[llvm-branch-commits] [lld] e134dc0 - [LLD][COFF] Emit ARM64X relocations for TLS directory (#213529)
Douglas Yung via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Fri Aug 7 01:24:56 PDT 2026
Author: Jacek Caban
Date: 2026-08-07T08:24:41Z
New Revision: e134dc02945a512d905b8e55ca875252a1dc02b6
URL: https://github.com/llvm/llvm-project/commit/e134dc02945a512d905b8e55ca875252a1dc02b6
DIFF: https://github.com/llvm/llvm-project/commit/e134dc02945a512d905b8e55ca875252a1dc02b6.diff
LOG: [LLD][COFF] Emit ARM64X relocations for TLS directory (#213529)
The current behavior of merging EC and native chunks to have a single
TLS directory for both views matches the MSVC linker, but it has its
shortcomings. In addition to merging, that solution requires all TLS
callbacks to use -arm64xsameaddress, leaving it to the CRT to handle. If
the appropriate EC object files are not pulled in by linked EC code and
thus never have a chance to mark the callback with -arm64xsameaddress,
this may lead to an invalid image that crashes at runtime.
This patch avoids the entire problem by using entirely separate TLS
directories for EC and native views along with the standard ARM64X
dynamic relocation mechanism. Since callback lists are now separate, a
missing -arm64xsameaddress is no longer a problem.
Also, mingw-w64-crt currently doesn't mark its TLS callbacks with
-arm64xsameaddress. That could be changed if needed, but with this
change, it is no longer necessary.
(cherry picked from commit 65e92e073539c3fe3523256c4fba35ac1dedcb92)
Added:
Modified:
lld/COFF/Driver.cpp
lld/COFF/Writer.cpp
lld/test/COFF/arm64x-tls.s
Removed:
################################################################################
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index 9d39aff73601b..6583e43271ad6 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -2841,8 +2841,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
if (ctx.hybridSymtab) {
// On ARM64X, merge tls chunks, there may be only one true _tls_start and
- // _tls_end chunk. Additionally, both views use the same _tls_used and
- // _tls_index.
+ // _tls_end chunk.
auto maybeReplaceWithNative = [&](StringRef name) {
auto nativeSym = dyn_cast_or_null<DefinedRegular>(
ctx.hybridSymtab->findUnderscore(name));
@@ -2852,8 +2851,6 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
dyn_cast_or_null<DefinedRegular>(ctx.symtab.findUnderscore(name)))
nativeSym->getChunk()->replace(ecSym->getChunk());
};
- maybeReplaceWithNative("_tls_used");
- maybeReplaceWithNative("_tls_index");
maybeReplaceWithNative("_tls_start");
maybeReplaceWithNative("_tls_end");
}
diff --git a/lld/COFF/Writer.cpp b/lld/COFF/Writer.cpp
index 33826c9146c50..3cab426df55cf 100644
--- a/lld/COFF/Writer.cpp
+++ b/lld/COFF/Writer.cpp
@@ -267,7 +267,7 @@ class Writer {
void sortBySectionOrder(std::vector<Chunk *> &chunks);
void fixPartialSectionChars(StringRef name, uint32_t chars);
bool fixGnuImportChunks();
- void fixTlsAlignment();
+ void fixTlsAlignment(SymbolTable &symtab);
PartialSection *createPartialSection(StringRef name, uint32_t outChars);
