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Merged
merged 1 commit into from
Dec 29, 2024

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cjacek
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@cjacek cjacek commented Dec 17, 2024

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cjacek commented Dec 17, 2024

Depends on #120324.

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llvmbot commented Dec 17, 2024

@llvm/pr-subscribers-platform-windows

@llvm/pr-subscribers-lld-coff

Author: Jacek Caban (cjacek)

Changes

Full diff: https://github.com/llvm/llvm-project/pull/120326.diff

9 Files Affected:

  • (modified) lld/COFF/Driver.cpp (+1)
  • (modified) lld/COFF/SymbolTable.cpp (+47)
  • (modified) lld/COFF/SymbolTable.h (+4)
  • (modified) lld/COFF/Writer.cpp (+24-49)
  • (modified) lld/test/COFF/arm64x-loadconfig.s (+2)
  • (modified) lld/test/COFF/guard-warnings.s (+1-1)
  • (added) lld/test/COFF/loadcfg-short.test (+33)
  • (added) lld/test/COFF/loadcfg-size.test (+33)
  • (added) lld/test/COFF/loadcfg-uninitialized.test (+33)
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index bef55abb7f856e..9d45e9b926b1f6 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -2822,6 +2822,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
 
   if (ctx.symtabEC)
     ctx.symtabEC->initializeECThunks();
+  ctx.forEachSymtab([](SymbolTable &symtab) { symtab.initializeLoadConfig(); });
 
   // Identify unreferenced COMDAT sections.
   if (config->doGC) {
diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cpp
index 6b3375e13e8393..7e243fc626d38d 100644
--- a/lld/COFF/SymbolTable.cpp
+++ b/lld/COFF/SymbolTable.cpp
@@ -27,6 +27,7 @@
 #include <utility>
 
 using namespace llvm;
+using namespace llvm::support;
 
 namespace lld::coff {
 
@@ -595,6 +596,52 @@ std::pair<Symbol *, bool> SymbolTable::insert(StringRef name, InputFile *file) {
   return result;
 }
 
+void SymbolTable::initializeLoadConfig() {
+  auto sym =
+      dyn_cast_or_null<DefinedRegular>(findUnderscore("_load_config_used"));
+  if (!sym) {
+    if (ctx.config.guardCF != GuardCFLevel::Off)
+      Warn(ctx)
+          << "Control Flow Guard is enabled but '_load_config_used' is missing";
+    if (ctx.config.dependentLoadFlags)
+      Warn(ctx) << "_load_config_used not found, /dependentloadflag will have "
+                   "no effect";
+    return;
+  }
+
+  SectionChunk *sc = sym->getChunk();
+  if (!sc->hasData) {
+    Err(ctx) << "_load_config_used points to uninitialized data";
+    return;
+  }
+  uint64_t offsetInChunk = sym->getValue();
+  if (offsetInChunk + 4 > sc->getSize()) {
+    Err(ctx) << "_load_config_used section chunk is too small";
+    return;
+  }
+
+  ArrayRef<uint8_t> secContents = sc->getContents();
+  loadConfigSize =
+      *reinterpret_cast<const ulittle32_t *>(&secContents[offsetInChunk]);
+  if (offsetInChunk + loadConfigSize > sc->getSize()) {
+    Err(ctx) << "_load_config_used specifies a size larger than its containing "
+                "section chunk";
+    return;
+  }
+
+  uint32_t expectedAlign = ctx.config.is64() ? 8 : 4;
+  if (sc->getAlignment() < expectedAlign)
+    Warn(ctx) << "'_load_config_used' is misaligned (expected alignment to be "
+              << expectedAlign << " bytes, got " << sc->getAlignment()
+              << " instead)";
+  else if (!isAligned(Align(expectedAlign), offsetInChunk))
+    Warn(ctx) << "'_load_config_used' is misaligned (section offset is 0x"
+              << Twine::utohexstr(sym->getValue()) << " not aligned to "
+              << expectedAlign << " bytes)";
+
+  loadConfigSym = sym;
+}
+
 void SymbolTable::addEntryThunk(Symbol *from, Symbol *to) {
   entryThunks.push_back({from, to});
 }
diff --git a/lld/COFF/SymbolTable.h b/lld/COFF/SymbolTable.h
index b694893b903aa3..8548a6d036a9db 100644
--- a/lld/COFF/SymbolTable.h
+++ b/lld/COFF/SymbolTable.h
@@ -138,6 +138,10 @@ class SymbolTable {
       callback(pair.second);
   }
 
