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-rw-r--r--ELF/Arch/AArch64.cpp466
1 files changed, 308 insertions, 158 deletions
diff --git a/ELF/Arch/AArch64.cpp b/ELF/Arch/AArch64.cpp
index 08ffe2a08c0f..4d4789702f03 100644
--- a/ELF/Arch/AArch64.cpp
+++ b/ELF/Arch/AArch64.cpp
@@ -1,9 +1,8 @@
//===- AArch64.cpp --------------------------------------------------------===//
//
-// The LLVM Linker
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// 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
//
//===----------------------------------------------------------------------===//
@@ -24,60 +23,59 @@ using namespace lld::elf;
// Page(Expr) is the page address of the expression Expr, defined
// as (Expr & ~0xFFF). (This applies even if the machine page size
// supported by the platform has a different value.)
-uint64_t elf::getAArch64Page(uint64_t Expr) {
- return Expr & ~static_cast<uint64_t>(0xFFF);
+uint64_t elf::getAArch64Page(uint64_t expr) {
+ return expr & ~static_cast<uint64_t>(0xFFF);
}
namespace {
-class AArch64 final : public TargetInfo {
+class AArch64 : public TargetInfo {
public:
AArch64();
- RelExpr getRelExpr(RelType Type, const Symbol &S,
- const uint8_t *Loc) const override;
- RelType getDynRel(RelType Type) const override;
- void writeGotPlt(uint8_t *Buf, const Symbol &S) const override;
- void writePltHeader(uint8_t *Buf) const override;
- void writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr, uint64_t PltEntryAddr,
- int32_t Index, unsigned RelOff) const override;
- bool needsThunk(RelExpr Expr, RelType Type, const InputFile *File,
- uint64_t BranchAddr, const Symbol &S) const override;
+ RelExpr getRelExpr(RelType type, const Symbol &s,
+ const uint8_t *loc) const override;
+ RelType getDynRel(RelType type) const override;
+ void writeGotPlt(uint8_t *buf, const Symbol &s) const override;
+ void writePltHeader(uint8_t *buf) const override;
+ void writePlt(uint8_t *buf, uint64_t gotPltEntryAddr, uint64_t pltEntryAddr,
+ int32_t index, unsigned relOff) const override;
+ bool needsThunk(RelExpr expr, RelType type, const InputFile *file,
+ uint64_t branchAddr, const Symbol &s) const override;
uint32_t getThunkSectionSpacing() const override;
- bool inBranchRange(RelType Type, uint64_t Src, uint64_t Dst) const override;
- bool usesOnlyLowPageBits(RelType Type) const override;
- void relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const override;
- RelExpr adjustRelaxExpr(RelType Type, const uint8_t *Data,
- RelExpr Expr) const override;
- void relaxTlsGdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const override;
- void relaxTlsGdToIe(uint8_t *Loc, RelType Type, uint64_t Val) const override;
- void relaxTlsIeToLe(uint8_t *Loc, RelType Type, uint64_t Val) const override;
+ bool inBranchRange(RelType type, uint64_t src, uint64_t dst) const override;
+ bool usesOnlyLowPageBits(RelType type) const override;
+ void relocateOne(uint8_t *loc, RelType type, uint64_t val) const override;
+ RelExpr adjustRelaxExpr(RelType type, const uint8_t *data,
+ RelExpr expr) const override;
+ void relaxTlsGdToLe(uint8_t *loc, RelType type, uint64_t val) const override;
+ void relaxTlsGdToIe(uint8_t *loc, RelType type, uint64_t val) const override;
+ void relaxTlsIeToLe(uint8_t *loc, RelType type, uint64_t val) const override;
};
} // namespace
AArch64::AArch64() {
- CopyRel = R_AARCH64_COPY;
- RelativeRel = R_AARCH64_RELATIVE;
- IRelativeRel = R_AARCH64_IRELATIVE;
- GotRel = R_AARCH64_GLOB_DAT;
- NoneRel = R_AARCH64_NONE;
- PltRel = R_AARCH64_JUMP_SLOT;
- TlsDescRel = R_AARCH64_TLSDESC;
- TlsGotRel = R_AARCH64_TLS_TPREL64;
- GotEntrySize = 8;
- GotPltEntrySize = 8;
- PltEntrySize = 16;
- PltHeaderSize = 32;
- DefaultMaxPageSize = 65536;
+ copyRel = R_AARCH64_COPY;
+ relativeRel = R_AARCH64_RELATIVE;
+ iRelativeRel = R_AARCH64_IRELATIVE;
+ gotRel = R_AARCH64_GLOB_DAT;
+ noneRel = R_AARCH64_NONE;
+ pltRel = R_AARCH64_JUMP_SLOT;
+ symbolicRel = R_AARCH64_ABS64;
+ tlsDescRel = R_AARCH64_TLSDESC;
+ tlsGotRel = R_AARCH64_TLS_TPREL64;
+ pltEntrySize = 16;
+ pltHeaderSize = 32;
+ defaultMaxPageSize = 65536;
// Align to the 2 MiB page size (known as a superpage or huge page).
