//=== aarch64.h - Generic JITLink aarch64 edge kinds, utilities -*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Generic utilities for graphs representing aarch64 objects.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_EXECUTIONENGINE_JITLINK_AARCH64_H
#define LLVM_EXECUTIONENGINE_JITLINK_AARCH64_H
#include "TableManager.h"
#include "llvm/ExecutionEngine/JITLink/JITLink.h"
#include "llvm/ExecutionEngine/Orc/Shared/MemoryFlags.h"
namespace llvm {
namespace jitlink {
namespace aarch64 {
/// Represents aarch64 fixups and other aarch64-specific edge kinds.
enum EdgeKind_aarch64 : Edge::Kind {
/// A plain 64-bit pointer value relocation.
///
/// Fixup expression:
/// Fixup <- Target + Addend : uint64
///
Pointer64 = Edge::FirstRelocation,
/// A plain 32-bit pointer value relocation.
///
/// Fixup expression:
/// Fixup <- Target + Addend : uint32
///
/// Errors:
/// - The target must reside in the low 32-bits of the address space,
/// otherwise an out-of-range error will be returned.
///
Pointer32,
/// A 64-bit delta.
///
/// Delta from the fixup to the target.
///
/// Fixup expression:
/// Fixup <- Target - Fixup + Addend : int64
///
Delta64,
/// A 32-bit delta.
///
/// Delta from the fixup to the target.
///
/// Fixup expression:
/// Fixup <- Target - Fixup + Addend : int64
///
/// Errors:
/// - The result of the fixup expression must fit into an int32, otherwise
/// an out-of-range error will be returned.
///
Delta32,
/// A 64-bit negative delta.
///
/// Delta from target back to the fixup.
///
/// Fixup expression:
/// Fixup <- Fixup - Target + Addend : int64
///
NegDelta64,
/// A 32-bit negative delta.
///
/// Delta from the target back to the fixup.
///
/// Fixup expression:
/// Fixup <- Fixup - Target + Addend : int32
///
/// Errors:
/// - The result of the fixup expression must fit into an int32, otherwise
/// an out-of-range error will be returned.
NegDelta32,
/// A 26-bit PC-relative branch.
///
/// Represents a PC-relative call or branch to a target within +/-128Mb. The
/// target must be 32-bit aligned.
///
/// Fixup expression:
/// Fixup <- (Target - Fixup + Addend) >> 2 : int26
///
/// Notes:
/// The '26' in the name refers to the number operand bits and follows the
/// naming convention used by the corresponding ELF and MachO relocations.
/// Since the low two bits must be zero (because of the 32-bit alignment of
/// the target) the operand is effectively a signed 28-bit number.
///
///
/// Errors:
/// - The result of the unshifted part of the fixup expression must be
/// 32-bit aligned otherwise an alignment error will be returned.
/// - The result of the fixup expression must fit into an int26 otherwise an
/// out-of-range error will be returned.
Branch26PCRel,
/// A 16-bit slice of the target address (which slice depends on the
/// instruction at the fixup location).
///
/// Used to fix up MOVK/MOVN/MOVZ instructions.
///
/// Fixup expression:
///
/// Fixup <- (Target + Addend) >> Shift : uint16
///
/// where Shift is encoded in the instruction at the fixup location.
///
MoveWide16,
/// The signed 21-bit delta from the fixup to the target.
///
/// Typically used to load a pointers at a PC-relative offset of +/- 1Mb. The
/// target must be 32-bit aligned.
///
/// Fixup expression:
///
/// Fixup <- (Target - Fixup) >> 2 : int19
///
/// Errors:
/// - The result of the unshifted part of the fixup expression must be
/// 32-bit aligned otherwise an alignment error will be returned.
/// - The result of the fixup expression must fit into an an int19 or an
/// out-of-range error will be returned.
LDRLiteral19,
/// The signed 21-bit delta from the fixup page to the page containing the
/// target.
///
/// Fixup expression:
///
/// Fixup <- (((Target + Addend) & ~0xfff) - (Fixup & ~0xfff)) >> 12 : int21
///
/// Notes:
/// For ADRP fixups.
///
/// Errors:
/// - The result of the fixup expression must fit into an int21 otherwise an
/// out-of-range error will be returned.
Page21,
/// The 12-bit (potentially shifted) offset of the target within its page.
///
/// Typically used to fix up LDR immediates.
///
/// Fixup expression:
///
/// Fixup <- ((Target + Addend) >> Shift) & 0xfff : uint12
///
/// where Shift is encoded in the size field of the instruction.
