[lld] [ELF] Add target-specific relocation scanning for AArch64 (PR #181099)
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Thu Feb 12 22:11:28 PST 2026
https://github.com/MaskRay updated https://github.com/llvm/llvm-project/pull/181099
>From e8c2b8e364ff4b6b67acc567e124f5b7e2717fe4 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Sat, 7 Feb 2026 22:52:13 -0800
Subject: [PATCH 1/3] [ELF] Add target-specific relocation scanning for AArch64
Implement AArch64::scanSectionImpl, following the pattern established
for x86 `#178846` and MIPS/PPC64 (`#163138`). This merges the getRelExpr
for SHF_ALLOC sections into the target-specific scanner, eliminating
abstraction overhead.
- Remove 7 AArch64-specific RelExpr members (RE_AARCH64_AUTH_GOT,
RE_AARCH64_AUTH_GOT_PC, RE_AARCH64_AUTH_GOT_PAGE_PC, RE_AARCH64_AUTH,
RE_AARCH64_AUTH_TLSDESC_PAGE, RE_AARCH64_AUTH_TLSDESC,
RE_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC) by using regular RelExpr
members with flag-based dispatch (NEEDS_GOT_AUTH, NEEDS_TLSDESC_AUTH).
AUTH GOT relocations now call `sym.setFlags(NEEDS_GOT | NEEDS_GOT_AUTH)`
and `rs.processAux` directly.
- Remove adjustTlsExpr and handleAArch64PAuthTlsRelocation by inlining
their logic into scanSectionImpl and relocateAlloc.
- Simplify getRelExpr to only handle relocations needed by
relocateNonAlloc and relocateEh.
---
lld/ELF/AArch64ErrataFix.cpp | 22 +--
lld/ELF/Arch/AArch64.cpp | 339 +++++++++++++++++++++++------------
lld/ELF/InputSection.cpp | 6 -
lld/ELF/RelocScan.h | 10 +-
lld/ELF/Relocations.cpp | 75 ++------
lld/ELF/Relocations.h | 6 -
6 files changed, 262 insertions(+), 196 deletions(-)
diff --git a/lld/ELF/AArch64ErrataFix.cpp b/lld/ELF/AArch64ErrataFix.cpp
index a2ab58f96b2b5..adaaf0c750b8f 100644
--- a/lld/ELF/AArch64ErrataFix.cpp
+++ b/lld/ELF/AArch64ErrataFix.cpp
@@ -539,20 +539,22 @@ static void implementPatch(Ctx &ctx, uint64_t adrpAddr, uint64_t patcheeOffset,
// Case 1: R_AARCH64_JUMP26 branch relocation. We have already patched this
// instance of the erratum on a previous patch and altered the relocation. We
// have nothing more to do.
- // Case 2: A TLS Relaxation R_RELAX_TLS_IE_TO_LE. In this case the ADRP that
- // we read will be transformed into a MOVZ later so we actually don't match
- // the sequence and have nothing more to do.
- // Case 3: A load/store register (unsigned immediate) class relocation. There
- // are two of these R_AARCH_LD64_ABS_LO12_NC and R_AARCH_LD64_GOT_LO12_NC and
- // they are both absolute. We need to add the same relocation to the patch,
- // and replace the relocation with a R_AARCH_JUMP26 branch relocation.
- // Case 4: No relocation. We must create a new R_AARCH64_JUMP26 branch
- // relocation at the offset.
+ // Case 2: A TLS IE to LE optimization. In this case the ADRP that we read
+ // will be transformed into a MOVZ later so we actually don't match the
+ // sequence and have nothing more to do. Case 3: A load/store register
+ // (unsigned immediate) class relocation. There are two of these
+ // R_AARCH_LD64_ABS_LO12_NC and R_AARCH_LD64_GOT_LO12_NC and they are both
+ // absolute. We need to add the same relocation to the patch, and replace the
+ // relocation with a R_AARCH_JUMP26 branch relocation. Case 4: No relocation.
+ // We must create a new R_AARCH64_JUMP26 branch relocation at the offset.
auto relIt = llvm::find_if(isec->relocs(), [=](const Relocation &r) {
return r.offset == patcheeOffset;
});
if (relIt != isec->relocs().end() &&
- (relIt->type == R_AARCH64_JUMP26 || relIt->expr == R_RELAX_TLS_IE_TO_LE))
+ (relIt->type == R_AARCH64_JUMP26 ||
+ ((relIt->type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21 ||
+ relIt->type == R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC) &&
+ relIt->expr == R_TPREL)))
return;
Log(ctx) << "detected cortex-a53-843419 erratum sequence starting at " <<
diff --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp
index 3c0d4ca645556..0c2d3d356becc 100644
--- a/lld/ELF/Arch/AArch64.cpp
+++ b/lld/ELF/Arch/AArch64.cpp
@@ -8,6 +8,7 @@
#include "InputFiles.h"
#include "OutputSections.h"
+#include "RelocScan.h"
#include "Symbols.h"
#include "SyntheticSections.h"
#include "Target.h"
@@ -86,10 +87,13 @@ class AArch64 : public TargetInfo {
bool usesOnlyLowPageBits(RelType type) const override;
void relocate(uint8_t *loc, const Relocation &rel,
uint64_t val) const override;
- RelExpr adjustTlsExpr(RelType type, RelExpr expr) const override;
void relocateAlloc(InputSection &sec, uint8_t *buf) const override;
void applyBranchToBranchOpt() const override;
+ template <class ELFT, class RelTy>
+ void scanSectionImpl(InputSectionBase &sec, Relocs<RelTy> rels);
+ void scanSection(InputSectionBase &sec) override;
+
private:
void relaxTlsGdToLe(uint8_t *loc, const Relocation &rel, uint64_t val) const;
void relaxTlsGdToIe(uint8_t *loc, const Relocation &rel, uint64_t val) const;
@@ -137,106 +141,16 @@ AArch64::AArch64(Ctx &ctx) : TargetInfo(ctx) {
needsThunks = true;
}
+// Only needed to support relocations used by relocateNonAlloc and relocateEh.
