding << 24) | OffsetInBits << 16 | SizeInBits;
}
void BTFTypeInt::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(Name);
}
void BTFTypeInt::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
OS.AddComment("0x" + Twine::utohexstr(IntVal));
OS.emitInt32(IntVal);
}
BTFTypeEnum::BTFTypeEnum(const DICompositeType *ETy, uint32_t VLen,
bool IsSigned) : ETy(ETy) {
Kind = BTF::BTF_KIND_ENUM;
BTFType.Info = IsSigned << 31 | Kind << 24 | VLen;
BTFType.Size = roundupToBytes(ETy->getSizeInBits());
}
void BTFTypeEnum::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(ETy->getName());
DINodeArray Elements = ETy->getElements();
for (const auto Element : Elements) {
const auto *Enum = cast<DIEnumerator>(Element);
struct BTF::BTFEnum BTFEnum;
BTFEnum.NameOff = BDebug.addString(Enum->getName());
// BTF enum value is 32bit, enforce it.
uint32_t Value;
if (Enum->isUnsigned())
Value = static_cast<uint32_t>(Enum->getValue().getZExtValue());
else
Value = static_cast<uint32_t>(Enum->getValue().getSExtValue());
BTFEnum.Val = Value;
EnumValues.push_back(BTFEnum);
}
}
void BTFTypeEnum::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
for (const auto &Enum : EnumValues) {
OS.emitInt32(Enum.NameOff);
OS.emitInt32(Enum.Val);
}
}
BTFTypeEnum64::BTFTypeEnum64(const DICompositeType *ETy, uint32_t VLen,
bool IsSigned) : ETy(ETy) {
Kind = BTF::BTF_KIND_ENUM64;
BTFType.Info = IsSigned << 31 | Kind << 24 | VLen;
BTFType.Size = roundupToBytes(ETy->getSizeInBits());
}
void BTFTypeEnum64::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(ETy->getName());
DINodeArray Elements = ETy->getElements();
for (const auto Element : Elements) {
const auto *Enum = cast<DIEnumerator>(Element);
struct BTF::BTFEnum64 BTFEnum;
BTFEnum.NameOff = BDebug.addString(Enum->getName());
uint64_t Value;
if (Enum->isUnsigned())
Value = static_cast<uint64_t>(Enum->getValue().getZExtValue());
else
Value = static_cast<uint64_t>(Enum->getValue().getSExtValue());
BTFEnum.Val_Lo32 = Value;
BTFEnum.Val_Hi32 = Value >> 32;
EnumValues.push_back(BTFEnum);
}
}
void BTFTypeEnum64::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
for (const auto &Enum : EnumValues) {
OS.emitInt32(Enum.NameOff);
OS.AddComment("0x" + Twine::utohexstr(Enum.Val_Lo32));
OS.emitInt32(Enum.Val_Lo32);
OS.AddComment("0x" + Twine::utohexstr(Enum.Val_Hi32));
OS.emitInt32(Enum.Val_Hi32);
}
}
BTFTypeArray::BTFTypeArray(uint32_t ElemTypeId, uint32_t NumElems) {
Kind = BTF::BTF_KIND_ARRAY;
BTFType.NameOff = 0;
BTFType.Info = Kind << 24;
BTFType.Size = 0;
ArrayInfo.ElemType = ElemTypeId;
ArrayInfo.Nelems = NumElems;
}
/// Represent a BTF array.
void BTFTypeArray::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
// The IR does not really have a type for the index.
// A special type for array index should have been
// created during initial type traversal. Just
// retrieve that type id.
ArrayInfo.IndexType = BDebug.getArrayIndexTypeId();
}
void BTFTypeArray::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
OS.emitInt32(ArrayInfo.ElemType);
OS.emitInt32(ArrayInfo.IndexType);
OS.emitInt32(ArrayInfo.Nelems);
}
/// Represent either a struct or a union.
BTFTypeStruct::BTFTypeStruct(const DICompositeType *STy, bool IsStruct,
bool HasBitField, uint32_t Vlen)
: STy(STy), HasBitField(HasBitField) {
Kind = IsStruct ? BTF::BTF_KIND_STRUCT : BTF::BTF_KIND_UNION;
BTFType.Size = roundupToBytes(STy->getSizeInBits());
BTFType.Info = (HasBitField << 31) | (Kind << 24) | Vlen;
}
void BTFTypeStruct::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(STy->getName());
// Add struct/union members.
const DINodeArray Elements = STy->getElements();
for (const auto *Element : Elements) {
struct BTF::BTFMember BTFMember;
const auto *DDTy = cast<DIDerivedType>(Element);
BTFMember.NameOff = BDebug.addString(DDTy->getName());
if (HasBitField) {
uint8_t BitFieldSize = DDTy->isBitField() ? DDTy->getSizeInBits() : 0;
BTFMember.Offset = BitFieldSize << 24 | DDTy->getOffsetInBits();
} else {
BTFMember.Offset = DDTy->getOffsetInBits();
}
const auto *BaseTy = DDTy->getBaseType();
BTFMember.Type = BDebug.getTypeId(BaseTy);
Members.push_back(BTFMember);
}
}
void BTFTypeStruct::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
for (const auto &Member : Members) {
OS.emitInt32(Member.NameOff);
OS.emitInt32(Member.Type);
OS.AddComment("0x" + Twine::utohexstr(Member.Offset));
OS.emitInt32(Member.Offset);
}
}
std::string BTFTypeStruct::getName() { return std::string(STy->getName()); }
/// The Func kind represents both subprogram and pointee of function
/// pointers. If the FuncName is empty, it represents a pointee of function
/// pointer. Otherwise, it represents a subprogram. The func arg names
/// are empty for pointee of function pointer case, and are valid names
/// for subprogram.
BTFTypeFuncProto::BTFTypeFuncProto(
const DISubroutineType *STy, uint32_t VLen,
const std::unordered_map<uint32_t, StringRef> &FuncArgNames)
: STy(STy), FuncArgNames(FuncArgNames) {
Kind = BTF::BTF_KIND_FUNC_PROTO;
BTFType.Info = (Kind << 24) | VLen;
}
void BTFTypeFuncProto::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
DITypeRefArray Elements = STy->getTypeArray();
auto RetType = Elements[0];
BTFType.Type = RetType ? BDebug.getTypeId(RetType) : 0;
BTFType.NameOff = 0;
// For null parameter which is typically the last one
// to represent the vararg, encode the NameOff/Type to be 0.