+  DefinedRegular *loadConfigSym = nullptr;
+  uint32_t loadConfigSize = 0;
+  void initializeLoadConfig();
+
 private:
   /// Given a name without "__imp_" prefix, returns a defined symbol
   /// with the "__imp_" prefix, if it exists.
diff --git a/lld/COFF/Writer.cpp b/lld/COFF/Writer.cpp
index 3c6112b7fc89ad..5946c2944aa212 100644
--- a/lld/COFF/Writer.cpp
+++ b/lld/COFF/Writer.cpp
@@ -282,7 +282,8 @@ class Writer {
   uint32_t getSizeOfInitializedData();
 
   void prepareLoadConfig();
-  template <typename T> void prepareLoadConfig(T *loadConfig);
+  template <typename T>
+  void prepareLoadConfig(SymbolTable &symtab, T *loadConfig);
 
   std::unique_ptr<FileOutputBuffer> &buffer;
   std::map<PartialSectionKey, PartialSection *> partialSections;
@@ -1837,22 +1838,10 @@ template <typename PEHeaderTy> void Writer::writeHeader() {
     dir[DEBUG_DIRECTORY].RelativeVirtualAddress = debugDirectory->getRVA();
     dir[DEBUG_DIRECTORY].Size = debugDirectory->getSize();
   }
-  if (Symbol *sym = ctx.symtab.findUnderscore("_load_config_used")) {
-    if (auto *b = dyn_cast<DefinedRegular>(sym)) {
-      SectionChunk *sc = b->getChunk();
-      assert(b->getRVA() >= sc->getRVA());
-      uint64_t offsetInChunk = b->getRVA() - sc->getRVA();
-      if (!sc->hasData || offsetInChunk + 4 > sc->getSize())
-        Fatal(ctx) << "_load_config_used is malformed";
-
-      ArrayRef<uint8_t> secContents = sc->getContents();
-      uint32_t loadConfigSize =
-          *reinterpret_cast<const ulittle32_t *>(&secContents[offsetInChunk]);
-      if (offsetInChunk + loadConfigSize > sc->getSize())
-        Fatal(ctx) << "_load_config_used is too large";
-      dir[LOAD_CONFIG_TABLE].RelativeVirtualAddress = b->getRVA();
-      dir[LOAD_CONFIG_TABLE].Size = loadConfigSize;
-    }
+  if (ctx.symtab.loadConfigSym) {
+    dir[LOAD_CONFIG_TABLE].RelativeVirtualAddress =
+        ctx.symtab.loadConfigSym->getRVA();
+    dir[LOAD_CONFIG_TABLE].Size = ctx.symtab.loadConfigSize;
   }
   if (!delayIdata.empty()) {
     dir[DELAY_IMPORT_DESCRIPTOR].RelativeVirtualAddress =
@@ -2649,39 +2638,25 @@ void Writer::fixTlsAlignment() {
 }
 
 void Writer::prepareLoadConfig() {
-  Symbol *sym = ctx.symtab.findUnderscore("_load_config_used");
-  auto *b = cast_if_present<DefinedRegular>(sym);
-  if (!b) {
-    if (ctx.config.guardCF != GuardCFLevel::Off)
-      Warn(ctx)
-          << "Control Flow Guard is enabled but '_load_config_used' is missing";
-    if (ctx.config.dependentLoadFlags)
-      Warn(ctx) << "_load_config_used not found, /dependentloadflag will have "
-                   "no effect";
-    return;
-  }
+  ctx.forEachSymtab([&](SymbolTable &symtab) {
+    if (!symtab.loadConfigSym)
+      return;
 
