Re: [PATCH 09/14] KVM: selftests: Explicitly disable builtins for mem*() overrides

[Paolo Bonzini]

On 12/13/22 01:16, Sean Christopherson wrote:
> Explicitly disable the compiler's builtin memcmp(), memcpy(), and
> memset().  Because only lib/string_override.c is built with -ffreestanding,
> the compiler reserves the right to do what it wants and can try to link the
> non-freestanding code to its own crud.
>
>    /usr/bin/x86_64-linux-gnu-ld: /lib/x86_64-linux-gnu/libc.a(memcmp.o): in function `memcmp_ifunc':
>    (.text+0x0): multiple definition of `memcmp'; tools/testing/selftests/kvm/lib/string_override.o:
>    tools/testing/selftests/kvm/lib/string_override.c:15: first defined here
>    clang: error: linker command failed with exit code 1 (use -v to see invocation)

Hmm, that's weird though.  I think it's an effect of ifunc and maybe 
even a linker bug.  The patch makes sense anyway.

Paolo