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    SubjectRe: [PATCH v2] vmlinux.lds.h: Handle clang's module.{c,d}tor sections
    On Fri, Jul 30, 2021 at 7:33 PM Nathan Chancellor <nathan@kernel.org> wrote:
    >
    > A recent change in LLVM causes module_{c,d}tor sections to appear when
    > CONFIG_K{A,C}SAN are enabled, which results in orphan section warnings
    > because these are not handled anywhere:
    >
    > ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_ctor) is being placed in '.text.asan.module_ctor'
    > ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.asan.module_dtor) is being placed in '.text.asan.module_dtor'
    > ld.lld: warning: arch/x86/pci/built-in.a(legacy.o):(.text.tsan.module_ctor) is being placed in '.text.tsan.module_ctor'
    >
    > Fangrui explains: "the function asan.module_ctor has the SHF_GNU_RETAIN
    > flag, so it is in a separate section even with -fno-function-sections
    > (default)".
    >
    > Place them in the TEXT_TEXT section so that these technologies continue
    > to work with the newer compiler versions. All of the KASAN and KCSAN
    > KUnit tests continue to pass after this change.
    >
    > Cc: stable@vger.kernel.org
    > Link: https://github.com/ClangBuiltLinux/linux/issues/1432
    > Link: https://github.com/llvm/llvm-project/commit/7b789562244ee941b7bf2cefeb3fc08a59a01865
    > Signed-off-by: Nathan Chancellor <nathan@kernel.org>

    Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>

    > ---
    >
    > v1 -> v2:
    >
    > * Fix inclusion of .text.tsan.* (Nick)
    >
    > * Drop .text.asan as it does not exist plus it would be handled by a
    > different line (Fangrui)
    >
    > * Add Fangrui's explanation about why the LLVM commit caused these
    > sections to appear.
    >
    > include/asm-generic/vmlinux.lds.h | 1 +
    > 1 file changed, 1 insertion(+)
    >
    > diff --git a/include/asm-generic/vmlinux.lds.h b/include/asm-generic/vmlinux.lds.h
    > index 17325416e2de..62669b36a772 100644
    > --- a/include/asm-generic/vmlinux.lds.h
    > +++ b/include/asm-generic/vmlinux.lds.h
    > @@ -586,6 +586,7 @@
    > NOINSTR_TEXT \
    > *(.text..refcount) \
    > *(.ref.text) \
    > + *(.text.asan.* .text.tsan.*) \
    > TEXT_CFI_JT \
    > MEM_KEEP(init.text*) \
    > MEM_KEEP(exit.text*) \
    >
    > base-commit: 4669e13cd67f8532be12815ed3d37e775a9bdc16
    > --
    > 2.32.0.264.g75ae10bc75
    >


    --
    Thanks,
    ~Nick Desaulniers

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