[PAC][lld][AArch64][ELF] Support signed TLSDESC

Support `R_AARCH64_AUTH_TLSDESC_ADR_PAGE21`, `R_AARCH64_AUTH_TLSDESC_LD64_LO12`
and `R_AARCH64_AUTH_TLSDESC_LD64_LO12` static TLSDESC relocations.

lld/ELF/Arch/AArch64.cpp

@@ -124,9 +124,14 @@ RelExpr AArch64::getRelExpr(RelType type, const Symbol &s,
     return R_AARCH64_AUTH;
   case R_AARCH64_TLSDESC_ADR_PAGE21:
     return R_AARCH64_TLSDESC_PAGE;
+  case R_AARCH64_AUTH_TLSDESC_ADR_PAGE21:
+    return R_AARCH64_AUTH_TLSDESC_PAGE;
   case R_AARCH64_TLSDESC_LD64_LO12:
   case R_AARCH64_TLSDESC_ADD_LO12:
     return R_TLSDESC;
+  case R_AARCH64_AUTH_TLSDESC_LD64_LO12:
+  case R_AARCH64_AUTH_TLSDESC_ADD_LO12:
+    return RelExpr::R_AARCH64_AUTH_TLSDESC;
   case R_AARCH64_TLSDESC_CALL:
     return R_TLSDESC_CALL;
   case R_AARCH64_TLSLE_ADD_TPREL_HI12:
@@ -446,6 +451,7 @@ void AArch64::relocate(uint8_t *loc, const Relocation &rel,
   case R_AARCH64_ADR_PREL_PG_HI21:
   case R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21:
   case R_AARCH64_TLSDESC_ADR_PAGE21:
+  case R_AARCH64_AUTH_TLSDESC_ADR_PAGE21:
     checkInt(loc, val, 33, rel);
     [[fallthrough]];
   case R_AARCH64_ADR_PREL_PG_HI21_NC:
@@ -497,6 +503,7 @@ void AArch64::relocate(uint8_t *loc, const Relocation &rel,
   case R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC:
   case R_AARCH64_TLSLE_LDST64_TPREL_LO12_NC:
   case R_AARCH64_TLSDESC_LD64_LO12:
+  case R_AARCH64_AUTH_TLSDESC_LD64_LO12:
     checkAlignment(loc, val, 8, rel);
     or32AArch64Imm(loc, getBits(val, 3, 11));
     break;
@@ -569,6 +576,7 @@ void AArch64::relocate(uint8_t *loc, const Relocation &rel,
     break;
   case R_AARCH64_TLSLE_ADD_TPREL_LO12_NC:
   case R_AARCH64_TLSDESC_ADD_LO12:
+  case R_AARCH64_AUTH_TLSDESC_ADD_LO12:
     or32AArch64Imm(loc, val);
     break;
   case R_AARCH64_TLSDESC:

lld/ELF/InputSection.cpp

@@ -870,12 +870,14 @@ uint64_t InputSectionBase::getRelocTargetVA(const InputFile *file, RelType type,
   case R_SIZE:
     return sym.getSize() + a;
   case R_TLSDESC:
+  case RelExpr::R_AARCH64_AUTH_TLSDESC:
     return in.got->getTlsDescAddr(sym) + a;
   case R_TLSDESC_PC:
     return in.got->getTlsDescAddr(sym) + a - p;
   case R_TLSDESC_GOTPLT:
     return in.got->getTlsDescAddr(sym) + a - in.gotPlt->getVA();
   case R_AARCH64_TLSDESC_PAGE:
+  case R_AARCH64_AUTH_TLSDESC_PAGE:
     return getAArch64Page(in.got->getTlsDescAddr(sym) + a) - getAArch64Page(p);
   case R_TLSGD_GOT:
     return in.got->getGlobalDynOffset(sym) + a;

lld/ELF/Relocations.cpp

@@ -1324,14 +1324,25 @@ static unsigned handleTlsRelocation(RelType type, Symbol &sym,
     return handleMipsTlsRelocation(type, sym, c, offset, addend, expr);
   bool isRISCV = config->emachine == EM_RISCV;
 