PartialSection *findPartialSection(StringRef name, uint32_t outChars);
@@ -815,7 +815,7 @@ void Writer::run() {
// Fix up the alignment in the TLS Directory's characteristic field,
// if a specific alignment value is needed
if (tlsAlignment)
- fixTlsAlignment();
+ ctx.forEachSymtab([&](SymbolTable &symtab) { fixTlsAlignment(symtab); });
}
if (!ctx.config.pdbPath.empty() && ctx.config.debug) {
@@ -2940,6 +2940,24 @@ void Writer::createDynamicRelocs() {
LOAD_CONFIG_TABLE * sizeof(data_directory) +
offsetof(data_directory, Size),
ctx.symtab.loadConfigSize);
+
+ auto nativeTlsUsed =
+ dyn_cast_or_null<Defined>(ctx.hybridSymtab->findUnderscore("_tls_used"));
+ auto ecTlsUsed =
+ dyn_cast_or_null<Defined>(ctx.symtab.findUnderscore("_tls_used"));
+ if (nativeTlsUsed || ecTlsUsed) {
+ ctx.dynamicRelocs->add(IMAGE_DVRT_ARM64X_FIXUP_TYPE_VALUE, sizeof(uint32_t),
+ dataDirOffset64 +
+ TLS_TABLE * sizeof(data_directory) +
+ offsetof(data_directory, RelativeVirtualAddress),
+ Arm64XRelocVal(ecTlsUsed));
+ if (!nativeTlsUsed || !ecTlsUsed)
+ ctx.dynamicRelocs->add(
+ IMAGE_DVRT_ARM64X_FIXUP_TYPE_VALUE, sizeof(uint32_t),
+ dataDirOffset64 + TLS_TABLE * sizeof(data_directory) +
+ offsetof(data_directory, Size),
+ ecTlsUsed ? sizeof(coff_tls_directory64) : 0);
+ }
}
PartialSection *Writer::createPartialSection(StringRef name,
@@ -2958,9 +2976,9 @@ PartialSection *Writer::findPartialSection(StringRef name, uint32_t outChars) {
return nullptr;
}
-void Writer::fixTlsAlignment() {
+void Writer::fixTlsAlignment(SymbolTable &symtab) {
Defined *tlsSym =
- dyn_cast_or_null<Defined>(ctx.symtab.findUnderscore("_tls_used"));
+ dyn_cast_or_null<Defined>(symtab.findUnderscore("_tls_used"));
if (!tlsSym)
return;
diff --git a/lld/test/COFF/arm64x-tls.s b/lld/test/COFF/arm64x-tls.s
index 608604fab2fb3..4a900edcee676 100644
--- a/lld/test/COFF/arm64x-tls.s
+++ b/lld/test/COFF/arm64x-tls.s
@@ -12,7 +12,7 @@
// RUN: llvm-lib -machine:arm64x -out:tls.lib tls-aarch64.obj tls-arm64ec.obj loadconfig-arm64ec.obj loadconfig-arm64.obj
// RUN: lld-link -machine:arm64x -dll -noentry aarch64.obj arm64ec.obj tls.lib -out:out.dll
-// Check that we're using native _tls_index and _tls_used for both views.
+// Check that we're using the right _tls_index and _tls_used for both views.
// RUN: llvm-readobj --coff-tls-directory --hex-dump=.ec --hex-dump=.a64 out.dll | FileCheck %s
// CHECK: Format: COFF-ARM64X
@@ -20,13 +20,13 @@
// CHECK-NEXT: AddressSize: 64bit
// CHECK-EMPTY:
// CHECK-NEXT: Hex dump of section '.a64':
-// CHECK-NEXT: 0x180004000 00500000 04500000 00700000 01700000
+// CHECK-NEXT: 0x180004000 00500000 04500000 00800000 01800000
// CHECK-EMPTY:
// CHECK-NEXT: Hex dump of section '.ec':
-// CHECK-NEXT: 0x180006000 00500000 04500000 00700000 01700000
+// CHECK-NEXT: 0x180007000 00600000 04600000 00800000 01800000
// CHECK-NEXT: TLSDirectory {
-// CHECK-NEXT: StartAddressOfRawData: 0x180007000
-// CHECK-NEXT: EndAddressOfRawData: 0x180007001
+// CHECK-NEXT: StartAddressOfRawData: 0x180008000
+// CHECK-NEXT: EndAddressOfRawData: 0x180008001
