[PAC][ELF] Support R_AARCH64_AUTH_TLSDESC_CALL relocation

llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp

@@ -3600,13 +3600,15 @@ void AArch64AsmPrinter::emitInstruction(const MachineInstr *MI) {
     ///    adrp  x0, :tlsdesc_auth:var
     ///    ldr   x16, [x0, #:tlsdesc_auth_lo12:var]
     ///    add   x0, x0, #:tlsdesc_auth_lo12:var
+    ///    .tlsauthdesccall var
     ///    blraa x16, x0
     ///    (TPIDR_EL0 offset now in x0)
     const MachineOperand &MO_Sym = MI->getOperand(0);
     MachineOperand MO_TLSDESC_LO12(MO_Sym), MO_TLSDESC(MO_Sym);
-    MCOperand SymTLSDescLo12, SymTLSDesc;
+    MCOperand Sym, SymTLSDescLo12, SymTLSDesc;
     MO_TLSDESC_LO12.setTargetFlags(AArch64II::MO_TLS | AArch64II::MO_PAGEOFF);
     MO_TLSDESC.setTargetFlags(AArch64II::MO_TLS | AArch64II::MO_PAGE);
+    MCInstLowering.lowerOperand(MO_Sym, Sym);
     MCInstLowering.lowerOperand(MO_TLSDESC_LO12, SymTLSDescLo12);
     MCInstLowering.lowerOperand(MO_TLSDESC, SymTLSDesc);
 
@@ -3632,8 +3634,15 @@ void AArch64AsmPrinter::emitInstruction(const MachineInstr *MI) {
     Add.addOperand(MCOperand::createImm(AArch64_AM::getShiftValue(0)));
     EmitToStreamer(*OutStreamer, Add);
 
-    // Authenticated TLSDESC accesses are not relaxed.
-    // Thus, do not emit .tlsdesccall for AUTH TLSDESC.
+    // Emit a relocation-annotation. This expands to no code, but requests
+    // the following instruction gets an R_AARCH64_AUTH_TLSDESC_CALL.
+    MCInst TLSAuthDescCall;
+    TLSAuthDescCall.setOpcode(AArch64::TLSAUTHDESCCALL);
+    TLSAuthDescCall.addOperand(Sym);
+    EmitToStreamer(*OutStreamer, TLSAuthDescCall);
+#ifndef NDEBUG
+    --InstsEmitted; // no code emitted
+#endif
 
     MCInst Blraa;
     Blraa.setOpcode(AArch64::BLRAA);

llvm/lib/Target/AArch64/AArch64InstrInfo.td

@@ -3773,6 +3773,14 @@ def TLSDESCCALL : Pseudo<(outs), (ins i64imm:$sym), []>, Sched<[]> {
   let AsmString = ".tlsdesccall $sym";
 }
 
+// This is a directive-like pseudo-instruction. The purpose is to insert an
+// R_AARCH64_AUTH_TLSDESC_CALL relocation at the offset of the following instruction
+// (which in the usual case is a BLRAA).
+let hasSideEffects = 1 in
+def TLSAUTHDESCCALL : Pseudo<(outs), (ins i64imm:$sym), []>, Sched<[]> {
+  let AsmString = ".tlsauthdesccall $sym";
+}
+
 // Pseudo instruction to tell the streamer to emit a 'B' character into the
 // augmentation string.
 def EMITBKEY : Pseudo<(outs), (ins), []>, Sched<[]> {}

llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp

@@ -191,7 +191,7 @@ class AArch64AsmParser : public MCTargetAsmParser {
   bool parseDirectiveCPU(SMLoc L);
   bool parseDirectiveInst(SMLoc L);
 