RelExpr AArch64::getRelExpr(RelType type, const Symbol &s,
const uint8_t *loc) const {
switch (type) {
- case R_AARCH64_ABS16:
case R_AARCH64_ABS32:
case R_AARCH64_ABS64:
- case R_AARCH64_FUNCINIT64:
- case R_AARCH64_ADD_ABS_LO12_NC:
- case R_AARCH64_LDST128_ABS_LO12_NC:
- case R_AARCH64_LDST16_ABS_LO12_NC:
- case R_AARCH64_LDST32_ABS_LO12_NC:
- case R_AARCH64_LDST64_ABS_LO12_NC:
- case R_AARCH64_LDST8_ABS_LO12_NC:
- case R_AARCH64_MOVW_SABS_G0:
- case R_AARCH64_MOVW_SABS_G1:
- case R_AARCH64_MOVW_SABS_G2:
- case R_AARCH64_MOVW_UABS_G0:
- case R_AARCH64_MOVW_UABS_G0_NC:
- case R_AARCH64_MOVW_UABS_G1:
- case R_AARCH64_MOVW_UABS_G1_NC:
- case R_AARCH64_MOVW_UABS_G2:
- case R_AARCH64_MOVW_UABS_G2_NC:
- case R_AARCH64_MOVW_UABS_G3:
- return R_ABS;
- case R_AARCH64_PATCHINST:
- if (!isAbsolute(s))
- Err(ctx) << getErrorLoc(ctx, loc)
- << "R_AARCH64_PATCHINST relocation against non-absolute symbol "
- << &s;
return R_ABS;
- case R_AARCH64_AUTH_ABS64:
- return RE_AARCH64_AUTH;
- case R_AARCH64_TLSDESC_ADR_PAGE21:
- return RE_AARCH64_TLSDESC_PAGE;
- case R_AARCH64_AUTH_TLSDESC_ADR_PAGE21:
- return RE_AARCH64_AUTH_TLSDESC_PAGE;
- case R_AARCH64_TLSDESC_LD64_LO12:
- case R_AARCH64_TLSDESC_ADD_LO12:
- return R_TLSDESC;
- case R_AARCH64_AUTH_TLSDESC_LD64_LO12:
- case R_AARCH64_AUTH_TLSDESC_ADD_LO12:
- return RE_AARCH64_AUTH_TLSDESC;
- case R_AARCH64_TLSDESC_CALL:
- return R_TLSDESC_CALL;
- case R_AARCH64_TLSLE_ADD_TPREL_HI12:
- case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
- case R_AARCH64_TLSLE_LDST8_TPREL_LO12_NC:
- case R_AARCH64_TLSLE_LDST16_TPREL_LO12_NC:
- case R_AARCH64_TLSLE_LDST32_TPREL_LO12_NC:
- case R_AARCH64_TLSLE_LDST64_TPREL_LO12_NC:
- case R_AARCH64_TLSLE_LDST128_TPREL_LO12_NC:
- case R_AARCH64_TLSLE_MOVW_TPREL_G0:
- case R_AARCH64_TLSLE_MOVW_TPREL_G0_NC:
- case R_AARCH64_TLSLE_MOVW_TPREL_G1:
- case R_AARCH64_TLSLE_MOVW_TPREL_G1_NC:
- case R_AARCH64_TLSLE_MOVW_TPREL_G2:
- return R_TPREL;
- case R_AARCH64_CALL26:
- case R_AARCH64_CONDBR19:
- case R_AARCH64_JUMP26:
- case R_AARCH64_TSTBR14:
- return R_PLT_PC;
- case R_AARCH64_PLT32:
- const_cast<Symbol &>(s).thunkAccessed = true;
- return R_PLT_PC;
- case R_AARCH64_PREL16:
case R_AARCH64_PREL32:
case R_AARCH64_PREL64:
- case R_AARCH64_ADR_PREL_LO21:
- case R_AARCH64_LD_PREL_LO19:
- case R_AARCH64_MOVW_PREL_G0:
- case R_AARCH64_MOVW_PREL_G0_NC:
- case R_AARCH64_MOVW_PREL_G1:
- case R_AARCH64_MOVW_PREL_G1_NC:
- case R_AARCH64_MOVW_PREL_G2:
- case R_AARCH64_MOVW_PREL_G2_NC:
- case R_AARCH64_MOVW_PREL_G3:
return R_PC;
- case R_AARCH64_ADR_PREL_PG_HI21:
- case R_AARCH64_ADR_PREL_PG_HI21_NC:
- return RE_AARCH64_PAGE_PC;
- case R_AARCH64_LD64_GOT_LO12_NC:
- case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
- return R_GOT;
- case R_AARCH64_AUTH_LD64_GOT_LO12_NC:
- case R_AARCH64_AUTH_GOT_ADD_LO12_NC:
- return RE_AARCH64_AUTH_GOT;
- case R_AARCH64_AUTH_GOT_LD_PREL19:
- case R_AARCH64_AUTH_GOT_ADR_PREL_LO21:
- return RE_AARCH64_AUTH_GOT_PC;
- case R_AARCH64_LD64_GOTPAGE_LO15:
- return RE_AARCH64_GOT_PAGE;
- case R_AARCH64_ADR_GOT_PAGE:
- case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
- return RE_AARCH64_GOT_PAGE_PC;
- case R_AARCH64_AUTH_ADR_GOT_PAGE:
- return RE_AARCH64_AUTH_GOT_PAGE_PC;
- case R_AARCH64_GOTPCREL32:
- case R_AARCH64_GOT_LD_PREL19:
- return R_GOT_PC;
case R_AARCH64_NONE:
return R_NONE;
default:
@@ -246,21 +160,14 @@ RelExpr AArch64::getRelExpr(RelType type, const Symbol &s,
}
}
-RelExpr AArch64::adjustTlsExpr(RelType type, RelExpr expr) const {
- if (expr == R_RELAX_TLS_GD_TO_IE) {