// FreeBSD automatically promotes 2 MiB-aligned allocations.
- DefaultImageBase = 0x200000;
+ defaultImageBase = 0x200000;
- NeedsThunks = true;
+ needsThunks = true;
}
-RelExpr AArch64::getRelExpr(RelType Type, const Symbol &S,
- const uint8_t *Loc) const {
- switch (Type) {
+RelExpr AArch64::getRelExpr(RelType type, const Symbol &s,
+ const uint8_t *loc) const {
+ switch (type) {
case R_AARCH64_TLSDESC_ADR_PAGE21:
return R_AARCH64_TLSDESC_PAGE;
case R_AARCH64_TLSDESC_LD64_LO12:
@@ -105,6 +103,7 @@ RelExpr AArch64::getRelExpr(RelType Type, const Symbol &S,
case R_AARCH64_LD_PREL_LO19:
return R_PC;
case R_AARCH64_ADR_PREL_PG_HI21:
+ case R_AARCH64_ADR_PREL_PG_HI21_NC:
return R_AARCH64_PAGE_PC;
case R_AARCH64_LD64_GOT_LO12_NC:
case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
@@ -119,18 +118,18 @@ RelExpr AArch64::getRelExpr(RelType Type, const Symbol &S,
}
}
-RelExpr AArch64::adjustRelaxExpr(RelType Type, const uint8_t *Data,
- RelExpr Expr) const {
- if (Expr == R_RELAX_TLS_GD_TO_IE) {
- if (Type == R_AARCH64_TLSDESC_ADR_PAGE21)
+RelExpr AArch64::adjustRelaxExpr(RelType type, const uint8_t *data,
+ RelExpr expr) const {
+ if (expr == R_RELAX_TLS_GD_TO_IE) {
+ if (type == R_AARCH64_TLSDESC_ADR_PAGE21)
return R_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC;
return R_RELAX_TLS_GD_TO_IE_ABS;
}
- return Expr;
+ return expr;
}
-bool AArch64::usesOnlyLowPageBits(RelType Type) const {
- switch (Type) {
+bool AArch64::usesOnlyLowPageBits(RelType type) const {
+ switch (type) {
default:
return false;
case R_AARCH64_ADD_ABS_LO12_NC:
@@ -147,18 +146,18 @@ bool AArch64::usesOnlyLowPageBits(RelType Type) const {
}
}
-RelType AArch64::getDynRel(RelType Type) const {
- if (Type == R_AARCH64_ABS32 || Type == R_AARCH64_ABS64)
- return Type;
+RelType AArch64::getDynRel(RelType type) const {
+ if (type == R_AARCH64_ABS64)
+ return type;
return R_AARCH64_NONE;
}
-void AArch64::writeGotPlt(uint8_t *Buf, const Symbol &) const {
- write64le(Buf, In.Plt->getVA());
+void AArch64::writeGotPlt(uint8_t *buf, const Symbol &) const {
+ write64le(buf, in.plt->getVA());
}
-void AArch64::writePltHeader(uint8_t *Buf) const {
- const uint8_t PltData[] = {
+void AArch64::writePltHeader(uint8_t *buf) const {
+ const uint8_t pltData[] = {
0xf0, 0x7b, 0xbf, 0xa9, // stp x16, x30, [sp,#-16]!
