linux-kernel - Re: [PATCH v6 07/19] arm64: introduce is_a32_task and is_a32

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Date:	Thu, 3 Dec 2015 12:13:03 +0000
From:	Catalin Marinas <catalin.marinas@....com>
To:	Yury Norov <ynorov@...iumnetworks.com>
Cc:	arnd@...db.de, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, pinskia@...il.com,
	Prasun.Kapoor@...iumnetworks.com, schwab@...e.de,
	Nathan_Lynch@...tor.com, agraf@...e.de, klimov.linux@...il.com,
	broonie@...nel.org, jan.dakinevich@...il.com,
	ddaney.cavm@...il.com, bamvor.zhangjian@...wei.com,
	philipp.tomsich@...obroma-systems.com, andrey.konovalov@...aro.org,
	joseph@...esourcery.com, christoph.muellner@...obroma-systems.com
Subject: Re: [PATCH v6 07/19] arm64: introduce is_a32_task and is_a32_thread
 (for AArch32 compat)

On Wed, Nov 18, 2015 at 12:16:47AM +0300, Yury Norov wrote:
> diff --git a/arch/arm64/include/asm/compat.h b/arch/arm64/include/asm/compat.h
> index 7fbed69..9700e5e 100644
> --- a/arch/arm64/include/asm/compat.h
> +++ b/arch/arm64/include/asm/compat.h
> @@ -299,19 +299,44 @@ struct compat_shmid64_ds {
>  	compat_ulong_t __unused5;
>  };
>  
> -static inline int is_compat_task(void)
> +#ifdef CONFIG_AARCH32_EL0
> +
> +static inline int is_a32_compat_task(void)
>  {
>  	return test_thread_flag(TIF_32BIT);
>  }
>  
> -static inline int is_compat_thread(struct thread_info *thread)
> +static inline int is_a32_compat_thread(struct thread_info *thread)
>  {
>  	return test_ti_thread_flag(thread, TIF_32BIT);
>  }
>  
> +#else
> +
> +static inline int is_a32_compat_task(void)
> +{
> +	return 0;
> +}
> +
> +static inline int is_a32_compat_thread(struct thread_info *thread)
> +{
> +	return 0;
> +}
> +#endif
> +
> +static inline int is_compat_task(void)
> +{
> +	return is_a32_compat_task();
> +}
> +
>  #else /* !CONFIG_COMPAT */
>  
> -static inline int is_compat_thread(struct thread_info *thread)
> +static inline int is_a32_compat_thread(struct thread_info *thread)
> +{
> +	return 0;
> +}
> +
> +static inline int is_a32_compat_task(void)
>  {
>  	return 0;
>  }

My main worry with this patch is a potential #include mess. I can see
that you already had to include asm/compat.h explicitly in
hw_breakpoint.c even though linux/compat.h was already included. In
subsequent files (asm/elf.h, asm/memory.h) you check is_compat_task()
without explicitly including asm/compat.h and hope that it won't break.

A solution would be to add these functions in a separate header file
that gets included where needed (also by asm/compat.h).

-- 
Catalin
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