///
/// Errors:
/// - The result of the unshifted part of the fixup expression must be
/// aligned otherwise an alignment error will be returned.
/// - The result of the fixup expression must fit into a uint12 otherwise an
/// out-of-range error will be returned.
PageOffset12,
/// A GOT entry getter/constructor, transformed to Page21 pointing at the GOT
/// entry for the original target.
///
/// Indicates that this edge should be transformed into a Page21 targeting
/// the GOT entry for the edge's current target, maintaining the same addend.
/// A GOT entry for the target should be created if one does not already
/// exist.
///
/// Edges of this kind are usually handled by a GOT builder pass inserted by
/// default.
///
/// Fixup expression:
/// NONE
///
/// Errors:
/// - *ASSERTION* Failure to handle edges of this kind prior to the fixup
/// phase will result in an assert/unreachable during the fixup phase.
///
RequestGOTAndTransformToPage21,
/// A GOT entry getter/constructor, transformed to Pageoffset12 pointing at
/// the GOT entry for the original target.
///
/// Indicates that this edge should be transformed into a PageOffset12
/// targeting the GOT entry for the edge's current target, maintaining the
/// same addend. A GOT entry for the target should be created if one does not
/// already exist.
///
/// Edges of this kind are usually handled by a GOT builder pass inserted by
/// default.
///
/// Fixup expression:
/// NONE
///
/// Errors:
/// - *ASSERTION* Failure to handle edges of this kind prior to the fixup
/// phase will result in an assert/unreachable during the fixup phase.
///
RequestGOTAndTransformToPageOffset12,
/// A GOT entry getter/constructor, transformed to Delta32 pointing at the GOT
/// entry for the original target.
///
/// Indicates that this edge should be transformed into a Delta32/ targeting
/// the GOT entry for the edge's current target, maintaining the same addend.
/// A GOT entry for the target should be created if one does not already
/// exist.
///
/// Edges of this kind are usually handled by a GOT builder pass inserted by
/// default.
///
/// Fixup expression:
/// NONE
///
/// Errors:
/// - *ASSERTION* Failure to handle edges of this kind prior to the fixup
/// phase will result in an assert/unreachable during the fixup phase.
///
RequestGOTAndTransformToDelta32,
/// A TLVP entry getter/constructor, transformed to Page21.
///
/// Indicates that this edge should be transformed into a Page21 targeting the
/// TLVP entry for the edge's current target. A TLVP entry for the target
/// should be created if one does not already exist.
///
/// Fixup expression:
/// NONE
///
/// Errors:
/// - *ASSERTION* Failure to handle edges of this kind prior to the fixup
/// phase will result in an assert/unreachable during the fixup phase.
///
RequestTLVPAndTransformToPage21,
/// A TLVP entry getter/constructor, transformed to PageOffset12.
///
/// Indicates that this edge should be transformed into a PageOffset12
/// targeting the TLVP entry for the edge's current target. A TLVP entry for
/// the target should be created if one does not already exist.
///
/// Fixup expression:
/// NONE
///
/// Errors:
/// - *ASSERTION* Failure to handle edges of this kind prior to the fixup
/// phase will result in an assert/unreachable during the fixup phase.
///
RequestTLVPAndTransformToPageOffset12,
/// A TLSDesc entry getter/constructor, transformed to Page21.
///
/// Indicates that this edge should be transformed into a Page21 targeting the
/// TLSDesc entry for the edge's current target. A TLSDesc entry for the
/// target should be created if one does not already exist.
///
/// Fixup expression:
/// NONE
///
/// Errors:
/// - *ASSERTION* Failure to handle edges of this kind prior to the fixup
/// phase will result in an assert/unreachable during the fixup phase.
///
RequestTLSDescEntryAndTransformToPage21,
/// A TLSDesc entry getter/constructor, transformed to PageOffset12.
///
/// Indicates that this edge should be transformed into a PageOffset12
/// targeting the TLSDesc entry for the edge's current target. A TLSDesc entry
/// for the target should be created if one does not already exist.
///
/// Fixup expression:
/// NONE
///
/// Errors:
/// - *ASSERTION* Failure to handle edges of this kind prior to the fixup
/// phase will result in an assert/unreachable during the fixup phase.
