libunwind changes needed to run code in sgx environment via rust-sgx. #57
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Is it possible to reframe this in a way that upstream LLVM would accept? We don't generally want to carry extra patches indefinitely. With backports, at least we know they'll go away in a future rebase. |
The Rust project effectively already does this by pointing at a a fork. That fork is based on LLVM version 5. Compared to using that external dependency, this PR is a large step in the right direction of bringing us much closer to upstream. |
jethrogb
reviewed
May 5, 2020
jethrogb
reviewed
May 8, 2020
|
Please note that we've moved to LLVM 10 since rust-lang/rust#67759, so we'll need this PR rebased onto |
Code is guarded via defines to enable only if 'RUST_SGX' is present. Main logic is in libunwind/src/AddressSpace.hpp We use 6 symbols to figure out where eh_frame / eh_frame_hdr is at runtime when loaded in an SGX enclave. (EH symbols + IMAGE base) These are set by 'fortanix-sgx-tools'. As notes: - Target above at the moment uses a pre-compiled libunwind.a from forked repo. - Goal of these changes is to use official llvm with patch. - Changes in rust-lang to use this are planned if/when this is accepted. - Ticket: fortanix/rust-sgx#174 - Original ported changes: llvm/llvm-project@release/5.x...fortanix:release/5.x
Thanks, I updated this PR with required changes and modified target. |
AdrianCX
changed the base branch from
rustc/9.0-2019-12-19
to
rustc/10.0-2020-05-05
|
Ok, I'm going to trust @jethrogb's review for SGX's sake, and this looks harmless to other targets. |
Manishearth
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Jun 26, 2020
Fortanix SGX target libunwind build process changes Ticket: fortanix/rust-sgx#174 LLVM related changes (merged): rust-lang/llvm-project#57 Description: libunwind changes needed to run code in sgx environment via rust-sgx. Target that uses this in rust: x86_64-fortanix-unknown-sgx. Without this change, rust std for this toolchain is forced to use a precompiled library loaded via environment variable. With this change we act the same as musl target.
nikic
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to nikic/llvm-project
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May 14, 2023
…callback
The `TypeSystemMap::m_mutex` guards against concurrent modifications
of members of `TypeSystemMap`. In particular, `m_map`.
`TypeSystemMap::ForEach` iterates through the entire `m_map` calling
a user-specified callback for each entry. This is all done while
`m_mutex` is locked. However, there's nothing that guarantees that
the callback itself won't call back into `TypeSystemMap` APIs on the
same thread. This lead to double-locking `m_mutex`, which is undefined
behaviour. We've seen this cause a deadlock in the swift plugin with
following backtrace:
```
int main() {
std::unique_ptr<int> up = std::make_unique<int>(5);
volatile int val = *up;
return val;
}
clang++ -std=c++2a -g -O1 main.cpp
./bin/lldb -o “br se -p return” -o run -o “v *up” -o “expr *up” -b
```
```
frame rust-lang#4: std::lock_guard<std::mutex>::lock_guard
frame rust-lang#5: lldb_private::TypeSystemMap::GetTypeSystemForLanguage <<<< Lock rust-lang#2
frame rust-lang#6: lldb_private::TypeSystemMap::GetTypeSystemForLanguage
frame rust-lang#7: lldb_private::Target::GetScratchTypeSystemForLanguage
...
frame rust-lang#26: lldb_private::SwiftASTContext::LoadLibraryUsingPaths
frame rust-lang#27: lldb_private::SwiftASTContext::LoadModule
frame rust-lang#30: swift::ModuleDecl::collectLinkLibraries
frame rust-lang#31: lldb_private::SwiftASTContext::LoadModule
frame rust-lang#34: lldb_private::SwiftASTContext::GetCompileUnitImportsImpl
frame rust-lang#35: lldb_private::SwiftASTContext::PerformCompileUnitImports
frame rust-lang#36: lldb_private::TypeSystemSwiftTypeRefForExpressions::GetSwiftASTContext
frame rust-lang#37: lldb_private::TypeSystemSwiftTypeRefForExpressions::GetPersistentExpressionState
frame rust-lang#38: lldb_private::Target::GetPersistentSymbol
frame rust-lang#41: lldb_private::TypeSystemMap::ForEach <<<< Lock #1
frame rust-lang#42: lldb_private::Target::GetPersistentSymbol
frame rust-lang#43: lldb_private::IRExecutionUnit::FindInUserDefinedSymbols
frame rust-lang#44: lldb_private::IRExecutionUnit::FindSymbol
frame rust-lang#45: lldb_private::IRExecutionUnit::MemoryManager::GetSymbolAddressAndPresence
frame rust-lang#46: lldb_private::IRExecutionUnit::MemoryManager::findSymbol
frame rust-lang#47: non-virtual thunk to lldb_private::IRExecutionUnit::MemoryManager::findSymbol
frame rust-lang#48: llvm::LinkingSymbolResolver::findSymbol
frame rust-lang#49: llvm::LegacyJITSymbolResolver::lookup
frame rust-lang#50: llvm::RuntimeDyldImpl::resolveExternalSymbols
frame rust-lang#51: llvm::RuntimeDyldImpl::resolveRelocations
frame rust-lang#52: llvm::MCJIT::finalizeLoadedModules
frame rust-lang#53: llvm::MCJIT::finalizeObject
frame rust-lang#54: lldb_private::IRExecutionUnit::ReportAllocations
frame rust-lang#55: lldb_private::IRExecutionUnit::GetRunnableInfo
frame rust-lang#56: lldb_private::ClangExpressionParser::PrepareForExecution
frame rust-lang#57: lldb_private::ClangUserExpression::TryParse
frame rust-lang#58: lldb_private::ClangUserExpression::Parse
```
Our solution is to simply iterate over a local copy of `m_map`.
**Testing**
* Confirmed on manual reproducer (would reproduce 100% of the time
before the patch)
Differential Revision: https://reviews.llvm.org/D149949
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Please advise on process as this is the first PR against rust-lang's llvm and I tried to follow instructions as close as possible..
Ticket: fortanix/rust-sgx#174
Description: libunwind changes needed to run code in sgx environment via rust-sgx.
Target that uses this in rust: x86_64-fortanix-unknown-sgx.
Rust-lang PR depends on this - plan is to raise it if this PR is accepted.
Without this change, rust std for this toolchain is forced to use a precompiled library loaded via environment variable.
Code is guarded via defines to enable only if 'RUST_SGX' is present.
Main logic is in libunwind/src/AddressSpace.hpp
We use 6 symbols to figure out where eh_frame / eh_frame_hdr is at runtime when loaded in an SGX enclave. (EH symbols + IMAGE base)
These are set when elf is converged to sgx format by 'fortanix-sgx-tools'.
Original ported changes: llvm/llvm-project@release/5.x...fortanix:release/5.x