0x10, 0x00, 0x00, 0x90, // adrp x16, Page(&(.plt.got[2]))
0x11, 0x02, 0x40, 0xf9, // ldr x17, [x16, Offset(&(.plt.got[2]))]
@@ -168,42 +167,42 @@ void AArch64::writePltHeader(uint8_t *Buf) const {
0x1f, 0x20, 0x03, 0xd5, // nop
0x1f, 0x20, 0x03, 0xd5 // nop
};
- memcpy(Buf, PltData, sizeof(PltData));
-
- uint64_t Got = In.GotPlt->getVA();
- uint64_t Plt = In.Plt->getVA();
- relocateOne(Buf + 4, R_AARCH64_ADR_PREL_PG_HI21,
- getAArch64Page(Got + 16) - getAArch64Page(Plt + 4));
- relocateOne(Buf + 8, R_AARCH64_LDST64_ABS_LO12_NC, Got + 16);
- relocateOne(Buf + 12, R_AARCH64_ADD_ABS_LO12_NC, Got + 16);
+ memcpy(buf, pltData, sizeof(pltData));
+
+ uint64_t got = in.gotPlt->getVA();
+ uint64_t plt = in.plt->getVA();
+ relocateOne(buf + 4, R_AARCH64_ADR_PREL_PG_HI21,
+ getAArch64Page(got + 16) - getAArch64Page(plt + 4));
+ relocateOne(buf + 8, R_AARCH64_LDST64_ABS_LO12_NC, got + 16);
+ relocateOne(buf + 12, R_AARCH64_ADD_ABS_LO12_NC, got + 16);
}
-void AArch64::writePlt(uint8_t *Buf, uint64_t GotPltEntryAddr,
- uint64_t PltEntryAddr, int32_t Index,
- unsigned RelOff) const {
- const uint8_t Inst[] = {
+void AArch64::writePlt(uint8_t *buf, uint64_t gotPltEntryAddr,
+ uint64_t pltEntryAddr, int32_t index,
+ unsigned relOff) const {
+ const uint8_t inst[] = {
0x10, 0x00, 0x00, 0x90, // adrp x16, Page(&(.plt.got[n]))
0x11, 0x02, 0x40, 0xf9, // ldr x17, [x16, Offset(&(.plt.got[n]))]
0x10, 0x02, 0x00, 0x91, // add x16, x16, Offset(&(.plt.got[n]))
0x20, 0x02, 0x1f, 0xd6 // br x17
};
- memcpy(Buf, Inst, sizeof(Inst));
+ memcpy(buf, inst, sizeof(inst));
- relocateOne(Buf, R_AARCH64_ADR_PREL_PG_HI21,
- getAArch64Page(GotPltEntryAddr) - getAArch64Page(PltEntryAddr));
- relocateOne(Buf + 4, R_AARCH64_LDST64_ABS_LO12_NC, GotPltEntryAddr);
- relocateOne(Buf + 8, R_AARCH64_ADD_ABS_LO12_NC, GotPltEntryAddr);
+ relocateOne(buf, R_AARCH64_ADR_PREL_PG_HI21,
+ getAArch64Page(gotPltEntryAddr) - getAArch64Page(pltEntryAddr));
+ relocateOne(buf + 4, R_AARCH64_LDST64_ABS_LO12_NC, gotPltEntryAddr);
+ relocateOne(buf + 8, R_AARCH64_ADD_ABS_LO12_NC, gotPltEntryAddr);
}
-bool AArch64::needsThunk(RelExpr Expr, RelType Type, const InputFile *File,
- uint64_t BranchAddr, const Symbol &S) const {
+bool AArch64::needsThunk(RelExpr expr, RelType type, const InputFile *file,
+ uint64_t branchAddr, const Symbol &s) const {
// ELF for the ARM 64-bit architecture, section Call and Jump relocations
// only permits range extension thunks for R_AARCH64_CALL26 and
// R_AARCH64_JUMP26 relocation types.
- if (Type != R_AARCH64_CALL26 && Type != R_AARCH64_JUMP26)
+ if (type != R_AARCH64_CALL26 && type != R_AARCH64_JUMP26)
return false;
- uint64_t Dst = (Expr == R_PLT_PC) ? S.getPltVA() : S.getVA();
- return !inBranchRange(Type, BranchAddr, Dst);
+ uint64_t dst = (expr == R_PLT_PC) ? s.getPltVA() : s.getVA();
+ return !inBranchRange(type, branchAddr, dst);
}
uint32_t AArch64::getThunkSectionSpacing() const {
@@ -213,71 +212,72 @@ uint32_t AArch64::getThunkSectionSpacing() const {
return (128 * 1024 * 1024) - 0x30000;
}
-bool AArch64::inBranchRange(RelType Type, uint64_t Src, uint64_t Dst) const {
- if (Type != R_AARCH64_CALL26 && Type != R_AARCH64_JUMP26)
+bool AArch64::inBranchRange(RelType type, uint64_t src, uint64_t dst) const {
+ if (type != R_AARCH64_CALL26 && type != R_AARCH64_JUMP26)
return true;
// The AArch64 call and unconditional branch instructions have a range of
// +/- 128 MiB.