-  OutputSection *sec = ctx.getOutputSection(b->getChunk());
-  uint8_t *buf = buffer->getBufferStart();
-  uint8_t *secBuf = buf + sec->getFileOff();
-  uint8_t *symBuf = secBuf + (b->getRVA() - sec->getRVA());
-  uint32_t expectedAlign = ctx.config.is64() ? 8 : 4;
-  if (b->getChunk()->getAlignment() < expectedAlign)
-    Warn(ctx) << "'_load_config_used' is misaligned (expected alignment to be "
-              << expectedAlign << " bytes, got "
-              << b->getChunk()->getAlignment() << " instead)";
-  else if (!isAligned(Align(expectedAlign), b->getRVA()))
-    Warn(ctx) << "'_load_config_used' is misaligned (RVA is 0x"
-              << Twine::utohexstr(b->getRVA()) << " not aligned to "
-              << expectedAlign << " bytes)";
-
-  if (ctx.config.is64())
-    prepareLoadConfig(reinterpret_cast<coff_load_configuration64 *>(symBuf));
-  else
-    prepareLoadConfig(reinterpret_cast<coff_load_configuration32 *>(symBuf));
+    OutputSection *sec = ctx.getOutputSection(symtab.loadConfigSym->getChunk());
+    uint8_t *secBuf = buffer->getBufferStart() + sec->getFileOff();
+    uint8_t *symBuf = secBuf + (symtab.loadConfigSym->getRVA() - sec->getRVA());
+
+    if (ctx.config.is64())
+      prepareLoadConfig(symtab,
+                        reinterpret_cast<coff_load_configuration64 *>(symBuf));
+    else
+      prepareLoadConfig(symtab,
+                        reinterpret_cast<coff_load_configuration32 *>(symBuf));
+  });
 }
 
-template <typename T> void Writer::prepareLoadConfig(T *loadConfig) {
+template <typename T>
+void Writer::prepareLoadConfig(SymbolTable &symtab, T *loadConfig) {
   size_t loadConfigSize = loadConfig->Size;
 
 #define RETURN_IF_NOT_CONTAINS(field)                                          \
@@ -2694,12 +2669,12 @@ template <typename T> void Writer::prepareLoadConfig(T *loadConfig) {
   if (loadConfigSize >= offsetof(T, field) + sizeof(T::field))
 
 #define CHECK_VA(field, sym)                                                   \
-  if (auto *s = dyn_cast<DefinedSynthetic>(ctx.symtab.findUnderscore(sym)))    \
+  if (auto *s = dyn_cast<DefinedSynthetic>(symtab.findUnderscore(sym)))        \
     if (loadConfig->field != ctx.config.imageBase + s->getRVA())               \
       Warn(ctx) << #field " not set correctly in '_load_config_used'";
 
 #define CHECK_ABSOLUTE(field, sym)                                             \
-  if (auto *s = dyn_cast<DefinedAbsolute>(ctx.symtab.findUnderscore(sym)))     \
+  if (auto *s = dyn_cast<DefinedAbsolute>(symtab.findUnderscore(sym)))         \
     if (loadConfig->field != s->getVA())                                       \
       Warn(ctx) << #field " not set correctly in '_load_config_used'";
 
diff --git a/lld/test/COFF/arm64x-loadconfig.s b/lld/test/COFF/arm64x-loadconfig.s
index 0d4fe0ed6d6e0a..6023828a2746f7 100644
--- a/lld/test/COFF/arm64x-loadconfig.s
+++ b/lld/test/COFF/arm64x-loadconfig.s
@@ -4,6 +4,7 @@
 // RUN: llvm-mc -filetype=obj -triple=aarch64-windows test.s -o test.obj
 // RUN: llvm-mc -filetype=obj -triple=aarch64-windows loadconfig.s -o loadconfig.obj
 // RUN: llvm-mc -filetype=obj -triple=aarch64-windows loadconfig-short.s -o loadconfig-short.obj
+// RUN: llvm-mc -filetype=obj -triple=arm64ec-windows loadconfig-short.s -o loadconfig-short-arm64ec.obj
 
 // RUN: lld-link -machine:arm64x -out:out.dll -dll -noentry loadconfig.obj test.obj
 
@@ -43,6 +44,7 @@
 // HEADERS-NEXT: VirtualSize: 0x38
 
 // RUN: lld-link -machine:arm64x -out:out-short.dll -dll -noentry loadconfig-short.obj 2>&1 | FileCheck --check-prefix=WARN-RELOC-SIZE %s
+// RUN: lld-link -machine:arm64x -out:out-short.dll -dll -noentry loadconfig-short-arm64ec.obj 2>&1 | FileCheck --check-prefix=WARN-RELOC-SIZE %s
 // WARN-RELOC-SIZE: lld-link: warning: '_load_config_used' structure too small to include dynamic relocations
 