for (unsigned I = 1, N = Elements.size(); I < N; ++I) {
struct BTF::BTFParam Param;
auto Element = Elements[I];
if (Element) {
Param.NameOff = BDebug.addString(FuncArgNames[I]);
Param.Type = BDebug.getTypeId(Element);
} else {
Param.NameOff = 0;
Param.Type = 0;
}
Parameters.push_back(Param);
}
}
void BTFTypeFuncProto::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
for (const auto &Param : Parameters) {
OS.emitInt32(Param.NameOff);
OS.emitInt32(Param.Type);
}
}
BTFTypeFunc::BTFTypeFunc(StringRef FuncName, uint32_t ProtoTypeId,
uint32_t Scope)
: Name(FuncName) {
Kind = BTF::BTF_KIND_FUNC;
BTFType.Info = (Kind << 24) | Scope;
BTFType.Type = ProtoTypeId;
}
void BTFTypeFunc::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(Name);
}
void BTFTypeFunc::emitType(MCStreamer &OS) { BTFTypeBase::emitType(OS); }
BTFKindVar::BTFKindVar(StringRef VarName, uint32_t TypeId, uint32_t VarInfo)
: Name(VarName) {
Kind = BTF::BTF_KIND_VAR;
BTFType.Info = Kind << 24;
BTFType.Type = TypeId;
Info = VarInfo;
}
void BTFKindVar::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(Name);
}
void BTFKindVar::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
OS.emitInt32(Info);
}
BTFKindDataSec::BTFKindDataSec(AsmPrinter *AsmPrt, std::string SecName)
: Asm(AsmPrt), Name(SecName) {
Kind = BTF::BTF_KIND_DATASEC;
BTFType.Info = Kind << 24;
BTFType.Size = 0;
}
void BTFKindDataSec::completeType(BTFDebug &BDebug) {
BTFType.NameOff = BDebug.addString(Name);
BTFType.Info |= Vars.size();
}
void BTFKindDataSec::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
for (const auto &V : Vars) {
OS.emitInt32(std::get<0>(V));
Asm->emitLabelReference(std::get<1>(V), 4);
OS.emitInt32(std::get<2>(V));
}
}
BTFTypeFloat::BTFTypeFloat(uint32_t SizeInBits, StringRef TypeName)
: Name(TypeName) {
Kind = BTF::BTF_KIND_FLOAT;
BTFType.Info = Kind << 24;
BTFType.Size = roundupToBytes(SizeInBits);
}
void BTFTypeFloat::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(Name);
}
BTFTypeDeclTag::BTFTypeDeclTag(uint32_t BaseTypeId, int ComponentIdx,
StringRef Tag)
: Tag(Tag) {
Kind = BTF::BTF_KIND_DECL_TAG;
BTFType.Info = Kind << 24;
BTFType.Type = BaseTypeId;
Info = ComponentIdx;
}
void BTFTypeDeclTag::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(Tag);
}
void BTFTypeDeclTag::emitType(MCStreamer &OS) {
BTFTypeBase::emitType(OS);
OS.emitInt32(Info);
}
BTFTypeTypeTag::BTFTypeTypeTag(uint32_t NextTypeId, StringRef Tag)
: DTy(nullptr), Tag(Tag) {
Kind = BTF::BTF_KIND_TYPE_TAG;
BTFType.Info = Kind << 24;
BTFType.Type = NextTypeId;
}
BTFTypeTypeTag::BTFTypeTypeTag(const DIDerivedType *DTy, StringRef Tag)
: DTy(DTy), Tag(Tag) {
Kind = BTF::BTF_KIND_TYPE_TAG;
BTFType.Info = Kind << 24;
}
void BTFTypeTypeTag::completeType(BTFDebug &BDebug) {
if (IsCompleted)
return;
IsCompleted = true;
BTFType.NameOff = BDebug.addString(Tag);
if (DTy) {
const DIType *ResolvedType = DTy->getBaseType();
if (!ResolvedType)
BTFType.Type = 0;
else
BTFType.Type = BDebug.getTypeId(ResolvedType);
}
}
uint32_t BTFStringTable::addString(StringRef S) {
// Check whether the string already exists.
for (auto &OffsetM : OffsetToIdMap) {
if (Table[OffsetM.second] == S)
return OffsetM.first;
}
// Not find, add to the string table.
uint32_t Offset = Size;
OffsetToIdMap[Offset] = Table.size();
Table.push_back(std::string(S));
Size += S.size() + 1;
return Offset;
}
BTFDebug::BTFDebug(AsmPrinter *AP)
: DebugHandlerBase(AP), OS(*Asm->OutStreamer), SkipInstruction(false),
LineInfoGenerated(false), SecNameOff(0), ArrayIndexTypeId(0),
MapDefNotCollected(true) {
addString("\0");
}
uint32_t BTFDebug::addType(std::unique_ptr<BTFTypeBase> TypeEntry,
const DIType *Ty) {
TypeEntry->setId(TypeEntries.size() + 1);
uint32_t Id = TypeEntry->getId();
DIToIdMap[Ty] = Id;
TypeEntries.push_back(std::move(TypeEntry));
return Id;
}
uint32_t BTFDebug::addType(std::unique_ptr<BTFTypeBase> TypeEntry) {
TypeEntry->setId(TypeEntries.size() + 1);
uint32_t Id = TypeEntry->getId();
TypeEntries.push_back(std::move(TypeEntry));
return Id;
}
void BTFDebug::visitBasicType(const DIBasicType *BTy, uint32_t &TypeId) {
// Only int and binary floating point types are supported in BTF.
uint32_t Encoding = BTy->getEncoding();
std::unique_ptr<BTFTypeBase> TypeEntry;
switch (Encoding) {
case dwarf::DW_ATE_boolean:
case dwarf::DW_ATE_signed:
case dwarf::DW_ATE_signed_char:
case dwarf::DW_ATE_unsigned:
case dwarf::DW_ATE_unsigned_char:
// Create a BTF type instance for this DIBasicType and put it into
// DIToIdMap for cross-type reference check.
TypeEntry = std::make_unique<BTFTypeInt>(
Encoding, BTy->getSizeInBits(), BTy->getOffsetInBits(), BTy->getName());
break;
case dwarf::DW_ATE_float:
TypeEntry =
std::make_unique<BTFTypeFloat>(BTy->getSizeInBits(), BTy->getName());
break;
default:
return;
}
TypeId = addType(std::move(TypeEntry), BTy);
}
/// Handle subprogram or subroutine types.
void BTFDebug::visitSubroutineType(
const DISubroutineType *STy, bool ForSubprog,
const std::unordered_map<uint32_t, StringRef> &FuncArgNames,
uint32_t &TypeId) {
DITypeRefArray Elements = STy->getTypeArray();
uint32_t VLen = Elements.size() - 1;
if (VLen > BTF::MAX_VLEN)
return;
// Subprogram has a valid non-zero-length name, and the pointee of
// a function pointer has an empty name. The subprogram type will
// not be added to DIToIdMap as it should not be referenced by
// any other types.
auto TypeEntry = std::make_unique<BTFTypeFuncProto>(STy, VLen, FuncArgNames);
if (ForSubprog)
TypeId = addType(std::move(TypeEntry)); // For subprogram
else
TypeId = addType(std::move(TypeEntry), STy); // For func ptr
// Visit return type and func arg types.
