[PAC][ELF] Support R_AARCH64_AUTH_TLSDESC_CALL relocation#198327
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[PAC][ELF] Support R_AARCH64_AUTH_TLSDESC_CALL relocation#198327kovdan01 wants to merge 2 commits into
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This was referenced May 18, 2026
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We need MC layer tests to show how |
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@MaskRay Just to ensure that we are talking about the same thing - do you mean tests like the following? For non-auth tlsdesc, we have no other MC-level tests except this and directives-case_insensitive.s (which is already covered by this PR) llvm-project/llvm/test/MC/AArch64/tls-relocs.s Lines 377 to 398 in 332c06b |
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@MaskRay Please let me know if a7f0877 addresses your concern and if you have any other comments regarding this PR |
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@llvm/pr-subscribers-llvm-binary-utilities @llvm/pr-subscribers-backend-aarch64 Author: Daniil Kovalev (kovdan01) ChangesThe R_AARCH64_AUTH_TLSDESC_CALL is introduced to allow linker relaxation of AUTH TLSDESC call sequences for non-preemptible undefined weak symbols. The lld patch introducing the relaxation: #194636 Corresponding ARM docs PR: ARM-software/abi-aa#395 Full diff: https://github.com/llvm/llvm-project/pull/198327.diff 8 Files Affected:
diff --git a/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def b/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
index 1cfcdbf67dac5..c8e9e1cd4f644 100644
--- a/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
+++ b/llvm/include/llvm/BinaryFormat/ELFRelocs/AArch64.def
@@ -162,6 +162,7 @@ ELF_RELOC(R_AARCH64_AUTH_GOT_ADR_PREL_LO21, 0x252)
ELF_RELOC(R_AARCH64_AUTH_TLSDESC_ADR_PAGE21, 0x253)
ELF_RELOC(R_AARCH64_AUTH_TLSDESC_LD64_LO12, 0x254)
ELF_RELOC(R_AARCH64_AUTH_TLSDESC_ADD_LO12, 0x255)
+ELF_RELOC(R_AARCH64_AUTH_TLSDESC_CALL, 0x256)
ELF_RELOC(R_AARCH64_AUTH_RELATIVE, 0x411)
ELF_RELOC(R_AARCH64_AUTH_GLOB_DAT, 0x412)
ELF_RELOC(R_AARCH64_AUTH_TLSDESC, 0x413)
diff --git a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
index 4eb475ef606de..35eac377779f7 100644
--- a/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ b/llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -3438,13 +3438,15 @@ 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
+ /// .tlsdescauthcall 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);
@@ -3470,8 +3472,15 @@ 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 TLSDescAuthCall;
+ TLSDescAuthCall.setOpcode(AArch64::TLSDESCAUTHCALL);
+ TLSDescAuthCall.addOperand(Sym);
+ EmitToStreamer(*OutStreamer, TLSDescAuthCall);
+#ifndef NDEBUG
+ --InstsEmitted; // no code emitted
+#endif
MCInst Blraa;
Blraa.setOpcode(AArch64::BLRAA);
diff --git a/llvm/lib/Target/AArch64/AArch64InstrInfo.td b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
index a8ca9f0f39a53..72ca351f6a602 100644
--- a/llvm/lib/Target/AArch64/AArch64InstrInfo.td
+++ b/llvm/lib/Target/AArch64/AArch64InstrInfo.td
@@ -3683,6 +3683,14 @@ def TLSDESCCALL : Pseudo<(outs), (ins i64imm:$sym), []>, Sched<[]> {
let AsmString = ".tlsdesccall $sym";
}
+// This is a directive-like pseudo-instruction. The purpose is to insert an
+// R_AARCH64_AUTH_TLSDESC_CALL relocation at the offset of the following instruction
+// (which in the usual case is a BLRAA).
