[lld] [ELF][Mips] Fix addend for preemptible static TLS (PR #150729)
Jessica Clarke via llvm-commits
llvm-commits at lists.llvm.org
Fri Jul 25 18:12:41 PDT 2025
https://github.com/jrtc27 created https://github.com/llvm/llvm-project/pull/150729
If the symbol is preemptible the addend should be 0, not our
definition's VA. Note that by using addAddendOnlyRelocIfNonPreemptible
the generic Elf_Rel code will ensure the VA is written out as the addend
if the symbol is non-preemptible, and so writeTo only needs to write out
the VA in the case that we don't call it (so long as we make sure to
call relocateAlloc to actually apply any such relocations).
This means we can remove AgainstSymbolWithTargetVA, which is a rather
strange kind to exist.
>From 32400cb0d5c16e16b6d0d259955ba060f561fefe Mon Sep 17 00:00:00 2001
From: Jessica Clarke <jrtc27 at jrtc27.com>
Date: Sat, 26 Jul 2025 02:12:18 +0100
Subject: [PATCH] =?UTF-8?q?[=F0=9D=98=80=F0=9D=97=BD=F0=9D=97=BF]=20initia?=
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Created using spr 1.3.5
---
lld/ELF/SyntheticSections.cpp | 16 ++++++++--------
lld/ELF/SyntheticSections.h | 9 +--------
lld/test/ELF/mips-mgot.s | 2 +-
lld/test/ELF/mips-tls-64.s | 2 +-
lld/test/ELF/mips-tls.s | 2 +-
5 files changed, 12 insertions(+), 19 deletions(-)
diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp
index efec41a737b62..0bb00c6d2bcff 100644
--- a/lld/ELF/SyntheticSections.cpp
+++ b/lld/ELF/SyntheticSections.cpp
@@ -1065,9 +1065,8 @@ void MipsGotSection::build() {
// for the TP-relative offset as we don't know how much other data will
// be allocated before us in the static TLS block.
if (s->isPreemptible || ctx.arg.shared)
- ctx.mainPart->relaDyn->addReloc(
- {ctx.target->tlsGotRel, this, offset,
- DynamicReloc::AgainstSymbolWithTargetVA, *s, 0, R_ABS});
+ ctx.mainPart->relaDyn->addAddendOnlyRelocIfNonPreemptible(
+ ctx.target->tlsGotRel, *this, offset, *s, ctx.target->symbolicRel);
}
for (std::pair<Symbol *, size_t> &p : got.dynTlsSymbols) {
Symbol *s = p.first;
@@ -1160,6 +1159,7 @@ void MipsGotSection::writeTo(uint8_t *buf) {
// if we had to do this.
writeUint(ctx, buf + ctx.arg.wordsize,
(uint64_t)1 << (ctx.arg.wordsize * 8 - 1));
+ ctx.target->relocateAlloc(*this, buf);
for (const FileGot &g : gots) {
auto write = [&](size_t i, const Symbol *s, int64_t a) {
uint64_t va = a;
@@ -1189,9 +1189,10 @@ void MipsGotSection::writeTo(uint8_t *buf) {
write(p.second, p.first, 0);
for (const std::pair<Symbol *, size_t> &p : g.relocs)
write(p.second, p.first, 0);
- for (const std::pair<Symbol *, size_t> &p : g.tls)
- write(p.second, p.first,
- p.first->isPreemptible || ctx.arg.shared ? 0 : -0x7000);
+ for (const std::pair<Symbol *, size_t> &p : g.tls) {
+ if (!p.first->isPreemptible && !ctx.arg.shared)
+ write(p.second, p.first, -0x7000);
+ }
for (const std::pair<Symbol *, size_t> &p : g.dynTlsSymbols) {
if (p.first == nullptr && !ctx.arg.shared)
write(p.second, nullptr, 1);
@@ -1653,8 +1654,7 @@ int64_t DynamicReloc::computeAddend(Ctx &ctx) const {
case AgainstSymbol:
assert(sym != nullptr);
return addend;
- case AddendOnlyWithTargetVA:
- case AgainstSymbolWithTargetVA: {
+ case AddendOnlyWithTargetVA: {
uint64_t ca = inputSec->getRelocTargetVA(
ctx, Relocation{expr, type, 0, addend, sym}, getOffset());
return ctx.arg.is64 ? ca : SignExtend64<32>(ca);
diff --git a/lld/ELF/SyntheticSections.h b/lld/ELF/SyntheticSections.h
index 5f01513630597..7612915b5b1dc 100644
--- a/lld/ELF/SyntheticSections.h
+++ b/lld/ELF/SyntheticSections.h
@@ -429,11 +429,6 @@ class DynamicReloc {
/// The resulting dynamic relocation references symbol #sym from the dynamic
/// symbol table and uses #addend as the value of computeAddend(ctx).