- if (type == R_AARCH64_TLSDESC_ADR_PAGE21)
- return RE_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC;
- return R_RELAX_TLS_GD_TO_IE_ABS;
- }
- return expr;
-}
-
bool AArch64::usesOnlyLowPageBits(RelType type) const {
switch (type) {
default:
return false;
case R_AARCH64_ADD_ABS_LO12_NC:
case R_AARCH64_LD64_GOT_LO12_NC:
+ case R_AARCH64_AUTH_LD64_GOT_LO12_NC:
+ case R_AARCH64_AUTH_GOT_ADD_LO12_NC:
case R_AARCH64_LDST128_ABS_LO12_NC:
case R_AARCH64_LDST16_ABS_LO12_NC:
case R_AARCH64_LDST32_ABS_LO12_NC:
@@ -273,6 +180,201 @@ bool AArch64::usesOnlyLowPageBits(RelType type) const {
}
}
+template <class ELFT, class RelTy>
+void AArch64::scanSectionImpl(InputSectionBase &sec, Relocs<RelTy> rels) {
+ RelocScan rs(ctx, &sec);
+ sec.relocations.reserve(rels.size());
+
+ for (auto it = rels.begin(); it != rels.end(); ++it) {
+ const RelTy &rel = *it;
+ uint32_t symIdx = rel.getSymbol(false);
+ Symbol &sym = sec.getFile<ELFT>()->getSymbol(symIdx);
+ uint64_t offset = rel.r_offset;
+ RelType type = rel.getType(false);
+ if (sym.isUndefined() && symIdx != 0 &&
+ rs.maybeReportUndefined(cast<Undefined>(sym), offset))
+ continue;
+ int64_t addend = rs.getAddend<ELFT>(rel, type);
+ RelExpr expr;
+ switch (type) {
+ case R_AARCH64_NONE:
+ continue;
+
+ // Absolute relocations:
+ case R_AARCH64_ABS16:
+ case R_AARCH64_ABS32:
+ case R_AARCH64_ABS64:
+ case R_AARCH64_FUNCINIT64:
+ case R_AARCH64_ADD_ABS_LO12_NC:
+ case R_AARCH64_LDST128_ABS_LO12_NC:
+ case R_AARCH64_LDST16_ABS_LO12_NC:
+ case R_AARCH64_LDST32_ABS_LO12_NC:
+ case R_AARCH64_LDST64_ABS_LO12_NC:
+ case R_AARCH64_LDST8_ABS_LO12_NC:
+ case R_AARCH64_MOVW_SABS_G0:
+ case R_AARCH64_MOVW_SABS_G1:
+ case R_AARCH64_MOVW_SABS_G2:
+ case R_AARCH64_MOVW_UABS_G0:
+ case R_AARCH64_MOVW_UABS_G0_NC:
+ case R_AARCH64_MOVW_UABS_G1:
+ case R_AARCH64_MOVW_UABS_G1_NC:
+ case R_AARCH64_MOVW_UABS_G2:
+ case R_AARCH64_MOVW_UABS_G2_NC:
+ case R_AARCH64_MOVW_UABS_G3:
+ expr = R_ABS;
+ break;
+
+ case R_AARCH64_AUTH_ABS64:
+ expr = RE_AARCH64_AUTH;
+ break;
+
+ case R_AARCH64_PATCHINST:
+ if (!isAbsolute(sym))
+ Err(ctx) << getErrorLoc(ctx, sec.content().data() + offset)
+ << "R_AARCH64_PATCHINST relocation against non-absolute "
+ "symbol "
+ << &sym;
+ expr = R_ABS;
+ break;
+
+ // PC-relative relocations:
+ case R_AARCH64_PREL16:
+ case R_AARCH64_PREL32:
+ case R_AARCH64_PREL64:
+ case R_AARCH64_ADR_PREL_LO21:
+ case R_AARCH64_LD_PREL_LO19:
+ case R_AARCH64_MOVW_PREL_G0:
+ case R_AARCH64_MOVW_PREL_G0_NC:
+ case R_AARCH64_MOVW_PREL_G1:
+ case R_AARCH64_MOVW_PREL_G1_NC:
+ case R_AARCH64_MOVW_PREL_G2:
+ case R_AARCH64_MOVW_PREL_G2_NC:
+ case R_AARCH64_MOVW_PREL_G3:
+ rs.processR_PC(type, offset, addend, sym);
+ continue;
+
+ // Page-PC relocations:
+ case R_AARCH64_ADR_PREL_PG_HI21:
+ case R_AARCH64_ADR_PREL_PG_HI21_NC:
+ expr = RE_AARCH64_PAGE_PC;
+ break;
+
+ // PLT-generating relocations:
+ case R_AARCH64_CALL26:
+ case R_AARCH64_CONDBR19:
+ case R_AARCH64_JUMP26:
+ case R_AARCH64_TSTBR14:
+ rs.processR_PLT_PC(type, offset, addend, sym);
+ continue;
+ case R_AARCH64_PLT32:
+ sym.thunkAccessed = true;
+ rs.processR_PLT_PC(type, offset, addend, sym);
+ continue;
+
+ // GOT relocations:
+ case R_AARCH64_LD64_GOT_LO12_NC:
+ expr = R_GOT;
+ break;
+ case R_AARCH64_AUTH_LD64_GOT_LO12_NC:
+ case R_AARCH64_AUTH_GOT_ADD_LO12_NC:
+ sym.setFlags(NEEDS_GOT | NEEDS_GOT_AUTH);
+ rs.processAux(R_GOT, type, offset, sym, addend);
+ continue;
+ case R_AARCH64_AUTH_GOT_LD_PREL19:
+ case R_AARCH64_AUTH_GOT_ADR_PREL_LO21:
+ sym.setFlags(NEEDS_GOT | NEEDS_GOT_AUTH);