-  bool parseDirectiveTLSDescCall(SMLoc L);
+  bool parseDirectiveTLSDescCall(SMLoc L, bool IsAuth);
 
   bool parseDirectiveLOH(StringRef LOH, SMLoc L);
   bool parseDirectiveLtorg(SMLoc L);
@@ -7074,7 +7074,9 @@ bool AArch64AsmParser::ParseDirective(AsmToken DirectiveID) {
   else if (IDVal == ".cpu")
     parseDirectiveCPU(Loc);
   else if (IDVal == ".tlsdesccall")
-    parseDirectiveTLSDescCall(Loc);
+    parseDirectiveTLSDescCall(Loc, /*IsAuth=*/false);
+  else if (IDVal == ".tlsauthdesccall")
+    parseDirectiveTLSDescCall(Loc, /*IsAuth=*/true);
   else if (IDVal == ".ltorg" || IDVal == ".pool")
     parseDirectiveLtorg(Loc);
   else if (IDVal == ".unreq")
@@ -7399,19 +7401,22 @@ bool AArch64AsmParser::parseDirectiveInst(SMLoc Loc) {
 }
 
 // parseDirectiveTLSDescCall:
-//   ::= .tlsdesccall symbol
-bool AArch64AsmParser::parseDirectiveTLSDescCall(SMLoc L) {
+//   ::= .tlsdesccall symbol (if IsAuth is false)
+//   ::= .tlsauthdesccall symbol (if IsAuth is true)
+bool AArch64AsmParser::parseDirectiveTLSDescCall(SMLoc L, bool IsAuth) {
   StringRef Name;
   if (check(getParser().parseIdentifier(Name), L, "expected symbol") ||
       parseToken(AsmToken::EndOfStatement))
     return true;
 
   MCSymbol *Sym = getContext().getOrCreateSymbol(Name);
   const MCExpr *Expr = MCSymbolRefExpr::create(Sym, getContext());
-  Expr = MCSpecifierExpr::create(Expr, AArch64::S_TLSDESC, getContext());
+  Expr = MCSpecifierExpr::create(
+      Expr, IsAuth ? AArch64::S_TLSDESC_AUTH : AArch64::S_TLSDESC,
+      getContext());
 
   MCInst Inst;
-  Inst.setOpcode(AArch64::TLSDESCCALL);
+  Inst.setOpcode(IsAuth ? AArch64::TLSAUTHDESCCALL : AArch64::TLSDESCCALL);
   Inst.addOperand(MCOperand::createExpr(Expr));
 
   getParser().getStreamer().emitInstruction(Inst, getSTI());

llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp

@@ -738,6 +738,15 @@ void AArch64MCCodeEmitter::encodeInstruction(const MCInst &MI,
     return;
   }
 
+  if (MI.getOpcode() == AArch64::TLSAUTHDESCCALL) {
+    // This is a directive which applies an R_AARCH64_AUTH_TLSDESC_CALL to the
+    // following (BLRAA) instruction. It doesn't emit any code itself so it
+    // doesn't go through the normal TableGenerated channels.
+    addFixup(Fixups, 0, MI.getOperand(0).getExpr(),
+             ELF::R_AARCH64_AUTH_TLSDESC_CALL);
+    return;
+  }
+
   if (MI.getOpcode() == AArch64::SPACE) {
     // SPACE just increases basic block size, in both cases no actual code.
     return;

llvm/test/CodeGen/AArch64/ptrauth-arm64-tls-dynamics.ll

@@ -18,14 +18,15 @@ define i32 @test_generaldynamic() {
 ; CHECK: adrp x[[TLSDESC_HI:[0-9]+]], :tlsdesc_auth:general_dynamic_var
 ; CHECK-NEXT: ldr x16, [x[[TLSDESC_HI]], :tlsdesc_auth_lo12:general_dynamic_var]
 ; CHECK-NEXT: add x0, x[[TLSDESC_HI]], :tlsdesc_auth_lo12:general_dynamic_var
+; CHECK-NEXT: .tlsauthdesccall general_dynamic_var
 ; CHECK-NEXT: blraa x16, x0
 ; CHECK-NEXT: mrs x[[TPIDR:[0-9]+]], TPIDR_EL0
 ; CHECK-NEXT: ldr w0, [x[[TPIDR]], x0]
 