for (const auto Element : Elements) {
visitTypeEntry(Element);
}
}
void BTFDebug::processDeclAnnotations(DINodeArray Annotations,
uint32_t BaseTypeId,
int ComponentIdx) {
if (!Annotations)
return;
for (const Metadata *Annotation : Annotations->operands()) {
const MDNode *MD = cast<MDNode>(Annotation);
const MDString *Name = cast<MDString>(MD->getOperand(0));
if (!Name->getString().equals("btf_decl_tag"))
continue;
const MDString *Value = cast<MDString>(MD->getOperand(1));
auto TypeEntry = std::make_unique<BTFTypeDeclTag>(BaseTypeId, ComponentIdx,
Value->getString());
addType(std::move(TypeEntry));
}
}
uint32_t BTFDebug::processDISubprogram(const DISubprogram *SP,
uint32_t ProtoTypeId, uint8_t Scope) {
auto FuncTypeEntry =
std::make_unique<BTFTypeFunc>(SP->getName(), ProtoTypeId, Scope);
uint32_t FuncId = addType(std::move(FuncTypeEntry));
// Process argument annotations.
for (const DINode *DN : SP->getRetainedNodes()) {
if (const auto *DV = dyn_cast<DILocalVariable>(DN)) {
uint32_t Arg = DV->getArg();
if (Arg)
processDeclAnnotations(DV->getAnnotations(), FuncId, Arg - 1);
}
}
processDeclAnnotations(SP->getAnnotations(), FuncId, -1);
return FuncId;
}
/// Generate btf_type_tag chains.
int BTFDebug::genBTFTypeTags(const DIDerivedType *DTy, int BaseTypeId) {
SmallVector<const MDString *, 4> MDStrs;
DINodeArray Annots = DTy->getAnnotations();
if (Annots) {
// For type with "int __tag1 __tag2 *p", the MDStrs will have
// content: [__tag1, __tag2].
for (const Metadata *Annotations : Annots->operands()) {
const MDNode *MD = cast<MDNode>(Annotations);
const MDString *Name = cast<MDString>(MD->getOperand(0));
if (!Name->getString().equals("btf_type_tag"))
continue;
MDStrs.push_back(cast<MDString>(MD->getOperand(1)));
}
}
if (MDStrs.size() == 0)
return -1;
// With MDStrs [__tag1, __tag2], the output type chain looks like
// PTR -> __tag2 -> __tag1 -> BaseType
// In the below, we construct BTF types with the order of __tag1, __tag2
// and PTR.
unsigned TmpTypeId;
std::unique_ptr<BTFTypeTypeTag> TypeEntry;
if (BaseTypeId >= 0)
TypeEntry =
std::make_unique<BTFTypeTypeTag>(BaseTypeId, MDStrs[0]->getString());
else
TypeEntry = std::make_unique<BTFTypeTypeTag>(DTy, MDStrs[0]->getString());
TmpTypeId = addType(std::move(TypeEntry));
for (unsigned I = 1; I < MDStrs.size(); I++) {
const MDString *Value = MDStrs[I];
TypeEntry = std::make_unique<BTFTypeTypeTag>(TmpTypeId, Value->getString());
TmpTypeId = addType(std::move(TypeEntry));
}
return TmpTypeId;
}
/// Handle structure/union types.
void BTFDebug::visitStructType(const DICompositeType *CTy, bool IsStruct,
uint32_t &TypeId) {
const DINodeArray Elements = CTy->getElements();
uint32_t VLen = Elements.size();
if (VLen > BTF::MAX_VLEN)
return;
// Check whether we have any bitfield members or not
bool HasBitField = false;
for (const auto *Element : Elements) {
auto E = cast<DIDerivedType>(Element);
if (E->isBitField()) {
HasBitField = true;
break;
}
}
auto TypeEntry =
std::make_unique<BTFTypeStruct>(CTy, IsStruct, HasBitField, VLen);
StructTypes.push_back(TypeEntry.get());
TypeId = addType(std::move(TypeEntry), CTy);
// Check struct/union annotations
processDeclAnnotations(CTy->getAnnotations(), TypeId, -1);
// Visit all struct members.
int FieldNo = 0;
for (const auto *Element : Elements) {
const auto Elem = cast<DIDerivedType>(Element);
visitTypeEntry(Elem);
processDeclAnnotations(Elem->getAnnotations(), TypeId, FieldNo);
FieldNo++;
}
}
void BTFDebug::visitArrayType(const DICompositeType *CTy, uint32_t &TypeId) {
// Visit array element type.
uint32_t ElemTypeId;
const DIType *ElemType = CTy->getBaseType();
visitTypeEntry(ElemType, ElemTypeId, false, false);
// Visit array dimensions.
DINodeArray Elements = CTy->getElements();
for (int I = Elements.size() - 1; I >= 0; --I) {
if (auto *Element = dyn_cast_or_null<DINode>(Elements[I]))
if (Element->getTag() == dwarf::DW_TAG_subrange_type) {
const DISubrange *SR = cast<DISubrange>(Element);
auto *CI = SR->getCount().dyn_cast<ConstantInt *>();
int64_t Count = CI->getSExtValue();
// For struct s { int b; char c[]; }, the c[] will be represented
// as an array with Count = -1.
auto TypeEntry =
std::make_unique<BTFTypeArray>(ElemTypeId,
Count >= 0 ? Count : 0);
if (I == 0)
ElemTypeId = addType(std::move(TypeEntry), CTy);
else
ElemTypeId = addType(std::move(TypeEntry));
}
}
// The array TypeId is the type id of the outermost dimension.
TypeId = ElemTypeId;
// The IR does not have a type for array index while BTF wants one.
// So create an array index type if there is none.
if (!ArrayIndexTypeId) {
auto TypeEntry = std::make_unique<BTFTypeInt>(dwarf::DW_ATE_unsigned, 32,
0, "__ARRAY_SIZE_TYPE__");
ArrayIndexTypeId = addType(std::move(TypeEntry));
}
}
void BTFDebug::visitEnumType(const DICompositeType *CTy, uint32_t &TypeId) {
DINodeArray Elements = CTy->getElements();
uint32_t VLen = Elements.size();
if (VLen > BTF::MAX_VLEN)
return;
bool IsSigned = false;
unsigned NumBits = 32;
// No BaseType implies forward declaration in which case a
// BTFTypeEnum with Vlen = 0 is emitted.
if (CTy->getBaseType() != nullptr) {
const auto *BTy = cast<DIBasicType>(CTy->getBaseType());
IsSigned = BTy->getEncoding() == dwarf::DW_ATE_signed ||
BTy->getEncoding() == dwarf::DW_ATE_signed_char;
NumBits = BTy->getSizeInBits();
}
if (NumBits <= 32) {
auto TypeEntry = std::make_unique<BTFTypeEnum>(CTy, VLen, IsSigned);
TypeId = addType(std::move(TypeEntry), CTy);
} else {
assert(NumBits == 64);
auto TypeEntry = std::make_unique<BTFTypeEnum64>(CTy, VLen, IsSigned);
TypeId = addType(std::move(TypeEntry), CTy);
}
// No need to visit base type as BTF does not encode it.