 #--- test.s
diff --git a/lld/test/COFF/guard-warnings.s b/lld/test/COFF/guard-warnings.s
index 77448ee95c0095..092871597d1f80 100644
--- a/lld/test/COFF/guard-warnings.s
+++ b/lld/test/COFF/guard-warnings.s
@@ -38,7 +38,7 @@
 
 # RUN: llvm-mc -triple x86_64-windows-msvc %t/loadcfg-misaligned2.s -filetype=obj -o %t/loadcfg-misaligned2.obj
 # RUN: lld-link %t/main.obj %t/loadcfg-misaligned2.obj -guard:cf,longjmp,ehcont -out:%t-misaligned2.exe -entry:main %basename_t-exp.lib 2>&1 | FileCheck %s --check-prefix=WARN_ALIGN2
-# WARN_ALIGN2: warning: '_load_config_used' is misaligned (RVA is 0x{{[0-9A-F]*}}2 not aligned to 8 bytes)
+# WARN_ALIGN2: warning: '_load_config_used' is misaligned (section offset is 0x{{[0-9A-F]*}}2 not aligned to 8 bytes)
 
 # RUN: llvm-mc -triple x86_64-windows-msvc %t/loadcfg-full.s -filetype=obj -o %t/loadcfg-full.obj
 # RUN: lld-link %t/main.obj %t/loadcfg-full.obj -guard:cf,longjmp,ehcont -out:%t.exe -entry:main %basename_t-exp.lib 2>&1 | FileCheck %s --check-prefix=NOWARN --allow-empty
diff --git a/lld/test/COFF/loadcfg-short.test b/lld/test/COFF/loadcfg-short.test
new file mode 100644
index 00000000000000..dd4d4389ddc1cc
--- /dev/null
+++ b/lld/test/COFF/loadcfg-short.test
@@ -0,0 +1,33 @@
+# RUN: yaml2obj %s -o %t.obj
+# RUN: not lld-link -out:%t.dll %t.obj -dll -noentry 2>&1 | FileCheck %s
+# CHECK: lld-link: error: _load_config_used section chunk is too small
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections:
+  - Name:            .rdata
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     '030000'
+symbols:
+  - Name:            .rdata
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          112
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          3
+  - Name:            _load_config_used
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...
diff --git a/lld/test/COFF/loadcfg-size.test b/lld/test/COFF/loadcfg-size.test
new file mode 100644
index 00000000000000..871590f2328b63
--- /dev/null
+++ b/lld/test/COFF/loadcfg-size.test
@@ -0,0 +1,33 @@
+# RUN: yaml2obj %s -o %t.obj
+# RUN: not lld-link -out:%t.dll %t.obj -dll -noentry 2>&1 | FileCheck %s
+# CHECK: lld-link: error: _load_config_used specifies a size larger than its containing section chunk
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections:
+  - Name:            .rdata
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     '0c00000000000000'
+symbols:
+  - Name:            .rdata
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          112
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          3
+  - Name:            _load_config_used
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...
diff --git a/lld/test/COFF/loadcfg-uninitialized.test b/lld/test/COFF/loadcfg-uninitialized.test
new file mode 100644
index 00000000000000..5f956bc7224bc9
--- /dev/null
+++ b/lld/test/COFF/loadcfg-uninitialized.test
@@ -0,0 +1,33 @@
+# RUN: yaml2obj %s -o %t.obj
+# RUN: not lld-link -out:%t.dll %t.obj -dll -noentry 2>&1 | FileCheck %s
+# CHECK: lld-link: error: _load_config_used points to uninitialized data
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections:
+  - Name:            .rdata
+    Characteristics: [ IMAGE_SCN_CNT_UNINITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    VirtualSize:     0x140
+symbols:
+  - Name:            .rdata
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          112
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          3
+  - Name:            _load_config_used
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

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llvmbot commented Dec 17, 2024

@llvm/pr-subscribers-lld

Author: Jacek Caban (cjacek)

