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Update sanitizers documentation (#562)

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Tomasz Miąsko 2020-02-10 16:53:59 +01:00 committed by GitHub
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# Sanitizers Support # Sanitizers Support
The rustc compiler contains basic support for following sanitizers: The rustc compiler contains support for following sanitizers:
* [AddressSanitizer][clang-asan] a faster memory error detector. Can * [AddressSanitizer][clang-asan] a faster memory error detector. Can
detect out-of-bounds access to heap, stack, and globals, use after free, use detect out-of-bounds access to heap, stack, and globals, use after free, use
@ -17,13 +17,12 @@ sanitizers please refer to [the unstable book](https://doc.rust-lang.org/unstabl
## How are sanitizers implemented in rustc? ## How are sanitizers implemented in rustc?
The implementation of sanitizers relies entirely on LLVM. It consists of The implementation of sanitizers relies almost entirely on LLVM. The rustc is
compile time instrumentation passes and runtime libraries. The role rustc plays an integration point for LLVM compile time instrumentation passes and runtime
in the implementation is limited to the execution of the following steps: libraries. Highlight of the most important aspects of the implementation:
1. The sanitizer runtime libraries are part of the [compiler-rt] project, and * The sanitizer runtime libraries are part of the [compiler-rt] project, and
[will be built as an LLVM subproject][sanitizer-build] when enabled in [will be built on supported targets][sanitizer-build] when enabled in `config.toml`:
`config.toml`:
```toml ```toml
[build] [build]
@ -32,27 +31,34 @@ in the implementation is limited to the execution of the following steps:
The runtimes are [placed into target libdir][sanitizer-copy]. The runtimes are [placed into target libdir][sanitizer-copy].
2. During LLVM code generation, the functions intended for instrumentation are * During LLVM code generation, the functions intended for instrumentation are
[marked][sanitizer-attribute] with `SanitizeAddress`, `SanitizeMemory`, or [marked][sanitizer-attribute] with appropriate LLVM attribute:
`SanitizeThread` attribute. Currently those attributes are applied in `SanitizeAddress`, `SanitizeMemory`, or `SanitizeThread`. By default all
indiscriminate manner. but in principle they could be used to perform functions are instrumented, but this behaviour can be changed with
instrumentation selectively. `#[no_sanitize(...)]`.
3. The LLVM IR generated by rustc is instrumented by [dedicated LLVM * The decision whether to perform instrumentation or not is possible only at a
function granularity. In the cases were those decision differ between
functions it might be necessary to inhibit inlining, both at [MIR
level][inline-mir] and [LLVM level][inline-llvm].
* The LLVM IR generated by rustc is instrumented by [dedicated LLVM
passes][sanitizer-pass], different for each sanitizer. Instrumentation passes][sanitizer-pass], different for each sanitizer. Instrumentation
passes are invoked after optimization passes. passes are invoked after optimization passes.
4. When producing an executable, the sanitizer specific runtime library is * When producing an executable, the sanitizer specific runtime library is
[linked in][sanitizer-link]. The libraries are searched for in target libdir [linked in][sanitizer-link]. The libraries are searched for in target libdir
relative to default system root, so that this process is not affected relative to default system root, so that this process is not affected
by sysroot overrides used for example by cargo `-Zbuild-std` functionality. by sysroot overrides used for example by cargo `-Zbuild-std` functionality.
[compiler-rt]: https://github.com/llvm/llvm-project/tree/master/compiler-rt [compiler-rt]: https://github.com/llvm/llvm-project/tree/master/compiler-rt
[sanitizer-build]: https://github.com/rust-lang/rust/blob/87c3eedffba64830b67e54e75dd479f9fd83cc7d/src/bootstrap/native.rs#L220-L225 [sanitizer-build]: https://github.com/rust-lang/rust/blob/a29424a2265411dda7d7446516ac5fd7499e2b55/src/bootstrap/native.rs#L566-L624
[sanitizer-copy]: https://github.com/rust-lang/rust/blob/87c3eedffba64830b67e54e75dd479f9fd83cc7d/src/bootstrap/compile.rs#L269-L321 [sanitizer-copy]: https://github.com/rust-lang/rust/blob/a29424a2265411dda7d7446516ac5fd7499e2b55/src/bootstrap/compile.rs#L270-L304
[sanitizer-attribute]: https://github.com/rust-lang/rust/blob/1.38.0/src/librustc_codegen_llvm/declare.rs#L53-L66 [sanitizer-attribute]: https://github.com/rust-lang/rust/blob/a29424a2265411dda7d7446516ac5fd7499e2b55/src/librustc_codegen_llvm/attributes.rs#L49-L72
[sanitizer-pass]: https://github.com/rust-lang/rust/blob/1.38.0/src/librustc_codegen_ssa/back/write.rs#L406-L420 [inline-mir]: https://github.com/rust-lang/rust/blob/a29424a2265411dda7d7446516ac5fd7499e2b55/src/librustc_mir/transform/inline.rs#L232-L252
[sanitizer-link]: https://github.com/rust-lang/rust/blob/87c3eedffba64830b67e54e75dd479f9fd83cc7d/src/librustc_codegen_ssa/back/link.rs#L729-L770 [inline-llvm]: https://github.com/rust-lang/llvm-project/blob/9330ec5a4c1df5fc1fa62f993ed6a04da68cb040/llvm/include/llvm/IR/Attributes.td#L225-L241
[sanitizer-pass]: https://github.com/rust-lang/rust/blob/a29424a2265411dda7d7446516ac5fd7499e2b55/src/librustc_codegen_llvm/back/write.rs#L454-L475
[sanitizer-link]: https://github.com/rust-lang/rust/blob/a29424a2265411dda7d7446516ac5fd7499e2b55/src/librustc_codegen_ssa/back/link.rs#L748-L787
## Additional Information ## Additional Information