+ rs.processAux(R_GOT_PC, type, offset, sym, addend);
+ continue;
+ case R_AARCH64_ADR_GOT_PAGE:
+ expr = RE_AARCH64_GOT_PAGE_PC;
+ break;
+ case R_AARCH64_AUTH_ADR_GOT_PAGE:
+ sym.setFlags(NEEDS_GOT | NEEDS_GOT_AUTH);
+ rs.processAux(RE_AARCH64_GOT_PAGE_PC, type, offset, sym, addend);
+ continue;
+ case R_AARCH64_LD64_GOTPAGE_LO15:
+ expr = RE_AARCH64_GOT_PAGE;
+ break;
+ case R_AARCH64_GOTPCREL32:
+ case R_AARCH64_GOT_LD_PREL19:
+ expr = R_GOT_PC;
+ break;
+
+ // TLS LE relocations:
+ case R_AARCH64_TLSLE_ADD_TPREL_HI12:
+ case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
+ case R_AARCH64_TLSLE_LDST8_TPREL_LO12_NC:
+ case R_AARCH64_TLSLE_LDST16_TPREL_LO12_NC:
+ case R_AARCH64_TLSLE_LDST32_TPREL_LO12_NC:
+ case R_AARCH64_TLSLE_LDST64_TPREL_LO12_NC:
+ case R_AARCH64_TLSLE_LDST128_TPREL_LO12_NC:
+ case R_AARCH64_TLSLE_MOVW_TPREL_G0:
+ case R_AARCH64_TLSLE_MOVW_TPREL_G0_NC:
+ case R_AARCH64_TLSLE_MOVW_TPREL_G1:
+ case R_AARCH64_TLSLE_MOVW_TPREL_G1_NC:
+ case R_AARCH64_TLSLE_MOVW_TPREL_G2:
+ if (rs.checkTlsLe(offset, sym, type))
+ continue;
+ expr = R_TPREL;
+ break;
+
+ // TLS IE relocations:
+ case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
+ rs.handleTlsIe(RE_AARCH64_GOT_PAGE_PC, type, offset, addend, sym);
+ continue;
+ case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
+ rs.handleTlsIe(R_GOT, type, offset, addend, sym);
+ continue;
+
+ // TLSDESC relocations:
+ case R_AARCH64_TLSDESC_ADR_PAGE21:
+ rs.handleTlsDesc(RE_AARCH64_TLSDESC_PAGE, RE_AARCH64_GOT_PAGE_PC, type,
+ offset, addend, sym);
+ continue;
+ case R_AARCH64_TLSDESC_LD64_LO12:
+ case R_AARCH64_TLSDESC_ADD_LO12:
+ rs.handleTlsDesc(R_TLSDESC, R_GOT, type, offset, addend, sym);
+ continue;
+ case R_AARCH64_TLSDESC_CALL:
+ sym.setFlags(NEEDS_TLSDESC_NONAUTH);
+ if (!ctx.arg.shared)
+ sec.addReloc({R_TPREL, type, offset, addend, &sym});
+ continue;
+
+ // AUTH TLSDESC relocations. Do not optimize to LE/IE because PAUTHELF64
+ // only supports the descriptor based TLS (TLSDESC).
+ // https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst#general-restrictions
+ case R_AARCH64_AUTH_TLSDESC_ADR_PAGE21:
+ sym.setFlags(NEEDS_TLSDESC | NEEDS_TLSDESC_AUTH);
+ sec.addReloc({RE_AARCH64_TLSDESC_PAGE, type, offset, addend, &sym});
+ continue;
+ case R_AARCH64_AUTH_TLSDESC_LD64_LO12:
+ case R_AARCH64_AUTH_TLSDESC_ADD_LO12:
+ sym.setFlags(NEEDS_TLSDESC | NEEDS_TLSDESC_AUTH);
+ sec.addReloc({R_TLSDESC, type, offset, addend, &sym});
+ continue;
+
+ default:
+ Err(ctx) << getErrorLoc(ctx, sec.content().data() + offset)
+ << "unknown relocation (" << type.v << ") against symbol "
+ << &sym;
+ continue;
+ }
+ rs.process(expr, type, offset, sym, addend);
+ }
+
+ if (ctx.arg.branchToBranch)
+ llvm::stable_sort(sec.relocs(),
+ [](auto &l, auto &r) { return l.offset < r.offset; });
+}
+
+void AArch64::scanSection(InputSectionBase &sec) {
+ if (ctx.arg.ekind == ELF64BEKind)
+ elf::scanSection1<AArch64, ELF64BE>(*this, sec);
+ else
+ elf::scanSection1<AArch64, ELF64LE>(*this, sec);
+}
+
RelType AArch64::getDynRel(RelType type) const {
if (type == R_AARCH64_ABS64 || type == R_AARCH64_AUTH_ABS64 ||
type == R_AARCH64_FUNCINIT64)
@@ -807,8 +909,7 @@ bool AArch64Relaxer::tryRelaxAdrpAdd(const Relocation &adrpRel,
// to
// NOP
// ADR xn, sym
- if (!ctx.arg.relax || adrpRel.type != R_AARCH64_ADR_PREL_PG_HI21 ||
- addRel.type != R_AARCH64_ADD_ABS_LO12_NC)
+ if (!ctx.arg.relax || addRel.type != R_AARCH64_ADD_ABS_LO12_NC)
return false;
// Check if the relocations apply to consecutive instructions.
