Add exploit mitigations chapter to the rustc book
This section documents the exploit mitigations applicable to the Rust compiler when building programs for the Linux operating system on the AMD64 architecture and equivalent. This was done for a project I'm currently working on, and I hope it'll also be helpful to others.
This section documents the exploit mitigations applicable to the Rust
compiler when building programs for the Linux operating system on the
AMD64 architecture and equivalent.
Demote i686-unknown-freebsd to tier 2 compiler target
While technically the `i686-unknown-freebsd` target has been a tier 2 development platform for a long time, with full toolchain tarballs available on static.rust-lang.org, due to a bug in the manifest generation the target was never available for download through rustup.
The infrastructure team privately inquired the FreeBSD package maintainers, and they weren't relying on those tarballs either, so it's a fair assumption to say practically nobody is using those tarballs.
This PR then removes the CI builder that produces full tarballs for the target, and moves the compilation of `rust-std` for the target in `dist-various-2`. The `x86_64-unknown-freebsd` target is *not* affected.
cc `@rust-lang/infra` `@rust-lang/compiler` `@rust-lang/release`
r? `@Mark-Simulacrum`
While technically the i686-unknown-freebsd target has been a tier 2
development platform for a long time, with full toolchain tarballs
available on static.rust-lang.org, due to a bug in the manifest
generation the target was never available for download through rustup.
The infrastructure team privately inquired the FreeBSD package
maintainers, and they weren't relying on those tarballs either, so it's
a fair assumption to say practically nobody is using those tarballs.
This PR then removes the CI builder that produces full tarballs for the
target, and moves the compilation of rust-std for the target in
dist-various-2.
The x86_64-unknown-freebsd target is *not* affected.
Promote aarch64-pc-windows-msvc to Tier 2 Development Platform
Adds a GitHub Actions CI build for `aarch64-pc-windows-msvc` via cross-compilation on an x86_64 host.
This promotes `aarch64-pc-windows-msvc` from a Tier 2 Compilation Target (std) to a Tier 2 Development Platform (std+rustc+cargo+tools).
Fixes#72881
r? `@pietroalbini`
Add aarch64-unknown-linux-musl host builds
This adds aarch64-unknown-linux-musl to the hosts list and adds the build to the dist-arm-linux builder as `@Mark-Simulacrum` suggested to me in Zulip. `@jyn514` requested to be mentioned 😄
I had to update the config for crosstool-ng as it had a prompt about the glibc version.
I ran `src/ci/docker/run.sh dist-arm-linux` to test it.
```
Build completed successfully in 1:31:50
Compile requests 8180
Compile requests executed 8135
Cache hits 287
Cache misses 7848
Cache timeouts 0
Cache read errors 0
Forced recaches 0
Cache write errors 0
Compilation failures 0
Cache errors 0
Non-cacheable compilations 0
Non-cacheable calls 36
Non-compilation calls 9
Unsupported compiler calls 0
Average cache write 0.000 s
Average cache read miss 6.389 s
Average cache read hit 0.000 s
Cache location Local disk: "/sccache"
Cache size 202 MiB
Max cache size 10 GiB
== clock drift check ==
local time: Sun Sep 6 19:30:17 UTC 2020
network time: Sun, 06 Sep 2020 19:30:17 GMT
== end clock drift check ==
```
Only errors were in miri due to struct fields being private (already been reported [here](https://github.com/rust-lang/rust/issues/76337))
Edit: Maybe it is helpful if I add that it is a working compiler
```sh
/rust-nightly-aarch64-unknown-linux-musl # ash install.sh
install: creating uninstall script at /usr/local/lib/rustlib/uninstall.sh
install: installing component 'rustc'
install: installing component 'cargo'
install: installing component 'rls-preview'
install: installing component 'rust-analyzer-preview'
install: installing component 'clippy-preview'
install: installing component 'rustfmt-preview'
install: installing component 'llvm-tools-preview'
install: installing component 'rust-analysis-aarch64-unknown-linux-musl'
install: installing component 'rust-std-aarch64-unknown-linux-musl'
install: WARNING: failed to run ldconfig. this may happen when not installing as root. run with --verbose to see the error
Rust is ready to roll.
/ # cat test.rs
fn main() { println!("hello world"); }
/ # rustc test.rs
/ # ./test
hello world
# file test
test: ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV), statically linked, not stripped
```
The current description of the trivial casts lint under the "allowed
by default" listing in the rustc book indicates the lint is for lints
which may be removed, which is less clear than saying it's for lints
which may be replaced by coercion (which is the wording used by the
error message included in the doc).
This commit changes the wording slightly to better describe what the
lint does.
A few updates:
- Some minor wording and formatting changes.
- Remove the `cargo` column.
- Explain the columns up-front.
- Add no-wrap on the target-triple, which looks better to me.
- Minor mention on how to install support for a built-in target via rustup.