- uint64_t Range = 128 * 1024 * 1024;
- if (Dst > Src) {
+ uint64_t range = 128 * 1024 * 1024;
+ if (dst > src) {
// Immediate of branch is signed.
- Range -= 4;
- return Dst - Src <= Range;
+ range -= 4;
+ return dst - src <= range;
}
- return Src - Dst <= Range;
+ return src - dst <= range;
}
-static void write32AArch64Addr(uint8_t *L, uint64_t Imm) {
- uint32_t ImmLo = (Imm & 0x3) << 29;
- uint32_t ImmHi = (Imm & 0x1FFFFC) << 3;
- uint64_t Mask = (0x3 << 29) | (0x1FFFFC << 3);
- write32le(L, (read32le(L) & ~Mask) | ImmLo | ImmHi);
+static void write32AArch64Addr(uint8_t *l, uint64_t imm) {
+ uint32_t immLo = (imm & 0x3) << 29;
+ uint32_t immHi = (imm & 0x1FFFFC) << 3;
+ uint64_t mask = (0x3 << 29) | (0x1FFFFC << 3);
+ write32le(l, (read32le(l) & ~mask) | immLo | immHi);
}
// Return the bits [Start, End] from Val shifted Start bits.
// For instance, getBits(0xF0, 4, 8) returns 0xF.
-static uint64_t getBits(uint64_t Val, int Start, int End) {
- uint64_t Mask = ((uint64_t)1 << (End + 1 - Start)) - 1;
- return (Val >> Start) & Mask;
+static uint64_t getBits(uint64_t val, int start, int end) {
+ uint64_t mask = ((uint64_t)1 << (end + 1 - start)) - 1;
+ return (val >> start) & mask;
}
-static void or32le(uint8_t *P, int32_t V) { write32le(P, read32le(P) | V); }
+static void or32le(uint8_t *p, int32_t v) { write32le(p, read32le(p) | v); }
// Update the immediate field in a AARCH64 ldr, str, and add instruction.
-static void or32AArch64Imm(uint8_t *L, uint64_t Imm) {
- or32le(L, (Imm & 0xFFF) << 10);
+static void or32AArch64Imm(uint8_t *l, uint64_t imm) {
+ or32le(l, (imm & 0xFFF) << 10);
}
-void AArch64::relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const {
- switch (Type) {
+void AArch64::relocateOne(uint8_t *loc, RelType type, uint64_t val) const {
+ switch (type) {
case R_AARCH64_ABS16:
case R_AARCH64_PREL16:
- checkIntUInt(Loc, Val, 16, Type);
- write16le(Loc, Val);
+ checkIntUInt(loc, val, 16, type);
+ write16le(loc, val);
break;
case R_AARCH64_ABS32:
case R_AARCH64_PREL32:
- checkIntUInt(Loc, Val, 32, Type);
- write32le(Loc, Val);
+ checkIntUInt(loc, val, 32, type);
+ write32le(loc, val);
break;
case R_AARCH64_ABS64:
- case R_AARCH64_GLOB_DAT:
case R_AARCH64_PREL64:
- write64le(Loc, Val);
+ write64le(loc, val);
break;
case R_AARCH64_ADD_ABS_LO12_NC:
- or32AArch64Imm(Loc, Val);
+ or32AArch64Imm(loc, val);
break;
case R_AARCH64_ADR_GOT_PAGE:
case R_AARCH64_ADR_PREL_PG_HI21:
case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
case R_AARCH64_TLSDESC_ADR_PAGE21:
- checkInt(Loc, Val, 33, Type);
- write32AArch64Addr(Loc, Val >> 12);
+ checkInt(loc, val, 33, type);
+ LLVM_FALLTHROUGH;
+ case R_AARCH64_ADR_PREL_PG_HI21_NC:
+ write32AArch64Addr(loc, val >> 12);
break;
case R_AARCH64_ADR_PREL_LO21:
- checkInt(Loc, Val, 21, Type);
- write32AArch64Addr(Loc, Val);
+ checkInt(loc, val, 21, type);
+ write32AArch64Addr(loc, val);
break;
case R_AARCH64_JUMP26:
// Normally we would just write the bits of the immediate field, however
@@ -287,75 +287,75 @@ void AArch64::relocateOne(uint8_t *Loc, RelType Type, uint64_t Val) const {
// opcode and the immediate (0 001 | 01 imm26) we can do this
// transformation by placing a R_AARCH64_JUMP26 relocation at the offset of
// the instruction we want to patch.
