linux-kernel - Re: [PATCH v12 1/6] uaccess: add generic fallback version of copy_mc_to

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Message-ID: <20240711155343.3729bc30@foz.lan>
Date: Thu, 11 Jul 2024 15:53:43 +0200
From: Mauro Carvalho Chehab <mchehab+huawei@...nel.org>
To: Tong Tiangen <tongtiangen@...wei.com>
Cc: Mark Rutland <mark.rutland@....com>, Catalin Marinas
 <catalin.marinas@....com>, Will Deacon <will@...nel.org>, Andrew Morton
 <akpm@...ux-foundation.org>, James Morse <james.morse@....com>, Robin
 Murphy <robin.murphy@....com>, Andrey Konovalov <andreyknvl@...il.com>,
 Dmitry Vyukov <dvyukov@...gle.com>, Vincenzo Frascino
 <vincenzo.frascino@....com>, Michael Ellerman <mpe@...erman.id.au>,
 Nicholas Piggin <npiggin@...il.com>, Andrey Ryabinin
 <ryabinin.a.a@...il.com>, Alexander Potapenko <glider@...gle.com>,
 Christophe Leroy <christophe.leroy@...roup.eu>, "Aneesh Kumar K.V"
 <aneesh.kumar@...nel.org>, "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
 Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
 <linux-arm-kernel@...ts.infradead.org>, <linux-mm@...ck.org>,
 <linuxppc-dev@...ts.ozlabs.org>, <linux-kernel@...r.kernel.org>,
 <wangkefeng.wang@...wei.com>, Guohanjun <guohanjun@...wei.com>
Subject: Re: [PATCH v12 1/6] uaccess: add generic fallback version of
 copy_mc_to_user()

Em Tue, 28 May 2024 16:59:10 +0800
Tong Tiangen <tongtiangen@...wei.com> escreveu:

> x86/powerpc has it's implementation of copy_mc_to_user(), we add generic
> fallback in include/linux/uaccess.h prepare for other architechures to
> enable CONFIG_ARCH_HAS_COPY_MC.
> 
> Signed-off-by: Tong Tiangen <tongtiangen@...wei.com>
> Acked-by: Michael Ellerman <mpe@...erman.id.au>
> ---
>  arch/powerpc/include/asm/uaccess.h | 1 +
>  arch/x86/include/asm/uaccess.h     | 1 +
>  include/linux/uaccess.h            | 8 ++++++++
>  3 files changed, 10 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/uaccess.h b/arch/powerpc/include/asm/uaccess.h
> index de10437fd206..df42e6ad647f 100644
> --- a/arch/powerpc/include/asm/uaccess.h
> +++ b/arch/powerpc/include/asm/uaccess.h
> @@ -381,6 +381,7 @@ copy_mc_to_user(void __user *to, const void *from, unsigned long n)
>  
>  	return n;
>  }
> +#define copy_mc_to_user copy_mc_to_user

Such define looks weird on my eyes. What to do you want to do here?

>  #endif
>  
>  extern long __copy_from_user_flushcache(void *dst, const void __user *src,
> diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h
> index 0f9bab92a43d..309f2439327e 100644
> --- a/arch/x86/include/asm/uaccess.h
> +++ b/arch/x86/include/asm/uaccess.h
> @@ -497,6 +497,7 @@ copy_mc_to_kernel(void *to, const void *from, unsigned len);
>  
>  unsigned long __must_check
>  copy_mc_to_user(void __user *to, const void *from, unsigned len);
> +#define copy_mc_to_user copy_mc_to_user

Same here.

>  #endif
>  
>  /*
> diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h
> index 3064314f4832..0dfa9241b6ee 100644
> --- a/include/linux/uaccess.h
> +++ b/include/linux/uaccess.h
> @@ -205,6 +205,14 @@ copy_mc_to_kernel(void *dst, const void *src, size_t cnt)
>  }
>  #endif
>  
> +#ifndef copy_mc_to_user
> +static inline unsigned long __must_check
> +copy_mc_to_user(void *dst, const void *src, size_t cnt)
> +{
> +	return copy_to_user(dst, src, cnt);
> +}
> +#endif
> +
>  static __always_inline void pagefault_disabled_inc(void)
>  {
>  	current->pagefault_disabled++;

Thanks,
Mauro