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADR_PAGE21
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_LD64_LO12
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADD_LO12
-; CHECK-OBJ-NOT: R_AARCH64_TLSDESC_CALL
+; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_CALL
 }
 
 define ptr @test_generaldynamic_addr() {
@@ -36,14 +37,15 @@ define ptr @test_generaldynamic_addr() {
 ; CHECK: adrp x[[TLSDESC_HI:[0-9]+]], :tlsdesc_auth:general_dynamic_var
 ; CHECK-NEXT: ldr x16, [x[[TLSDESC_HI]], :tlsdesc_auth_lo12:general_dynamic_var]
 ; CHECK-NEXT: add x0, x[[TLSDESC_HI]], :tlsdesc_auth_lo12:general_dynamic_var
+; CHECK-NEXT: .tlsauthdesccall general_dynamic_var
 ; CHECK-NEXT: blraa x16, x0
 ; CHECK-NEXT: mrs [[TP:x[0-9]+]], TPIDR_EL0
 ; CHECK-NEXT: add x0, [[TP]], x0
 
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADR_PAGE21
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_LD64_LO12
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADD_LO12
-; CHECK-OBJ-NOT: R_AARCH64_TLSDESC_CALL
+; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_CALL
 }
 
 ;; Note: with signed TLSDESC, general dynamic model is always used,
@@ -60,14 +62,15 @@ define i32 @test_localdynamic() {
 ; CHECK: adrp x[[TLSDESC_HI:[0-9]+]], :tlsdesc_auth:local_dynamic_var
 ; CHECK-NEXT: ldr x16, [x[[TLSDESC_HI]], :tlsdesc_auth_lo12:local_dynamic_var]
 ; CHECK-NEXT: add x0, x[[TLSDESC_HI]], :tlsdesc_auth_lo12:local_dynamic_var
+; CHECK-NEXT: .tlsauthdesccall local_dynamic_var
 ; CHECK-NEXT: blraa x16, x0
 ; CHECK-NEXT: mrs x[[TPIDR:[0-9]+]], TPIDR_EL0
 ; CHECK-NEXT: ldr w0, [x[[TPIDR]], x0]
 
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADR_PAGE21
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_LD64_LO12
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADD_LO12
-; CHECK-OBJ-NOT: R_AARCH64_TLSDESC_CALL
+; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_CALL
 }
 
 define ptr @test_localdynamic_addr() {
@@ -78,14 +81,15 @@ define ptr @test_localdynamic_addr() {
 ; CHECK: adrp x[[TLSDESC_HI:[0-9]+]], :tlsdesc_auth:local_dynamic_var
 ; CHECK-NEXT: ldr x16, [x[[TLSDESC_HI]], :tlsdesc_auth_lo12:local_dynamic_var]
 ; CHECK-NEXT: add x0, x[[TLSDESC_HI]], :tlsdesc_auth_lo12:local_dynamic_var
+; CHECK-NEXT: .tlsauthdesccall local_dynamic_var
 ; CHECK-NEXT: blraa x16, x0
 ; CHECK-NEXT: mrs x[[TPIDR:[0-9]+]], TPIDR_EL0
 ; CHECK-NEXT: add x0, x[[TPIDR]], x0
 
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADR_PAGE21
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_LD64_LO12
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADD_LO12
-; CHECK-OBJ-NOT: R_AARCH64_TLSDESC_CALL
+; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_CALL
 }
 
 @extern_weak_var = extern_weak thread_local global i32
@@ -99,14 +103,15 @@ define i32 @test_extern_weak() {
 ; CHECK: adrp x[[TLSDESC_HI:[0-9]+]], :tlsdesc_auth:extern_weak_var
 ; CHECK-NEXT: ldr x16, [x[[TLSDESC_HI]], :tlsdesc_auth_lo12:extern_weak_var]
 ; CHECK-NEXT: add x0, x[[TLSDESC_HI]], :tlsdesc_auth_lo12:extern_weak_var
+; CHECK-NEXT: .tlsauthdesccall extern_weak_var
 ; CHECK-NEXT: blraa x16, x0
 ; CHECK-NEXT: mrs x[[TPIDR:[0-9]+]], TPIDR_EL0
 ; CHECK-NEXT: ldr w0, [x[[TPIDR]], x0]
 