///
RequestTLSDescEntryAndTransformToPageOffset12,
};
/// Returns a string name for the given aarch64 edge. For debugging purposes
/// only
const char *getEdgeKindName(Edge::Kind K);
// Returns whether the Instr is LD/ST (imm12)
inline bool isLoadStoreImm12(uint32_t Instr) {
constexpr uint32_t LoadStoreImm12Mask = 0x3b000000;
return (Instr & LoadStoreImm12Mask) == 0x39000000;
}
// Returns the amount the address operand of LD/ST (imm12)
// should be shifted right by.
//
// The shift value varies by the data size of LD/ST instruction.
// For instance, LDH instructoin needs the address to be shifted
// right by 1.
inline unsigned getPageOffset12Shift(uint32_t Instr) {
constexpr uint32_t Vec128Mask = 0x04800000;
if (isLoadStoreImm12(Instr)) {
uint32_t ImplicitShift = Instr >> 30;
if (ImplicitShift == 0)
if ((Instr & Vec128Mask) == Vec128Mask)
ImplicitShift = 4;
return ImplicitShift;
}
return 0;
}
// Returns whether the Instr is MOVK/MOVZ (imm16) with a zero immediate field
inline bool isMoveWideImm16(uint32_t Instr) {
constexpr uint32_t MoveWideImm16Mask = 0x5f9fffe0;
return (Instr & MoveWideImm16Mask) == 0x52800000;
}
// Returns the amount the address operand of MOVK/MOVZ (imm16)
// should be shifted right by.
//
// The shift value is specfied in the assembly as LSL #<shift>.
inline unsigned getMoveWide16Shift(uint32_t Instr) {
if (isMoveWideImm16(Instr)) {
uint32_t ImplicitShift = (Instr >> 21) & 0b11;
return ImplicitShift << 4;
}
return 0;
}
/// Apply fixup expression for edge to block content.
inline Error applyFixup(LinkGraph &G, Block &B, const Edge &E) {
using namespace support;
char *BlockWorkingMem = B.getAlreadyMutableContent().data();
char *FixupPtr = BlockWorkingMem + E.getOffset();
orc::ExecutorAddr FixupAddress = B.getAddress() + E.getOffset();
switch (E.getKind()) {
case Pointer64: {
uint64_t Value = E.getTarget().getAddress().getValue() + E.getAddend();
*(ulittle64_t *)FixupPtr = Value;
break;
}
case Pointer32: {
uint64_t Value = E.getTarget().getAddress().getValue() + E.getAddend();
if (Value > std::numeric_limits<uint32_t>::max())
return makeTargetOutOfRangeError(G, B, E);
*(ulittle32_t *)FixupPtr = Value;
break;
}
case Delta32:
case Delta64:
case NegDelta32:
case NegDelta64: {
int64_t Value;
if (E.getKind() == Delta32 || E.getKind() == Delta64)
Value = E.getTarget().getAddress() - FixupAddress + E.getAddend();
else
Value = FixupAddress - E.getTarget().getAddress() + E.getAddend();
if (E.getKind() == Delta32 || E.getKind() == NegDelta32) {
if (Value < std::numeric_limits<int32_t>::min() ||
Value > std::numeric_limits<int32_t>::max())
return makeTargetOutOfRangeError(G, B, E);
*(little32_t *)FixupPtr = Value;
} else
*(little64_t *)FixupPtr = Value;
break;
}
case Branch26PCRel: {
assert((FixupAddress.getValue() & 0x3) == 0 &&
"Branch-inst is not 32-bit aligned");
int64_t Value = E.getTarget().getAddress() - FixupAddress + E.getAddend();
if (static_cast<uint64_t>(Value) & 0x3)
return make_error<JITLinkError>("BranchPCRel26 target is not 32-bit "
"aligned");
if (Value < -(1 << 27) || Value > ((1 << 27) - 1))
return makeTargetOutOfRangeError(G, B, E);
uint32_t RawInstr = *(little32_t *)FixupPtr;
assert((RawInstr & 0x7fffffff) == 0x14000000 &&
"RawInstr isn't a B or BR immediate instruction");
uint32_t Imm = (static_cast<uint32_t>(Value) & ((1 << 28) - 1)) >> 2;
uint32_t FixedInstr = RawInstr | Imm;
*(little32_t *)FixupPtr = FixedInstr;
break;
}
case MoveWide16: {
uint64_t TargetOffset =
(E.getTarget().getAddress() + E.getAddend()).getValue();
uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