Changes

Full diff: https://github.com/llvm/llvm-project/pull/120326.diff

9 Files Affected:

  • (modified) lld/COFF/Driver.cpp (+1)
  • (modified) lld/COFF/SymbolTable.cpp (+47)
  • (modified) lld/COFF/SymbolTable.h (+4)
  • (modified) lld/COFF/Writer.cpp (+24-49)
  • (modified) lld/test/COFF/arm64x-loadconfig.s (+2)
  • (modified) lld/test/COFF/guard-warnings.s (+1-1)
  • (added) lld/test/COFF/loadcfg-short.test (+33)
  • (added) lld/test/COFF/loadcfg-size.test (+33)
  • (added) lld/test/COFF/loadcfg-uninitialized.test (+33)
diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
index bef55abb7f856e..9d45e9b926b1f6 100644
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -2822,6 +2822,7 @@ void LinkerDriver::linkerMain(ArrayRef<const char *> argsArr) {
 
   if (ctx.symtabEC)
     ctx.symtabEC->initializeECThunks();
+  ctx.forEachSymtab([](SymbolTable &symtab) { symtab.initializeLoadConfig(); });
 
   // Identify unreferenced COMDAT sections.
   if (config->doGC) {
diff --git a/lld/COFF/SymbolTable.cpp b/lld/COFF/SymbolTable.cpp
index 6b3375e13e8393..7e243fc626d38d 100644
--- a/lld/COFF/SymbolTable.cpp
+++ b/lld/COFF/SymbolTable.cpp
@@ -27,6 +27,7 @@
 #include <utility>
 
 using namespace llvm;
+using namespace llvm::support;
 
 namespace lld::coff {
 
@@ -595,6 +596,52 @@ std::pair<Symbol *, bool> SymbolTable::insert(StringRef name, InputFile *file) {
   return result;
 }
 
+void SymbolTable::initializeLoadConfig() {
+  auto sym =
+      dyn_cast_or_null<DefinedRegular>(findUnderscore("_load_config_used"));
+  if (!sym) {
+    if (ctx.config.guardCF != GuardCFLevel::Off)
+      Warn(ctx)
+          << "Control Flow Guard is enabled but '_load_config_used' is missing";
+    if (ctx.config.dependentLoadFlags)
+      Warn(ctx) << "_load_config_used not found, /dependentloadflag will have "
+                   "no effect";
+    return;
+  }
+
+  SectionChunk *sc = sym->getChunk();
+  if (!sc->hasData) {
+    Err(ctx) << "_load_config_used points to uninitialized data";
+    return;
+  }
+  uint64_t offsetInChunk = sym->getValue();
+  if (offsetInChunk + 4 > sc->getSize()) {
+    Err(ctx) << "_load_config_used section chunk is too small";
+    return;
+  }
+
+  ArrayRef<uint8_t> secContents = sc->getContents();
+  loadConfigSize =
+      *reinterpret_cast<const ulittle32_t *>(&secContents[offsetInChunk]);
+  if (offsetInChunk + loadConfigSize > sc->getSize()) {
+    Err(ctx) << "_load_config_used specifies a size larger than its containing "
+                "section chunk";
+    return;
+  }
+
+  uint32_t expectedAlign = ctx.config.is64() ? 8 : 4;
+  if (sc->getAlignment() < expectedAlign)
+    Warn(ctx) << "'_load_config_used' is misaligned (expected alignment to be "
+              << expectedAlign << " bytes, got " << sc->getAlignment()
+              << " instead)";
+  else if (!isAligned(Align(expectedAlign), offsetInChunk))
+    Warn(ctx) << "'_load_config_used' is misaligned (section offset is 0x"
+              << Twine::utohexstr(sym->getValue()) << " not aligned to "
+              << expectedAlign << " bytes)";
+
+  loadConfigSym = sym;
+}
+
 void SymbolTable::addEntryThunk(Symbol *from, Symbol *to) {
   entryThunks.push_back({from, to});
 }
diff --git a/lld/COFF/SymbolTable.h b/lld/COFF/SymbolTable.h
index b694893b903aa3..8548a6d036a9db 100644
--- a/lld/COFF/SymbolTable.h
+++ b/lld/COFF/SymbolTable.h
@@ -138,6 +138,10 @@ class SymbolTable {
       callback(pair.second);
   }
 