}
/// Handle structure/union forward declarations.
void BTFDebug::visitFwdDeclType(const DICompositeType *CTy, bool IsUnion,
uint32_t &TypeId) {
auto TypeEntry = std::make_unique<BTFTypeFwd>(CTy->getName(), IsUnion);
TypeId = addType(std::move(TypeEntry), CTy);
}
/// Handle structure, union, array and enumeration types.
void BTFDebug::visitCompositeType(const DICompositeType *CTy,
uint32_t &TypeId) {
auto Tag = CTy->getTag();
if (Tag == dwarf::DW_TAG_structure_type || Tag == dwarf::DW_TAG_union_type) {
// Handle forward declaration differently as it does not have members.
if (CTy->isForwardDecl())
visitFwdDeclType(CTy, Tag == dwarf::DW_TAG_union_type, TypeId);
else
visitStructType(CTy, Tag == dwarf::DW_TAG_structure_type, TypeId);
} else if (Tag == dwarf::DW_TAG_array_type)
visitArrayType(CTy, TypeId);
else if (Tag == dwarf::DW_TAG_enumeration_type)
visitEnumType(CTy, TypeId);
}
bool BTFDebug::IsForwardDeclCandidate(const DIType *Base) {
if (const auto *CTy = dyn_cast<DICompositeType>(Base)) {
auto CTag = CTy->getTag();
if ((CTag == dwarf::DW_TAG_structure_type ||
CTag == dwarf::DW_TAG_union_type) &&
!CTy->getName().empty() && !CTy->isForwardDecl())
return true;
}
return false;
}
/// Handle pointer, typedef, const, volatile, restrict and member types.
void BTFDebug::visitDerivedType(const DIDerivedType *DTy, uint32_t &TypeId,
bool CheckPointer, bool SeenPointer) {
unsigned Tag = DTy->getTag();
/// Try to avoid chasing pointees, esp. structure pointees which may
/// unnecessary bring in a lot of types.
if (CheckPointer && !SeenPointer) {
SeenPointer = Tag == dwarf::DW_TAG_pointer_type;
}
if (CheckPointer && SeenPointer) {
const DIType *Base = DTy->getBaseType();
if (Base) {
if (IsForwardDeclCandidate(Base)) {
/// Find a candidate, generate a fixup. Later on the struct/union
/// pointee type will be replaced with either a real type or
/// a forward declaration.
auto TypeEntry = std::make_unique<BTFTypeDerived>(DTy, Tag, true);
auto &Fixup = FixupDerivedTypes[cast<DICompositeType>(Base)];
Fixup.push_back(std::make_pair(DTy, TypeEntry.get()));
TypeId = addType(std::move(TypeEntry), DTy);
return;
}
}
}
if (Tag == dwarf::DW_TAG_pointer_type) {
int TmpTypeId = genBTFTypeTags(DTy, -1);
if (TmpTypeId >= 0) {
auto TypeDEntry =
std::make_unique<BTFTypeDerived>(TmpTypeId, Tag, DTy->getName());
TypeId = addType(std::move(TypeDEntry), DTy);
} else {
auto TypeEntry = std::make_unique<BTFTypeDerived>(DTy, Tag, false);
TypeId = addType(std::move(TypeEntry), DTy);
}
} else if (Tag == dwarf::DW_TAG_typedef || Tag == dwarf::DW_TAG_const_type ||
Tag == dwarf::DW_TAG_volatile_type ||
Tag == dwarf::DW_TAG_restrict_type) {
auto TypeEntry = std::make_unique<BTFTypeDerived>(DTy, Tag, false);
TypeId = addType(std::move(TypeEntry), DTy);
if (Tag == dwarf::DW_TAG_typedef)
processDeclAnnotations(DTy->getAnnotations(), TypeId, -1);
} else if (Tag != dwarf::DW_TAG_member) {
return;
}
// Visit base type of pointer, typedef, const, volatile, restrict or
// struct/union member.
uint32_t TempTypeId = 0;
if (Tag == dwarf::DW_TAG_member)
visitTypeEntry(DTy->getBaseType(), TempTypeId, true, false);
else
visitTypeEntry(DTy->getBaseType(), TempTypeId, CheckPointer, SeenPointer);
}
/// Visit a type entry. CheckPointer is true if the type has
/// one of its predecessors as one struct/union member. SeenPointer
/// is true if CheckPointer is true and one of its predecessors
/// is a pointer. The goal of CheckPointer and SeenPointer is to
/// do pruning for struct/union types so some of these types
/// will not be emitted in BTF and rather forward declarations
/// will be generated.
void BTFDebug::visitTypeEntry(const DIType *Ty, uint32_t &TypeId,
bool CheckPointer, bool SeenPointer) {
if (!Ty || DIToIdMap.find(Ty) != DIToIdMap.end()) {
TypeId = DIToIdMap[Ty];
// To handle the case like the following:
// struct t;
// typedef struct t _t;
// struct s1 { _t *c; };
// int test1(struct s1 *arg) { ... }
//
// struct t { int a; int b; };
// struct s2 { _t c; }
// int test2(struct s2 *arg) { ... }
//
// During traversing test1() argument, "_t" is recorded
// in DIToIdMap and a forward declaration fixup is created
// for "struct t" to avoid pointee type traversal.
//
// During traversing test2() argument, even if we see "_t" is
// already defined, we should keep moving to eventually
// bring in types for "struct t". Otherwise, the "struct s2"
// definition won't be correct.
//
// In the above, we have following debuginfo:
// {ptr, struct_member} -> typedef -> struct
// and BTF type for 'typedef' is generated while 'struct' may
// be in FixUp. But let us generalize the above to handle
// {different types} -> [various derived types]+ -> another type.
