clang-nightly: ERROR: modpost: "wcslen" [fs/smb/client/cifs.ko] undefined!

clang-nightly: ERROR: modpost: "wcslen" [fs/smb/client/cifs.ko] undefined!

[Naresh Kamboju]

Regressions on arm, powerpc, s390 defconfig builds failed with
toolchain clang-nightly on the mainline master branch.

First seen on the v6.14-12245-g91e5bfe317d8
 Good: v6.14-11270-g08733088b566
 Bad: v6.14-12245-g91e5bfe317d8

Regressions found on arm:
  - build/clang-nightly-nhk8815_defconfig

Regressions found on powerpc:
  - build/clang-nightly-lkftconfig-lto-full
  - build/clang-nightly-ppc64e_defconfig
  - build/clang-nightly-lkftconfig-lto-thing
  - build/clang-nightly-defconfig
  - build/clang-nightly-lkftconfig-hardening

Regressions found on s390:
  - build/clang-nightly-lkftconfig-lto-thing
  - build/clang-nightly-lkftconfig-lto-full
  - build/clang-nightly-defconfig
  - build/clang-nightly-lkftconfig-hardening


Regression Analysis:
 - New regression? Yes
 - Reproducibility? Yes

Build regression: arm powerpc s390 modpost "wcslen" fs smb client
cifs.ko undefined

Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>

## Build log

ERROR: modpost: "wcslen" [fs/smb/client/cifs.ko] undefined!

## Source
* Kernel version: 6.14.0
* Git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
* Git sha: 91e5bfe317d8f8471fbaa3e70cf66cae1314a516
* Git describe: v6.14-12245-g91e5bfe317d8
* Project details:
https://qa-reports.linaro.org/lkft/linux-mainline-master/build/v6.14-12245-g91e5bfe317d8/
* Arcitures: arm, powerpc, s390
* Toolchains: clang-nightly

## Build
* Build log: https://qa-reports.linaro.org/lkft/linux-mainline-master/build/v6.14-12245-g91e5bfe317d8/testrun/27856145/suite/build/test/clang-nightly-nhk8815_defconfig/log
* Build history:
https://qa-reports.linaro.org/lkft/linux-mainline-master/build/v6.14-12245-g91e5bfe317d8/testrun/27856145/suite/build/test/clang-nightly-nhk8815_defconfig/history/
* Build details:
https://qa-reports.linaro.org/lkft/linux-mainline-master/build/v6.14-12245-g91e5bfe317d8/testrun/27856145/suite/build/test/clang-nightly-nhk8815_defconfig/
* Build link: https://storage.tuxsuite.com/public/linaro/lkft/builds/2v9EdO7KHQCCZBICM0MvpaTUbLm/
* Kernel config:
https://storage.tuxsuite.com/public/linaro/lkft/builds/2v9EdO7KHQCCZBICM0MvpaTUbLm/config

## Steps to reproduce
 - tuxmake --runtime podman --target-arch arm --toolchain
clang-nightly --kconfig nhk8815_defconfig LLVM=1 LLVM_IAS=1
 - tuxmake --runtime podman --target-arch powerpc --toolchain
clang-nightly --kconfig defconfig LLVM=1 LLVM_IAS=0
LD=powerpc64le-linux-gnu-ld
 - tuxmake --runtime podman --target-arch s390 --toolchain
clang-nightly --kconfig defconfig LLVM_IAS=1

--
Linaro LKFT
https://lkft.linaro.org

Re: clang-nightly: ERROR: modpost: "wcslen" [fs/smb/client/cifs.ko] undefined!

[Arnd Bergmann]

On Wed, Apr 2, 2025, at 14:21, Naresh Kamboju wrote:
> Build regression: arm powerpc s390 modpost "wcslen" fs smb client
> cifs.ko undefined
>
> Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
>
> ## Build log
>
> ERROR: modpost: "wcslen" [fs/smb/client/cifs.ko] undefined!

This is from the latest clang release, and Nathan already sent a fix:

https://lore.kernel.org/lkml/20250328-string-add-wcslen-for-llvm-opt-v3-1-a180b4c0c1c4@kernel.org/

     Arnd