- write32le(Loc, 0x14000000);
+ write32le(loc, 0x14000000);
LLVM_FALLTHROUGH;
case R_AARCH64_CALL26:
- checkInt(Loc, Val, 28, Type);
- or32le(Loc, (Val & 0x0FFFFFFC) >> 2);
+ checkInt(loc, val, 28, type);
+ or32le(loc, (val & 0x0FFFFFFC) >> 2);
break;
case R_AARCH64_CONDBR19:
case R_AARCH64_LD_PREL_LO19:
- checkAlignment(Loc, Val, 4, Type);
- checkInt(Loc, Val, 21, Type);
- or32le(Loc, (Val & 0x1FFFFC) << 3);
+ checkAlignment(loc, val, 4, type);
+ checkInt(loc, val, 21, type);
+ or32le(loc, (val & 0x1FFFFC) << 3);
break;
case R_AARCH64_LDST8_ABS_LO12_NC:
case R_AARCH64_TLSLE_LDST8_TPREL_LO12_NC:
- or32AArch64Imm(Loc, getBits(Val, 0, 11));
+ or32AArch64Imm(loc, getBits(val, 0, 11));
break;
case R_AARCH64_LDST16_ABS_LO12_NC:
case R_AARCH64_TLSLE_LDST16_TPREL_LO12_NC:
- checkAlignment(Loc, Val, 2, Type);
- or32AArch64Imm(Loc, getBits(Val, 1, 11));
+ checkAlignment(loc, val, 2, type);
+ or32AArch64Imm(loc, getBits(val, 1, 11));
break;
case R_AARCH64_LDST32_ABS_LO12_NC:
case R_AARCH64_TLSLE_LDST32_TPREL_LO12_NC:
- checkAlignment(Loc, Val, 4, Type);
- or32AArch64Imm(Loc, getBits(Val, 2, 11));
+ checkAlignment(loc, val, 4, type);
+ or32AArch64Imm(loc, getBits(val, 2, 11));
break;
case R_AARCH64_LDST64_ABS_LO12_NC:
case R_AARCH64_LD64_GOT_LO12_NC:
case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
case R_AARCH64_TLSLE_LDST64_TPREL_LO12_NC:
case R_AARCH64_TLSDESC_LD64_LO12:
- checkAlignment(Loc, Val, 8, Type);
- or32AArch64Imm(Loc, getBits(Val, 3, 11));
+ checkAlignment(loc, val, 8, type);
+ or32AArch64Imm(loc, getBits(val, 3, 11));
break;
case R_AARCH64_LDST128_ABS_LO12_NC:
case R_AARCH64_TLSLE_LDST128_TPREL_LO12_NC:
- checkAlignment(Loc, Val, 16, Type);
- or32AArch64Imm(Loc, getBits(Val, 4, 11));
+ checkAlignment(loc, val, 16, type);
+ or32AArch64Imm(loc, getBits(val, 4, 11));
break;
case R_AARCH64_MOVW_UABS_G0_NC:
- or32le(Loc, (Val & 0xFFFF) << 5);
+ or32le(loc, (val & 0xFFFF) << 5);
break;
case R_AARCH64_MOVW_UABS_G1_NC:
- or32le(Loc, (Val & 0xFFFF0000) >> 11);
+ or32le(loc, (val & 0xFFFF0000) >> 11);
break;
case R_AARCH64_MOVW_UABS_G2_NC:
- or32le(Loc, (Val & 0xFFFF00000000) >> 27);
+ or32le(loc, (val & 0xFFFF00000000) >> 27);
break;
case R_AARCH64_MOVW_UABS_G3:
- or32le(Loc, (Val & 0xFFFF000000000000) >> 43);
+ or32le(loc, (val & 0xFFFF000000000000) >> 43);
break;
case R_AARCH64_TSTBR14:
- checkInt(Loc, Val, 16, Type);
- or32le(Loc, (Val & 0xFFFC) << 3);
+ checkInt(loc, val, 16, type);
+ or32le(loc, (val & 0xFFFC) << 3);
break;
case R_AARCH64_TLSLE_ADD_TPREL_HI12:
- checkUInt(Loc, Val, 24, Type);
- or32AArch64Imm(Loc, Val >> 12);
+ checkUInt(loc, val, 24, type);
+ or32AArch64Imm(loc, val >> 12);
break;
case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
case R_AARCH64_TLSDESC_ADD_LO12:
- or32AArch64Imm(Loc, Val);
+ or32AArch64Imm(loc, val);
break;
default:
- error(getErrorLocation(Loc) + "unrecognized reloc " + Twine(Type));
+ error(getErrorLocation(loc) + "unrecognized relocation " + toString(type));
}
}
-void AArch64::relaxTlsGdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const {
