Add LLVM AllocToken and Heap Partitioning Support to the Rust compiler. - #160298
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Add LLVM AllocToken and Heap Partitioning Support to the Rust compiler.#160298rcvalle wants to merge 8 commits into
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Add the `-Zsanitizer=alloc-token` sanitizer option, including target support specification (i.e., `supported_sanitizers` in target specifications), and the accompanying `-Zsanitizer-alloc-token-scheme`, `-Zsanitizer-alloc-token-max`, `-Zsanitizer-alloc-token-extended`, and `-Zsanitizer-alloc-token-fast-abi` options.
Add the `#[alloc_token_hint(contains_pointers = ..., type_name = "...")]` attribute to allow the user to define the allocation token hint (i.e., the contains-pointer classification and type name encoding) for user-defined types, and the internal `#[rustc_alloc_token_hint]` attribute to annotate typed allocation functions whose type parameter identifies the allocated type.
…ning schemes Add the `rustc_sanitizers::alloc_token` module, organized and structured similarly to `rustc_sanitizers::cfi::typeid` (i.e., the `hint` module provides the interface for computing allocation token hints for a given `Ty` and dispatches to the selected heap partitioning scheme implementation, such as `type_hash_pointer_split`).
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Some changes occurred in compiler/rustc_hir/src/attrs cc @jdonszelmann, @JonathanBrouwer Some changes occurred to the intrinsics. Make sure the CTFE / Miri interpreter cc @rust-lang/miri, @RalfJung, @oli-obk, @lcnr
cc @bjorn3 Any special-casing of Miri in the standard library requires review. cc @rust-lang/miri Some changes occurred in src/doc/unstable-book/src/compiler-flags/sanitizer.md cc @rust-lang/project-exploit-mitigations
Some changes occurred in compiler/rustc_attr_parsing cc @jdonszelmann, @JonathanBrouwer These commits modify the If this was unintentional then you should revert the changes before this PR is merged. Some changes occurred in compiler/rustc_passes/src/check_attr.rs cc @jdonszelmann, @JonathanBrouwer These commits modify compiler targets. Some changes occurred in src/tools/compiletest cc @jieyouxu |
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@bjorn3 For whenever you have time. Thank you! |
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…nt it for LLVM backend Add the `set_alloc_token_hint` and `get_alloc_token_id` methods to the backend-agnostic `BuilderMethods` trait, and implement them for the LLVM backend; and add the `SanitizeAllocToken` LLVM function attribute, and the `alloc-token-mode`, `alloc-token-max`, `alloc-token-extended`, and `alloc-token-fast-abi` module flags.
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Add `alloc_typed` and `alloc_array_typed`, internal, unstable, generic allocation functions annotated with `#[rustc_alloc_token_hint]`. Route `Box::new` and `RawVec::<T, Global>::with_capacity` through them when LLVM AllocToken and heap partitioning support is enabled, so the allocation call within them is annotated with the allocation token hint (i.e., the contents of the `!alloc_token` metadata) for its type parameter `T`.
…brary Extend the Rust compiler allocator shim generation to also generate the token-enabled versions of the `__rust_alloc`, `__rust_alloc_zeroed`, and `__rust_realloc` allocation functions (i.e., `__alloc_token___rust_alloc`, `__alloc_token___rust_alloc_zeroed`, and `__alloc_token___rust_realloc`), forwarding to new unstable, token-enabled methods of the `GlobalAlloc` trait (i.e., `alloc_with_token`, `alloc_zeroed_with_token`, and `realloc_with_token`), with default implementations that ignore the token identifier and call the non-token-enabled methods, for backward compatibility with existing allocators. In the `System` allocator implementation, the token-enabled methods forward to the token-enabled C allocator interface (i.e., `__alloc_token_malloc`, `__alloc_token_calloc`, and `__alloc_token_realloc`), so that programs using the default allocator can use a token-enabled C memory allocator for the whole program, including foreign code, in mixed binaries. The token-enabled versions of these allocation functions are also added to the allocator shim exported symbols. For allocators registered with the `#[global_allocator]` attribute, the token-enabled versions of these allocation functions forward to the non-token-enabled allocation functions of the registered allocator, ignoring the token identifier, for backward compatibility with existing allocators.
Add the `alloc_token_infer` intrinsic (i.e., the Rust equivalent of the Clang `__builtin_infer_alloc_token` builtin, lowered to the `llvm.alloc.token.id` intrinsic) for allocator and arena implementers to query the token identifier for a given type at compile time (e.g., `core::intrinsics::alloc_token_infer::<T>() -> usize`), so it can be passed to a token-enabled allocator interface directly.
Add documentation for the LLVM AllocToken and heap partitioning support in the Rust compiler.
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The job Click to see the possible cause of the failure (guessed by this bot) |
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Has this been RFC'd or at least MCP'd? It seems to propose deep changes to the core semantics of Rust which definitely needs some wider discussion. Rust does not have typed memory, so "typed allocation" is an oxymoron. |
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Okay, looking at your writeup, this isn't "typed memory" / "typed allocations" at all. I can store whatever types I want into these allocations without causing UB. It's just a hint to the allocator which allocations to put near each other and which not. I would strongly recommend to avoid calling this "typed X" (which you didn't in this PR but you did in the tracking issue) since some of us in Rust have strong feelings about typed memory, and Rust is very unlikely to ever have "typed allocations" in the sense of "allocations that are required to only hold data of a certain type". The concrete API proposed here with these "tokens" seems very strange to me, but this will need a least an MCP anyway for the compiler and intrinsic part and discussion with libs-api for how to expose it and how it changes the global allocator story (and maybe lang, depending on how magic these intrinsics are -- in particular, is the type partition this induces arbitrary and we can change it any time in principle, or are we making any promises about how types are grouped and which Rust types correspond to which C types). Given that the entire project as a whole spans non-trivial changes for multiple teams, this should probably be an RFC. So I'll wait for that to properly explain to us why we need "tokens" to partition heap allocations. :) tl;dr this is a big enough change to Rust that we need to ensure the relevant teams have agreed to the general design before we start landing anything. (Also the PR looks like it could likely be split up into smaller parts which would help a lot.) |
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Add LLVM AllocToken and heap partitioning support to the Rust compiler.
For more information about LLVM AllocToken and heap partitioning support for the Rust compiler, see the design document in the tracking issue #159111.
r? @bjorn3