Re: [Xen-devel] [PATCH 07/12] xen/arm: cpuerrata: Match register size with value size in check_workaround_*

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 27 Mar 2019, Julien Grall wrote:
> Clang is pickier than GCC for the register size in asm statement. It
> expects the register size to match the value size.
> 
> The asm statement expects a 32-bit (resp. 64-bit) value on Arm32
> (resp. Arm64) whereas the value is a boolean (Clang consider to be
> 32-bit).
> 
> It would be possible to impose 32-bit register for both architecture
> but this require the code to use __OP32. However, it does not really
> improve the assembly generated. Instead, replace switch the variable
> to use register_t.
> 
> Signed-off-by: Julien Grall <julien.grall@xxxxxxx>
> ---
>  xen/include/asm-arm/cpuerrata.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/xen/include/asm-arm/cpuerrata.h b/xen/include/asm-arm/cpuerrata.h
> index 55ddfda272..88ef3ca934 100644
> --- a/xen/include/asm-arm/cpuerrata.h
> +++ b/xen/include/asm-arm/cpuerrata.h
> @@ -14,7 +14,7 @@ static inline bool check_workaround_##erratum(void)         
>     \
>          return false;                                           \
>      else                                                        \
>      {                                                           \
> -        bool ret;                                               \
> +        register_t ret;                                         \
>                                                                  \
>          asm volatile (ALTERNATIVE("mov %0, #0",                 \
>                                    "mov %0, #1",                 \

This is OK. Could you please also change the return statement below?
Maybe something like:

  return unlikely(!!ret);

Thank you!

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