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From:   Trevor Gross <tmgross@umich.edu>
Date:   Thu, 12 Oct 2023 16:13:10 -0400
Message-ID: <CALNs47vtnOfUarrH8qiJAZpp6bs1jjcsMyb3-A2Gy9YiaDFVEw@mail.gmail.com>
Subject: Re: [PATCH] x86: Enable IBT in Rust if enabled in C
To:     Matthew Maurer <mmaurer@google.com>
Cc:     peterz@infradead.org, Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        Miguel Ojeda <ojeda@kernel.org>,
        Alex Gaynor <alex.gaynor@gmail.com>,
        Wedson Almeida Filho <wedsonaf@gmail.com>,
        "H. Peter Anvin" <hpa@zytor.com>,
        Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>,
        =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>,
        Benno Lossin <benno.lossin@proton.me>,
        Andreas Hindborg <a.hindborg@samsung.com>,
        Alice Ryhl <aliceryhl@google.com>,
        linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org
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On Mon, Oct 9, 2023 at 6:44=E2=80=AFPM Matthew Maurer <mmaurer@google.com> =
wrote:
> +KBUILD_RUSTFLAGS +=3D -Zcf-protection=3Dbranch -Zno-jump-tables

I have not tested this, but is it possible to enable these options via
`-Cllvm-args=3D...` instead of using the unstable flags?

If so, I think this would be preferred in case the exact flags change
before they become stable. It sounds like they are likely to change,
see [1].

If not, no big deal since it would just need an update at a rust version bu=
mp.

- Trevor

[1]: https://rust-lang.zulipchat.com/#narrow/stream/131828-t-compiler/topic=
/.60-Zbranch-protection.60.20stability