[llvm] 216b67e - AArch64: diagnose out of range relocation addends on MachO.

[Tim Northover via llvm-commits]

Author: Tim Northover
Date: 2020-07-27T13:01:22+01:00
New Revision: 216b67e2023315ff30c2802c911a8ae0c7640c30

URL: https://github.com/llvm/llvm-project/commit/216b67e2023315ff30c2802c911a8ae0c7640c30
DIFF: https://github.com/llvm/llvm-project/commit/216b67e2023315ff30c2802c911a8ae0c7640c30.diff

LOG: AArch64: diagnose out of range relocation addends on MachO.

MachO only has 24-bit addends for most relocations, small enough that it can
overflow in semi-reasonable functions and cause insidious bugs if compiled
without assertions enabled. Switch it to an actual error instead.

The condition isn't quite identical because ld64 treats the addend as a signed
number.

Added: 
    llvm/test/MC/AArch64/macho-addend-range.s

Modified: 
    llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
index b0f414bd27ed..012661edbbfd 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MachObjectWriter.cpp
@@ -373,7 +373,11 @@ void AArch64MachObjectWriter::recordRelocation(
        Type == MachO::ARM64_RELOC_PAGE21 ||
        Type == MachO::ARM64_RELOC_PAGEOFF12) &&
       Value) {
-    assert((Value & 0xff000000) == 0 && "Added relocation out of range!");
+    if (!isInt<24>(Value)) {
+      Asm.getContext().reportError(Fixup.getLoc(),
+                                   "addend too big for relocation");
+      return;
+    }
 
     MachO::any_relocation_info MRE;
     MRE.r_word0 = FixupOffset;

diff  --git a/llvm/test/MC/AArch64/macho-addend-range.s b/llvm/test/MC/AArch64/macho-addend-range.s
new file mode 100644
index 000000000000..fdcb9123c768
--- /dev/null
+++ b/llvm/test/MC/AArch64/macho-addend-range.s
@@ -0,0 +1,14 @@
+// RUN: not llvm-mc -triple arm64-apple-ios -filetype=obj -o /dev/null %s 2>&1 | FileCheck %s
+        .global _foo
+        adrp x0, (_foo + 1)@PAGE
+        adrp x0, (_foo - 1)@PAGE
+        adrp x0, (_foo + 0x7fffff)@PAGE
+        adrp x0, (_foo - 0x800000)@PAGE
+
+        // CHECK-NOT: error:
+        // CHECK: error: addend too big for relocation
+        // CHECK:      adrp x0, (_foo + 0x800000)@PAGE
+        // CHECK: error: addend too big for relocation
+        // CHECK:      adrp x0, (_foo - 0x800001)@PAGE
+        adrp x0, (_foo + 0x800000)@PAGE
+        adrp x0, (_foo - 0x800001)@PAGE