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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-4412150a092sm23750898f8f.23.2026.04.24.02.14.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 24 Apr 2026 02:14:27 -0700 (PDT) Date: Fri, 24 Apr 2026 10:14:25 +0100 From: David Laight To: "Mukesh Kumar Chaurasiya (IBM)" Cc: maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, peterz@infradead.org, jpoimboe@kernel.org, jbaron@akamai.com, aliceryhl@google.com, rostedt@goodmis.org, ardb@kernel.org, sumit.semwal@linaro.org, christian.koenig@amd.com, ojeda@kernel.org, boqun@kernel.org, gary@garyguo.net, bjorn3_gh@protonmail.com, lossin@kernel.org, a.hindborg@kernel.org, tmgross@umich.edu, dakr@kernel.org, nathan@kernel.org, nick.desaulniers+lkml@gmail.com, morbo@google.com, justinstitt@google.com, tamird@kernel.org, arnd@arndb.de, nsc@kernel.org, simona.vetter@ffwll.ch, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linaro-mm-sig@lists.linaro.org, rust-for-linux@vger.kernel.org, llvm@lists.linux.dev, Link Mauve Subject: Re: [PATCH V13 5/7] rust: Make __udivdi3() and __umoddi3() panic Message-ID: <20260424101425.6bde0e17@pumpkin> In-Reply-To: <20260424054742.45832-6-mkchauras@gmail.com> References: <20260424054742.45832-1-mkchauras@gmail.com> <20260424054742.45832-6-mkchauras@gmail.com> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Fri, 24 Apr 2026 11:17:40 +0530 "Mukesh Kumar Chaurasiya (IBM)" wrote: > From: Link Mauve >=20 > The core crate currently depends on these two functions for i64/u64/ > i128/u128/core::time::Duration formatting, but we shouldn=E2=80=99t use t= hat in > the kernel so let=E2=80=99s panic if they are ever called. Ugg. Surely you can make it a link-time failure? Or change the underlying code to avoid the divide. David >=20 > This doesn=E2=80=99t yet fix drm_panic_qr.rs, which also uses __udivdi3 w= hen > CONFIG_CC_OPTIMIZE_FOR_SIZE=3Dy, but at least makes the rest of the kernel > build on PPC32. >=20 > Signed-off-by: Link Mauve > Signed-off-by: Mukesh Kumar Chaurasiya (IBM) > --- > rust/Makefile | 4 ++++ > rust/compiler_builtins.rs | 6 ++++++ > 2 files changed, 10 insertions(+) >=20 > diff --git a/rust/Makefile b/rust/Makefile > index 2a5428a5503d..ee11fba7a03d 100644 > --- a/rust/Makefile > +++ b/rust/Makefile > @@ -616,6 +616,10 @@ ifneq ($(or $(CONFIG_ARM64),$(and $(CONFIG_RISCV),$(= CONFIG_64BIT))),) > __ashrti3 \ > __ashlti3 __lshrti3 > endif > +ifdef CONFIG_PPC32 > + redirect-intrinsics +=3D \ > + __udivdi3 __umoddi3 > +endif > =20 > ifdef CONFIG_MODVERSIONS > cmd_gendwarfksyms =3D $(if $(skip_gendwarfksyms),, \ > diff --git a/rust/compiler_builtins.rs b/rust/compiler_builtins.rs > index dd16c1dc899c..fc6b54636dd5 100644 > --- a/rust/compiler_builtins.rs > +++ b/rust/compiler_builtins.rs > @@ -97,5 +97,11 @@ pub extern "C" fn $ident() { > __aeabi_uldivmod, > }); > =20 > +#[cfg(target_arch =3D "powerpc")] > +define_panicking_intrinsics!("`u64` division/modulo should not be used",= { > + __udivdi3, > + __umoddi3, > +}); > + > // NOTE: if you are adding a new intrinsic here, you should also add it = to > // `redirect-intrinsics` in `rust/Makefile`.