From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001 From: Andrew Udvare Date: Fri, 9 Oct 2026 18:58:59 -0400 Subject: [PATCH 1/3] ld64: never emit chained fixups for deltas buildChainedFixupInfo() leaves any fixup cluster containing a subtraction out of the chain, but applyFixUps() still encoded 32- and 64-bit stores of such deltas as chained pointers unless the atom was in a code/CFI/unwind/DOF section. Clang 23 emits relative lookup tables (32-bit target - table deltas) in __TEXT,__const, so linking dyld failed with "chained binds not implemented yet". A 64-bit delta in a data section would have been silently encoded as a rebase. Apply deltas directly, matching the chain builder. Signed-off-by: Andrew Udvare --- cctools/ld64/src/ld/OutputFile.cpp | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/cctools/ld64/src/ld/OutputFile.cpp b/cctools/ld64/src/ld/OutputFile.cpp index 7d1fa52..95faa1d 100644 --- a/cctools/ld64/src/ld/OutputFile.cpp +++ b/cctools/ld64/src/ld/OutputFile.cpp @@ -1362,12 +1362,16 @@ void OutputFile::applyFixUps(ld::Internal& state, uint64_t mhAddress, const ld:: bool is_blx; bool is_b; bool thumbTarget = false; + // a delta (target - from) is resolved at link time and never needs a chained fixup + bool isDelta = false; std::map usedByHints; #if SUPPORT_ARCH_arm64e Fixup::AuthData authData; #endif for (ld::Fixup::iterator fit = atom->fixupsBegin(), end=atom->fixupsEnd(); fit != end; ++fit) { uint8_t* fixUpLocation = &buffer[fit->offsetInAtom]; + if ( fit->firstInCluster() ) + isDelta = false; ld::Fixup::LOH_arm64 lohExtra; switch ( (ld::Fixup::Kind)(fit->kind) ) { case ld::Fixup::kindNone: @@ -1389,6 +1393,7 @@ void OutputFile::applyFixUps(ld::Internal& state, uint64_t mhAddress, const ld:: delta = addressOf(state, fit, &fromTarget); if ( ! fit->contentAddendOnly ) accumulator -= delta; + isDelta = true; break; case ld::Fixup::kindAddAddend: if ( ! fit->contentIgnoresAddend ) { @@ -1430,7 +1435,7 @@ void OutputFile::applyFixUps(ld::Internal& state, uint64_t mhAddress, const ld:: break; case ld::Fixup::kindStoreLittleEndian32: rangeCheckAbsolute32(accumulator, state, atom, fit); - if ( _options.makeChainedFixups() && !fit->contentAddendOnly && (atom->contentType() != ld::Atom::ContentType::typeCFI) + if ( _options.makeChainedFixups() && !fit->contentAddendOnly && !isDelta && (atom->contentType() != ld::Atom::ContentType::typeCFI) && (atom->section().type() != ld::Section::typeUnwindInfo) && (atom->section().type() != ld::Section::typeCode) && (atom->section().type() != ld::Section::typeDtraceDOF) ) setFixup32(fixUpLocation, accumulator, toTarget); @@ -1438,7 +1443,7 @@ void OutputFile::applyFixUps(ld::Internal& state, uint64_t mhAddress, const ld:: set32LE(fixUpLocation, accumulator); break; case ld::Fixup::kindStoreLittleEndian64: - if ( _options.makeChainedFixups() && !fit->contentAddendOnly && (atom->contentType() != ld::Atom::ContentType::typeCFI) ) + if ( _options.makeChainedFixups() && !fit->contentAddendOnly && !isDelta && (atom->contentType() != ld::Atom::ContentType::typeCFI) ) setFixup64(fixUpLocation, accumulator, toTarget); else set64LE(fixUpLocation, accumulator);