+void AArch64::relaxTlsGdToLe(uint8_t *loc, RelType type, uint64_t val) const {
// TLSDESC Global-Dynamic relocation are in the form:
// adrp x0, :tlsdesc:v [R_AARCH64_TLSDESC_ADR_PAGE21]
// ldr x1, [x0, #:tlsdesc_lo12:v [R_AARCH64_TLSDESC_LD64_LO12]
@@ -367,25 +367,25 @@ void AArch64::relaxTlsGdToLe(uint8_t *Loc, RelType Type, uint64_t Val) const {
// movk x0, #0x10
// nop
// nop
- checkUInt(Loc, Val, 32, Type);
+ checkUInt(loc, val, 32, type);
- switch (Type) {
+ switch (type) {
case R_AARCH64_TLSDESC_ADD_LO12:
case R_AARCH64_TLSDESC_CALL:
- write32le(Loc, 0xd503201f); // nop
+ write32le(loc, 0xd503201f); // nop
return;
case R_AARCH64_TLSDESC_ADR_PAGE21:
- write32le(Loc, 0xd2a00000 | (((Val >> 16) & 0xffff) << 5)); // movz
+ write32le(loc, 0xd2a00000 | (((val >> 16) & 0xffff) << 5)); // movz
return;
case R_AARCH64_TLSDESC_LD64_LO12:
- write32le(Loc, 0xf2800000 | ((Val & 0xffff) << 5)); // movk
+ write32le(loc, 0xf2800000 | ((val & 0xffff) << 5)); // movk
return;
default:
llvm_unreachable("unsupported relocation for TLS GD to LE relaxation");
}
}
-void AArch64::relaxTlsGdToIe(uint8_t *Loc, RelType Type, uint64_t Val) const {
+void AArch64::relaxTlsGdToIe(uint8_t *loc, RelType type, uint64_t val) const {
// TLSDESC Global-Dynamic relocation are in the form:
// adrp x0, :tlsdesc:v [R_AARCH64_TLSDESC_ADR_PAGE21]
// ldr x1, [x0, #:tlsdesc_lo12:v [R_AARCH64_TLSDESC_LD64_LO12]
@@ -398,43 +398,193 @@ void AArch64::relaxTlsGdToIe(uint8_t *Loc, RelType Type, uint64_t Val) const {
// nop
// nop
- switch (Type) {
+ switch (type) {
case R_AARCH64_TLSDESC_ADD_LO12:
case R_AARCH64_TLSDESC_CALL:
- write32le(Loc, 0xd503201f); // nop
+ write32le(loc, 0xd503201f); // nop
break;
case R_AARCH64_TLSDESC_ADR_PAGE21:
- write32le(Loc, 0x90000000); // adrp
- relocateOne(Loc, R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21, Val);
+ write32le(loc, 0x90000000); // adrp
+ relocateOne(loc, R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21, val);
break;
case R_AARCH64_TLSDESC_LD64_LO12:
- write32le(Loc, 0xf9400000); // ldr
- relocateOne(Loc, R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC, Val);
+ write32le(loc, 0xf9400000); // ldr
+ relocateOne(loc, R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC, val);
break;
default:
llvm_unreachable("unsupported relocation for TLS GD to LE relaxation");
}
}
-void AArch64::relaxTlsIeToLe(uint8_t *Loc, RelType Type, uint64_t Val) const {
- checkUInt(Loc, Val, 32, Type);
+void AArch64::relaxTlsIeToLe(uint8_t *loc, RelType type, uint64_t val) const {
+ checkUInt(loc, val, 32, type);
- if (Type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21) {
+ if (type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21) {
// Generate MOVZ.
- uint32_t RegNo = read32le(Loc) & 0x1f;
- write32le(Loc, (0xd2a00000 | RegNo) | (((Val >> 16) & 0xffff) << 5));
+ uint32_t regNo = read32le(loc) & 0x1f;
+ write32le(loc, (0xd2a00000 | regNo) | (((val >> 16) & 0xffff) << 5));
return;
}
- if (Type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC) {
+ if (type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC) {
// Generate MOVK.