// For example,
// {func_param, struct_member} -> const -> ptr -> volatile -> struct
// We will traverse const/ptr/volatile which already have corresponding
// BTF types and generate type for 'struct' which might be in Fixup
// state.
if (Ty && (!CheckPointer || !SeenPointer)) {
if (const auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
while (DTy) {
const DIType *BaseTy = DTy->getBaseType();
if (!BaseTy)
break;
if (DIToIdMap.find(BaseTy) != DIToIdMap.end()) {
DTy = dyn_cast<DIDerivedType>(BaseTy);
} else {
if (CheckPointer && DTy->getTag() == dwarf::DW_TAG_pointer_type) {
SeenPointer = true;
if (IsForwardDeclCandidate(BaseTy))
break;
}
uint32_t TmpTypeId;
visitTypeEntry(BaseTy, TmpTypeId, CheckPointer, SeenPointer);
break;
}
}
}
}
return;
}
if (const auto *BTy = dyn_cast<DIBasicType>(Ty))
visitBasicType(BTy, TypeId);
else if (const auto *STy = dyn_cast<DISubroutineType>(Ty))
visitSubroutineType(STy, false, std::unordered_map<uint32_t, StringRef>(),
TypeId);
else if (const auto *CTy = dyn_cast<DICompositeType>(Ty))
visitCompositeType(CTy, TypeId);
else if (const auto *DTy = dyn_cast<DIDerivedType>(Ty))
visitDerivedType(DTy, TypeId, CheckPointer, SeenPointer);
else
llvm_unreachable("Unknown DIType");
}
void BTFDebug::visitTypeEntry(const DIType *Ty) {
uint32_t TypeId;
visitTypeEntry(Ty, TypeId, false, false);
}
void BTFDebug::visitMapDefType(const DIType *Ty, uint32_t &TypeId) {
if (!Ty || DIToIdMap.find(Ty) != DIToIdMap.end()) {
TypeId = DIToIdMap[Ty];
return;
}
// MapDef type may be a struct type or a non-pointer derived type
const DIType *OrigTy = Ty;
while (auto *DTy = dyn_cast<DIDerivedType>(Ty)) {
auto Tag = DTy->getTag();
if (Tag != dwarf::DW_TAG_typedef && Tag != dwarf::DW_TAG_const_type &&
Tag != dwarf::DW_TAG_volatile_type &&
Tag != dwarf::DW_TAG_restrict_type)
break;
Ty = DTy->getBaseType();
}
const auto *CTy = dyn_cast<DICompositeType>(Ty);
if (!CTy)
return;
auto Tag = CTy->getTag();
if (Tag != dwarf::DW_TAG_structure_type || CTy->isForwardDecl())
return;
// Visit all struct members to ensure pointee type is visited
const DINodeArray Elements = CTy->getElements();
for (const auto *Element : Elements) {
const auto *MemberType = cast<DIDerivedType>(Element);
visitTypeEntry(MemberType->getBaseType());
}
// Visit this type, struct or a const/typedef/volatile/restrict type
visitTypeEntry(OrigTy, TypeId, false, false);
}
/// Read file contents from the actual file or from the source
std::string BTFDebug::populateFileContent(const DISubprogram *SP) {
auto File = SP->getFile();
std::string FileName;
if (!File->getFilename().startswith("/") && File->getDirectory().size())
FileName = File->getDirectory().str() + "/" + File->getFilename().str();
else
FileName = std::string(File->getFilename());
// No need to populate the contends if it has been populated!
if (FileContent.contains(FileName))
return FileName;
std::vector<std::string> Content;
std::string Line;
Content.push_back(Line); // Line 0 for empty string
std::unique_ptr<MemoryBuffer> Buf;
auto Source = File->getSource();
if (Source)
Buf = MemoryBuffer::getMemBufferCopy(*Source);
else if (ErrorOr<std::unique_ptr<MemoryBuffer>> BufOrErr =
MemoryBuffer::getFile(FileName))
Buf = std::move(*BufOrErr);
if (Buf)
for (line_iterator I(*Buf, false), E; I != E; ++I)
Content.push_back(std::string(*I));
FileContent[FileName] = Content;
return FileName;
}
void BTFDebug::constructLineInfo(const DISubprogram *SP, MCSymbol *Label,
uint32_t Line, uint32_t Column) {
std::string FileName = populateFileContent(SP);
BTFLineInfo LineInfo;
LineInfo.Label = Label;
LineInfo.FileNameOff = addString(FileName);
// If file content is not available, let LineOff = 0.
if (Line < FileContent[FileName].size())
LineInfo.LineOff = addString(FileContent[FileName][Line]);
else
LineInfo.LineOff = 0;
LineInfo.LineNum = Line;
LineInfo.ColumnNum = Column;
LineInfoTable[SecNameOff].push_back(LineInfo);
}
void BTFDebug::emitCommonHeader() {
OS.AddComment("0x" + Twine::utohexstr(BTF::MAGIC));
OS.emitIntValue(BTF::MAGIC, 2);
OS.emitInt8(BTF::VERSION);
OS.emitInt8(0);
}
void BTFDebug::emitBTFSection() {
// Do not emit section if no types and only "" string.
if (!TypeEntries.size() && StringTable.getSize() == 1)
return;
MCContext &Ctx = OS.getContext();
MCSectionELF *Sec = Ctx.getELFSection(".BTF", ELF::SHT_PROGBITS, 0);
Sec->setAlignment(Align(4));
OS.switchSection(Sec);
// Emit header.
emitCommonHeader();
OS.emitInt32(BTF::HeaderSize);
uint32_t TypeLen = 0, StrLen;
for (const auto &TypeEntry : TypeEntries)
TypeLen += TypeEntry->getSize();
StrLen = StringTable.getSize();
OS.emitInt32(0);
OS.emitInt32(TypeLen);
OS.emitInt32(TypeLen);
OS.emitInt32(StrLen);
// Emit type table.
for (const auto &TypeEntry : TypeEntries)
TypeEntry->emitType(OS);
// Emit string table.
uint32_t StringOffset = 0;
for (const auto &S : StringTable.getTable()) {
OS.AddComment("string offset=" + std::to_string(StringOffset));
OS.emitBytes(S);
OS.emitBytes(StringRef("\0", 1));
StringOffset += S.size() + 1;
}
}
void BTFDebug::emitBTFExtSection() {
// Do not emit section if empty FuncInfoTable and LineInfoTable
// and FieldRelocTable.
if (!FuncInfoTable.size() && !LineInfoTable.size() &&
!FieldRelocTable.size())
return;
MCContext &Ctx = OS.getContext();
MCSectionELF *Sec = Ctx.getELFSection(".BTF.ext", ELF::SHT_PROGBITS, 0);
Sec->setAlignment(Align(4));
OS.switchSection(Sec);
// Emit header.
emitCommonHeader();
OS.emitInt32(BTF::ExtHeaderSize);
// Account for FuncInfo/LineInfo record size as well.
uint32_t FuncLen = 4, LineLen = 4;
// Do not account for optional FieldReloc.
uint32_t FieldRelocLen = 0;
for (const auto &FuncSec : FuncInfoTable) {
FuncLen += BTF::SecFuncInfoSize;
FuncLen += FuncSec.second.size() * BTF::BPFFuncInfoSize;
}
for (const auto &LineSec : LineInfoTable) {
LineLen += BTF::SecLineInfoSize;
LineLen += LineSec.second.size() * BTF::BPFLineInfoSize;
}
for (const auto &FieldRelocSec : FieldRelocTable) {
FieldRelocLen += BTF::SecFieldRelocSize;
FieldRelocLen += FieldRelocSec.second.size() * BTF::BPFFieldRelocSize;
}
if (FieldRelocLen)
FieldRelocLen += 4;
OS.emitInt32(0);
OS.emitInt32(FuncLen);
OS.emitInt32(FuncLen);
OS.emitInt32(LineLen);
OS.emitInt32(FuncLen + LineLen);
OS.emitInt32(FieldRelocLen);
// Emit func_info table.