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADR_PAGE21
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_LD64_LO12
 ; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_ADD_LO12
-; CHECK-OBJ-NOT: R_AARCH64_TLSDESC_CALL
+; CHECK-OBJ: R_AARCH64_AUTH_TLSDESC_CALL
 ; CHECK-OBJ: 0000000000000000     0 TLS     WEAK   DEFAULT   UND extern_weak_var
 }
 

llvm/test/MC/AArch64/directives-case_insensitive.s

@@ -46,5 +46,8 @@ fred .REQ x5
 .TLSDESCCALL var
 // CHECK: .tlsdesccall var
 
+.TLSAUTHDESCCALL var
+// CHECK: .tlsauthdesccall var
+
 .LTORG
 .POOL

llvm/test/MC/AArch64/tls-auth-relocs.s

@@ -0,0 +1,32 @@
+// RUN: llvm-mc -triple=aarch64-none-linux-gnu -mattr=+pauth -show-encoding %s | FileCheck %s
+// RUN: llvm-mc -triple=aarch64-none-linux-gnu -mattr=+pauth -filetype=obj %s -o - | \
+// RUN:   llvm-readelf -r -s - | FileCheck --check-prefix=CHECK-ELF %s
+
+adrp x8, :tlsdesc_auth:var
+ldr x7, [x6, :tlsdesc_auth_lo12:var]
+add x5, x4, #:tlsdesc_auth_lo12:var
+.tlsauthdesccall var
+blraa x3, x2
+
+// CHECK:      adrp   x8, :tlsdesc_auth:var            // encoding: [0x08'A',A,A,0x90'A']
+// CHECK-NEXT:                                         // fixup A - offset: 0, value: :tlsdesc_auth:var, kind: fixup_aarch64_pcrel_adrp_imm21
+// CHECK:      ldr    x7, [x6, :tlsdesc_auth_lo12:var] // encoding: [0xc7,0bAAAAAA00,0b01AAAAAA,0xf9]
+// CHECK-NEXT:                                         // fixup A - offset: 0, value: :tlsdesc_auth_lo12:var, kind: fixup_aarch64_ldst_imm12_scale8
+// CHECK:      add    x5, x4, :tlsdesc_auth_lo12:var   // encoding: [0x85,0bAAAAAA00,0b00AAAAAA,0x91]
+// CHECK-NEXT:                                         // fixup A - offset: 0, value: :tlsdesc_auth_lo12:var, kind: fixup_aarch64_add_imm12
+// CHECK:      .tlsauthdesccall var                    // encoding: []
+// CHECK-NEXT:                                         // fixup A - offset: 0, value: var, relocation type: 598
+// CHECK:      blraa  x3, x2                           // encoding: [0x62,0x08,0x3f,0xd7]
+
+// CHECK-ELF:      Relocation section '.rela.text' at offset 0x98 contains 4 entries:
+// CHECK-ELF-NEXT: Offset           Info             Type                              Symbol's Value   Symbol's Name + Addend
+// CHECK-ELF-NEXT: 0000000000000000 0000000200000253 R_AARCH64_AUTH_TLSDESC_ADR_PAGE21 0000000000000000 var + 0
+// CHECK-ELF-NEXT: 0000000000000004 0000000200000254 R_AARCH64_AUTH_TLSDESC_LD64_LO12  0000000000000000 var + 0
+// CHECK-ELF-NEXT: 0000000000000008 0000000200000255 R_AARCH64_AUTH_TLSDESC_ADD_LO12   0000000000000000 var + 0
+// CHECK-ELF-NEXT: 000000000000000c 0000000200000256 R_AARCH64_AUTH_TLSDESC_CALL       0000000000000000 var + 0
+
+// Make sure symbol has type STT_TLS:
+
+// CHECK-ELF:      Symbol table '.symtab' contains [[#]] entries:
+// CHECK-ELF-NEXT: Num:   Value            Size Type Bind   Vis     Ndx Name
+// CHECK-ELF:      [[#]]: 0000000000000000 0    TLS  GLOBAL DEFAULT UND var