+  DefinedRegular *loadConfigSym = nullptr;
+  uint32_t loadConfigSize = 0;
+  void initializeLoadConfig();
+
 private:
   /// Given a name without "__imp_" prefix, returns a defined symbol
   /// with the "__imp_" prefix, if it exists.
diff --git a/lld/COFF/Writer.cpp b/lld/COFF/Writer.cpp
index 3c6112b7fc89ad..5946c2944aa212 100644
--- a/lld/COFF/Writer.cpp
+++ b/lld/COFF/Writer.cpp
@@ -282,7 +282,8 @@ class Writer {
   uint32_t getSizeOfInitializedData();
 
   void prepareLoadConfig();
-  template <typename T> void prepareLoadConfig(T *loadConfig);
+  template <typename T>
+  void prepareLoadConfig(SymbolTable &symtab, T *loadConfig);
 
   std::unique_ptr<FileOutputBuffer> &buffer;
   std::map<PartialSectionKey, PartialSection *> partialSections;
@@ -1837,22 +1838,10 @@ template <typename PEHeaderTy> void Writer::writeHeader() {
     dir[DEBUG_DIRECTORY].RelativeVirtualAddress = debugDirectory->getRVA();
     dir[DEBUG_DIRECTORY].Size = debugDirectory->getSize();
   }
-  if (Symbol *sym = ctx.symtab.findUnderscore("_load_config_used")) {
-    if (auto *b = dyn_cast<DefinedRegular>(sym)) {
-      SectionChunk *sc = b->getChunk();
-      assert(b->getRVA() >= sc->getRVA());
-      uint64_t offsetInChunk = b->getRVA() - sc->getRVA();
-      if (!sc->hasData || offsetInChunk + 4 > sc->getSize())
-        Fatal(ctx) << "_load_config_used is malformed";
-
-      ArrayRef<uint8_t> secContents = sc->getContents();
-      uint32_t loadConfigSize =
-          *reinterpret_cast<const ulittle32_t *>(&secContents[offsetInChunk]);
-      if (offsetInChunk + loadConfigSize > sc->getSize())
-        Fatal(ctx) << "_load_config_used is too large";
-      dir[LOAD_CONFIG_TABLE].RelativeVirtualAddress = b->getRVA();
-      dir[LOAD_CONFIG_TABLE].Size = loadConfigSize;
-    }
+  if (ctx.symtab.loadConfigSym) {
+    dir[LOAD_CONFIG_TABLE].RelativeVirtualAddress =
+        ctx.symtab.loadConfigSym->getRVA();
+    dir[LOAD_CONFIG_TABLE].Size = ctx.symtab.loadConfigSize;
   }
   if (!delayIdata.empty()) {
     dir[DELAY_IMPORT_DESCRIPTOR].RelativeVirtualAddress =
@@ -2649,39 +2638,25 @@ void Writer::fixTlsAlignment() {
 }
 
 void Writer::prepareLoadConfig() {
-  Symbol *sym = ctx.symtab.findUnderscore("_load_config_used");
-  auto *b = cast_if_present<DefinedRegular>(sym);
-  if (!b) {
-    if (ctx.config.guardCF != GuardCFLevel::Off)
-      Warn(ctx)
-          << "Control Flow Guard is enabled but '_load_config_used' is missing";
-    if (ctx.config.dependentLoadFlags)
-      Warn(ctx) << "_load_config_used not found, /dependentloadflag will have "
-                   "no effect";
-    return;
-  }
+  ctx.forEachSymtab([&](SymbolTable &symtab) {
+    if (!symtab.loadConfigSym)
+      return;
 
