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Subject: Re: [PATCH v3 02/22] compat: provide compat_ptr() on all
 architectures
To:     Arnd Bergmann <arnd@arndb.de>,
        "James E.J. Bottomley" <jejb@linux.ibm.com>,
        "Martin K. Petersen" <martin.petersen@oracle.com>
Cc:     Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Ralf Baechle <ralf@linux-mips.org>,
        Paul Burton <paulburton@kernel.org>,
        James Hogan <jhogan@kernel.org>,
        "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>,
        Helge Deller <deller@gmx.de>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Robert Richter <rric@kernel.org>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@de.ibm.com>,
        "David S. Miller" <davem@davemloft.net>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, linux-kernel@vger.kernel.org,
        linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org,
        linuxppc-dev@lists.ozlabs.org, oprofile-list@lists.sf.net,
        linux-s390@vger.kernel.org, sparclinux@vger.kernel.org
References: <20200102145552.1853992-1-arnd@arndb.de>
 <20200102145552.1853992-3-arnd@arndb.de>
From:   "H. Peter Anvin" <hpa@zytor.com>
Message-ID: <e2c7b4d7-587e-f71c-f0df-810e8d9869f2@zytor.com>
Date:   Mon, 6 Jan 2020 09:59:16 -0800
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On 2020-01-02 06:55, Arnd Bergmann wrote:
> In order to avoid needless #ifdef CONFIG_COMPAT checks,
> move the compat_ptr() definition to linux/compat.h
> where it can be seen by any file regardless of the
> architecture.
> 
> Only s390 needs a special definition, this can use the
> self-#define trick we have elsewhere.
> 
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> ---
>  arch/arm64/include/asm/compat.h   | 17 -----------------
>  arch/mips/include/asm/compat.h    | 18 ------------------
>  arch/parisc/include/asm/compat.h  | 17 -----------------
>  arch/powerpc/include/asm/compat.h | 17 -----------------
>  arch/powerpc/oprofile/backtrace.c |  2 +-
>  arch/s390/include/asm/compat.h    |  6 +-----
>  arch/sparc/include/asm/compat.h   | 17 -----------------
>  arch/x86/include/asm/compat.h     | 17 -----------------
>  include/linux/compat.h            | 18 ++++++++++++++++++
>  9 files changed, 20 insertions(+), 109 deletions(-)
> 

For x86:

Reviewed-by: H. Peter Anvin <hpa@zytor.com>

It still suffers from the zero-one-infinity rule failure of the compat
architecture as a whole, but that is a very different problem. In this case
"compat" is obviously meaning "a 32-on-64 ABI" and simply centralizes a common
API, which is a Good Thing[TM].

	-hpa