Kernel build: arch/x86/tools/insn_decoder_test: error: malformed line

[dhodovsk]

While testing the mainline kernel, we get an error during the x86_64 build:

00:29:20 arch/x86/tools/insn_decoder_test: error: malformed line 3733181:
00:29:20 2_>:ffffffff81c92050
00:29:20 make[4]: *** [arch/x86/tools/Makefile:26: posttest] Error 3
00:29:20 make[3]: *** [arch/x86/Makefile:310: bzImage] Error 2
00:29:20 make[3]: *** Waiting for unfinished jobs....

For us, it started happening two weeks ago, since the Merge tag 'rust-6.13' of https://github.com/Rust-for-Linux/linux commit in kernel mainline.

The issue was already discussed in linux-kernel Mailing List, but it seems the suggested patches didn't come through.

Links:

• list of the affected trees and branches: https://datawarehouse.cki-project.org/issue/3332
• our pipeline: https://gitlab.com/redhat/red-hat-ci-tools/kernel/cki-internal-pipelines/cki-trusted-contributors/-/jobs/8607023441
• the full build log: https://s3.amazonaws.com/arr-cki-prod-trusted-artifacts/trusted-artifacts/1583189702/build_x86_64/8607023441/artifacts/build.log
• kernel config: https://s3.amazonaws.com/arr-cki-prod-trusted-artifacts/trusted-artifacts/1583189702/build_x86_64/8607023441/artifacts/kernel-upstream-mainline-redhat_1583189702-x86_64-kernel.config

---

I first wrongly reported this in the clang repo and they pointed me to this repository and also provided a reproducer :)

f92f4749861b ("Merge tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux")

$ rustc --version
rustc 1.83.0 (90b35a623 2024-11-26)

$ clang --version | head -1
ClangBuiltLinux clang version 19.1.5 (https://github.com/llvm/llvm-project.git ab4b5a2db582958af1ee308a790cfdb42bd24720)

$ curl -LSso .config https://s3.amazonaws.com/arr-cki-prod-trusted-artifacts/trusted-artifacts/1583189702/build_x86_64/8607023441/artifacts/kernel-upstream-mainline-redhat_1583189702-x86_64-kernel.config

$ make -skj"$(nproc)" ARCH=x86_64 LLVM=1 olddefconfig bzImage
...
arch/x86/tools/insn_decoder_test: error: malformed line 3735255:
2_>:ffffffff81c94190
make[4]: *** [arch/x86/tools/Makefile:26: posttest] Error 3
...

[ojeda]

Thanks for the report -- yeah, the issue is known and old. The latest report (and patch) about it that I am aware of is https://lore.kernel.org/rust-for-linux/CANiq72nyMi5NUwmg20ZzX8RNC8+dP2J3Zey9Qfn+5CaoeET+7A@mail.gmail.com/.

Could you please reply (ping) in Lore, i.e. in one of the proposed patches like the one above? If this is breaking a particularly important use case (e.g. at your company), then it may be useful to mention that clearly in the message so that they raise the priority of this.

Thanks!

[sergiocollado]

Hello,
This should be fixed with this patch:
https://lore.kernel.org/rust-for-linux/CABVgOSm=5Q0fM6neBhxSbOUHBgNzmwf2V22vsYC10YRBT=kN1g@mail.gmail.com/T/#t

[ojeda]

Yeah, that is commit c104c16 ("Kunit to check the longest symbol length") that landed in v6.15, so I think this can be closed.

Having said that, should it be backported to the LTSs? i.e. at least the arch/x86/tools/insn_decoder_test.c part. (I replied on the list since I cannot find the handles of everybody, sorry! @sulix @shuahkh)

If so, @sergiocollado, would you like to submit it? It is not a complex procedure, and may be a nice experience (https://docs.kernel.org/process/stable-kernel-rules.html). Otherwise, I or someone else can do that.

Thanks!

[sergiocollado]

sure, I will backport it