assert(isMoveWideImm16(RawInstr) &&
"RawInstr isn't a MOVK/MOVZ instruction");
unsigned ImmShift = getMoveWide16Shift(RawInstr);
uint32_t Imm = (TargetOffset >> ImmShift) & 0xffff;
uint32_t FixedInstr = RawInstr | (Imm << 5);
*(ulittle32_t *)FixupPtr = FixedInstr;
break;
}
case LDRLiteral19: {
assert((FixupAddress.getValue() & 0x3) == 0 && "LDR is not 32-bit aligned");
assert(E.getAddend() == 0 && "LDRLiteral19 with non-zero addend");
uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
assert(RawInstr == 0x58000010 && "RawInstr isn't a 64-bit LDR literal");
int64_t Delta = E.getTarget().getAddress() - FixupAddress;
if (Delta & 0x3)
return make_error<JITLinkError>("LDR literal target is not 32-bit "
"aligned");
if (Delta < -(1 << 20) || Delta > ((1 << 20) - 1))
return makeTargetOutOfRangeError(G, B, E);
uint32_t EncodedImm = ((static_cast<uint32_t>(Delta) >> 2) & 0x7ffff) << 5;
uint32_t FixedInstr = RawInstr | EncodedImm;
*(ulittle32_t *)FixupPtr = FixedInstr;
break;
}
case Page21: {
uint64_t TargetPage =
(E.getTarget().getAddress().getValue() + E.getAddend()) &
~static_cast<uint64_t>(4096 - 1);
uint64_t PCPage =
FixupAddress.getValue() & ~static_cast<uint64_t>(4096 - 1);
int64_t PageDelta = TargetPage - PCPage;
if (!isInt<33>(PageDelta))
return makeTargetOutOfRangeError(G, B, E);
uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
assert((RawInstr & 0xffffffe0) == 0x90000000 &&
"RawInstr isn't an ADRP instruction");
uint32_t ImmLo = (static_cast<uint64_t>(PageDelta) >> 12) & 0x3;
uint32_t ImmHi = (static_cast<uint64_t>(PageDelta) >> 14) & 0x7ffff;
uint32_t FixedInstr = RawInstr | (ImmLo << 29) | (ImmHi << 5);
*(ulittle32_t *)FixupPtr = FixedInstr;
break;
}
case PageOffset12: {
uint64_t TargetOffset =
(E.getTarget().getAddress() + E.getAddend()).getValue() & 0xfff;
uint32_t RawInstr = *(ulittle32_t *)FixupPtr;
unsigned ImmShift = getPageOffset12Shift(RawInstr);
if (TargetOffset & ((1 << ImmShift) - 1))
return make_error<JITLinkError>("PAGEOFF12 target is not aligned");
uint32_t EncodedImm = (TargetOffset >> ImmShift) << 10;
uint32_t FixedInstr = RawInstr | EncodedImm;
*(ulittle32_t *)FixupPtr = FixedInstr;
break;
}
default:
return make_error<JITLinkError>(
"In graph " + G.getName() + ", section " + B.getSection().getName() +
" unsupported edge kind " + getEdgeKindName(E.getKind()));
}
return Error::success();
}
/// aarch64 pointer size.
constexpr uint64_t PointerSize = 8;
/// AArch64 null pointer content.
extern const char NullPointerContent[PointerSize];
/// AArch64 pointer jump stub content.
///
/// Contains the instruction sequence for an indirect jump via an in-memory
/// pointer:
/// ADRP x16, ptr@page21
/// LDR x16, [x16, ptr@pageoff12]
/// BR x16
extern const char PointerJumpStubContent[12];
/// Creates a new pointer block in the given section and returns an
/// Anonymous symobl pointing to it.
///
/// If InitialTarget is given then an Pointer64 relocation will be added to the
/// block pointing at InitialTarget.
///
/// The pointer block will have the following default values:
/// alignment: 64-bit
/// alignment-offset: 0
/// address: highest allowable (~7U)
inline Symbol &createAnonymousPointer(LinkGraph &G, Section &PointerSection,
Symbol *InitialTarget = nullptr,
uint64_t InitialAddend = 0) {
auto &B = G.createContentBlock(PointerSection, NullPointerContent,
orc::ExecutorAddr(~uint64_t(7)), 8, 0);
if (InitialTarget)
B.addEdge(Pointer64, 0, *InitialTarget, InitialAddend);
return G.addAnonymousSymbol(B, 0, 8, false, false);
}
/// Create a jump stub block that jumps via the pointer at the given symbol.