+let hasSideEffects = 1 in
+def TLSDESCAUTHCALL : Pseudo<(outs), (ins i64imm:$sym), []>, Sched<[]> {
+ let AsmString = ".tlsdescauthcall $sym";
+}
+
// Pseudo instruction to tell the streamer to emit a 'B' character into the
// augmentation string.
def EMITBKEY : Pseudo<(outs), (ins), []>, Sched<[]> {}
diff --git a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp b/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
index 6a6b73b8a4c88..f33d84db7ccec 100644
--- a/llvm/lib/Target/AArch64/AsmParser/AArch64AsmParser.cpp
+++ b/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);
@@ -7271,7 +7271,9 @@ bool AArch64AsmParser::ParseDirective(AsmToken DirectiveID) {
else if (IDVal == ".cpu")
parseDirectiveCPU(Loc);
else if (IDVal == ".tlsdesccall")
- parseDirectiveTLSDescCall(Loc);
+ parseDirectiveTLSDescCall(Loc, /*IsAuth=*/false);
+ else if (IDVal == ".tlsdescauthcall")
+ parseDirectiveTLSDescCall(Loc, /*IsAuth=*/true);
else if (IDVal == ".ltorg" || IDVal == ".pool")
parseDirectiveLtorg(Loc);
else if (IDVal == ".unreq")
@@ -7594,8 +7596,9 @@ bool AArch64AsmParser::parseDirectiveInst(SMLoc Loc) {
}
// parseDirectiveTLSDescCall:
-// ::= .tlsdesccall symbol
-bool AArch64AsmParser::parseDirectiveTLSDescCall(SMLoc L) {
+// ::= .tlsdesccall symbol (if IsAuth is false)
+// ::= .tlsdescauthcall 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))
@@ -7603,10 +7606,12 @@ bool AArch64AsmParser::parseDirectiveTLSDescCall(SMLoc L) {
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::TLSDESCAUTHCALL : AArch64::TLSDESCCALL);
Inst.addOperand(MCOperand::createExpr(Expr));
getParser().getStreamer().emitInstruction(Inst, getSTI());
diff --git a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp
index 21ff55e9d9a7f..0183b826c1cb0 100644
--- a/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp
+++ b/llvm/lib/Target/AArch64/MCTargetDesc/AArch64MCCodeEmitter.cpp
@@ -738,6 +738,15 @@ void AArch64MCCodeEmitter::encodeInstruction(const MCInst &MI,
return;
}
+ if (MI.getOpcode() == AArch64::TLSDESCAUTHCALL) {
+ // 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;
diff --git a/llvm/test/CodeGen/AArch64/ptrauth-arm64-tls-dynamics.ll b/llvm/test/CodeGen/AArch64/ptrauth-arm64-tls-dynamics.ll
index 2d8085cf489b9..d6cbe9d50c2ba 100644
--- a/llvm/test/CodeGen/AArch64/ptrauth-arm64-tls-dynamics.ll
+++ b/llvm/test/CodeGen/AArch64/ptrauth-arm64-tls-dynamics.ll
@@ -16,6 +16,7 @@ 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: .tlsdescauthcall general_dynamic_var
; CHECK-NEXT: blraa x16, x0
; CHECK-NEXT: mrs x[[TPIDR:[0-9]+]], TPIDR_EL0
; CHECK-NEXT: ldr w0, [x[[TPIDR]], x0]
@@ -23,7 +24,7 @@ define i32 @test_generaldynamic() {
; 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-ERR: LLVM ERROR: cannot select: %1:gpr64sp(p0) = G_GLOBAL_VALUE @general_dynamic_var (in function: test_generaldynamic)
}
@@ -36,6 +37,7 @@ 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: .tlsdescauthcall general_dynamic_var
; CHECK-NEXT: blraa x16, x0
; CHECK-NEXT: mrs [[TP:x[0-9]+]], TPIDR_EL0
; CHECK-NEXT: add x0, [[TP]], x0
@@ -43,7 +45,7 @@ define ptr @test_generaldynamic_addr() {
; 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,
@@ -60,6 +62,7 @@ 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: .tlsdescauthcall local_dynamic_var
