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[lld] [MTE] Allow android note for static executables. #77078

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Merged
merged 1 commit into from
Jan 8, 2024
Merged

[lld] [MTE] Allow android note for static executables. #77078

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3 changes: 1 addition & 2 deletions lld/ELF/Arch/AArch64.cpp
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Expand Up @@ -1025,8 +1025,7 @@ addTaggedSymbolReferences(InputSectionBase &sec,
// symbols should also be built with tagging. But, to handle these cases, we
// demote the symbol to be untagged.
void lld::elf::createTaggedSymbols(const SmallVector<ELFFileBase *, 0> &files) {
assert(config->emachine == EM_AARCH64 &&
config->androidMemtagMode != ELF::NT_MEMTAG_LEVEL_NONE);
assert(hasMemtag());

// First, collect all symbols that are marked as tagged, and count how many
// times they're marked as tagged.
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2 changes: 1 addition & 1 deletion lld/ELF/SyntheticSections.cpp
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Expand Up @@ -1450,7 +1450,7 @@ DynamicSection<ELFT>::computeContents() {
if (config->zPacPlt)
addInt(DT_AARCH64_PAC_PLT, 0);

if (config->androidMemtagMode != ELF::NT_MEMTAG_LEVEL_NONE) {
if (hasMemtag()) {
addInt(DT_AARCH64_MEMTAG_MODE, config->androidMemtagMode == NT_MEMTAG_LEVEL_ASYNC);
addInt(DT_AARCH64_MEMTAG_HEAP, config->androidMemtagHeap);
addInt(DT_AARCH64_MEMTAG_STACK, config->androidMemtagStack);
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16 changes: 11 additions & 5 deletions lld/ELF/Writer.cpp
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Expand Up @@ -291,15 +291,19 @@ static void demoteSymbolsAndComputeIsPreemptible() {
}
}

bool elf::hasMemtag() {
return config->emachine == EM_AARCH64 &&
config->androidMemtagMode != ELF::NT_MEMTAG_LEVEL_NONE;
}

// Fully static executables don't support MTE globals at this point in time, as
// we currently rely on:
// - A dynamic loader to process relocations, and
// - Dynamic entries.
// This restriction could be removed in future by re-using some of the ideas
// that ifuncs use in fully static executables.
bool elf::canHaveMemtagGlobals() {
return config->emachine == EM_AARCH64 &&
config->androidMemtagMode != ELF::NT_MEMTAG_LEVEL_NONE &&
return hasMemtag() &&
(config->relocatable || config->shared || needsInterpSection());
}

Expand Down Expand Up @@ -397,11 +401,13 @@ template <class ELFT> void elf::createSyntheticSections() {
std::make_unique<SymbolTableSection<ELFT>>(*part.dynStrTab);
part.dynamic = std::make_unique<DynamicSection<ELFT>>();

if (canHaveMemtagGlobals()) {
if (hasMemtag()) {
part.memtagAndroidNote = std::make_unique<MemtagAndroidNote>();
add(*part.memtagAndroidNote);
part.memtagDescriptors = std::make_unique<MemtagDescriptors>();
add(*part.memtagDescriptors);
if (canHaveMemtagGlobals()) {
part.memtagDescriptors = std::make_unique<MemtagDescriptors>();
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driveby, potentially in another CL: can we rename MemtagDescriptors to MemtagGlobalDescriptors?

add(*part.memtagDescriptors);
}
}

if (config->androidPackDynRelocs)
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1 change: 1 addition & 0 deletions lld/ELF/Writer.h
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Expand Up @@ -57,6 +57,7 @@ bool isMipsN32Abi(const InputFile *f);
bool isMicroMips();
bool isMipsR6();

bool hasMemtag();
bool canHaveMemtagGlobals();
} // namespace lld::elf

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12 changes: 12 additions & 0 deletions lld/test/ELF/aarch64-memtag-android-abi.s
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Expand Up @@ -56,6 +56,18 @@
# BAD-MODE: error: unknown --android-memtag-mode value: "asymm", should be one of
# BAD-MODE: {async, sync, none}

# RUN: ld.lld -static --android-memtag-mode=sync --android-memtag-heap \
# RUN: --android-memtag-stack %t.o -o %t
# RUN: llvm-readelf --memtag %t | FileCheck %s --check-prefixes=STATIC

# STATIC: Memtag Dynamic Entries:
# STATIC-NEXT: < none found >
# STATIC: Memtag Android Note:
# STATIC-NEXT: Tagging Mode: SYNC
# STATIC-NEXT: Heap: Enabled
# STATIC-NEXT: Stack: Enabled


.globl _start
_start:
ret