- uint32_t RegNo = read32le(Loc) & 0x1f;
- write32le(Loc, (0xf2800000 | RegNo) | ((Val & 0xffff) << 5));
+ uint32_t regNo = read32le(loc) & 0x1f;
+ write32le(loc, (0xf2800000 | regNo) | ((val & 0xffff) << 5));
return;
}
llvm_unreachable("invalid relocation for TLS IE to LE relaxation");
}
-TargetInfo *elf::getAArch64TargetInfo() {
- static AArch64 Target;
- return &Target;
+// AArch64 may use security features in variant PLT sequences. These are:
+// Pointer Authentication (PAC), introduced in armv8.3-a and Branch Target
+// Indicator (BTI) introduced in armv8.5-a. The additional instructions used
+// in the variant Plt sequences are encoded in the Hint space so they can be
+// deployed on older architectures, which treat the instructions as a nop.
+// PAC and BTI can be combined leading to the following combinations:
+// writePltHeader
+// writePltHeaderBti (no PAC Header needed)
+// writePlt
+// writePltBti (BTI only)
+// writePltPac (PAC only)
+// writePltBtiPac (BTI and PAC)
+//
+// When PAC is enabled the dynamic loader encrypts the address that it places
+// in the .got.plt using the pacia1716 instruction which encrypts the value in
+// x17 using the modifier in x16. The static linker places autia1716 before the
+// indirect branch to x17 to authenticate the address in x17 with the modifier
+// in x16. This makes it more difficult for an attacker to modify the value in
+// the .got.plt.
+//
+// When BTI is enabled all indirect branches must land on a bti instruction.
+// The static linker must place a bti instruction at the start of any PLT entry
+// that may be the target of an indirect branch. As the PLT entries call the
+// lazy resolver indirectly this must have a bti instruction at start. In
+// general a bti instruction is not needed for a PLT entry as indirect calls
+// are resolved to the function address and not the PLT entry for the function.
+// There are a small number of cases where the PLT address can escape, such as
+// taking the address of a function or ifunc via a non got-generating
+// relocation, and a shared library refers to that symbol.
+//
+// We use the bti c variant of the instruction which permits indirect branches
+// (br) via x16/x17 and indirect function calls (blr) via any register. The ABI
+// guarantees that all indirect branches from code requiring BTI protection
+// will go via x16/x17
+
+namespace {
+class AArch64BtiPac final : public AArch64 {
+public:
+ AArch64BtiPac();
+ void writePltHeader(uint8_t *buf) const override;
+ void writePlt(uint8_t *buf, uint64_t gotPltEntryAddr, uint64_t pltEntryAddr,
+ int32_t index, unsigned relOff) const override;
+
+private:
+ bool btiHeader; // bti instruction needed in PLT Header
+ bool btiEntry; // bti instruction needed in PLT Entry
+ bool pacEntry; // autia1716 instruction needed in PLT Entry
+};
+} // namespace
+
+AArch64BtiPac::AArch64BtiPac() {
+ btiHeader = (config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_BTI);
+ // A BTI (Branch Target Indicator) Plt Entry is only required if the
+ // address of the PLT entry can be taken by the program, which permits an
+ // indirect jump to the PLT entry. This can happen when the address
+ // of the PLT entry for a function is canonicalised due to the address of
+ // the function in an executable being taken by a shared library.
+ // FIXME: There is a potential optimization to omit the BTI if we detect
+ // that the address of the PLT entry isn't taken.
+ btiEntry = btiHeader && !config->shared;
+ pacEntry = (config->andFeatures & GNU_PROPERTY_AARCH64_FEATURE_1_PAC);
+
+ if (btiEntry || pacEntry)
+ pltEntrySize = 24;
}
+
+void AArch64BtiPac::writePltHeader(uint8_t *buf) const {
+ const uint8_t btiData[] = { 0x5f, 0x24, 0x03, 0xd5 }; // bti c
+ const uint8_t pltData[] = {
+ 0xf0, 0x7b, 0xbf, 0xa9, // stp x16, x30, [sp,#-16]!