; CHECK-NEXT: blraa x16, x0
; CHECK-NEXT: mrs x[[TPIDR:[0-9]+]], TPIDR_EL0
; CHECK-NEXT: ldr w0, [x[[TPIDR]], x0]
@@ -67,7 +70,7 @@ define i32 @test_localdynamic() {
; 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() {
@@ -78,6 +81,7 @@ 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: .tlsdescauthcall local_dynamic_var
; CHECK-NEXT: blraa x16, x0
; CHECK-NEXT: mrs x[[TPIDR:[0-9]+]], TPIDR_EL0
; CHECK-NEXT: add x0, x[[TPIDR]], x0
@@ -85,7 +89,7 @@ define ptr @test_localdynamic_addr() {
; 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
@@ -99,6 +103,7 @@ 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: .tlsdescauthcall extern_weak_var
; CHECK-NEXT: blraa x16, x0
; CHECK-NEXT: mrs x[[TPIDR:[0-9]+]], TPIDR_EL0
; CHECK-NEXT: ldr w0, [x[[TPIDR]], x0]
@@ -106,7 +111,7 @@ define i32 @test_extern_weak() {
; 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
}
diff --git a/llvm/test/MC/AArch64/directives-case_insensitive.s b/llvm/test/MC/AArch64/directives-case_insensitive.s
index c2bdec73e349e..d653d35858d17 100644
--- a/llvm/test/MC/AArch64/directives-case_insensitive.s
+++ b/llvm/test/MC/AArch64/directives-case_insensitive.s
@@ -44,5 +44,8 @@ fred .REQ x5
.TLSDESCCALL var
// CHECK: .tlsdesccall var
+.TLSDESCAUTHCALL var
+// CHECK: .tlsdescauthcall var
+
.LTORG
.POOL
diff --git a/llvm/test/MC/AArch64/tls-auth-relocs.s b/llvm/test/MC/AArch64/tls-auth-relocs.s
new file mode 100644
index 0000000000000..500564661ddef
--- /dev/null
+++ b/llvm/test/MC/AArch64/tls-auth-relocs.s
@@ -0,0 +1,36 @@
+// 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-readobj -r --symbols - | 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
+ .tlsdescauthcall 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: .tlsdescauthcall var // encoding: []
+// CHECK-NEXT: // fixup A - offset: 0, value: var, relocation type: 598
+// CHECK: blraa x3, x2 // encoding: [0x62,0x08,0x3f,0xd7]
+
+// CHECK-ELF: Relocations [
+// CHECK-ELF-NEXT: Section {{.*}} .rela.text {
+// CHECK-ELF-NEXT: 0x0 R_AARCH64_AUTH_TLSDESC_ADR_PAGE21 [[VARSYM:[^ ]+]]
+// CHECK-ELF-NEXT: 0x4 R_AARCH64_AUTH_TLSDESC_LD64_LO12 [[VARSYM]]
+// CHECK-ELF-NEXT: 0x8 R_AARCH64_AUTH_TLSDESC_ADD_LO12 [[VARSYM]]
+// CHECK-ELF-NEXT: 0xC R_AARCH64_AUTH_TLSDESC_CALL [[VARSYM]]
+
+// Make sure symbol has type STT_TLS:
+
+// CHECK-ELF: Symbols [
+// CHECK-ELF: Symbol {
+// CHECK-ELF: Name: var
+// CHECK-ELF-NEXT: Value:
+// CHECK-ELF-NEXT: Size:
+// CHECK-ELF-NEXT: Binding: Global
+// CHECK-ELF-NEXT: Type: TLS
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The R_AARCH64_AUTH_TLSDESC_CALL is introduced to allow linker relaxation of AUTH TLSDESC call sequences for non-preemptible undefined weak symbols. The lld patch introducing the relaxation: #194636 Corresponding ARM docs PR: ARM-software/abi-aa#395
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I thought we were still discussing things on the spec side? |
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The R_AARCH64_AUTH_TLSDESC_CALL is introduced to allow linker relaxation of AUTH TLSDESC call sequences for non-preemptible undefined weak symbols.
The lld patch introducing the relaxation: #194636
Corresponding ARM docs PR: ARM-software/abi-aa#395