linux-kernel - Re: [PATCH] usercopy: use unsigned long instead of uintptr

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Message-ID: <ec7f0c59-f67e-1d7e-c0b3-b0a409623e98@csgroup.eu>
Date:   Fri, 17 Jun 2022 11:05:32 +0000
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
CC:     Matthew Wilcox <willy@...radead.org>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        Linux-MM <linux-mm@...ck.org>,
        linux-xfs <linux-xfs@...r.kernel.org>,
        "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Uladzislau Rezki <urezki@...il.com>,
        Kees Cook <keescook@...omium.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Joe Perches <joe@...ches.com>
Subject: Re: [PATCH] usercopy: use unsigned long instead of uintptr_t



Le 17/06/2022 à 09:58, Geert Uytterhoeven a écrit :
>> But it then causes pointless problems when people can't really rely on
>> more than 32 bits for atomic bit operations, and on 64-bit
>> architectures we unnecessarily use "long" and waste the upper bits.
> 
> Well, atomic works up to native word size, i.e. long.
> 

powerpc64 has a pair of instructions to perform 128bits atomic 
operations : lqarx / stqcx.