| From: Nathan Chancellor <nathan@kernel.org> |
| Subject: kbuild: raise the minimum supported version of LLVM to 13.0.1 |
| Date: Thu, 25 Jan 2024 15:55:07 -0700 |
| |
| Patch series "Bump the minimum supported version of LLVM to 13.0.1". |
| |
| This series bumps the minimum supported version of LLVM for building the |
| kernel to 13.0.1. The first patch does the bump and all subsequent |
| patches clean up all the various workarounds and checks for earlier |
| versions. |
| |
| Quoting the first patch's commit message for those that were only on CC |
| for the clean ups: |
| |
| When __builtin_mul_overflow() has arguments that differ in terms of |
| signedness and width, LLVM may generate a libcall to __muloti4 because |
| it performs the checks in terms of 65-bit multiplication. This issue |
| becomes harder to hit (but still possible) after LLVM 12.0.0, which |
| includes a special case for matching widths but different signs. |
| |
| To gain access to this special case, which the kernel can take advantage |
| of when calls to __muloti4 appear, bump the minimum supported version of |
| LLVM for building the kernel to 13.0.1. 13.0.1 was chosen because there |
| is minimal impact to distribution support while allowing a few more |
| workarounds to be dropped in the kernel source than if 12.0.0 were |
| chosen. Looking at container images of up to date distribution versions: |
| |
| archlinux:latest clang version 16.0.6 |
| debian:oldoldstable-slim clang version 7.0.1-8+deb10u2 (tags/RELEASE_701/final) |
| debian:oldstable-slim Debian clang version 11.0.1-2 |
| debian:stable-slim Debian clang version 14.0.6 |
| debian:testing-slim Debian clang version 16.0.6 (19) |
| debian:unstable-slim Debian clang version 16.0.6 (19) |
| fedora:38 clang version 16.0.6 (Fedora 16.0.6-3.fc38) |
| fedora:latest clang version 17.0.6 (Fedora 17.0.6-1.fc39) |
| fedora:rawhide clang version 17.0.6 (Fedora 17.0.6-1.fc40) |
| opensuse/leap:latest clang version 15.0.7 |
| opensuse/tumbleweed:latest clang version 17.0.6 |
| ubuntu:focal clang version 10.0.0-4ubuntu1 |
| ubuntu:latest Ubuntu clang version 14.0.0-1ubuntu1.1 |
| ubuntu:rolling Ubuntu clang version 16.0.6 (15) |
| ubuntu:devel Ubuntu clang version 17.0.6 (3) |
| |
| The only distribution that gets left behind is Debian Bullseye, as the |
| default version is 11.0.1; other distributions either have a newer |
| version than 13.0.1 or one older than the current minimum of 11.0.0. |
| Debian has easy access to more recent LLVM versions through |
| apt.llvm.org, so this is not as much of a concern. There are also the |
| kernel.org LLVM toolchains, which should work with distributions with |
| glibc 2.28 and newer. |
| |
| Another benefit of slimming up the number of supported versions of LLVM |
| for building the kernel is reducing the build capacity needed to support |
| a matrix that builds with each supported version, which allows a matrix |
| to reallocate the freed up build capacity towards something else, such |
| as more configuration combinations. |
| |
| This passes my build matrix with all supported versions. |
| |
| This is based on Andrew's mm-nonmm-unstable to avoid trivial conflicts |
| with my series to update the LLVM links across the repository [1] but I |
| can easily rebase it to linux-kbuild if Masahiro would rather these |
| patches go through there (and defer the conflict resolution to the merge |
| window). |
| |
| [1]: https://lore.kernel.org/20240109-update-llvm-links-v1-0-eb09b59db071@kernel.org/ |
| |
| |
| This patch (of 11): |
| |
| When __builtin_mul_overflow() has arguments that differ in terms of |
| signedness and width, LLVM may generate a libcall to __muloti4 because it |
| performs the checks in terms of 65-bit multiplication. This issue becomes |
| harder to hit (but still possible) after LLVM 12.0.0, which includes a |
| special case for matching widths but different signs. |
| |
| To gain access to this special case, which the kernel can take advantage |
| of when calls to __muloti4 appear, bump the minimum supported version of |
| LLVM for building the kernel to 13.0.1. 13.0.1 was chosen because there |
| is minimal impact to distribution support while allowing a few more |
| workarounds to be dropped in the kernel source than if 12.0.0 were chosen. |