if (adrpRel.offset + 4 != addRel.offset)
@@ -945,34 +1046,44 @@ void AArch64::relocateAlloc(InputSection &sec, uint8_t *buf) const {
continue;
}
- switch (rel.expr) {
- case RE_AARCH64_GOT_PAGE_PC:
+ switch (rel.type) {
+ case R_AARCH64_ADR_GOT_PAGE:
if (i + 1 < size &&
relaxer.tryRelaxAdrpLdr(rel, relocs[i + 1], secAddr, buf)) {
++i;
continue;
}
break;
- case RE_AARCH64_PAGE_PC:
+ case R_AARCH64_ADR_PREL_PG_HI21:
if (i + 1 < size &&
relaxer.tryRelaxAdrpAdd(rel, relocs[i + 1], secAddr, buf)) {
++i;
continue;
}
break;
- case RE_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC:
- case R_RELAX_TLS_GD_TO_IE_ABS:
- relaxTlsGdToIe(loc, rel, val);
- continue;
- case R_RELAX_TLS_GD_TO_LE:
- relaxTlsGdToLe(loc, rel, val);
+
+ case R_AARCH64_TLSDESC_ADR_PAGE21:
+ case R_AARCH64_TLSDESC_LD64_LO12:
+ case R_AARCH64_TLSDESC_ADD_LO12:
+ case R_AARCH64_TLSDESC_CALL:
+ if (rel.expr == R_TPREL)
+ relaxTlsGdToLe(loc, rel, val);
+ else if (rel.expr == RE_AARCH64_GOT_PAGE_PC || rel.expr == R_GOT)
+ relaxTlsGdToIe(loc, rel, val);
+ else
+ relocate(loc, rel, val);
continue;
- case R_RELAX_TLS_IE_TO_LE:
- relaxTlsIeToLe(loc, rel, val);
+ case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
+ case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
+ if (rel.expr == R_TPREL)
+ relaxTlsIeToLe(loc, rel, val);
+ else
+ relocate(loc, rel, val);
continue;
default:
break;
}
+
relocate(loc, rel, val);
}
}
diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp
index 7402c8454c023..dd83a06ca6d43 100644
--- a/lld/ELF/InputSection.cpp
+++ b/lld/ELF/InputSection.cpp
@@ -821,7 +821,6 @@ uint64_t InputSectionBase::getRelocTargetVA(Ctx &ctx, const Relocation &r,
case RE_ARM_SBREL:
return r.sym->getVA(ctx, a) - getARMStaticBase(*r.sym);
case R_GOT:
- case RE_AARCH64_AUTH_GOT:
case R_RELAX_TLS_GD_TO_IE_ABS:
return r.sym->getGotVA(ctx) + a;
case RE_LOONGARCH_GOT:
@@ -849,13 +848,10 @@ uint64_t InputSectionBase::getRelocTargetVA(Ctx &ctx, const Relocation &r,
case R_RELAX_TLS_GD_TO_IE_GOT_OFF:
return r.sym->getGotOffset(ctx) + a;
case RE_AARCH64_GOT_PAGE_PC:
- case RE_AARCH64_AUTH_GOT_PAGE_PC:
- case RE_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC:
return getAArch64Page(r.sym->getGotVA(ctx) + a) - getAArch64Page(p);
case RE_AARCH64_GOT_PAGE:
return r.sym->getGotVA(ctx) + a - getAArch64Page(ctx.in.got->getVA());
case R_GOT_PC:
- case RE_AARCH64_AUTH_GOT_PC:
case R_RELAX_TLS_GD_TO_IE:
return r.sym->getGotVA(ctx) + a - p;
case R_GOTPLT_GOTREL:
@@ -1015,14 +1011,12 @@ uint64_t InputSectionBase::getRelocTargetVA(Ctx &ctx, const Relocation &r,
case R_SIZE:
return r.sym->getSize() + a;
case R_TLSDESC:
- case RE_AARCH64_AUTH_TLSDESC:
return ctx.in.got->getTlsDescAddr(*r.sym) + a;
case R_TLSDESC_PC:
return ctx.in.got->getTlsDescAddr(*r.sym) + a - p;
case R_TLSDESC_GOTPLT:
return ctx.in.got->getTlsDescAddr(*r.sym) + a - ctx.in.gotPlt->getVA();
case RE_AARCH64_TLSDESC_PAGE:
- case RE_AARCH64_AUTH_TLSDESC_PAGE:
return getAArch64Page(ctx.in.got->getTlsDescAddr(*r.sym) + a) -
getAArch64Page(p);
case RE_LOONGARCH_TLSDESC_PAGE_PC:
diff --git a/lld/ELF/RelocScan.h b/lld/ELF/RelocScan.h
index d52afda26effb..64c1f992a0ef5 100644
--- a/lld/ELF/RelocScan.h
+++ b/lld/ELF/RelocScan.h
@@ -112,8 +112,9 @@ class RelocScan {
ctx.hasTlsIe.store(true, std::memory_order_relaxed);
sym.setFlags(NEEDS_TLSIE);
// R_GOT (absolute GOT address) needs a RELATIVE dynamic relocation in
- // PIC. This is used by R_386_TLS_IE.
- if (ieExpr == R_GOT && ctx.arg.isPic)
+ // PIC when the relocation uses the full address (not just low page bits).
