Extends AArch64 branch protection support to include GCS

[CrooseGit]

Extends existing support for AArch64 branch protection to include support for Guarded Control Stacks.

[rustbot]

r? @davidtwco

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[rustbot]

Some changes occurred in src/doc/unstable-book/src/compiler-flags/branch-protection.md

cc @rust-lang/project-exploit-mitigations, @rcvalle

[davidtwco]

I've reviewed this internally so will reroll. GCS is exposed in Clang through their -mbranch-protection flag, so this just mirrors that like the rest of this flag.

r? compiler

[Urgau]

Seems pretty straightforward, and looks consistent with clang.

View changes since this review

[Urgau]

r=me with the updated test output and CI green

r? Urgau
@bors delegate+

[bors]

✌️ @CrooseGit, you can now approve this pull request!

If @Urgau told you to "r=me" after making some further change, please make that change, then do @bors r=@Urgau

[nnethercote]

Thanks, @Urgau!

View changes since this review

[Urgau]

Does your local rustc uses LLVM 19 (like the job)? Or are you building LLVM locally/with download-ci-llvm?

[davidtwco]

Checked locally and it's the LLVM version that is causing this, just add a //@ min-llvm-version: 21 directive only for the GCS revision (or //@ min-llvm-version: 20 if it works with that version).

[CrooseGit]

@bors r=@Urgau

Thank you

[bors]

📌 Commit 661289b has been approved by Urgau

It is now in the queue for this repository.

[rust-bors]

💔 Test for d260a23 failed: CI. Failed jobs:

• try - aarch64-apple (web logs, extended logs)

[Urgau]

@bors try jobs=aarch64

[rust-bors]

💔 Test for c3587c9 failed: CI. Failed jobs:

• try - aarch64-apple (web logs, extended logs)

[davidtwco]

@bors r=Urgau,davidtwco rollup-

@CrooseGit thinks that the CI failures should be resolved now and this will be able to be merged

[bors]

📌 Commit 08020de has been approved by Urgau,davidtwco

It is now in the queue for this repository.

[davidtwco]

@bors rollup=never

Failed in rollups a bunch previously

[bors]

⌛ Testing commit 08020de with merge 15283f6...

[bors]

☀️ Test successful - checks-actions
Approved by: Urgau,davidtwco
Pushing 15283f6 to master...

[github-actions]

What is this?

This is an experimental post-merge analysis report that shows differences in test outcomes between the merged PR and its parent PR.

Comparing e9385f9 (parent) -> 15283f6 (this PR)

Test differences

Show 30 test diffs

Stage 1

• [assembly] tests/assembly-llvm/aarch64-pointer-auth.rs#GCS: [missing] -> ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) (J0)
• [codegen] tests/codegen-llvm/branch-protection.rs#GCS: [missing] -> pass (J0)

Stage 2

• [assembly] tests/assembly-llvm/aarch64-pointer-auth.rs#GCS: [missing] -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [assembly] tests/assembly-llvm/nvptx-safe-naming.rs#LLVM21: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [assembly] tests/assembly-llvm/sanitizer/kcfi/emit-arity-indicator.rs#x86_64: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [codegen] tests/codegen-llvm/dead_on_return.rs: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [codegen] tests/codegen-llvm/enum/enum-discriminant-eq.rs#LLVM21: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [codegen] tests/codegen-llvm/issues/issue-101082.rs#x86-64-v3: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [codegen] tests/codegen-llvm/issues/issue-122734-match-eq.rs: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [codegen] tests/codegen-llvm/issues/matches-logical-or-141497.rs: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [codegen] tests/codegen-llvm/issues/saturating-sub-index-139759.rs: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [codegen] tests/codegen-llvm/option-niche-eq.rs#LLVM21: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [codegen] tests/codegen-llvm/read-only-capture-opt.rs: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [codegen] tests/codegen-llvm/sanitizer/kcfi/add-kcfi-arity-flag.rs#x86_64: ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) -> ignore (ignored when the LLVM version 20.1.8 is older than 21.0.0) (J1)
• [debuginfo-gdb] tests/debuginfo/include_string.rs: pass -> ignore (ignored when the GDB version is between 15.0 - 99.0) (J2)
• [debuginfo-gdb] tests/debuginfo/macro-stepping.rs: ignore (ignored when the GDB version is lower than 13.0) -> ignore (ignored when the architecture is aarch64) (J2)
• [debuginfo-gdb] tests/debuginfo/method-on-enum.rs: ignore (ignored when the GDB version is lower than 13.0) -> pass (J2)
• [debuginfo-gdb] tests/debuginfo/multiline-calls.rs: ignore (ignored when the GDB version is lower than 16.0) -> pass (J2)
• [debuginfo-gdb] tests/debuginfo/option-like-enum.rs: ignore (ignored when the GDB version is lower than 13.0) -> pass (J2)
• [debuginfo-gdb] tests/debuginfo/strings-and-strs.rs: ignore (ignored when the GDB version is lower than 14.0) -> pass (J2)
• [debuginfo-gdb] tests/debuginfo/unsized.rs: pass -> ignore (ignored when the GDB version is between 13.1 - 99.0) (J2)
• [debuginfo-gdb] tests/debuginfo/vec-slices.rs: pass -> ignore (ignored when the GDB version is between 15.0 - 99.0) (J2)
• [assembly] tests/assembly-llvm/aarch64-pointer-auth.rs#GCS: [missing] -> pass (J3)
• [assembly] tests/assembly-llvm/aarch64-pointer-auth.rs#GCS: [missing] -> ignore (ignored when the target vendor is Apple ((XCode version needs updating))) (J4)
• [run-make] tests/run-make/pointer-auth-link-with-c: pass -> ignore (ignored when the target vendor is Apple) (J4)
• [run-make] tests/run-make/pointer-auth-link-with-c-lto-clang: ignore (ignored when RUSTBUILD_FORCE_CLANG_BASED_TESTS is not set) -> ignore (ignored when the target vendor is Apple) (J4)
• [assembly] tests/assembly-llvm/aarch64-pointer-auth.rs#GCS: [missing] -> ignore (ignored when the LLVM version 20.1.2 is older than 21.0.0) (J5)
• [codegen] tests/codegen-llvm/branch-protection.rs#GCS: [missing] -> pass (J6)

