[ELF][AArch64] Improve error message for unknown relocations

[MaskRay]

Summary

Like rLLD354040.

Previously, for unrecognized relocation types, in -no-pie/-pie mode, we got something like:

foo.o: unrecognized relocation ...

In -shared mode:

error: can't create dynamic relocation ... against symbol: yyy in readonly segment

[grimar]

How about adding a test case? See test\ELF\invalid\invalid-relocation-x64.test for example.

[peter.smith]

Looks good to me. George's suggestion for a test is a good one. From a brief look some of the other targets also return R_ABS by default from getRelExpr, such as ARM, PPC, PPC64, Hexagon, MSP430, AVR. I don't think it is worth applying this method universally to all of them, but it may be worth ARM, PPC and PPC64. When this goes in I'd be happy to submit a similar patch for ARM.

[MaskRay]

Add ELF\invalid\invalid-relocation-aarch64.test

[MaskRay]

Clarify.

error: can't create dynamic relocation ... against symbol:

was in -shared mode

[grimar]

LGTM. 2 nits are below.

test/ELF/invalid/invalid-relocation-aarch64.test

4

Why do you need --defsym=foo=0?

12

I think you do not need "OSABI".

[MaskRay]

Delete OSABI

Add Section: .text and delete --defsym=foo=0

ELF/Arch/AArch64.cpp

AArch64::AArch64() {
   defaultImageBase = 0x200000;
 
   needsThunks = true;
 }
 
 RelExpr AArch64::getRelExpr(RelType type, const Symbol &s,
                             const uint8_t *loc) const {
   switch (type) {
+  case R_AARCH64_ABS16:
+  case R_AARCH64_ABS32:
+  case R_AARCH64_ABS64:
+  case R_AARCH64_ADD_ABS_LO12_NC:
+  case R_AARCH64_LDST128_ABS_LO12_NC:
+  case R_AARCH64_LDST16_ABS_LO12_NC:
+  case R_AARCH64_LDST32_ABS_LO12_NC:
+  case R_AARCH64_LDST64_ABS_LO12_NC:
+  case R_AARCH64_LDST8_ABS_LO12_NC:
+  case R_AARCH64_MOVW_SABS_G0:
+  case R_AARCH64_MOVW_SABS_G1:
+  case R_AARCH64_MOVW_SABS_G2:
+  case R_AARCH64_MOVW_UABS_G0:
+  case R_AARCH64_MOVW_UABS_G0_NC:
+  case R_AARCH64_MOVW_UABS_G1:
+  case R_AARCH64_MOVW_UABS_G1_NC:
+  case R_AARCH64_MOVW_UABS_G2:
+  case R_AARCH64_MOVW_UABS_G2_NC:
+  case R_AARCH64_MOVW_UABS_G3:
+    return R_ABS;
   case R_AARCH64_TLSDESC_ADR_PAGE21:
     return R_AARCH64_TLSDESC_PAGE;
   case R_AARCH64_TLSDESC_LD64_LO12:
   case R_AARCH64_TLSDESC_ADD_LO12:
     return R_TLSDESC;
   case R_AARCH64_TLSDESC_CALL:
     return R_TLSDESC_CALL;
   case R_AARCH64_TLSLE_ADD_TPREL_HI12:
RelExpr AArch64::getRelExpr(RelType type, const Symbol &s,
   case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
     return R_GOT;
   case R_AARCH64_ADR_GOT_PAGE:
   case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
     return R_AARCH64_GOT_PAGE_PC;
   case R_AARCH64_NONE:
     return R_NONE;
   default:
-    return R_ABS;
+    error(getErrorLocation(loc) + "unknown relocation (" + Twine(type) +
+          ") against symbol " + toString(s));
+    return R_NONE;
   }
 }
 
 RelExpr AArch64::adjustRelaxExpr(RelType type, const uint8_t *data,
                                  RelExpr expr) const {
   if (expr == R_RELAX_TLS_GD_TO_IE) {
     if (type == R_AARCH64_TLSDESC_ADR_PAGE21)
       return R_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC;
case R_AARCH64_TLSLE_ADD_TPREL_HI12:
     checkUInt(loc, val, 24, type);
     or32AArch64Imm(loc, val >> 12);
     break;
   case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
   case R_AARCH64_TLSDESC_ADD_LO12:
     or32AArch64Imm(loc, val);
     break;
   default:
-    error(getErrorLocation(loc) + "unrecognized relocation " + toString(type));
+    llvm_unreachable("unknown relocation");
   }
 }
 
 void AArch64::relaxTlsGdToLe(uint8_t *loc, RelType type, uint64_t val) const {
   // TLSDESC Global-Dynamic relocation are in the form:
   //   adrp    x0, :tlsdesc:v             [R_AARCH64_TLSDESC_ADR_PAGE21]
   //   ldr     x1, [x0, #:tlsdesc_lo12:v  [R_AARCH64_TLSDESC_LD64_LO12]
   //   add     x0, x0, :tlsdesc_los:v     [R_AARCH64_TLSDESC_ADD_LO12]

test/ELF/invalid/invalid-relocation-aarch64.test

+# REQUIRES: aarch64
+# RUN: yaml2obj %s -o %t.o
+# RUN: not ld.lld %t.o --defsym=foo=0 -o /dev/null 2>&1 | FileCheck %s
+# CHECK: error: unknown relocation (1024) against symbol foo
+# CHECK: error: unknown relocation (1025) against symbol foo
+
+!ELF
+FileHeader:
+  Class:           ELFCLASS64
+  Data:            ELFDATA2LSB
+  OSABI:           ELFOSABI_FREEBSD
+  Type:            ET_REL
+  Machine:         EM_AARCH64
+Sections:
+  - Name:            .text
+    Type:            SHT_PROGBITS
+    Flags:           [ SHF_ALLOC ]
+  - Name:            .rela.text
+    Type:            SHT_RELA
+    Link:            .symtab
+    Info:            .text
+    Relocations:
+      - Offset:          0x0000000000000000
+        Symbol:          foo
+        Type:            0x400
+      - Offset:          0x0000000000000000
+        Symbol:          foo
+        Type:            0x401
+Symbols:
+  - Name:            foo
+    Binding:         STB_GLOBAL