// CHECK-NEXT: AddressOfIndex: 0x180005000
// CHECK-NEXT: AddressOfCallBacks: 0x0
// CHECK-NEXT: SizeOfZeroFill: 0x0
@@ -40,14 +40,14 @@
// CHECK-NEXT: AddressSize: 64bit
// CHECK-EMPTY:
// CHECK-NEXT: Hex dump of section '.a64':
-// CHECK-NEXT: 0x180004000 00500000 04500000 00700000 01700000
+// CHECK-NEXT: 0x180004000 00500000 04500000 00800000 01800000
// CHECK-EMPTY:
// CHECK-NEXT: Hex dump of section '.ec':
-// CHECK-NEXT: 0x180006000 00500000 04500000 00700000 01700000
+// CHECK-NEXT: 0x180007000 00600000 04600000 00800000 01800000
// CHECK-NEXT: TLSDirectory {
-// CHECK-NEXT: StartAddressOfRawData: 0x180007000
-// CHECK-NEXT: EndAddressOfRawData: 0x180007001
-// CHECK-NEXT: AddressOfIndex: 0x180005000
+// CHECK-NEXT: StartAddressOfRawData: 0x180008000
+// CHECK-NEXT: EndAddressOfRawData: 0x180008001
+// CHECK-NEXT: AddressOfIndex: 0x180006000
// CHECK-NEXT: AddressOfCallBacks: 0x0
// CHECK-NEXT: SizeOfZeroFill: 0x0
// CHECK-NEXT: Characteristics [ (0x100000)
@@ -56,6 +56,52 @@
// CHECK-NEXT: }
// CHECK-NEXT: }
+// RUN: lld-link -machine:arm64x -dll -noentry arm64ec.obj tls.lib -out:out-ec.dll
+// RUN: llvm-readobj --coff-tls-directory out-ec.dll | FileCheck --check-prefix=EC-ONLY %s
+// EC-ONLY: Format: COFF-ARM64X
+// EC-ONLY-NEXT: Arch: aarch64
+// EC-ONLY-NEXT: AddressSize: 64bit
+// EC-ONLY-NEXT: TLSDirectory {
+// EC-ONLY-NEXT: }
+// EC-ONLY-NEXT: HybridObject {
+// EC-ONLY-NEXT: Format: COFF-ARM64EC
+// EC-ONLY-NEXT: Arch: aarch64
+// EC-ONLY-NEXT: AddressSize: 64bit
+// EC-ONLY-NEXT: TLSDirectory {
+// EC-ONLY-NEXT: StartAddressOfRawData: 0x180006000
+// EC-ONLY-NEXT: EndAddressOfRawData: 0x180006001
+// EC-ONLY-NEXT: AddressOfIndex: 0x180004000
+// EC-ONLY-NEXT: AddressOfCallBacks: 0x0
+// EC-ONLY-NEXT: SizeOfZeroFill: 0x0
+// EC-ONLY-NEXT: Characteristics [ (0x100000)
+// EC-ONLY-NEXT: IMAGE_SCN_ALIGN_1BYTES (0x100000)
+// EC-ONLY-NEXT: ]
+// EC-ONLY-NEXT: }
+// EC-ONLY-NEXT: }
+
+// RUN: lld-link -machine:arm64x -dll -noentry aarch64.obj tls.lib -out:out-native.dll
+// RUN: llvm-readobj --coff-tls-directory out-native.dll | FileCheck --check-prefix=NATIVE-ONLY %s
+// NATIVE-ONLY: Format: COFF-ARM64X
+// NATIVE-ONLY-NEXT: Arch: aarch64
+// NATIVE-ONLY-NEXT: AddressSize: 64bit
+// NATIVE-ONLY-NEXT: TLSDirectory {
+// NATIVE-ONLY-NEXT: StartAddressOfRawData: 0x180006000
+// NATIVE-ONLY-NEXT: EndAddressOfRawData: 0x180006001
+// NATIVE-ONLY-NEXT: AddressOfIndex: 0x180005000
+// NATIVE-ONLY-NEXT: AddressOfCallBacks: 0x0
+// NATIVE-ONLY-NEXT: SizeOfZeroFill: 0x0
+// NATIVE-ONLY-NEXT: Characteristics [ (0x100000)
+// NATIVE-ONLY-NEXT: IMAGE_SCN_ALIGN_1BYTES (0x100000)
+// NATIVE-ONLY-NEXT: ]
+// NATIVE-ONLY-NEXT: }
+// NATIVE-ONLY-NEXT: HybridObject {
+// NATIVE-ONLY-NEXT: Format: COFF-ARM64EC
+// NATIVE-ONLY-NEXT: Arch: aarch64
+// NATIVE-ONLY-NEXT: AddressSize: 64bit
+// NATIVE-ONLY-NEXT: TLSDirectory {
+// NATIVE-ONLY-NEXT: }
+// NATIVE-ONLY-NEXT: }
+
#--- tls-aarch64.s
.section .defa64,"dr",discard,_tls_index
.globl _tls_index
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