| Looking at container images of up to date distribution versions: |
| |
| archlinux:latest clang version 16.0.6 |
| debian:oldoldstable-slim clang version 7.0.1-8+deb10u2 (tags/RELEASE_701/final) |
| debian:oldstable-slim Debian clang version 11.0.1-2 |
| debian:stable-slim Debian clang version 14.0.6 |
| debian:testing-slim Debian clang version 16.0.6 (19) |
| debian:unstable-slim Debian clang version 16.0.6 (19) |
| fedora:38 clang version 16.0.6 (Fedora 16.0.6-3.fc38) |
| fedora:latest clang version 17.0.6 (Fedora 17.0.6-1.fc39) |
| fedora:rawhide clang version 17.0.6 (Fedora 17.0.6-1.fc40) |
| opensuse/leap:latest clang version 15.0.7 |
| opensuse/tumbleweed:latest clang version 17.0.6 |
| ubuntu:focal clang version 10.0.0-4ubuntu1 |
| ubuntu:latest Ubuntu clang version 14.0.0-1ubuntu1.1 |
| ubuntu:rolling Ubuntu clang version 16.0.6 (15) |
| ubuntu:devel Ubuntu clang version 17.0.6 (3) |
| |
| The only distribution that gets left behind is Debian Bullseye, as the |
| default version is 11.0.1; other distributions either have a newer version |
| than 13.0.1 or one older than the current minimum of 11.0.0. Debian has |
| easy access to more recent LLVM versions through apt.llvm.org, so this is |
| not as much of a concern. There are also the kernel.org LLVM toolchains, |
| which should work with distributions with glibc 2.28 and newer. |
| |
| Another benefit of slimming up the number of supported versions of LLVM |
| for building the kernel is reducing the build capacity needed to support a |
| matrix that builds with each supported version, which allows a matrix to |
| reallocate the freed up build capacity towards something else, such as |
| more configuration combinations. |
| |
| Link: https://lkml.kernel.org/r/20240125-bump-min-llvm-ver-to-13-0-1-v1-0-f5ff9bda41c5@kernel.org |
| Closes: https://github.com/ClangBuiltLinux/linux/issues/1975 |
| Link: https://github.com/llvm/llvm-project/issues/38013 |
| Link: https://github.com/llvm/llvm-project/commit/3203143f1356a4e4e3ada231156fc6da6e1a9f9d |
| Link: https://mirrors.edge.kernel.org/pub/tools/llvm/ |
| Link: https://lkml.kernel.org/r/20240125-bump-min-llvm-ver-to-13-0-1-v1-1-f5ff9bda41c5@kernel.org |
| Signed-off-by: Nathan Chancellor <nathan@kernel.org> |
| Reviewed-by: Kees Cook <keescook@chromium.org> |
| Cc: Albert Ou <aou@eecs.berkeley.edu> |
| Cc: "Aneesh Kumar K.V (IBM)" <aneesh.kumar@kernel.org> |
| Cc: Ard Biesheuvel <ardb@kernel.org> |
| Cc: Borislav Petkov (AMD) <bp@alien8.de> |
| Cc: Catalin Marinas <catalin.marinas@arm.com> |
| Cc: Conor Dooley <conor@kernel.org> |
| Cc: Dave Hansen <dave.hansen@linux.intel.com> |
| Cc: Ingo Molnar <mingo@redhat.com> |
| Cc: Mark Rutland <mark.rutland@arm.com> |
| Cc: Masahiro Yamada <masahiroy@kernel.org> |
| Cc: Michael Ellerman <mpe@ellerman.id.au> |
| Cc: Nathan Chancellor <nathan@kernel.org> |
| Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com> |
| Cc: Nicholas Piggin <npiggin@gmail.com> |
| Cc: Nicolas Schier <nicolas@fjasle.eu> |
| Cc: Palmer Dabbelt <palmer@dabbelt.com> |
| Cc: Paul Walmsley <paul.walmsley@sifive.com> |
| Cc: Russell King <linux@armlinux.org.uk> |
| Cc: Thomas Gleixner <tglx@linutronix.de> |
| Cc: Will Deacon <will@kernel.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| --- |
| |
| Documentation/process/changes.rst | 2 +- |
| scripts/min-tool-version.sh | 2 +- |
| 2 files changed, 2 insertions(+), 2 deletions(-) |
| |
| --- a/Documentation/process/changes.rst~kbuild-raise-the-minimum-supported-version-of-llvm-to-1301 |
| +++ a/Documentation/process/changes.rst |
| @@ -30,7 +30,7 @@ you probably needn't concern yourself wi |
| Program Minimal version Command to check the version |
| ====================== =============== ======================================== |
| GNU C 5.1 gcc --version |
| -Clang/LLVM (optional) 11.0.0 clang --version |
| +Clang/LLVM (optional) 13.0.1 clang --version |
| Rust (optional) 1.74.1 rustc --version |
| bindgen (optional) 0.65.1 bindgen --version |
| GNU make 3.82 make --version |
| --- a/scripts/min-tool-version.sh~kbuild-raise-the-minimum-supported-version-of-llvm-to-1301 |
| +++ a/scripts/min-tool-version.sh |
| @@ -29,7 +29,7 @@ llvm) |
| elif [ "$SRCARCH" = loongarch ]; then |
| echo 18.0.0 |
| else |
| - echo 11.0.0 |
| + echo 13.0.1 |
| fi |
| ;; |
| rustc) |
| _ |