OS.AddComment("FuncInfo");
OS.emitInt32(BTF::BPFFuncInfoSize);
for (const auto &FuncSec : FuncInfoTable) {
OS.AddComment("FuncInfo section string offset=" +
std::to_string(FuncSec.first));
OS.emitInt32(FuncSec.first);
OS.emitInt32(FuncSec.second.size());
for (const auto &FuncInfo : FuncSec.second) {
Asm->emitLabelReference(FuncInfo.Label, 4);
OS.emitInt32(FuncInfo.TypeId);
}
}
// Emit line_info table.
OS.AddComment("LineInfo");
OS.emitInt32(BTF::BPFLineInfoSize);
for (const auto &LineSec : LineInfoTable) {
OS.AddComment("LineInfo section string offset=" +
std::to_string(LineSec.first));
OS.emitInt32(LineSec.first);
OS.emitInt32(LineSec.second.size());
for (const auto &LineInfo : LineSec.second) {
Asm->emitLabelReference(LineInfo.Label, 4);
OS.emitInt32(LineInfo.FileNameOff);
OS.emitInt32(LineInfo.LineOff);
OS.AddComment("Line " + std::to_string(LineInfo.LineNum) + " Col " +
std::to_string(LineInfo.ColumnNum));
OS.emitInt32(LineInfo.LineNum << 10 | LineInfo.ColumnNum);
}
}
// Emit field reloc table.
if (FieldRelocLen) {
OS.AddComment("FieldReloc");
OS.emitInt32(BTF::BPFFieldRelocSize);
for (const auto &FieldRelocSec : FieldRelocTable) {
OS.AddComment("Field reloc section string offset=" +
std::to_string(FieldRelocSec.first));
OS.emitInt32(FieldRelocSec.first);
OS.emitInt32(FieldRelocSec.second.size());
for (const auto &FieldRelocInfo : FieldRelocSec.second) {
Asm->emitLabelReference(FieldRelocInfo.Label, 4);
OS.emitInt32(FieldRelocInfo.TypeID);
OS.emitInt32(FieldRelocInfo.OffsetNameOff);
OS.emitInt32(FieldRelocInfo.RelocKind);
}
}
}
}
void BTFDebug::beginFunctionImpl(const MachineFunction *MF) {
auto *SP = MF->getFunction().getSubprogram();
auto *Unit = SP->getUnit();
if (Unit->getEmissionKind() == DICompileUnit::NoDebug) {
SkipInstruction = true;
return;
}
SkipInstruction = false;
// Collect MapDef types. Map definition needs to collect
// pointee types. Do it first. Otherwise, for the following
// case:
// struct m { ...};
// struct t {
// struct m *key;
// };
// foo(struct t *arg);
//
// struct mapdef {
// ...
// struct m *key;
// ...
// } __attribute__((section(".maps"))) hash_map;
//
// If subroutine foo is traversed first, a type chain
// "ptr->struct m(fwd)" will be created and later on
// when traversing mapdef, since "ptr->struct m" exists,
// the traversal of "struct m" will be omitted.
if (MapDefNotCollected) {
processGlobals(true);
MapDefNotCollected = false;
}
// Collect all types locally referenced in this function.
// Use RetainedNodes so we can collect all argument names
// even if the argument is not used.
std::unordered_map<uint32_t, StringRef> FuncArgNames;
for (const DINode *DN : SP->getRetainedNodes()) {
if (const auto *DV = dyn_cast<DILocalVariable>(DN)) {
// Collect function arguments for subprogram func type.
uint32_t Arg = DV->getArg();
if (Arg) {
visitTypeEntry(DV->getType());
FuncArgNames[Arg] = DV->getName();
}
}
}
// Construct subprogram func proto type.
uint32_t ProtoTypeId;
visitSubroutineType(SP->getType(), true, FuncArgNames, ProtoTypeId);
// Construct subprogram func type
uint8_t Scope = SP->isLocalToUnit() ? BTF::FUNC_STATIC : BTF::FUNC_GLOBAL;
uint32_t FuncTypeId = processDISubprogram(SP, ProtoTypeId, Scope);
for (const auto &TypeEntry : TypeEntries)
TypeEntry->completeType(*this);
// Construct funcinfo and the first lineinfo for the function.
MCSymbol *FuncLabel = Asm->getFunctionBegin();
BTFFuncInfo FuncInfo;
FuncInfo.Label = FuncLabel;
FuncInfo.TypeId = FuncTypeId;
if (FuncLabel->isInSection()) {
MCSection &Section = FuncLabel->getSection();
const MCSectionELF *SectionELF = dyn_cast<MCSectionELF>(&Section);
assert(SectionELF && "Null section for Function Label");
SecNameOff = addString(SectionELF->getName());
} else {
SecNameOff = addString(".text");
}
FuncInfoTable[SecNameOff].push_back(FuncInfo);
}
void BTFDebug::endFunctionImpl(const MachineFunction *MF) {
SkipInstruction = false;
LineInfoGenerated = false;
SecNameOff = 0;
}
/// On-demand populate types as requested from abstract member
/// accessing or preserve debuginfo type.
unsigned BTFDebug::populateType(const DIType *Ty) {
unsigned Id;
visitTypeEntry(Ty, Id, false, false);
for (const auto &TypeEntry : TypeEntries)
TypeEntry->completeType(*this);
return Id;
}
/// Generate a struct member field relocation.