+ if (ieExpr == R_GOT && ctx.arg.isPic &&
+ !ctx.target->usesOnlyLowPageBits(type))
sec->getPartition(ctx).relaDyn->addRelativeReloc(
ctx.target->relativeRel, *sec, offset, sym, addend, type, ieExpr);
else
@@ -156,11 +157,12 @@ class RelocScan {
return true;
}
- // Handle TLSDESC relocation.
+ // Handle TLSDESC relocation. NEEDS_TLSDESC_NONAUTH is a no-op for
+ // non-AArch64 targets and detects incompatibility with NEEDS_TLSDESC_AUTH.
void handleTlsDesc(RelExpr sharedExpr, RelExpr ieExpr, RelType type,
uint64_t offset, int64_t addend, Symbol &sym) {
if (ctx.arg.shared) {
- sym.setFlags(NEEDS_TLSDESC);
+ sym.setFlags(NEEDS_TLSDESC | NEEDS_TLSDESC_NONAUTH);
sec->addReloc({sharedExpr, type, offset, addend, &sym});
} else if (sym.isPreemptible) {
// Optimize to Initial Exec.
diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp
index 797acb08b0506..09625c2673c84 100644
--- a/lld/ELF/Relocations.cpp
+++ b/lld/ELF/Relocations.cpp
@@ -134,10 +134,8 @@ static bool needsPlt(RelExpr expr) {
}
bool lld::elf::needsGot(RelExpr expr) {
- return oneof<R_GOT, RE_AARCH64_AUTH_GOT, RE_AARCH64_AUTH_GOT_PC, R_GOT_OFF,
- RE_MIPS_GOT_LOCAL_PAGE, RE_MIPS_GOT_OFF, RE_MIPS_GOT_OFF32,
- RE_AARCH64_GOT_PAGE_PC, RE_AARCH64_AUTH_GOT_PAGE_PC,
- RE_AARCH64_AUTH_GOT_PAGE_PC, R_GOT_PC, R_GOTPLT,
+ return oneof<R_GOT, R_GOT_OFF, RE_MIPS_GOT_LOCAL_PAGE, RE_MIPS_GOT_OFF,
+ RE_MIPS_GOT_OFF32, RE_AARCH64_GOT_PAGE_PC, R_GOT_PC, R_GOTPLT,
RE_AARCH64_GOT_PAGE, RE_LOONGARCH_GOT, RE_LOONGARCH_GOT_PAGE_PC>(
expr);
}
@@ -841,15 +839,14 @@ bool RelocScan::isStaticLinkTimeConstant(RelExpr e, RelType type,
const Symbol &sym,
uint64_t relOff) const {
// These expressions always compute a constant
- if (oneof<
- R_GOTPLT, R_GOT_OFF, R_RELAX_HINT, RE_MIPS_GOT_LOCAL_PAGE,
- RE_MIPS_GOTREL, RE_MIPS_GOT_OFF, RE_MIPS_GOT_OFF32, RE_MIPS_GOT_GP_PC,
- RE_AARCH64_GOT_PAGE_PC, RE_AARCH64_AUTH_GOT_PAGE_PC, R_GOT_PC,
- R_GOTONLY_PC, R_GOTPLTONLY_PC, R_PLT_PC, R_PLT_GOTREL, R_PLT_GOTPLT,
- R_GOTPLT_GOTREL, R_GOTPLT_PC, RE_PPC32_PLTREL, RE_PPC64_CALL_PLT,
- RE_PPC64_RELAX_TOC, RE_RISCV_ADD, RE_AARCH64_GOT_PAGE,
- RE_AARCH64_AUTH_GOT, RE_AARCH64_AUTH_GOT_PC, RE_LOONGARCH_PLT_PAGE_PC,
- RE_LOONGARCH_GOT, RE_LOONGARCH_GOT_PAGE_PC>(e))
+ if (oneof<R_GOTPLT, R_GOT_OFF, R_RELAX_HINT, RE_MIPS_GOT_LOCAL_PAGE,
+ RE_MIPS_GOTREL, RE_MIPS_GOT_OFF, RE_MIPS_GOT_OFF32,
+ RE_MIPS_GOT_GP_PC, RE_AARCH64_GOT_PAGE_PC, R_GOT_PC, R_GOTONLY_PC,
+ R_GOTPLTONLY_PC, R_PLT_PC, R_PLT_GOTREL, R_PLT_GOTPLT,
+ R_GOTPLT_GOTREL, R_GOTPLT_PC, RE_PPC32_PLTREL, RE_PPC64_CALL_PLT,
+ RE_PPC64_RELAX_TOC, RE_RISCV_ADD, RE_AARCH64_GOT_PAGE,
+ RE_LOONGARCH_PLT_PAGE_PC, RE_LOONGARCH_GOT,
+ RE_LOONGARCH_GOT_PAGE_PC>(e))
return true;
// These never do, except if the entire file is position dependent or if
@@ -971,11 +968,7 @@ void RelocScan::process(RelExpr expr, RelType type, uint64_t offset,
} else if (!sym.isTls() || ctx.arg.emachine != EM_LOONGARCH) {
// Many LoongArch TLS relocs reuse the RE_LOONGARCH_GOT type, in which
// case the NEEDS_GOT flag shouldn't get set.
- if (expr == RE_AARCH64_AUTH_GOT || expr == RE_AARCH64_AUTH_GOT_PAGE_PC ||
- expr == RE_AARCH64_AUTH_GOT_PC)
- sym.setFlags(NEEDS_GOT | NEEDS_GOT_AUTH);
- else
- sym.setFlags(NEEDS_GOT | NEEDS_GOT_NONAUTH);
+ sym.setFlags(NEEDS_GOT | NEEDS_GOT_NONAUTH);
}
} else if (needsPlt(expr)) {
sym.setFlags(NEEDS_PLT);
@@ -1142,27 +1135,6 @@ void RelocScan::processAux(RelExpr expr, RelType type, uint64_t offset,
printLocation(diag, *sec, sym, offset);
}
-static unsigned handleAArch64PAuthTlsRelocation(InputSectionBase *sec,
- RelExpr expr, RelType type,
- uint64_t offset, Symbol &sym,
- int64_t addend) {
- // Do not optimize signed TLSDESC to LE/IE (as described in pauthabielf64).
