Date:   Thu, 16 Mar 2023 15:33:54 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Marco Elver <elver@google.com>
Cc:     Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>, kasan-dev@googlegroups.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Nathan Chancellor <nathan@kernel.org>
Subject: Re: [PATCH] kfence, kcsan: avoid passing -g for tests
Message-Id: <20230316153354.bc31b9583eae6a79a1789de0@linux-foundation.org>
In-Reply-To: <20230316155104.594662-1-elver@google.com>
References: <20230316155104.594662-1-elver@google.com>
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On Thu, 16 Mar 2023 16:51:04 +0100 Marco Elver <elver@google.com> wrote:

> Nathan reported that when building with GNU as and a version of clang
> that defaults to DWARF5:
> 
>   $ make -skj"$(nproc)" ARCH=riscv CROSS_COMPILE=riscv64-linux-gnu- \
> 			LLVM=1 LLVM_IAS=0 O=build \
> 			mrproper allmodconfig mm/kfence/kfence_test.o
>   /tmp/kfence_test-08a0a0.s: Assembler messages:
>   /tmp/kfence_test-08a0a0.s:14627: Error: non-constant .uleb128 is not supported
>   /tmp/kfence_test-08a0a0.s:14628: Error: non-constant .uleb128 is not supported
>   /tmp/kfence_test-08a0a0.s:14632: Error: non-constant .uleb128 is not supported
>   /tmp/kfence_test-08a0a0.s:14633: Error: non-constant .uleb128 is not supported
>   /tmp/kfence_test-08a0a0.s:14639: Error: non-constant .uleb128 is not supported
>   ...
> 
> This is because `-g` defaults to the compiler debug info default. If the
> assembler does not support some of the directives used, the above errors
> occur. To fix, remove the explicit passing of `-g`.
> 
> All these tests want is that stack traces print valid function names,
> and debug info is not required for that. I currently cannot recall why I
> added the explicit `-g`.

Does this need to be backported into earlier kernels?

If so, we'd need to do it as two patches, each with the relevant
Fixes:, which appear to be a146fed56f8 and bc8fbc5f30.