Additionally, 2 doctest diffs were found. These are ignored, as they are noisy.

Job group index

• J0: x86_64-gnu-llvm-20-3
• J1: aarch64-gnu-llvm-20-1
• J2: aarch64-gnu
• J3: aarch64-gnu, aarch64-msvc-1, arm-android, armhf-gnu, dist-i586-gnu-i586-i686-musl, i686-gnu-1, i686-gnu-nopt-1, i686-msvc-1, test-various, x86_64-gnu, x86_64-gnu-nopt, x86_64-gnu-stable, x86_64-mingw-1, x86_64-msvc-1
• J4: aarch64-apple
• J5: x86_64-gnu-llvm-20-2
• J6: aarch64-apple, aarch64-gnu, aarch64-gnu-llvm-20-1, aarch64-msvc-1, arm-android, armhf-gnu, dist-i586-gnu-i586-i686-musl, i686-gnu-1, i686-gnu-nopt-1, i686-msvc-1, test-various, x86_64-gnu, x86_64-gnu-llvm-20-2, x86_64-gnu-nopt, x86_64-gnu-stable, x86_64-mingw-1, x86_64-msvc-1

Test dashboard

Run

cargo run --manifest-path src/ci/citool/Cargo.toml -- \
    test-dashboard 15283f6fe95e5b604273d13a428bab5fc0788f5a --output-dir test-dashboard

And then open test-dashboard/index.html in your browser to see an overview of all executed tests.

Job duration changes

1. aarch64-gnu-debug: 4081.5s -> 9697.6s (137.6%)
2. aarch64-gnu: 6710.2s -> 8865.2s (32.1%)
3. pr-check-1: 1474.0s -> 1857.3s (26.0%)
4. aarch64-gnu-llvm-20-2: 2154.5s -> 2626.6s (21.9%)
5. x86_64-gnu-llvm-20: 2361.1s -> 2789.7s (18.2%)
6. dist-apple-various: 3663.1s -> 4259.5s (16.3%)
7. aarch64-gnu-llvm-20-1: 3383.6s -> 3921.4s (15.9%)
8. pr-check-2: 2180.3s -> 2478.9s (13.7%)
9. i686-gnu-nopt-1: 7277.3s -> 8090.1s (11.2%)
10. i686-gnu-2: 5482.1s -> 6011.9s (9.7%)

How to interpret the job duration changes?

Job durations can vary a lot, based on the actual runner instance
that executed the job, system noise, invalidated caches, etc. The table above is provided
mostly for t-infra members, for simpler debugging of potential CI slow-downs.

[rust-timer]

Finished benchmarking commit (15283f6): comparison URL.

Overall result: ❌✅ regressions and improvements - no action needed

@rustbot label: -perf-regression

Instruction count

Our most reliable metric. Used to determine the overall result above. However, even this metric can be noisy.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	0.2%	[0.2%, 0.2%]	1
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-0.3%	[-0.3%, -0.3%]	1
All ❌✅ (primary)	-	-	0

Max RSS (memory usage)

Results (primary -0.7%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	2.1%	[2.1%, 2.1%]	1
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-3.5%	[-3.5%, -3.5%]	1
Improvements ✅ (secondary)	-	-	0
All ❌✅ (primary)	-0.7%	[-3.5%, 2.1%]	2

Cycles

Results (secondary -3.1%)

A less reliable metric. May be of interest, but not used to determine the overall result above.

	mean	range	count
Regressions ❌ (primary)	-	-	0
Regressions ❌ (secondary)	-	-	0
Improvements ✅ (primary)	-	-	0
Improvements ✅ (secondary)	-3.1%	[-3.5%, -2.7%]	2
All ❌✅ (primary)	-	-	0

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 471.559s -> 471.213s (-0.07%)
Artifact size: 387.91 MiB -> 387.83 MiB (-0.02%)