-  OutputSection *sec = ctx.getOutputSection(b->getChunk());
-  uint8_t *buf = buffer->getBufferStart();
-  uint8_t *secBuf = buf + sec->getFileOff();
-  uint8_t *symBuf = secBuf + (b->getRVA() - sec->getRVA());
-  uint32_t expectedAlign = ctx.config.is64() ? 8 : 4;
-  if (b->getChunk()->getAlignment() < expectedAlign)
-    Warn(ctx) << "'_load_config_used' is misaligned (expected alignment to be "
-              << expectedAlign << " bytes, got "
-              << b->getChunk()->getAlignment() << " instead)";
-  else if (!isAligned(Align(expectedAlign), b->getRVA()))
-    Warn(ctx) << "'_load_config_used' is misaligned (RVA is 0x"
-              << Twine::utohexstr(b->getRVA()) << " not aligned to "
-              << expectedAlign << " bytes)";
-
-  if (ctx.config.is64())
-    prepareLoadConfig(reinterpret_cast<coff_load_configuration64 *>(symBuf));
-  else
-    prepareLoadConfig(reinterpret_cast<coff_load_configuration32 *>(symBuf));
+    OutputSection *sec = ctx.getOutputSection(symtab.loadConfigSym->getChunk());
+    uint8_t *secBuf = buffer->getBufferStart() + sec->getFileOff();
+    uint8_t *symBuf = secBuf + (symtab.loadConfigSym->getRVA() - sec->getRVA());
+
+    if (ctx.config.is64())
+      prepareLoadConfig(symtab,
+                        reinterpret_cast<coff_load_configuration64 *>(symBuf));
+    else
+      prepareLoadConfig(symtab,
+                        reinterpret_cast<coff_load_configuration32 *>(symBuf));
+  });
 }
 
-template <typename T> void Writer::prepareLoadConfig(T *loadConfig) {
+template <typename T>
+void Writer::prepareLoadConfig(SymbolTable &symtab, T *loadConfig) {
   size_t loadConfigSize = loadConfig->Size;
 
 #define RETURN_IF_NOT_CONTAINS(field)                                          \
@@ -2694,12 +2669,12 @@ template <typename T> void Writer::prepareLoadConfig(T *loadConfig) {
   if (loadConfigSize >= offsetof(T, field) + sizeof(T::field))
 
 #define CHECK_VA(field, sym)                                                   \
-  if (auto *s = dyn_cast<DefinedSynthetic>(ctx.symtab.findUnderscore(sym)))    \
+  if (auto *s = dyn_cast<DefinedSynthetic>(symtab.findUnderscore(sym)))        \
     if (loadConfig->field != ctx.config.imageBase + s->getRVA())               \
       Warn(ctx) << #field " not set correctly in '_load_config_used'";
 
 #define CHECK_ABSOLUTE(field, sym)                                             \
-  if (auto *s = dyn_cast<DefinedAbsolute>(ctx.symtab.findUnderscore(sym)))     \
+  if (auto *s = dyn_cast<DefinedAbsolute>(symtab.findUnderscore(sym)))         \
     if (loadConfig->field != s->getVA())                                       \
       Warn(ctx) << #field " not set correctly in '_load_config_used'";
 
diff --git a/lld/test/COFF/arm64x-loadconfig.s b/lld/test/COFF/arm64x-loadconfig.s
index 0d4fe0ed6d6e0a..6023828a2746f7 100644
--- a/lld/test/COFF/arm64x-loadconfig.s
+++ b/lld/test/COFF/arm64x-loadconfig.s
@@ -4,6 +4,7 @@
 // RUN: llvm-mc -filetype=obj -triple=aarch64-windows test.s -o test.obj
 // RUN: llvm-mc -filetype=obj -triple=aarch64-windows loadconfig.s -o loadconfig.obj
 // RUN: llvm-mc -filetype=obj -triple=aarch64-windows loadconfig-short.s -o loadconfig-short.obj
+// RUN: llvm-mc -filetype=obj -triple=arm64ec-windows loadconfig-short.s -o loadconfig-short-arm64ec.obj
 
 // RUN: lld-link -machine:arm64x -out:out.dll -dll -noentry loadconfig.obj test.obj
 
@@ -43,6 +44,7 @@
 // HEADERS-NEXT: VirtualSize: 0x38
 
 // RUN: lld-link -machine:arm64x -out:out-short.dll -dll -noentry loadconfig-short.obj 2>&1 | FileCheck --check-prefix=WARN-RELOC-SIZE %s
+// RUN: lld-link -machine:arm64x -out:out-short.dll -dll -noentry loadconfig-short-arm64ec.obj 2>&1 | FileCheck --check-prefix=WARN-RELOC-SIZE %s
 // WARN-RELOC-SIZE: lld-link: warning: '_load_config_used' structure too small to include dynamic relocations
 
