[lld] r340715 - [COFF] Check the instructions in ARM MOV32T relocations

[Martin Storsjo via llvm-commits]

Author: mstorsjo
Date: Sun Aug 26 23:04:36 2018
New Revision: 340715

URL: http://llvm.org/viewvc/llvm-project?rev=340715&view=rev
Log:
[COFF] Check the instructions in ARM MOV32T relocations

For this relocation, which applies to two consecutive instructions,
it's plausible that the second instruction might not actually be
the right one.

Differential Revision: https://reviews.llvm.org/D50998

Added:
    lld/trunk/test/COFF/broken-arm-reloc.yaml
Modified:
    lld/trunk/COFF/Chunks.cpp

Modified: lld/trunk/COFF/Chunks.cpp
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/COFF/Chunks.cpp?rev=340715&r1=340714&r2=340715&view=diff
==============================================================================
--- lld/trunk/COFF/Chunks.cpp (original)
+++ lld/trunk/COFF/Chunks.cpp Sun Aug 26 23:04:36 2018
@@ -124,16 +124,22 @@ static void applyMOV(uint8_t *Off, uint1
   write16le(Off + 2, (read16le(Off + 2) & 0x8f00) | ((V & 0x700) << 4) | (V & 0xff));
 }
 
-static uint16_t readMOV(uint8_t *Off) {
+static uint16_t readMOV(uint8_t *Off, bool MOVT) {
   uint16_t Op1 = read16le(Off);
+  if ((Op1 & 0xfbf0) != (MOVT ? 0xf2c0 : 0xf240))
+    error("unexpected instruction in " + Twine(MOVT ? "MOVT" : "MOVW") +
+          " instruction in MOV32T relocation");
   uint16_t Op2 = read16le(Off + 2);
+  if ((Op2 & 0x8000) != 0)
+    error("unexpected instruction in " + Twine(MOVT ? "MOVT" : "MOVW") +
+          " instruction in MOV32T relocation");
   return (Op2 & 0x00ff) | ((Op2 >> 4) & 0x0700) | ((Op1 << 1) & 0x0800) |
          ((Op1 & 0x000f) << 12);
 }
 
 void applyMOV32T(uint8_t *Off, uint32_t V) {
-  uint16_t ImmW = readMOV(Off);     // read MOVW operand
-  uint16_t ImmT = readMOV(Off + 4); // read MOVT operand
+  uint16_t ImmW = readMOV(Off, false);    // read MOVW operand
+  uint16_t ImmT = readMOV(Off + 4, true); // read MOVT operand
   uint32_t Imm = ImmW | (ImmT << 16);
   V += Imm;                         // add the immediate offset
   applyMOV(Off, V);           // set MOVW operand

Added: lld/trunk/test/COFF/broken-arm-reloc.yaml
URL: http://llvm.org/viewvc/llvm-project/lld/trunk/test/COFF/broken-arm-reloc.yaml?rev=340715&view=auto
==============================================================================
--- lld/trunk/test/COFF/broken-arm-reloc.yaml (added)
+++ lld/trunk/test/COFF/broken-arm-reloc.yaml Sun Aug 26 23:04:36 2018
@@ -0,0 +1,92 @@
+# REQUIRES: arm
+
+#    .global main
+#    .global variable
+#    .text
+#    .thumb
+#main:
+#    movw r0, :lower16:variable
+#    nop
+#    movt r0, :upper16:variable
+#    ldr  r0, [r0]
+#    bx   lr
+#    .data
+#variable:
+#    .long 42
+
+# RUN: yaml2obj %s > %t.obj
+# RUN: not lld-link -out:%t.exe -entry:main %t.obj 2>&1 | FileCheck %s
+
+# CHECK: error: unexpected instruction in MOVT instruction in MOV32T relocation
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_ARMNT
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     40F2000000BFC0F2000000687047
+    Relocations:
+      - VirtualAddress:  0
+        SymbolName:      variable
+        Type:            IMAGE_REL_ARM_MOV32T
+  - Name:            .data
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_MEM_READ, IMAGE_SCN_MEM_WRITE ]
+    Alignment:       4
+    SectionData:     2A000000
+  - Name:            .bss
+    Characteristics: [ IMAGE_SCN_CNT_UNINITIALIZED_DATA, IMAGE_SCN_MEM_READ, IMAGE_SCN_MEM_WRITE ]
+    Alignment:       4
+    SectionData:     ''
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          14
+      NumberOfRelocations: 1
+      NumberOfLinenumbers: 0
+      CheckSum:        2762100735
+      Number:          1
+  - Name:            .data
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          4
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        3482275674
+      Number:          2
+  - Name:            .bss
+    Value:           0
+    SectionNumber:   3
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          0
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        0
+      Number:          3
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            variable
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...