-  if (oneof<R_AARCH64_TLSDESC_PAGE, R_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC,
+  if (oneof<R_AARCH64_TLSDESC_PAGE, R_AARCH64_AUTH_TLSDESC_PAGE, R_TLSDESC,
+            RelExpr::R_AARCH64_AUTH_TLSDESC, R_TLSDESC_CALL, R_TLSDESC_PC,
             R_TLSDESC_GOTPLT>(expr) &&
       config->shared) {
     // R_RISCV_TLSDESC_{LOAD_LO12,ADD_LO12_I,CALL} reference a label. Do not
     // set NEEDS_TLSDESC on the label.
     if (expr != R_TLSDESC_CALL) {
-      if (!isRISCV || type == R_RISCV_TLSDESC_HI20)
-        sym.setFlags(NEEDS_TLSDESC);
+      bool needsTlsDescAuth =
+          (expr == R_AARCH64_AUTH_TLSDESC_PAGE || expr == RelExpr::R_AARCH64_AUTH_TLSDESC);
+      if (!sym.hasFlag(NEEDS_TLSDESC)) {
+        if (!isRISCV || type == R_RISCV_TLSDESC_HI20)
+          sym.setFlags(NEEDS_TLSDESC);
+        if (needsTlsDescAuth)
+          sym.setFlags(NEEDS_TLSDESC_AUTH);
+      } else if (needsTlsDescAuth != sym.hasFlag(NEEDS_TLSDESC_AUTH)) {
+        fatal("both AUTH and non-AUTH TLSDESC entries for '" + sym.getName() +
+              "' requested, but only one type of TLSDESC entry per symbol is "
+              "supported");
+      }
       c.addReloc({expr, type, offset, addend, &sym});
     }
     return 1;
@@ -1788,9 +1799,13 @@ void elf::postScanRelocations() {
 
     if (flags & NEEDS_TLSDESC) {
       got->addTlsDescEntry(sym);
+      RelType tlsDescRel = target->tlsDescRel;
+      if (flags & NEEDS_TLSDESC_AUTH) {
+        assert(config->emachine == EM_AARCH64);
+        tlsDescRel = ELF::R_AARCH64_AUTH_TLSDESC;
+      }
       mainPart->relaDyn->addAddendOnlyRelocIfNonPreemptible(
-          target->tlsDescRel, *got, got->getTlsDescOffset(sym), sym,
-          target->tlsDescRel);
+          tlsDescRel, *got, got->getTlsDescOffset(sym), sym, tlsDescRel);
     }
     if (flags & NEEDS_TLSGD) {
       got->addDynTlsEntry(sym);

lld/ELF/Relocations.h

@@ -90,6 +90,10 @@ enum RelExpr {
   R_AARCH64_PAGE_PC,
   R_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC,
   R_AARCH64_TLSDESC_PAGE,
+  R_AARCH64_AUTH_TLSDESC_PAGE,
+  // TODO: maybe it's better to rename this expression
+  // to avoid name conflict with dynamic reloc
+  R_AARCH64_AUTH_TLSDESC,
   R_AARCH64_AUTH,
   R_ARM_PCA,
   R_ARM_SBREL,

lld/ELF/Symbols.h

@@ -55,6 +55,7 @@ enum {
   NEEDS_GOT_DTPREL = 1 << 7,
   NEEDS_TLSIE = 1 << 8,
   NEEDS_GOT_AUTH = 1 << 9,
+  NEEDS_TLSDESC_AUTH = 1 << 10,
 };
 
 // Some index properties of a symbol are stored separately in this auxiliary

lld/ELF/SyntheticSections.cpp

@@ -665,6 +665,11 @@ bool GotSection::addTlsDescEntry(const Symbol &sym) {
   assert(sym.auxIdx == symAux.size() - 1);
   symAux.back().tlsDescIdx = numEntries;
   numEntries += 2;
+  if (sym.hasFlag(NEEDS_TLSDESC_AUTH)) {
+    assert(config->emachine == EM_AARCH64);
+    authEntries.push_back({(numEntries - 2) * config->wordsize, true});
+    authEntries.push_back({(numEntries - 1) * config->wordsize, false});
+  }
   return true;
 }
 

