Add support for -Zsanitizer-cfi-minimal-runtime

[jakos-sec]

For production use, we should only link in the ubsan_minimal runtime,
instead of the complete ubsan runtime. This adds support for both
cfi-recover and cfi-diag to use the minimal runtime when
-Zsanitizer-cfi-minimal-runtime is specified.

This also includes tests, to ensure the flag can only be used if either
cfi-recover or cfi-diag is enabled, it doesn't disrupt the original
behavior, and links in the correct runtime when specified.

cc @1c3t3a

?r rcvalle

[rustbot]

Some changes occurred in tests/codegen-llvm/sanitizer

cc @rcvalle

This PR changes how LLVM is built. Consider updating src/bootstrap/download-ci-llvm-stamp.

Some changes occurred in tests/ui/sanitizer

cc @rcvalle

[rustbot]

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[folkertdev]

r? rcvalle

[rcvalle]

Would you mind adding tests it similarly to https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/generalize-pointers-requires-cfi.rs and https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/normalize-integers-requires-cfi.rs (i.e., requires CFI, not just CFI diagnostics or CFI recovery)?

[jakos-sec]

Would you mind adding tests it similarly to https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/generalize-pointers-requires-cfi.rs and https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/normalize-integers-requires-cfi.rs (i.e., requires CFI, not just CFI diagnostics or CFI recovery)?

I'm not entirely sure what the best behavior is here. -Zsanitizer-cfi-minimal-runtime is strictly dependent on -Zsanitizer-cfi-recover / -Zsanitizer-cfi-diag (and both of those are dependent on -Zsanitizer=cfi.

Now that we have tests that cfi-diag and cfi-recover require cfi, this should already be enough. Otherwise we would need to add a separate error message for all the different cases (you need a specific error message for -Zsanitizer-cfi-minimal-runtime if used without cfi, without cfi-recover/diag or used without both).

[jakos-sec]

The job test-aarch64-gnu-llvm-21-1 failed! Check out the build log: (web) (plain enhanced) (plain)

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Failing tests I need to look at / fix before another round of reviews.

[rcvalle]

Would you mind adding tests it similarly to https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/generalize-pointers-requires-cfi.rs and https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/normalize-integers-requires-cfi.rs (i.e., requires CFI, not just CFI diagnostics or CFI recovery)?

Would you mind adding tests it similarly to https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/generalize-pointers-requires-cfi.rs and https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/normalize-integers-requires-cfi.rs (i.e., requires CFI, not just CFI diagnostics or CFI recovery)?

I'm not entirely sure what the best behavior is here. -Zsanitizer-cfi-minimal-runtime is strictly dependent on -Zsanitizer-cfi-recover / -Zsanitizer-cfi-diag (and both of those are dependent on -Zsanitizer=cfi.

Now that we have tests that cfi-diag and cfi-recover require cfi, this should already be enough. Otherwise we would need to add a separate error message for all the different cases (you need a specific error message for -Zsanitizer-cfi-minimal-runtime if used without cfi, without cfi-recover/diag or used without both).

Yes, I think this is how the Rust compiler does it and historically this is how we've been doing it. This also aligns with the philosophy of having clear and helpful error messages. In this case, with only one incorrect run, the user would be able to see both requirements without requiring one additional run.

[jakos-sec]

Would you mind adding tests it similarly to https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/generalize-pointers-requires-cfi.rs and https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/normalize-integers-requires-cfi.rs (i.e., requires CFI, not just CFI diagnostics or CFI recovery)?

Would you mind adding tests it similarly to https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/generalize-pointers-requires-cfi.rs and https://github.com/rust-lang/rust/blob/main/tests/ui/sanitizer/cfi/normalize-integers-requires-cfi.rs (i.e., requires CFI, not just CFI diagnostics or CFI recovery)?

I'm not entirely sure what the best behavior is here. -Zsanitizer-cfi-minimal-runtime is strictly dependent on -Zsanitizer-cfi-recover / -Zsanitizer-cfi-diag (and both of those are dependent on -Zsanitizer=cfi.
Now that we have tests that cfi-diag and cfi-recover require cfi, this should already be enough. Otherwise we would need to add a separate error message for all the different cases (you need a specific error message for -Zsanitizer-cfi-minimal-runtime if used without cfi, without cfi-recover/diag or used without both).

Yes, I think this is how the Rust compiler does it and historically this is how we've been doing it. This also aligns with the philosophy of having clear and helpful error messages. In this case, with only one incorrect run, the user would be able to see both requirements without requiring one additional run.

Makes sense, should be added now.

The job test-aarch64-gnu-llvm-21-1 failed! Check out the build log: (web) (plain enhanced) (plain)
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Failing tests I need to look at / fix before another round of reviews.

These should also be addressed now.

[rust-bors]

☔ The latest upstream changes (presumably #162631) made this pull request unmergeable. Please resolve the merge conflicts by rebasing.