Subject: Re: [PATCH 07/11] arm64: add basic pointer authentication support
To: Mark Rutland <mark.rutland@arm.com>,
        linux-arm-kernel@lists.infradead.org
References: <1500480092-28480-1-git-send-email-mark.rutland@arm.com>
 <1500480092-28480-8-git-send-email-mark.rutland@arm.com>
Cc: arnd@arndb.de, catalin.marinas@arm.com, christoffer.dall@linaro.org,
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        linux-arch@vger.kernel.org, marc.zyngier@arm.com,
        suzuki.poulose@arm.com, will.deacon@arm.com,
        linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com
From: Yao Qi <yao.qi@arm.com>
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Date: Fri, 11 Aug 2017 08:46:28 +0100
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Hi Mark,

On 19/07/17 17:01, Mark Rutland wrote:
> +#define HWCAP_APIA           (1 << 16)

Can you rename it to HWCAP_ARM64_APIA or HWCAP_ARM_APIA?  When we
use it in user space, at least in GDB, we usually do this,

#ifndef HWCAP_APIA
#define HWCAP_APIA (1 << 16)
#endif

However, the code use this macro can be compiled on !arm64 host.
If HWCAP_APIA is defined on other !arm64 host and its value is not
(1 << 16), the program "aarch64_hwcap & HWCAP_APIA ? XXX : XXX;" is
wrong, and compiler doesn't complain.

I notice that mips, mn10300, sparc, and s390 define their HWCAP this
way, like HWCAP_SPARC_FLUSH, HWCAP_MIPS_R6, HWCAP_S390_DFP, etc.
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