 #--- test.s
diff --git a/lld/test/COFF/guard-warnings.s b/lld/test/COFF/guard-warnings.s
index 77448ee95c0095..092871597d1f80 100644
--- a/lld/test/COFF/guard-warnings.s
+++ b/lld/test/COFF/guard-warnings.s
@@ -38,7 +38,7 @@
 
 # RUN: llvm-mc -triple x86_64-windows-msvc %t/loadcfg-misaligned2.s -filetype=obj -o %t/loadcfg-misaligned2.obj
 # RUN: lld-link %t/main.obj %t/loadcfg-misaligned2.obj -guard:cf,longjmp,ehcont -out:%t-misaligned2.exe -entry:main %basename_t-exp.lib 2>&1 | FileCheck %s --check-prefix=WARN_ALIGN2
-# WARN_ALIGN2: warning: '_load_config_used' is misaligned (RVA is 0x{{[0-9A-F]*}}2 not aligned to 8 bytes)
+# WARN_ALIGN2: warning: '_load_config_used' is misaligned (section offset is 0x{{[0-9A-F]*}}2 not aligned to 8 bytes)
 
 # RUN: llvm-mc -triple x86_64-windows-msvc %t/loadcfg-full.s -filetype=obj -o %t/loadcfg-full.obj
 # RUN: lld-link %t/main.obj %t/loadcfg-full.obj -guard:cf,longjmp,ehcont -out:%t.exe -entry:main %basename_t-exp.lib 2>&1 | FileCheck %s --check-prefix=NOWARN --allow-empty
diff --git a/lld/test/COFF/loadcfg-short.test b/lld/test/COFF/loadcfg-short.test
new file mode 100644
index 00000000000000..dd4d4389ddc1cc
--- /dev/null
+++ b/lld/test/COFF/loadcfg-short.test
@@ -0,0 +1,33 @@
+# RUN: yaml2obj %s -o %t.obj
+# RUN: not lld-link -out:%t.dll %t.obj -dll -noentry 2>&1 | FileCheck %s
+# CHECK: lld-link: error: _load_config_used section chunk is too small
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections:
+  - Name:            .rdata
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     '030000'
+symbols:
+  - Name:            .rdata
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          112
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          3
+  - Name:            _load_config_used
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...
diff --git a/lld/test/COFF/loadcfg-size.test b/lld/test/COFF/loadcfg-size.test
new file mode 100644
index 00000000000000..871590f2328b63
--- /dev/null
+++ b/lld/test/COFF/loadcfg-size.test
@@ -0,0 +1,33 @@
+# RUN: yaml2obj %s -o %t.obj
+# RUN: not lld-link -out:%t.dll %t.obj -dll -noentry 2>&1 | FileCheck %s
+# CHECK: lld-link: error: _load_config_used specifies a size larger than its containing section chunk
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections:
+  - Name:            .rdata
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     '0c00000000000000'
+symbols:
+  - Name:            .rdata
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          112
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          3
+  - Name:            _load_config_used
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...
diff --git a/lld/test/COFF/loadcfg-uninitialized.test b/lld/test/COFF/loadcfg-uninitialized.test
new file mode 100644
index 00000000000000..5f956bc7224bc9
--- /dev/null
+++ b/lld/test/COFF/loadcfg-uninitialized.test
@@ -0,0 +1,33 @@
+# RUN: yaml2obj %s -o %t.obj
+# RUN: not lld-link -out:%t.dll %t.obj -dll -noentry 2>&1 | FileCheck %s
+# CHECK: lld-link: error: _load_config_used points to uninitialized data
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: []
+sections:
+  - Name:            .rdata
+    Characteristics: [ IMAGE_SCN_CNT_UNINITIALIZED_DATA, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    VirtualSize:     0x140
+symbols:
+  - Name:            .rdata
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          112
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          3
+  - Name:            _load_config_used
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

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@mstorsjo mstorsjo left a comment

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LGTM

@cjacek cjacek force-pushed the arm64x-prepare-loadcfg branch from 1693c46 to 878f226 Compare December 29, 2024 11:44
@cjacek cjacek merged commit 7144325 into llvm:main Dec 29, 2024
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@cjacek cjacek deleted the arm64x-prepare-loadcfg branch December 29, 2024 11:55
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3 participants