AgainstSymbol,
- /// The resulting dynamic relocation references symbol #sym from the dynamic
- /// symbol table and uses InputSection::getRelocTargetVA() + #addend for the
- /// final addend. It can be used for relocations that write the symbol VA as
- // the addend (e.g. R_MIPS_TLS_TPREL64) but still reference the symbol.
- AgainstSymbolWithTargetVA,
/// This is used by the MIPS multi-GOT implementation. It relocates
/// addresses of 64kb pages that lie inside the output section.
MipsMultiGotPage,
@@ -460,9 +455,7 @@ class DynamicReloc {
uint64_t getOffset() const;
uint32_t getSymIndex(SymbolTableBaseSection *symTab) const;
- bool needsDynSymIndex() const {
- return kind == AgainstSymbol || kind == AgainstSymbolWithTargetVA;
- }
+ bool needsDynSymIndex() const { return kind == AgainstSymbol; }
/// Computes the addend of the dynamic relocation. Note that this is not the
/// same as the #addend member variable as it may also include the symbol
diff --git a/lld/test/ELF/mips-mgot.s b/lld/test/ELF/mips-mgot.s
index 6978b5d9623b4..67bd5e6619f12 100644
--- a/lld/test/ELF/mips-mgot.s
+++ b/lld/test/ELF/mips-mgot.s
@@ -23,7 +23,7 @@
# CHECK: Contents of section .got:
# CHECK-NEXT: 70000 00000000 80000000 [[FOO0]] [[FOO2]]
-# CHECK-NEXT: 70010 00000000 00000004 00010000 00020000
+# CHECK-NEXT: 70010 00000000 00000000 00010000 00020000
# CHECK-NEXT: 70020 00030000 00040000 00050000 00060000
# CHECK-NEXT: 70030 00000000 00000000 00000000 00000000
# CHECK-NEXT: 70040 00000000 00000000 00000000
diff --git a/lld/test/ELF/mips-tls-64.s b/lld/test/ELF/mips-tls-64.s
index 3976b50274be4..8a00b93c77e2f 100644
--- a/lld/test/ELF/mips-tls-64.s
+++ b/lld/test/ELF/mips-tls-64.s
@@ -75,7 +75,7 @@
# DIS-SO: Contents of section .got:
# DIS-SO-NEXT: 30000 00000000 00000000 80000000 00000000
# DIS-SO-NEXT: 30010 00000000 00000000 00000000 00000000
-# DIS-SO-NEXT: 30020 00000000 00000004 00000000 00000000
+# DIS-SO-NEXT: 30020 00000000 00000000 00000000 00000000
# DIS-SO-NEXT: 30030 00000000 00000000 00000000 00000000
# DIS-SO-NEXT: 30040 00000000 00000000 00000000 00000000
# DIS-SO-NEXT: 30050 00000000 00000000
diff --git a/lld/test/ELF/mips-tls.s b/lld/test/ELF/mips-tls.s
index b98f3bb53d18d..804b29cf724d9 100644
--- a/lld/test/ELF/mips-tls.s
+++ b/lld/test/ELF/mips-tls.s
@@ -71,7 +71,7 @@
# DIS-SO: Contents of section .got:
# DIS-SO-NEXT: 30000 00000000 80000000 00000000 00000000
-# DIS-SO-NEXT: 30010 00000004 00000000 00000000 00000000
+# DIS-SO-NEXT: 30010 00000000 00000000 00000000 00000000
# DIS-SO-NEXT: 30020 00000000 00000000 00000000
# SO: Relocations [
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