///
/// The stub block will have the following default values:
/// alignment: 32-bit
/// alignment-offset: 0
/// address: highest allowable: (~11U)
inline Block &createPointerJumpStubBlock(LinkGraph &G, Section &StubSection,
Symbol &PointerSymbol) {
auto &B = G.createContentBlock(StubSection, PointerJumpStubContent,
orc::ExecutorAddr(~uint64_t(11)), 1, 0);
B.addEdge(Page21, 0, PointerSymbol, 0);
B.addEdge(PageOffset12, 4, PointerSymbol, 0);
return B;
}
/// Create a jump stub that jumps via the pointer at the given symbol and
/// an anonymous symbol pointing to it. Return the anonymous symbol.
///
/// The stub block will be created by createPointerJumpStubBlock.
inline Symbol &createAnonymousPointerJumpStub(LinkGraph &G,
Section &StubSection,
Symbol &PointerSymbol) {
return G.addAnonymousSymbol(
createPointerJumpStubBlock(G, StubSection, PointerSymbol), 0,
sizeof(PointerJumpStubContent), true, false);
}
/// Global Offset Table Builder.
class GOTTableManager : public TableManager<GOTTableManager> {
public:
static StringRef getSectionName() { return "$__GOT"; }
bool visitEdge(LinkGraph &G, Block *B, Edge &E) {
Edge::Kind KindToSet = Edge::Invalid;
const char *BlockWorkingMem = B->getContent().data();
const char *FixupPtr = BlockWorkingMem + E.getOffset();
switch (E.getKind()) {
case aarch64::RequestGOTAndTransformToPage21:
case aarch64::RequestTLVPAndTransformToPage21: {
KindToSet = aarch64::Page21;
break;
}
case aarch64::RequestGOTAndTransformToPageOffset12:
case aarch64::RequestTLVPAndTransformToPageOffset12: {
KindToSet = aarch64::PageOffset12;
uint32_t RawInstr = *(const support::ulittle32_t *)FixupPtr;
(void)RawInstr;
assert(E.getAddend() == 0 &&
"GOTPageOffset12/TLVPageOffset12 with non-zero addend");
assert((RawInstr & 0xfffffc00) == 0xf9400000 &&
"RawInstr isn't a 64-bit LDR immediate");
break;
}
case aarch64::RequestGOTAndTransformToDelta32: {
KindToSet = aarch64::Delta32;
break;
}
default:
return false;
}
assert(KindToSet != Edge::Invalid &&
"Fell through switch, but no new kind to set");
DEBUG_WITH_TYPE("jitlink", {
dbgs() << " Fixing " << G.getEdgeKindName(E.getKind()) << " edge at "
<< B->getFixupAddress(E) << " (" << B->getAddress() << " + "
<< formatv("{0:x}", E.getOffset()) << ")\n";
});
E.setKind(KindToSet);
E.setTarget(getEntryForTarget(G, E.getTarget()));
return true;
}
Symbol &createEntry(LinkGraph &G, Symbol &Target) {
return createAnonymousPointer(G, getGOTSection(G), &Target);
}
private:
Section &getGOTSection(LinkGraph &G) {
if (!GOTSection)
GOTSection = &G.createSection(getSectionName(),
orc::MemProt::Read | orc::MemProt::Exec);
return *GOTSection;
}
Section *GOTSection = nullptr;
};
/// Procedure Linkage Table Builder.
class PLTTableManager : public TableManager<PLTTableManager> {
public:
PLTTableManager(GOTTableManager &GOT) : GOT(GOT) {}
static StringRef getSectionName() { return "$__STUBS"; }
bool visitEdge(LinkGraph &G, Block *B, Edge &E) {
if (E.getKind() == aarch64::Branch26PCRel && !E.getTarget().isDefined()) {
DEBUG_WITH_TYPE("jitlink", {
dbgs() << " Fixing " << G.getEdgeKindName(E.getKind()) << " edge at "
<< B->getFixupAddress(E) << " (" << B->getAddress() << " + "
<< formatv("{0:x}", E.getOffset()) << ")\n";
});
E.setTarget(getEntryForTarget(G, E.getTarget()));
return true;
}
return false;
}
Symbol &createEntry(LinkGraph &G, Symbol &Target) {
return createAnonymousPointerJumpStub(G, getStubsSection(G),
GOT.getEntryForTarget(G, Target));
}
public:
Section &getStubsSection(LinkGraph &G) {
if (!StubsSection)
StubsSection = &G.createSection(getSectionName(),
orc::MemProt::Read | orc::MemProt::Exec);
return *StubsSection;
}
GOTTableManager &GOT;
Section *StubsSection = nullptr;
};
} // namespace aarch64
} // namespace jitlink
} // namespace llvm
#endif // LLVM_EXECUTIONENGINE_JITLINK_AARCH64_H