Re: [Xen-devel] [PATCH v3 6/9] x86/genapic: patch indirect calls to direct ones

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Tue, Sep 11, 2018 at 07:35:33AM -0600, Jan Beulich wrote:
> For (I hope) obvious reasons only the ones used at runtime get
> converted.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> v2: Drop open-coded numbers from macro invocations.
> 
> --- a/xen/arch/x86/smp.c
> +++ b/xen/arch/x86/smp.c
> @@ -29,12 +29,12 @@
>  
>  void send_IPI_mask(const cpumask_t *mask, int vector)
>  {
> -    genapic.send_IPI_mask(mask, vector);
> +    alternative_vcall(genapic.send_IPI_mask, mask, vector);
>  }
>  
>  void send_IPI_self(int vector)
>  {
> -    genapic.send_IPI_self(vector);
> +    alternative_vcall(genapic.send_IPI_self, vector);
>  }
>  
>  /*
> --- a/xen/include/asm-x86/mach-generic/mach_apic.h
> +++ b/xen/include/asm-x86/mach-generic/mach_apic.h
> @@ -15,8 +15,18 @@
>  #define TARGET_CPUS ((const typeof(cpu_online_map) *)&cpu_online_map)
>  #define init_apic_ldr (genapic.init_apic_ldr)
>  #define clustered_apic_check (genapic.clustered_apic_check)
> -#define cpu_mask_to_apicid (genapic.cpu_mask_to_apicid)
> -#define vector_allocation_cpumask(cpu) 
> (genapic.vector_allocation_cpumask(cpu))
> +#define cpu_mask_to_apicid(mask) ({ \
> +     /* \
> +      * There are a number of places where the address of a local variable \
> +      * gets passed here. The use of ?: in alternative_call<N>() triggers an 
> \
> +      * "address of ... is always true" warning in such a case with at least 
> \
> +      * gcc 7 and 8. Hence the seemingly pointless local variable here. \
> +      */ \

Is this still needed given you have brought back the middle operand in ?: in
patch 1?

Wei.

> +     const cpumask_t *m_ = (mask); \
> +     alternative_call(genapic.cpu_mask_to_apicid, m_); \
> +})
> +#define vector_allocation_cpumask(cpu) \
> +     alternative_call(genapic.vector_allocation_cpumask, cpu)
>  
>  static inline void enable_apic_mode(void)
>  {
> 
> 
> 
> 

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