+ 0x10, 0x00, 0x00, 0x90, // adrp x16, Page(&(.plt.got[2]))
+ 0x11, 0x02, 0x40, 0xf9, // ldr x17, [x16, Offset(&(.plt.got[2]))]
+ 0x10, 0x02, 0x00, 0x91, // add x16, x16, Offset(&(.plt.got[2]))
+ 0x20, 0x02, 0x1f, 0xd6, // br x17
+ 0x1f, 0x20, 0x03, 0xd5, // nop
+ 0x1f, 0x20, 0x03, 0xd5 // nop
+ };
+ const uint8_t nopData[] = { 0x1f, 0x20, 0x03, 0xd5 }; // nop
+
+ uint64_t got = in.gotPlt->getVA();
+ uint64_t plt = in.plt->getVA();
+
+ if (btiHeader) {
+ // PltHeader is called indirectly by plt[N]. Prefix pltData with a BTI C
+ // instruction.
+ memcpy(buf, btiData, sizeof(btiData));
+ buf += sizeof(btiData);
+ plt += sizeof(btiData);
+ }
+ memcpy(buf, pltData, sizeof(pltData));
+
+ relocateOne(buf + 4, R_AARCH64_ADR_PREL_PG_HI21,
+ getAArch64Page(got + 16) - getAArch64Page(plt + 8));
+ relocateOne(buf + 8, R_AARCH64_LDST64_ABS_LO12_NC, got + 16);
+ relocateOne(buf + 12, R_AARCH64_ADD_ABS_LO12_NC, got + 16);
+ if (!btiHeader)
+ // We didn't add the BTI c instruction so round out size with NOP.
+ memcpy(buf + sizeof(pltData), nopData, sizeof(nopData));
+}
+
+void AArch64BtiPac::writePlt(uint8_t *buf, uint64_t gotPltEntryAddr,
+ uint64_t pltEntryAddr, int32_t index,
+ unsigned relOff) const {
+ // The PLT entry is of the form:
+ // [btiData] addrInst (pacBr | stdBr) [nopData]
+ const uint8_t btiData[] = { 0x5f, 0x24, 0x03, 0xd5 }; // bti c
+ const uint8_t addrInst[] = {
+ 0x10, 0x00, 0x00, 0x90, // adrp x16, Page(&(.plt.got[n]))
+ 0x11, 0x02, 0x40, 0xf9, // ldr x17, [x16, Offset(&(.plt.got[n]))]
+ 0x10, 0x02, 0x00, 0x91 // add x16, x16, Offset(&(.plt.got[n]))
+ };
+ const uint8_t pacBr[] = {
+ 0x9f, 0x21, 0x03, 0xd5, // autia1716
+ 0x20, 0x02, 0x1f, 0xd6 // br x17
+ };
+ const uint8_t stdBr[] = {
+ 0x20, 0x02, 0x1f, 0xd6, // br x17
+ 0x1f, 0x20, 0x03, 0xd5 // nop
+ };
+ const uint8_t nopData[] = { 0x1f, 0x20, 0x03, 0xd5 }; // nop
+
+ if (btiEntry) {
+ memcpy(buf, btiData, sizeof(btiData));
+ buf += sizeof(btiData);
+ pltEntryAddr += sizeof(btiData);
+ }
+
+ memcpy(buf, addrInst, sizeof(addrInst));
+ relocateOne(buf, R_AARCH64_ADR_PREL_PG_HI21,
+ getAArch64Page(gotPltEntryAddr) -
+ getAArch64Page(pltEntryAddr));
+ relocateOne(buf + 4, R_AARCH64_LDST64_ABS_LO12_NC, gotPltEntryAddr);
+ relocateOne(buf + 8, R_AARCH64_ADD_ABS_LO12_NC, gotPltEntryAddr);
+
+ if (pacEntry)
+ memcpy(buf + sizeof(addrInst), pacBr, sizeof(pacBr));
+ else
+ memcpy(buf + sizeof(addrInst), stdBr, sizeof(stdBr));
+ if (!btiEntry)
+ // We didn't add the BTI c instruction so round out size with NOP.
+ memcpy(buf + sizeof(addrInst) + sizeof(stdBr), nopData, sizeof(nopData));
+}
+
+static TargetInfo *getTargetInfo() {
+ if (config->andFeatures & (GNU_PROPERTY_AARCH64_FEATURE_1_BTI |
+ GNU_PROPERTY_AARCH64_FEATURE_1_PAC)) {
+ static AArch64BtiPac t;
+ return &t;
+ }
+ static AArch64 t;
+ return &t;
+}
+
+TargetInfo *elf::getAArch64TargetInfo() { return getTargetInfo(); }
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-09 22:52:02 +0000