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X-CSE-ConnectionGUID: CdBjOO+SSIeNMrHLrwLIHw== X-CSE-MsgGUID: qZ47kCAgQ6mjXOUIH5qfbA== X-IronPort-AV: E=McAfee;i="6700,10204,11365"; a="41584168" X-IronPort-AV: E=Sophos;i="6.14,227,1736841600"; d="scan'208";a="41584168" Received: from fmviesa006.fm.intel.com ([10.60.135.146]) by fmvoesa112.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2025 13:34:40 -0800 X-CSE-ConnectionGUID: TjNpjkleT1KD4jAol2Nagg== X-CSE-MsgGUID: LUOTfIhnRIOiyQ7OYzQDrQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.14,227,1736841600"; d="scan'208";a="118973440" Received: from kinlongk-mobl1.amr.corp.intel.com (HELO [10.125.110.90]) ([10.125.110.90]) by fmviesa006-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2025 13:34:40 -0800 Message-ID: <3e354397-1666-4d63-b863-ef9f9d31fa37@intel.com> Date: Thu, 6 Mar 2025 13:35:01 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/4] x86/asm: inline constant inputs in rdpkru(), wrpkru() To: Alexey Dobriyan , tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com Cc: x86@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org References: <20250306210710.3403-1-adobriyan@gmail.com> Content-Language: en-US From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 3/6/25 13:07, Alexey Dobriyan wrote: > static inline void wrpkru(u32 pkru) > { > - u32 ecx = 0, edx = 0; > - > /* > * "wrpkru" instruction. Loads contents in EAX to PKRU, > * requires that ecx = edx = 0. > */ > asm volatile(".byte 0x0f,0x01,0xef\n\t" > - : : "a" (pkru), "c"(ecx), "d"(edx)); > + : : "a" (pkru), "c" (0), "d" (0)); > } Hey Alexey, I appreciate the patch. But I do like how it's written currently. I honestly kinda wish it went even further and did: u32 eax = pkru;