- // https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst#general-restrictions
- // > PAUTHELF64 only supports the descriptor based TLS (TLSDESC).
- if (oneof<RE_AARCH64_AUTH_TLSDESC_PAGE, RE_AARCH64_AUTH_TLSDESC>(expr)) {
- sym.setFlags(NEEDS_TLSDESC | NEEDS_TLSDESC_AUTH);
- sec->addReloc({expr, type, offset, addend, &sym});
- return 1;
- }
-
- // TLSDESC_CALL hint relocation should not be emitted by compiler with signed
- // TLSDESC enabled.
- if (expr == R_TLSDESC_CALL)
- sym.setFlags(NEEDS_TLSDESC_NONAUTH);
-
- return 0;
-}
-
// Notes about General Dynamic and Local Dynamic TLS models below. They may
// require the generation of a pair of GOT entries that have associated dynamic
// relocations. The pair of GOT entries created are of the form GOT[e0] Module
@@ -1173,27 +1145,18 @@ static unsigned handleAArch64PAuthTlsRelocation(InputSectionBase *sec,
unsigned RelocScan::handleTlsRelocation(RelExpr expr, RelType type,
uint64_t offset, Symbol &sym,
int64_t addend) {
- bool isAArch64 = ctx.arg.emachine == EM_AARCH64;
-
- if (isAArch64)
- if (unsigned processed = handleAArch64PAuthTlsRelocation(
- sec, expr, type, offset, sym, addend))
- return processed;
-
if (expr == R_TPREL || expr == R_TPREL_NEG)
return checkTlsLe(offset, sym, type) ? 1 : 0;
bool isRISCV = ctx.arg.emachine == EM_RISCV;
- if (oneof<RE_AARCH64_TLSDESC_PAGE, R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC,
- R_TLSDESC_GOTPLT, RE_LOONGARCH_TLSDESC_PAGE_PC>(expr) &&
+ if (oneof<R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC, R_TLSDESC_GOTPLT,
+ RE_LOONGARCH_TLSDESC_PAGE_PC>(expr) &&
ctx.arg.shared) {
// R_RISCV_TLSDESC_{LOAD_LO12,ADD_LO12_I,CALL} reference a label. Do not
// set NEEDS_TLSDESC on the label.
if (expr != R_TLSDESC_CALL) {
- if (isAArch64)
- sym.setFlags(NEEDS_TLSDESC | NEEDS_TLSDESC_NONAUTH);
- else if (!isRISCV || type == R_RISCV_TLSDESC_HI20)
+ if (!isRISCV || type == R_RISCV_TLSDESC_HI20)
sym.setFlags(NEEDS_TLSDESC);
sec->addReloc({expr, type, offset, addend, &sym});
}
@@ -1279,9 +1242,9 @@ unsigned RelocScan::handleTlsRelocation(RelExpr expr, RelType type,
return 1;
}
- if (oneof<RE_AARCH64_TLSDESC_PAGE, R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC,
- R_TLSDESC_GOTPLT, R_TLSGD_GOT, R_TLSGD_GOTPLT, R_TLSGD_PC,
- RE_LOONGARCH_TLSGD_PAGE_PC, RE_LOONGARCH_TLSDESC_PAGE_PC>(expr)) {
+ if (oneof<R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC, R_TLSDESC_GOTPLT,
+ R_TLSGD_GOT, R_TLSGD_GOTPLT, R_TLSGD_PC, RE_LOONGARCH_TLSGD_PAGE_PC,
+ RE_LOONGARCH_TLSDESC_PAGE_PC>(expr)) {
if (!execOptimize) {
sym.setFlags(NEEDS_TLSGD);
sec->addReloc({expr, type, offset, addend, &sym});
@@ -1305,8 +1268,8 @@ unsigned RelocScan::handleTlsRelocation(RelExpr expr, RelType type,
return ctx.target->getTlsGdRelaxSkip(type);
}
- if (oneof<R_GOT, R_GOTPLT, R_GOT_PC, RE_AARCH64_GOT_PAGE_PC,
- RE_LOONGARCH_GOT_PAGE_PC, R_GOT_OFF, R_TLSIE_HINT>(expr)) {
+ if (oneof<R_GOT, R_GOTPLT, R_GOT_PC, RE_LOONGARCH_GOT_PAGE_PC, R_GOT_OFF,
+ R_TLSIE_HINT>(expr)) {
ctx.hasTlsIe.store(true, std::memory_order_relaxed);
// Initial-Exec relocs can be optimized to Local-Exec if the symbol is
// locally defined. This is not supported on SystemZ.
diff --git a/lld/ELF/Relocations.h b/lld/ELF/Relocations.h
index 680eb66e3356a..43a3dcb09b007 100644
--- a/lld/ELF/Relocations.h
+++ b/lld/ELF/Relocations.h
@@ -95,15 +95,9 @@ enum RelExpr {
// of a relocation type, there are some relocations whose semantics are
// unique to a target. Such relocation are marked with RE_<TARGET_NAME>.
