[PATCH] ARM: Change arch/arm/lib/mem*.S to use WEAK instead of .weak

[Nick Desaulniers]

On Thu, Nov 5, 2020 at 10:15 AM Fangrui Song <maskray at google.com> wrote:
>
> Commit d6d51a96c7d6 ("ARM: 9014/2: Replace string mem* functions for
> KASan") add .weak directives to memcpy/memmove/memset to avoid collision
> with KASAN interceptors.
>
> This does not work with LLVM's integrated assembler (the assembly snippet
> `.weak memcpy ... .globl memcpy` produces a STB_GLOBAL memcpy while GNU as
> produces a STB_WEAK memcpy). LLVM 12 (since https://reviews.llvm.org/D90108)
> will error on such an overridden symbol binding.
>
> Use the appropriate WEAK macro instead.
>
> Fixes: d6d51a96c7d6 ("ARM: 9014/2: Replace string mem* functions for KASan")
> Reported-by: Nick Desaulniers <ndesaulniers at google.com>
> Signed-off-by: Fangrui Song <maskray at google.com>
> Link: https://github.com/ClangBuiltLinux/linux/issues/1190

Thank you, this fixes a recent regression for me using LLVM_IAS=1 with ToT LLVM.

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

> ---
>  arch/arm/lib/memcpy.S  | 3 +--
>  arch/arm/lib/memmove.S | 3 +--
>  arch/arm/lib/memset.S  | 3 +--
>  3 files changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm/lib/memcpy.S b/arch/arm/lib/memcpy.S
> index ad4625d16e11..e4caf48c089f 100644
> --- a/arch/arm/lib/memcpy.S
> +++ b/arch/arm/lib/memcpy.S
> @@ -58,10 +58,9 @@
>
>  /* Prototype: void *memcpy(void *dest, const void *src, size_t n); */
>
> -.weak memcpy
>  ENTRY(__memcpy)
>  ENTRY(mmiocpy)
> -ENTRY(memcpy)
> +WEAK(memcpy)
>
>  #include "copy_template.S"
>
> diff --git a/arch/arm/lib/memmove.S b/arch/arm/lib/memmove.S
> index fd123ea5a5a4..6fecc12a1f51 100644
> --- a/arch/arm/lib/memmove.S
> +++ b/arch/arm/lib/memmove.S
> @@ -24,9 +24,8 @@
>   * occurring in the opposite direction.
>   */
>
> -.weak memmove
>  ENTRY(__memmove)
> -ENTRY(memmove)
> +WEAK(memmove)
>         UNWIND( .fnstart                        )
>
>                 subs    ip, r0, r1
> diff --git a/arch/arm/lib/memset.S b/arch/arm/lib/memset.S
> index 0e7ff0423f50..9817cb258c1a 100644
> --- a/arch/arm/lib/memset.S
> +++ b/arch/arm/lib/memset.S
> @@ -13,10 +13,9 @@
>         .text
>         .align  5
>
> -.weak memset
>  ENTRY(__memset)
>  ENTRY(mmioset)
> -ENTRY(memset)
> +WEAK(memset)
>  UNWIND( .fnstart         )
>         ands    r3, r0, #3              @ 1 unaligned?
>         mov     ip, r0                  @ preserve r0 as return value
> --
> 2.29.1.341.ge80a0c044ae-goog
>


-- 
Thanks,
~Nick Desaulniers