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Peter Anvin" , linux-kernel@vger.kernel.org, llvm@lists.linux.dev, Boqun Feng , Gary Guo , =?ISO-8859-1?Q?Bj=F6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Daniel Almeida , Tamir Duberstein , Alexandre Courbot , =?ISO-8859-1?Q?Onur_=D6zkan?= , rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org, stable@vger.kernel.org, Kent Overstreet Subject: =?US-ASCII?Q?Re=3A_=5BPATCH=5D_x86/rust=3A_use_=60-Zindirect-?= =?US-ASCII?Q?branch-cs-prefix=60_for_RETPOLINE_builds?= User-Agent: K-9 Mail for Android In-Reply-To: References: <20261018175457.87803-1-ojeda@kernel.org> Message-ID: X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On November 10, 2026 8:31:08 PM UTC, Miguel Ojeda wrote: >On Sun, Oct 18, 2026 at 7:55=E2=80=AFPM Miguel Ojeda = wrote: >> >> The C compiler is asked to add a `cs` prefix to the `call` and `jmp` >> instructions that go through the indirect thunks for the `r8`-`r15` >> registers, which makes them 6 bytes long instead of 5=2E That gives >> `patch_retpoline()` enough room to inline them, e=2Eg=2E as `lfence; ca= ll >> *%r11` for `spectre_v2=3Dretpoline,lfence`=2E >> >> However, Rust code does not get the prefix, e=2Eg=2E for a >> `CONFIG_MITIGATION_RETPOLINE=3Dy` build: > >Any comments on this? > >If it helps, then I am happy to take it via one of the Rust trees with >an Acked-by from x86=2E > >Thanks! > >Cheers, >Miguel LGTM=2E Acked-by: Borislav Petkov --=20 Small device=2E Typos and formatting crap