Extends AArch64 branch protection support to include GCS #146338

CrooseGit · 2025-09-08T15:32:01Z

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

- Adds option to rustc config to enable GCS - Passes `guarded-control-stack` flag to llvm if enabled

rustbot · 2025-09-08T15:32:06Z

rustbot has assigned @davidtwco.
They will have a look at your PR within the next two weeks and either review your PR or reassign to another reviewer.

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rustbot · 2025-09-08T15:32:10Z

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

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

davidtwco · 2025-09-08T15:35:55Z

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.

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Urgau · 2025-09-08T16:08:54Z

tests/ui/invalid-compile-flags/branch-protection-missing-pac-ret.BADFLAGS.stderr

@@ -1,2 +1,2 @@
-error: incorrect value `leaf` for unstable option `branch-protection` - a `,` separated combination of `bti`, `pac-ret`, followed by a combination of `pc`, `b-key`, or `leaf` was expected
+error: incorrect value `leaf` for unstable option `branch-protection` - a `,` separated combination of `bti`, `gcs`, `pac-ret`, followed by a combination of `pc`, `b-key`, or `leaf` was expected


(this will need to be blessed, as per the updated description)

Ah yes, thank you. I have now fixed it.

Urgau · 2025-09-08T16:11:04Z

r=me with the updated test output and CI green

r? Urgau
@bors delegate+

bors · 2025-09-08T16:11:07Z

✌️ @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!

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Urgau · 2025-09-09T15:27:04Z

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

davidtwco · 2025-09-09T16:48:11Z

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 · 2025-09-11T09:51:30Z

@bors r=@Urgau

Thank you

bors · 2025-09-11T09:51:33Z

📌 Commit 661289b has been approved by Urgau

It is now in the queue for this repository.

…ble-GCS, r=Urgau Extends AArch64 branch protection support to include GCS Extends existing support for AArch64 branch protection to include support for [Guarded Control Stacks](https://community.arm.com/arm-community-blogs/b/architectures-and-processors-blog/posts/arm-a-profile-architecture-2022#guarded-control-stack-gcs:~:text=Extraction%20or%20tracking.-,Guarded%20Control%20Stack%20(GCS),-With%20the%202022).

Rollup of 16 pull requests Successful merges: - #145660 (initial implementation of the darwin_objc unstable feature) - #145895 (thread parking: fix docs and examples) - #146308 (support integer literals in `${concat()}`) - #146323 (check before test for hardware capabilites in bits 32~63 of usize) - #146332 (tidy: make behavior of extra-checks more uniform) - #146338 (Extends AArch64 branch protection support to include GCS) - #146374 (Update `browser-ui-test` version to `0.22.2`) - #146413 (Improve suggestion in case a bare URL is surrounded by brackets) - #146426 (Bump miow to 0.60.1) - #146432 (Implement `Socket::take_error` for Hermit) - #146433 (rwlock tests: fix miri macos test regression) - #146435 (Change the default value of `gcc.download-ci-gcc` to `true`) - #146439 (fix cfg for poison test macro) - #146448 ([rustdoc] Correctly handle literal search on paths) - #146449 (Fix `libgccjit` symlink when we build GCC locally) - #146455 (test: remove an outdated normalization for rustc versions) Failed merges: - #146389 (Convert `no_std` and `no_core` to the new attribute infrastructure) r? `@ghost` `@rustbot` modify labels: rollup

Zalathar · 2025-09-12T04:01:15Z

Probably failed in rollup: #146461 (comment)

@bors r-

Zalathar · 2025-09-12T04:01:50Z

@bors try jobs=x86_64-gnu-llvm-20-3

…<try> Extends AArch64 branch protection support to include GCS try-job: x86_64-gnu-llvm-20-3

rust-bors · 2025-09-12T04:45:07Z

💔 Test for a1acb51 failed: CI. Failed jobs:

try - x86_64-gnu-llvm-20-3 (web logs, extended logs)

GCS support was added to GCC in version 15, thus the rmake test for this patch requires GCC15

CrooseGit · 2025-09-15T12:39:34Z

@bors r=@Urgau

I believe I have fixed the issue that caused the CI to fail in the rollup.
Thanks again.

bors · 2025-09-15T12:39:37Z

📌 Commit dbb94e7 has been approved by Urgau

It is now in the queue for this repository.

…ble-GCS, r=Urgau Extends AArch64 branch protection support to include GCS Extends existing support for AArch64 branch protection to include support for [Guarded Control Stacks](https://community.arm.com/arm-community-blogs/b/architectures-and-processors-blog/posts/arm-a-profile-architecture-2022#guarded-control-stack-gcs:~:text=Extraction%20or%20tracking.-,Guarded%20Control%20Stack%20(GCS),-With%20the%202022).

Adds AArch64 GCS support

d2f21b8

- Adds option to rustc config to enable GCS - Passes `guarded-control-stack` flag to llvm if enabled

rustbot assigned davidtwco Sep 8, 2025

rustbot assigned nnethercote and unassigned davidtwco Sep 8, 2025

Urgau approved these changes Sep 8, 2025

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rustbot assigned Urgau Sep 8, 2025

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CrooseGit force-pushed the dev/reucru01/AArch64-enable-GCS branch from b50c4db to d949360 Compare September 9, 2025 10:11

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CrooseGit force-pushed the dev/reucru01/AArch64-enable-GCS branch from d949360 to 7ade636 Compare September 10, 2025 10:25

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rustbot added A-CI Area: Our Github Actions CI A-testsuite Area: The testsuite used to check the correctness of rustc T-infra Relevant to the infrastructure team, which will review and decide on the PR/issue. labels Sep 10, 2025

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Sep 11, 2025

Zalathar mentioned this pull request Sep 12, 2025

Rollup of 16 pull requests #146461

Closed

bors added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. labels Sep 12, 2025

rust-bors bot added a commit that referenced this pull request Sep 12, 2025

Auto merge of #146338 - CrooseGit:dev/reucru01/AArch64-enable-GCS, r=…

a1acb51

…<try> Extends AArch64 branch protection support to include GCS try-job: x86_64-gnu-llvm-20-3

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CrooseGit added 2 commits September 15, 2025 10:29

Extends branch protection tests to include GCS

3a57d28

Updates arch64 llvm-19 CI to use GCC15

dbb94e7

GCS support was added to GCC in version 15, thus the rmake test for this patch requires GCC15

CrooseGit force-pushed the dev/reucru01/AArch64-enable-GCS branch from 661289b to dbb94e7 Compare September 15, 2025 09:33

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Sep 15, 2025

Zalathar mentioned this pull request Sep 15, 2025

Rollup of 12 pull requests #146589

Open

		@@ -1,2 +1,2 @@
		error: incorrect value `leaf` for unstable option `branch-protection` - a `,` separated combination of `bti`, `pac-ret`, followed by a combination of `pc`, `b-key`, or `leaf` was expected
		error: incorrect value `leaf` for unstable option `branch-protection` - a `,` separated combination of `bti`, `gcs`, `pac-ret`, followed by a combination of `pc`, `b-key`, or `leaf` was expected

Extends AArch64 branch protection support to include GCS #146338

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Extends AArch64 branch protection support to include GCS #146338

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