libunwind changes needed to run code in sgx environment via rust-sgx. #57
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
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
added a commit
to Manishearth/rust
that referenced
this pull request
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
pushed a commit
to nikic/llvm-project
that referenced
this pull request
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
# for free
to join this conversation on GitHub.
Already have an account?
# to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
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