[COFF] Align import address chunks to the pointer size

This fixes cases on ARM64 when importing from more than one DLL,
in case the imports from the first DLL ended up unaligned.

When fixing up a IMAGE_REL_ARM64_PAGEOFFSET_12L, which shifts the
offset by the load/store size, check that the shift doesn't discard
any bits. (This would also detect if the import address chunks were
unaligned.)

Differential revision: https://reviews.llvm.org/D35640

llvm-svn: 308585

lld/COFF/Chunks.cpp

@@ -184,6 +184,8 @@ static void applyArm64Imm(uint8_t *Off, uint64_t Imm) {
 
 static void applyArm64Ldr(uint8_t *Off, uint64_t Imm) {
   int Size = read32le(Off) >> 30;
+  if ((Imm & ((1 << Size) - 1)) != 0)
+    fatal("misaligned ldr/str offset");
   Imm >>= Size;
   applyArm64Imm(Off, Imm);
 }

lld/COFF/DLL.cpp

@@ -61,7 +61,7 @@ private:
 // A chunk for the import descriptor table.
 class LookupChunk : public Chunk {
 public:
-  explicit LookupChunk(Chunk *C) : HintName(C) {}
+  explicit LookupChunk(Chunk *C) : HintName(C) { Align = ptrSize(); }
   size_t getSize() const override { return ptrSize(); }
 
   void writeTo(uint8_t *Buf) const override {
@@ -76,7 +76,7 @@ public:
 // See Microsoft PE/COFF spec 7.1. Import Header for details.
 class OrdinalOnlyChunk : public Chunk {
 public:
-  explicit OrdinalOnlyChunk(uint16_t V) : Ordinal(V) {}
+  explicit OrdinalOnlyChunk(uint16_t V) : Ordinal(V) { Align = ptrSize(); }
   size_t getSize() const override { return ptrSize(); }
 
   void writeTo(uint8_t *Buf) const override {
@@ -262,7 +262,7 @@ public:
 // A chunk for the import descriptor table.
 class DelayAddressChunk : public Chunk {
 public:
-  explicit DelayAddressChunk(Chunk *C) : Thunk(C) {}
+  explicit DelayAddressChunk(Chunk *C) : Thunk(C) { Align = ptrSize(); }
   size_t getSize() const override { return ptrSize(); }
 
   void writeTo(uint8_t *Buf) const override {

lld/test/COFF/Inputs/library2.def

@@ -0,0 +1,3 @@
+LIBRARY library2
+EXPORTS
+  function2

lld/test/COFF/arm64-import2.test

@@ -0,0 +1,85 @@
+# REQUIRES: aarch64
+
+# RUN: yaml2obj < %s > %t.obj
+# RUN: llvm-objdump -d %t.obj | FileCheck %s -check-prefix BEFORE
+# RUN: lld-link /entry:main /subsystem:console /out:%t.exe %t.obj %p/Inputs/library-arm64.lib %p/Inputs/library2-arm64.lib
+# RUN: llvm-objdump -d %t.exe | FileCheck %s -check-prefix AFTER
+# RUN: llvm-readobj -coff-imports %t.exe | FileCheck %s -check-prefix IMPORTS
+
+# BEFORE: Disassembly of section .text:
+# BEFORE:        0:       00 00 00 94     bl      #0
+# BEFORE:        4:       00 00 00 94     bl      #0
+# BEFORE:        8:       c0 03 5f d6     ret
+
+# AFTER: Disassembly of section .text:
+# AFTER:  140001000:      03 00 00 94     bl      #12
+# AFTER:  140001004:      05 00 00 94     bl      #20
+# AFTER:  140001008:      c0 03 5f d6     ret
+# AFTER:  14000100c:      10 00 00 b0     adrp    x16, #4096
+# AFTER:  140001010:      10 32 40 f9     ldr     x16, [x16, #96]
+# AFTER:  140001014:      00 02 1f d6     br      x16
+# AFTER:  140001018:      10 00 00 b0     adrp    x16, #4096
+# AFTER:  14000101c:      10 3a 40 f9     ldr     x16, [x16, #112]
+# AFTER:  140001020:      00 02 1f d6     br      x16
+
+# IMPORTS: Import {
+# IMPORTS:   Name: library.dll
+# IMPORTS:   ImportLookupTableRVA: 0x2040
+# IMPORTS:   ImportAddressTableRVA: 0x2060
+# IMPORTS:   Symbol: function (2)
+# IMPORTS: }
+# IMPORTS: Import {
+# IMPORTS:   Name: library2.dll
+# IMPORTS:   ImportLookupTableRVA: 0x2050
+# IMPORTS:   ImportAddressTableRVA: 0x2070
+# IMPORTS:   Symbol: function2 (0)
+# IMPORTS: }
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_ARM64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     0000009400000094C0035FD6
+    Relocations:
+      - VirtualAddress:  0
+        SymbolName:      function
+        Type:            3
+      - VirtualAddress:  4
+        SymbolName:      function2
+        Type:            3
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          12
+      NumberOfRelocations: 2
+      NumberOfLinenumbers: 0
+      CheckSum:        1438860354
+      Number:          1
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            function
+    Value:           0
+    SectionNumber:   0
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            function2
+    Value:           0
+    SectionNumber:   0
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...