void BTFDebug::generatePatchImmReloc(const MCSymbol *ORSym, uint32_t RootId,
const GlobalVariable *GVar, bool IsAma) {
BTFFieldReloc FieldReloc;
FieldReloc.Label = ORSym;
FieldReloc.TypeID = RootId;
StringRef AccessPattern = GVar->getName();
size_t FirstDollar = AccessPattern.find_first_of('$');
if (IsAma) {
size_t FirstColon = AccessPattern.find_first_of(':');
size_t SecondColon = AccessPattern.find_first_of(':', FirstColon + 1);
StringRef IndexPattern = AccessPattern.substr(FirstDollar + 1);
StringRef RelocKindStr = AccessPattern.substr(FirstColon + 1,
SecondColon - FirstColon);
StringRef PatchImmStr = AccessPattern.substr(SecondColon + 1,
FirstDollar - SecondColon);
FieldReloc.OffsetNameOff = addString(IndexPattern);
FieldReloc.RelocKind = std::stoull(std::string(RelocKindStr));
PatchImms[GVar] = std::make_pair(std::stoll(std::string(PatchImmStr)),
FieldReloc.RelocKind);
} else {
StringRef RelocStr = AccessPattern.substr(FirstDollar + 1);
FieldReloc.OffsetNameOff = addString("0");
FieldReloc.RelocKind = std::stoull(std::string(RelocStr));
PatchImms[GVar] = std::make_pair(RootId, FieldReloc.RelocKind);
}
FieldRelocTable[SecNameOff].push_back(FieldReloc);
}
void BTFDebug::processGlobalValue(const MachineOperand &MO) {
// check whether this is a candidate or not
if (MO.isGlobal()) {
const GlobalValue *GVal = MO.getGlobal();
auto *GVar = dyn_cast<GlobalVariable>(GVal);
if (!GVar) {
// Not a global variable. Maybe an extern function reference.
processFuncPrototypes(dyn_cast<Function>(GVal));
return;
}
if (!GVar->hasAttribute(BPFCoreSharedInfo::AmaAttr) &&
!GVar->hasAttribute(BPFCoreSharedInfo::TypeIdAttr))
return;
MCSymbol *ORSym = OS.getContext().createTempSymbol();
OS.emitLabel(ORSym);
MDNode *MDN = GVar->getMetadata(LLVMContext::MD_preserve_access_index);
uint32_t RootId = populateType(dyn_cast<DIType>(MDN));
generatePatchImmReloc(ORSym, RootId, GVar,
GVar->hasAttribute(BPFCoreSharedInfo::AmaAttr));
}
}
void BTFDebug::beginInstruction(const MachineInstr *MI) {
DebugHandlerBase::beginInstruction(MI);
if (SkipInstruction || MI->isMetaInstruction() ||
MI->getFlag(MachineInstr::FrameSetup))
return;
if (MI->isInlineAsm()) {
// Count the number of register definitions to find the asm string.
unsigned NumDefs = 0;
while (true) {
const MachineOperand &MO = MI->getOperand(NumDefs);
if (MO.isReg() && MO.isDef()) {
++NumDefs;
continue;
}
// Skip this inline asm instruction if the asmstr is empty.
const char *AsmStr = MO.getSymbolName();
if (AsmStr[0] == 0)
return;
break;
}
}
if (MI->getOpcode() == BPF::LD_imm64) {
// If the insn is "r2 = LD_imm64 @<an AmaAttr global>",
// add this insn into the .BTF.ext FieldReloc subsection.
// Relocation looks like:
// . SecName:
// . InstOffset
// . TypeID
// . OffSetNameOff
// . RelocType
// Later, the insn is replaced with "r2 = <offset>"
// where "<offset>" equals to the offset based on current
// type definitions.
//
// If the insn is "r2 = LD_imm64 @<an TypeIdAttr global>",
// The LD_imm64 result will be replaced with a btf type id.
processGlobalValue(MI->getOperand(1));
} else if (MI->getOpcode() == BPF::CORE_LD64 ||
MI->getOpcode() == BPF::CORE_LD32 ||
MI->getOpcode() == BPF::CORE_ST ||
MI->getOpcode() == BPF::CORE_SHIFT) {
// relocation insn is a load, store or shift insn.
processGlobalValue(MI->getOperand(3));
} else if (MI->getOpcode() == BPF::JAL) {
// check extern function references
const MachineOperand &MO = MI->getOperand(0);
if (MO.isGlobal()) {
processFuncPrototypes(dyn_cast<Function>(MO.getGlobal()));
}
}
if (!CurMI) // no debug info
return;
// Skip this instruction if no DebugLoc or the DebugLoc
// is the same as the previous instruction.
const DebugLoc &DL = MI->getDebugLoc();
if (!DL || PrevInstLoc == DL) {
// This instruction will be skipped, no LineInfo has
// been generated, construct one based on function signature.
if (LineInfoGenerated == false) {
auto *S = MI->getMF()->getFunction().getSubprogram();
if (!S)
return;
MCSymbol *FuncLabel = Asm->getFunctionBegin();
constructLineInfo(S, FuncLabel, S->getLine(), 0);
LineInfoGenerated = true;
}
return;
}
// Create a temporary label to remember the insn for lineinfo.
MCSymbol *LineSym = OS.getContext().createTempSymbol();
OS.emitLabel(LineSym);
// Construct the lineinfo.
auto SP = DL->getScope()->getSubprogram();
constructLineInfo(SP, LineSym, DL.getLine(), DL.getCol());
LineInfoGenerated = true;
PrevInstLoc = DL;
}
void BTFDebug::processGlobals(bool ProcessingMapDef) {
// Collect all types referenced by globals.
const Module *M = MMI->getModule();
for (const GlobalVariable &Global : M->globals()) {
// Decide the section name.
StringRef SecName;
std::optional<SectionKind> GVKind;
if (!Global.isDeclarationForLinker())
GVKind = TargetLoweringObjectFile::getKindForGlobal(&Global, Asm->TM);
if (Global.isDeclarationForLinker())
SecName = Global.hasSection() ? Global.getSection() : "";
else if (GVKind->isCommon())
SecName = ".bss";
else {
TargetLoweringObjectFile *TLOF = Asm->TM.getObjFileLowering();
MCSection *Sec = TLOF->SectionForGlobal(&Global, Asm->TM);
SecName = Sec->getName();
}
if (ProcessingMapDef != SecName.startswith(".maps"))
continue;
// Create a .rodata datasec if the global variable is an initialized
// constant with private linkage and if it won't be in .rodata.str<#>
// and .rodata.cst<#> sections.
if (SecName == ".rodata" && Global.hasPrivateLinkage() &&
DataSecEntries.find(std::string(SecName)) == DataSecEntries.end()) {
// skip .rodata.str<#> and .rodata.cst<#> sections
if (!GVKind->isMergeableCString() && !GVKind->isMergeableConst()) {
DataSecEntries[std::string(SecName)] =
std::make_unique<BTFKindDataSec>(Asm, std::string(SecName));
}
}
SmallVector<DIGlobalVariableExpression *, 1> GVs;
Global.getDebugInfo(GVs);
// No type information, mostly internal, skip it.
if (GVs.size() == 0)
continue;
uint32_t GVTypeId = 0;
DIGlobalVariable *DIGlobal = nullptr;
for (auto *GVE : GVs) {
DIGlobal = GVE->getVariable();
if (SecName.startswith(".maps"))
visitMapDefType(DIGlobal->getType(), GVTypeId);
else
visitTypeEntry(DIGlobal->getType(), GVTypeId, false, false);
break;
}
// Only support the following globals:
// . static variables
// . non-static weak or non-weak global variables
// . weak or non-weak extern global variables
// Whether DataSec is readonly or not can be found from corresponding ELF
// section flags. Whether a BTF_KIND_VAR is a weak symbol or not
// can be found from the corresponding ELF symbol table.
