From: Arnd Bergmann <arnd@arndb.de>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: bamvor.zhangjian@huawei.com, pinskia@gmail.com,
        Prasun.Kapoor@caviumnetworks.com, schwab@suse.de,
        joseph@codesourcery.com, Nathan_Lynch@mentor.com, agraf@suse.de,
        linux-kernel@vger.kernel.org, klimov.linux@gmail.com,
        Andrew Pinski <Andrew.Pinski@caviumnetworks.com>, broonie@kernel.org,
        Yury Norov <ynorov@caviumnetworks.com>,
        Andrew Pinski <apinski@cavium.com>, ddaney.cavm@gmail.com,
        jan.dakinevich@gmail.com, philipp.tomsich@theobroma-systems.com,
        linux-arm-kernel@lists.infradead.org,
        christoph.muellner@theobroma-systems.com
Subject: Re: [PATCH v6 09/20] arm64:ilp32: share HWCAP between LP64 and ILP32
Date: Thu, 17 Dec 2015 14:56:24 +0100
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On Thursday 17 December 2015 10:54:47 Catalin Marinas wrote:
> > > IIUC, we may have a problem with this. elf_hwcap is 64-bit long while
> > > elf_info[n] is 32-bit (Elf32_Addr), so we truncate AT_HWCAP if we ever
> > > go beyond bit 31. The above may need to look something like:
> > > 
> > > #define COMPAT_ELF_HWCAP        \
> > >         (is_a32_compat_task()   \
> > >          ? compat_elf_hwcap     \
> > >          : (u32)elf_hwcap)
> > > 
> > > #define COMPAT_ELF_HWCAP2       \
> > >         (is_a32_compat_task()   \
> > >          ? compat_elf_hwcap2    \
> > >          : (u32)(elf_hwcap >> 32))
> > 
> > Yes, interesting find.
> 
> BTW, we need to make sure this series (primarily the ABI) is big-endian
> safe. I know it is not targeted at this initially but given that the
> reason for doing it is legacy networking code, I wouldn't be surprised
> if someone asks for BE at some point in the future.

Yes, I'm sure that will be needed.

	Arnd
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