From 9178708c3bf926fe0d7767e26344f3f98b1e92ec Mon Sep 17 00:00:00 2001 From: Daniil Kovalev Date: Wed, 22 Jan 2025 12:18:05 +0300 Subject: [PATCH] [PAC][lld][AArch64][ELF] Support signed TLSDESC (#113817) Depends on #120010 Support `R_AARCH64_AUTH_TLSDESC_ADR_PAGE21`, `R_AARCH64_AUTH_TLSDESC_LD64_LO12` and `R_AARCH64_AUTH_TLSDESC_LD64_LO12` static relocations and `R_AARCH64_AUTH_TLSDESC` dynamic relocation. IE/LE optimization is not currently supported for AUTH TLSDESC. --- lld/ELF/Arch/AArch64.cpp | 8 ++ lld/ELF/InputSection.cpp | 2 + lld/ELF/Relocations.cpp | 47 +++++++++- lld/ELF/Relocations.h | 2 + lld/ELF/Symbols.h | 2 + lld/ELF/SyntheticSections.cpp | 5 + lld/ELF/SyntheticSections.h | 1 + lld/test/ELF/aarch64-tlsdesc-pauth.s | 134 +++++++++++++++++++++++++++ 8 files changed, 198 insertions(+), 3 deletions(-) create mode 100644 lld/test/ELF/aarch64-tlsdesc-pauth.s diff --git a/lld/ELF/Arch/AArch64.cpp b/lld/ELF/Arch/AArch64.cpp index b63551d0f682..9538dd4a70ba 100644 --- a/lld/ELF/Arch/AArch64.cpp +++ b/lld/ELF/Arch/AArch64.cpp @@ -157,9 +157,14 @@ RelExpr AArch64::getRelExpr(RelType type, const Symbol &s, return RE_AARCH64_AUTH; case R_AARCH64_TLSDESC_ADR_PAGE21: return RE_AARCH64_TLSDESC_PAGE; + case R_AARCH64_AUTH_TLSDESC_ADR_PAGE21: + return RE_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 RE_AARCH64_AUTH_TLSDESC; case R_AARCH64_TLSDESC_CALL: return R_TLSDESC_CALL; case R_AARCH64_TLSLE_ADD_TPREL_HI12: @@ -545,6 +550,7 @@ 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(ctx, loc, val, 33, rel); [[fallthrough]]; case R_AARCH64_ADR_PREL_PG_HI21_NC: @@ -597,6 +603,7 @@ 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(ctx, loc, val, 8, rel); write32Imm12(loc, getBits(val, 3, 11)); break; @@ -671,6 +678,7 @@ 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: write32Imm12(loc, val); break; case R_AARCH64_TLSDESC: diff --git a/lld/ELF/InputSection.cpp b/lld/ELF/InputSection.cpp index efa7ba3e7cb0..42ef530b79d8 100644 --- a/lld/ELF/InputSection.cpp +++ b/lld/ELF/InputSection.cpp @@ -966,12 +966,14 @@ uint64_t InputSectionBase::getRelocTargetVA(Ctx &ctx, const Relocation &r, case R_SIZE: return r.sym->getSize() + a; case R_TLSDESC: + case RE_AARCH64_AUTH_TLSDESC: return ctx.in.got->getTlsDescAddr(*r.sym) + a; case R_TLSDESC_PC: return ctx.in.got->getTlsDescAddr(*r.sym) + a - p; case R_TLSDESC_GOTPLT: return ctx.in.got->getTlsDescAddr(*r.sym) + a - ctx.in.gotPlt->getVA(); case RE_AARCH64_TLSDESC_PAGE: + case RE_AARCH64_AUTH_TLSDESC_PAGE: return getAArch64Page(ctx.in.got->getTlsDescAddr(*r.sym) + a) - getAArch64Page(p); case RE_LOONGARCH_TLSDESC_PAGE_PC: diff --git a/lld/ELF/Relocations.cpp b/lld/ELF/Relocations.cpp index 77b90172bc1c..76b151b93d51 100644 --- a/lld/ELF/Relocations.cpp +++ b/lld/ELF/Relocations.cpp @@ -1292,6 +1292,27 @@ static unsigned handleMipsTlsRelocation(Ctx &ctx, RelType type, Symbol &sym, return 0; } +static unsigned handleAArch64PAuthTlsRelocation(InputSectionBase *sec, + RelExpr expr, RelType type, + uint64_t offset, Symbol &sym, + int64_t addend) { + // Do not optimize signed TLSDESC to LE/IE (as described in pauthabielf64). + // https://github.com/ARM-software/abi-aa/blob/main/pauthabielf64/pauthabielf64.rst#general-restrictions + // > PAUTHELF64 only supports the descriptor based TLS (TLSDESC). + if (oneof(expr)) { + sym.setFlags(NEEDS_TLSDESC | NEEDS_TLSDESC_AUTH); + sec->addReloc({expr, type, offset, addend, &sym}); + return 1; + } + + // TLSDESC_CALL hint relocation should not be emitted by compiler with signed + // TLSDESC enabled. + if (expr == R_TLSDESC_CALL) + sym.setFlags(NEEDS_TLSDESC_NONAUTH); + + return 0; +} + // Notes about General Dynamic and Local Dynamic TLS models below. They may // require the generation of a pair of GOT entries that have associated dynamic // relocations. The pair of GOT entries created are of the form GOT[e0] Module @@ -1302,6 +1323,13 @@ static unsigned handleMipsTlsRelocation(Ctx &ctx, RelType type, Symbol &sym, unsigned RelocationScanner::handleTlsRelocation(RelExpr expr, RelType type, uint64_t offset, Symbol &sym, int64_t addend) { + bool isAArch64 = ctx.arg.emachine == EM_AARCH64; + + if (isAArch64) + if (unsigned processed = handleAArch64PAuthTlsRelocation( + sec, expr, type, offset, sym, addend)) + return processed; + if (expr == R_TPREL || expr == R_TPREL_NEG) { if (ctx.arg.shared) { auto diag = Err(ctx); @@ -1336,7 +1364,9 @@ unsigned RelocationScanner::handleTlsRelocation(RelExpr expr, RelType type, // 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) + if (isAArch64) + sym.setFlags(NEEDS_TLSDESC | NEEDS_TLSDESC_NONAUTH); + else if (!isRISCV || type == R_RISCV_TLSDESC_HI20) sym.setFlags(NEEDS_TLSDESC); sec->addReloc({expr, type, offset, addend, &sym}); } @@ -1847,10 +1877,21 @@ void elf::postScanRelocations(Ctx &ctx) { GotSection *got = ctx.in.got.get(); if (flags & NEEDS_TLSDESC) { + if ((flags & NEEDS_TLSDESC_AUTH) && (flags & NEEDS_TLSDESC_NONAUTH)) { + Err(ctx) + << "both AUTH and non-AUTH TLSDESC entries for '" << sym.getName() + << "' requested, but only one type of TLSDESC entry per symbol is " + "supported"; + return; + } got->addTlsDescEntry(sym); + RelType tlsDescRel = ctx.target->tlsDescRel; + if (flags & NEEDS_TLSDESC_AUTH) { + got->addTlsDescAuthEntry(); + tlsDescRel = ELF::R_AARCH64_AUTH_TLSDESC; + } ctx.mainPart->relaDyn->addAddendOnlyRelocIfNonPreemptible( - ctx.target->tlsDescRel, *got, got->getTlsDescOffset(sym), sym, - ctx.target->tlsDescRel); + tlsDescRel, *got, got->getTlsDescOffset(sym), sym, tlsDescRel); } if (flags & NEEDS_TLSGD) { got->addDynTlsEntry(sym); diff --git a/lld/ELF/Relocations.h b/lld/ELF/Relocations.h index fde25a230b72..d2a77bc95310 100644 --- a/lld/ELF/Relocations.h +++ b/lld/ELF/Relocations.h @@ -99,6 +99,8 @@ enum RelExpr { RE_AARCH64_PAGE_PC, RE_AARCH64_RELAX_TLS_GD_TO_IE_PAGE_PC, RE_AARCH64_TLSDESC_PAGE, + RE_AARCH64_AUTH_TLSDESC_PAGE, + RE_AARCH64_AUTH_TLSDESC, RE_AARCH64_AUTH, RE_ARM_PCA, RE_ARM_SBREL, diff --git a/lld/ELF/Symbols.h b/lld/ELF/Symbols.h index a59faf1037cb..48df6f60db86 100644 --- a/lld/ELF/Symbols.h +++ b/lld/ELF/Symbols.h @@ -53,6 +53,8 @@ enum { NEEDS_TLSIE = 1 << 8, NEEDS_GOT_AUTH = 1 << 9, NEEDS_GOT_NONAUTH = 1 << 10, + NEEDS_TLSDESC_AUTH = 1 << 11, + NEEDS_TLSDESC_NONAUTH = 1 << 12, }; // The base class for real symbol classes. diff --git a/lld/ELF/SyntheticSections.cpp b/lld/ELF/SyntheticSections.cpp index 10cbfe19b3b0..eb07d82fc960 100644 --- a/lld/ELF/SyntheticSections.cpp +++ b/lld/ELF/SyntheticSections.cpp @@ -681,6 +681,11 @@ bool GotSection::addTlsDescEntry(const Symbol &sym) { return true; } +void GotSection::addTlsDescAuthEntry() { + authEntries.push_back({(numEntries - 2) * ctx.arg.wordsize, true}); + authEntries.push_back({(numEntries - 1) * ctx.arg.wordsize, false}); +} + bool GotSection::addDynTlsEntry(const Symbol &sym) { assert(sym.auxIdx == ctx.symAux.size() - 1); ctx.symAux.back().tlsGdIdx = numEntries; diff --git a/lld/ELF/SyntheticSections.h b/lld/ELF/SyntheticSections.h index 9fcee3b481af..c977562f0b17 100644 --- a/lld/ELF/SyntheticSections.h +++ b/lld/ELF/SyntheticSections.h @@ -114,6 +114,7 @@ public: void addEntry(const Symbol &sym); void addAuthEntry(const Symbol &sym); bool addTlsDescEntry(const Symbol &sym); + void addTlsDescAuthEntry(); bool addDynTlsEntry(const Symbol &sym); bool addTlsIndex(); uint32_t getTlsDescOffset(const Symbol &sym) const; diff --git a/lld/test/ELF/aarch64-tlsdesc-pauth.s b/lld/test/ELF/aarch64-tlsdesc-pauth.s new file mode 100644 index 000000000000..bf0ae4a87f32 --- /dev/null +++ b/lld/test/ELF/aarch64-tlsdesc-pauth.s @@ -0,0 +1,134 @@ +// REQUIRES: aarch64 +// RUN: rm -rf %t && split-file %s %t && cd %t + +//--- a.s +.section .tbss,"awT",@nobits +.global a +a: +.xword 0 + +//--- ok.s +// RUN: llvm-mc -filetype=obj -triple=aarch64-pc-linux -mattr=+pauth ok.s -o ok.o +// RUN: ld.lld -shared ok.o -o ok.so +// RUN: llvm-objdump --no-print-imm-hex -d --no-show-raw-insn ok.so | \ +// RUN: FileCheck -DP=20 -DA=896 -DB=912 -DC=928 %s +// RUN: llvm-readobj -r -x .got ok.so | FileCheck --check-prefix=REL \ +// RUN: -DP1=20 -DA1=380 -DB1=390 -DC1=3A0 -DP2=020 -DA2=380 -DB2=390 -DC2=3a0 %s + +// RUN: llvm-mc -filetype=obj -triple=aarch64-pc-linux -mattr=+pauth a.s -o a.so.o +// RUN: ld.lld -shared a.so.o -soname=so -o a.so +// RUN: ld.lld ok.o a.so -o ok +// RUN: llvm-objdump --no-print-imm-hex -d --no-show-raw-insn ok | \ +// RUN: FileCheck -DP=220 -DA=936 -DB=952 -DC=968 %s +// RUN: llvm-readobj -r -x .got ok | FileCheck --check-prefix=REL \ +// RUN: -DP1=220 -DA1=3A8 -DB1=3B8 -DC1=3C8 -DP2=220 -DA2=3a8 -DB2=3b8 -DC2=3c8 %s + + .text + adrp x0, :tlsdesc_auth:a + ldr x16, [x0, :tlsdesc_auth_lo12:a] + add x0, x0, :tlsdesc_auth_lo12:a + blraa x16, x0 + +// CHECK: adrp x0, 0x[[P]]000 +// CHECK-NEXT: ldr x16, [x0, #[[A]]] +// CHECK-NEXT: add x0, x0, #[[A]] +// CHECK-NEXT: blraa x16, x0 + +/// 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 + blraa x16, x0 + +// CHECK: adrp x0, 0x[[P]]000 +// CHECK-NEXT: ldr x16, [x0, #[[B]]] +// CHECK-NEXT: add x0, x0, #[[B]] +// CHECK-NEXT: blraa x16, x0 + + adrp x0, :tlsdesc_auth:local2 + ldr x16, [x0, :tlsdesc_auth_lo12:local2] + add x0, x0, :tlsdesc_auth_lo12:local2 + blraa x16, x0 + +// CHECK: adrp x0, 0x[[P]]000 +// CHECK-NEXT: ldr x16, [x0, #[[C]]] +// CHECK-NEXT: add x0, x0, #[[C]] +// CHECK-NEXT: blraa x16, x0 + + .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 (5) .rela.dyn { +// REL-NEXT: 0x[[P1]][[B1]] R_AARCH64_AUTH_TLSDESC - 0x0 +// REL-NEXT: 0x[[P1]][[C1]] R_AARCH64_AUTH_TLSDESC - 0x8 +// REL-NEXT: 0x[[P1]][[A1]] R_AARCH64_AUTH_TLSDESC a 0x0 +// REL-NEXT: } +// REL-NEXT: ] + +// REL: Hex dump of section '.got': +// REL-NEXT: 0x00[[P2]][[A2]] 00000000 00000080 00000000 000000a0 +// REL-NEXT: 0x00[[P2]][[B2]] 00000000 00000080 00000000 000000a0 +// REL-NEXT: 0x00[[P2]][[C2]] 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 + +//--- err1.s +// RUN: llvm-mc -filetype=obj -triple=aarch64-pc-linux -mattr=+pauth err1.s -o err1.o +// RUN: not ld.lld -shared err1.o 2>&1 | FileCheck --check-prefix=ERR1 --implicit-check-not=error: %s +// ERR1: 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 + blraa x16, x0 + + adrp x0, :tlsdesc:a + ldr x1, [x0, :tlsdesc_lo12:a] + add x0, x0, :tlsdesc_lo12:a + blr x1 + +//--- err2.s +// RUN: llvm-mc -filetype=obj -triple=aarch64-pc-linux -mattr=+pauth err2.s -o err2.o +// RUN: not ld.lld -shared err2.o 2>&1 | FileCheck --check-prefix=ERR2 --implicit-check-not=error: %s +// ERR2: 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:a + ldr x1, [x0, :tlsdesc_lo12:a] + add x0, x0, :tlsdesc_lo12:a + blr x1 + + adrp x0, :tlsdesc_auth:a + ldr x16, [x0, :tlsdesc_auth_lo12:a] + add x0, x0, :tlsdesc_auth_lo12:a + blraa x16, x0 + +//--- err3.s +// RUN: llvm-mc -filetype=obj -triple=aarch64-pc-linux -mattr=+pauth err3.s -o err3.o +// RUN: not ld.lld -shared err3.o 2>&1 | FileCheck --check-prefix=ERR3 --implicit-check-not=error: %s +// ERR3: 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 + .tlsdesccall a + blraa x16, x0