auto Linkage = Global.getLinkage();
if (Linkage != GlobalValue::InternalLinkage &&
Linkage != GlobalValue::ExternalLinkage &&
Linkage != GlobalValue::WeakAnyLinkage &&
Linkage != GlobalValue::WeakODRLinkage &&
Linkage != GlobalValue::ExternalWeakLinkage)
continue;
uint32_t GVarInfo;
if (Linkage == GlobalValue::InternalLinkage) {
GVarInfo = BTF::VAR_STATIC;
} else if (Global.hasInitializer()) {
GVarInfo = BTF::VAR_GLOBAL_ALLOCATED;
} else {
GVarInfo = BTF::VAR_GLOBAL_EXTERNAL;
}
auto VarEntry =
std::make_unique<BTFKindVar>(Global.getName(), GVTypeId, GVarInfo);
uint32_t VarId = addType(std::move(VarEntry));
processDeclAnnotations(DIGlobal->getAnnotations(), VarId, -1);
// An empty SecName means an extern variable without section attribute.
if (SecName.empty())
continue;
// Find or create a DataSec
if (DataSecEntries.find(std::string(SecName)) == DataSecEntries.end()) {
DataSecEntries[std::string(SecName)] =
std::make_unique<BTFKindDataSec>(Asm, std::string(SecName));
}
// Calculate symbol size
const DataLayout &DL = Global.getParent()->getDataLayout();
uint32_t Size = DL.getTypeAllocSize(Global.getValueType());
DataSecEntries[std::string(SecName)]->addDataSecEntry(VarId,
Asm->getSymbol(&Global), Size);
}
}
/// Emit proper patchable instructions.
bool BTFDebug::InstLower(const MachineInstr *MI, MCInst &OutMI) {
if (MI->getOpcode() == BPF::LD_imm64) {
const MachineOperand &MO = MI->getOperand(1);
if (MO.isGlobal()) {
const GlobalValue *GVal = MO.getGlobal();
auto *GVar = dyn_cast<GlobalVariable>(GVal);
if (GVar) {
// Emit "mov ri, <imm>"
int64_t Imm;
uint32_t Reloc;
if (GVar->hasAttribute(BPFCoreSharedInfo::AmaAttr) ||
GVar->hasAttribute(BPFCoreSharedInfo::TypeIdAttr)) {
Imm = PatchImms[GVar].first;
Reloc = PatchImms[GVar].second;
} else {
return false;
}
if (Reloc == BTF::ENUM_VALUE_EXISTENCE || Reloc == BTF::ENUM_VALUE ||
Reloc == BTF::BTF_TYPE_ID_LOCAL || Reloc == BTF::BTF_TYPE_ID_REMOTE)
OutMI.setOpcode(BPF::LD_imm64);
else
OutMI.setOpcode(BPF::MOV_ri);
OutMI.addOperand(MCOperand::createReg(MI->getOperand(0).getReg()));
OutMI.addOperand(MCOperand::createImm(Imm));
return true;
}
}
} else if (MI->getOpcode() == BPF::CORE_LD64 ||
MI->getOpcode() == BPF::CORE_LD32 ||
MI->getOpcode() == BPF::CORE_ST ||
MI->getOpcode() == BPF::CORE_SHIFT) {
const MachineOperand &MO = MI->getOperand(3);
if (MO.isGlobal()) {
const GlobalValue *GVal = MO.getGlobal();
auto *GVar = dyn_cast<GlobalVariable>(GVal);
if (GVar && GVar->hasAttribute(BPFCoreSharedInfo::AmaAttr)) {
uint32_t Imm = PatchImms[GVar].first;
OutMI.setOpcode(MI->getOperand(1).getImm());
if (MI->getOperand(0).isImm())
OutMI.addOperand(MCOperand::createImm(MI->getOperand(0).getImm()));
else
OutMI.addOperand(MCOperand::createReg(MI->getOperand(0).getReg()));
OutMI.addOperand(MCOperand::createReg(MI->getOperand(2).getReg()));
OutMI.addOperand(MCOperand::createImm(Imm));
return true;
}
}
}
return false;
}
void BTFDebug::processFuncPrototypes(const Function *F) {
if (!F)
return;
const DISubprogram *SP = F->getSubprogram();
if (!SP || SP->isDefinition())
return;
// Do not emit again if already emitted.
if (!ProtoFunctions.insert(F).second)
return;
uint32_t ProtoTypeId;
const std::unordered_map<uint32_t, StringRef> FuncArgNames;
visitSubroutineType(SP->getType(), false, FuncArgNames, ProtoTypeId);
uint32_t FuncId = processDISubprogram(SP, ProtoTypeId, BTF::FUNC_EXTERN);
if (F->hasSection()) {
StringRef SecName = F->getSection();
if (DataSecEntries.find(std::string(SecName)) == DataSecEntries.end()) {
DataSecEntries[std::string(SecName)] =
std::make_unique<BTFKindDataSec>(Asm, std::string(SecName));
}
// We really don't know func size, set it to 0.
DataSecEntries[std::string(SecName)]->addDataSecEntry(FuncId,
Asm->getSymbol(F), 0);
}
}
void BTFDebug::endModule() {
// Collect MapDef globals if not collected yet.
if (MapDefNotCollected) {
processGlobals(true);
MapDefNotCollected = false;
}
// Collect global types/variables except MapDef globals.
processGlobals(false);
for (auto &DataSec : DataSecEntries)
addType(std::move(DataSec.second));
// Fixups
for (auto &Fixup : FixupDerivedTypes) {
const DICompositeType *CTy = Fixup.first;
StringRef TypeName = CTy->getName();
bool IsUnion = CTy->getTag() == dwarf::DW_TAG_union_type;
// Search through struct types
uint32_t StructTypeId = 0;
for (const auto &StructType : StructTypes) {
if (StructType->getName() == TypeName) {
StructTypeId = StructType->getId();
break;
}
}
if (StructTypeId == 0) {
auto FwdTypeEntry = std::make_unique<BTFTypeFwd>(TypeName, IsUnion);
StructTypeId = addType(std::move(FwdTypeEntry));
}
for (auto &TypeInfo : Fixup.second) {
const DIDerivedType *DTy = TypeInfo.first;
BTFTypeDerived *BDType = TypeInfo.second;
int TmpTypeId = genBTFTypeTags(DTy, StructTypeId);
if (TmpTypeId >= 0)
BDType->setPointeeType(TmpTypeId);
else
BDType->setPointeeType(StructTypeId);
}
}
// Complete BTF type cross refereences.
for (const auto &TypeEntry : TypeEntries)
TypeEntry->completeType(*this);
// Emit BTF sections.
emitBTFSection();
emitBTFExtSection();
}