RE_AARCH64_GOT_PAGE_PC,
- RE_AARCH64_AUTH_GOT_PAGE_PC,
RE_AARCH64_GOT_PAGE,
- RE_AARCH64_AUTH_GOT,
- RE_AARCH64_AUTH_GOT_PC,
RE_AARCH64_PAGE_PC,
- RE_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC,
RE_AARCH64_TLSDESC_PAGE,
- RE_AARCH64_AUTH_TLSDESC_PAGE,
- RE_AARCH64_AUTH_TLSDESC,
RE_AARCH64_AUTH,
RE_ARM_PCA,
RE_ARM_SBREL,
>From 8a3a70cc17f6d558f8e6d1527e6c736a20279e76 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Thu, 12 Feb 2026 10:15:28 -0800
Subject: [PATCH 2/3] comments
---
lld/ELF/AArch64ErrataFix.cpp | 14 ++++++++------
lld/ELF/Arch/AArch64.cpp | 3 +++
lld/ELF/RelocScan.h | 5 +++--
3 files changed, 14 insertions(+), 8 deletions(-)
diff --git a/lld/ELF/AArch64ErrataFix.cpp b/lld/ELF/AArch64ErrataFix.cpp
index adaaf0c750b8f..6e1169c6d90f0 100644
--- a/lld/ELF/AArch64ErrataFix.cpp
+++ b/lld/ELF/AArch64ErrataFix.cpp
@@ -541,15 +541,17 @@ static void implementPatch(Ctx &ctx, uint64_t adrpAddr, uint64_t patcheeOffset,
// have nothing more to do.
// Case 2: A TLS IE to LE optimization. In this case the ADRP that we read
// will be transformed into a MOVZ later so we actually don't match the
- // sequence and have nothing more to do. Case 3: A load/store register
- // (unsigned immediate) class relocation. There are two of these
- // R_AARCH_LD64_ABS_LO12_NC and R_AARCH_LD64_GOT_LO12_NC and they are both
- // absolute. We need to add the same relocation to the patch, and replace the
- // relocation with a R_AARCH_JUMP26 branch relocation. Case 4: No relocation.
- // We must create a new R_AARCH64_JUMP26 branch relocation at the offset.
+ // sequence and have nothing more to do.
+ // Case 3: A load/store register (unsigned immediate) class relocation. There
+ // are two of these R_AARCH_LD64_ABS_LO12_NC and R_AARCH_LD64_GOT_LO12_NC and
+ // they are both absolute. We need to add the same relocation to the patch,
+ // and replace the relocation with a R_AARCH_JUMP26 branch relocation.
+ // Case 4: No relocation. We must create a new R_AARCH64_JUMP26 branch
+ // relocation at the offset.
auto relIt = llvm::find_if(isec->relocs(), [=](const Relocation &r) {
return r.offset == patcheeOffset;
});
+ // Detect and skip Case 1 and Case 2 above.
if (relIt != isec->relocs().end() &&
(relIt->type == R_AARCH64_JUMP26 ||
((relIt->type == R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21 ||
diff --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp
index 0c2d3d356becc..d672932e2e5ba 100644
--- a/lld/ELF/Arch/AArch64.cpp
+++ b/lld/ELF/Arch/AArch64.cpp
@@ -196,6 +196,9 @@ void AArch64::scanSectionImpl(InputSectionBase &sec, Relocs<RelTy> rels) {
continue;
int64_t addend = rs.getAddend<ELFT>(rel, type);
RelExpr expr;
+ // Relocation types that only need a RelExpr set `expr` and break out of
+ // the switch to reach rs.process(). Types that need special handling
+ // (fast-path helpers, TLS) call a handler and use `continue`.
switch (type) {
case R_AARCH64_NONE:
continue;
diff --git a/lld/ELF/RelocScan.h b/lld/ELF/RelocScan.h
index 64c1f992a0ef5..dae075c8d43e4 100644
--- a/lld/ELF/RelocScan.h
+++ b/lld/ELF/RelocScan.h
@@ -157,11 +157,12 @@ class RelocScan {
return true;
}
- // Handle TLSDESC relocation. NEEDS_TLSDESC_NONAUTH is a no-op for
- // non-AArch64 targets and detects incompatibility with NEEDS_TLSDESC_AUTH.
+ // Handle TLSDESC relocation.
void handleTlsDesc(RelExpr sharedExpr, RelExpr ieExpr, RelType type,
uint64_t offset, int64_t addend, Symbol &sym) {
if (ctx.arg.shared) {
+ // NEEDS_TLSDESC_NONAUTH is a no-op for non-AArch64 targets and detects
+ // incompatibility with NEEDS_TLSDESC_AUTH.
sym.setFlags(NEEDS_TLSDESC | NEEDS_TLSDESC_NONAUTH);
sec->addReloc({sharedExpr, type, offset, addend, &sym});
} else if (sym.isPreemptible) {
>From b9c52323aadf1322ad32f320aac7755b1ec15615 Mon Sep 17 00:00:00 2001
From: Fangrui Song <i at maskray.me>
Date: Thu, 12 Feb 2026 10:17:23 -0800
Subject: [PATCH 3/3] PLT32
---
lld/ELF/Arch/AArch64.cpp | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp
index d672932e2e5ba..c0abfe019b786 100644
--- a/lld/ELF/Arch/AArch64.cpp
+++ b/lld/ELF/Arch/AArch64.cpp
@@ -263,16 +263,15 @@ void AArch64::scanSectionImpl(InputSectionBase &sec, Relocs<RelTy> rels) {
break;
// PLT-generating relocations:
+ case R_AARCH64_PLT32:
+ sym.thunkAccessed = true;
+ [[fallthrough]];
case R_AARCH64_CALL26:
case R_AARCH64_CONDBR19:
case R_AARCH64_JUMP26:
case R_AARCH64_TSTBR14:
rs.processR_PLT_PC(type, offset, addend, sym);
continue;
- case R_AARCH64_PLT32:
- sym.thunkAccessed = true;
- rs.processR_PLT_PC(type, offset, addend, sym);
- continue;
// GOT relocations:
case R_AARCH64_LD64_GOT_LO12_NC:
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