lld/test/ELF/aarch64-tlsdesc-auth.s

@@ -0,0 +1,106 @@
+// REQUIRES: aarch64
+// RUN: rm -rf %t && split-file %s %t && cd %t
+
+//--- ok.s
+
+// RUN: llvm-mc -filetype=obj -triple=aarch64-pc-linux -mattr=+pauth ok.s -o ok.o
+// RUN: ld.lld --hash-style=sysv -shared ok.o -o ok.so
+// RUN: llvm-objdump --no-print-imm-hex -d --no-show-raw-insn ok.so | FileCheck %s
+// RUN: llvm-readobj -r -x .got ok.so | FileCheck --check-prefix=REL %s
+
+        .text
+        adrp    x0, :tlsdesc_auth:a
+        ldr     x16, [x0, :tlsdesc_auth_lo12:a]
+        add     x0, x0, :tlsdesc_auth_lo12:a
+        autia   x16, x0
+        .tlsdesccall a
+        blr     x16
+
+// CHECK:      10298: adrp    x0, 0x20000
+// CHECK-NEXT: 1029c: ldr     x16, [x0, #872]
+// CHECK-NEXT: 102a0: add     x0, x0, #872
+// CHECK-NEXT: 102a4: autia   x16, x0
+// CHECK-NEXT: 102a8: blr     x16
+
+// Create relocation against local TLS symbols where linker should
+// create target specific dynamic TLSDESC relocation where addend is
+// the symbol VMA in tls block.
+
+        adrp    x0, :tlsdesc_auth:local1
+        ldr     x16, [x0, :tlsdesc_auth_lo12:local1]
+        add     x0, x0, :tlsdesc_auth_lo12:local1
+        autia   x16, x0
+        .tlsdesccall a
+        blr     x16
+
+// CHECK:      102ac: adrp    x0, 0x20000
+// CHECK-NEXT: 102b0: ldr     x16, [x0, #888]
+// CHECK-NEXT: 102b4: add     x0, x0, #888
+// CHECK-NEXT: 102b8: autia   x16, x0
+// CHECK-NEXT: 102bc: blr     x16
+
+        adrp    x0, :tlsdesc_auth:local2
+        ldr     x16, [x0, :tlsdesc_auth_lo12:local2]
+        add     x0, x0, :tlsdesc_auth_lo12:local2
+        autia   x16, x0
+        .tlsdesccall a
+        blr     x16
+
+// CHECK:      102c0: adrp    x0, 0x20000
+// CHECK-NEXT: 102c4: ldr     x16, [x0, #904]
+// CHECK-NEXT: 102c8: add     x0, x0, #904
+// CHECK-NEXT: 102cc: autia   x16, x0
+// CHECK-NEXT: 102d0: blr     x16
+
+        .section .tbss,"awT",@nobits
+        .type   local1,@object
+        .p2align 2
+local1:
+        .word   0
+        .size   local1, 4
+
+        .type   local2,@object
+        .p2align 3
+local2:
+        .xword  0
+        .size   local2, 8
+
+
+// R_AARCH64_AUTH_TLSDESC - 0x0 -> start of tls block
+// R_AARCH64_AUTH_TLSDESC - 0x8 -> align (sizeof (local1), 8)
+
+// REL:      Relocations [
+// REL-NEXT:   Section (4) .rela.dyn {
+// REL-NEXT:     0x20378 R_AARCH64_AUTH_TLSDESC - 0x0
+// REL-NEXT:     0x20388 R_AARCH64_AUTH_TLSDESC - 0x8
+// REL-NEXT:     0x20368 R_AARCH64_AUTH_TLSDESC a 0x0
+// REL-NEXT:   }
+// REL-NEXT: ]
+
+// REL:      Hex dump of section '.got':
+// REL-NEXT: 0x00020368 00000000 00000080 00000000 000000a0
+// REL-NEXT: 0x00020378 00000000 00000080 00000000 000000a0
+// REL-NEXT: 0x00020388 00000000 00000080 00000000 000000a0
+//                                     ^^
+//                                     0b10000000 bit 63 address diversity = true, bits 61..60 key = IA
+//                                                       ^^
+//                                                       0b10100000 bit 63 address diversity = true, bits 61..60 key = DA
+
+//--- err.s
+
+// RUN: llvm-mc -filetype=obj -triple=aarch64-pc-linux -mattr=+pauth err.s -o err.o
+// RUN: not ld.lld --hash-style=sysv -shared err.o -o err.so 2>&1 | FileCheck --check-prefix=ERR %s
+// ERR: error: both AUTH and non-AUTH TLSDESC entries for 'a' requested, but only one type of TLSDESC entry per symbol is supported
+        .text
+        adrp    x0, :tlsdesc_auth:a
+        ldr     x16, [x0, :tlsdesc_auth_lo12:a]
+        add     x0, x0, :tlsdesc_auth_lo12:a
+        autia   x16, x0
+        .tlsdesccall a
+        blr     x16
+
+        adrp    x0, :tlsdesc:a
+        ldr     x1, [x0, :tlsdesc_lo12:a]
+        add     x0, x0, :tlsdesc_lo12:a
+        .tlsdesccall a
+        blr     x1