From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 97C8E43AA9 for ; Fri, 12 Jul 2024 17:41:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720806110; cv=none; b=bQtLwud9FWEv/P0DJjJbJIW081s/OhRweY/1aGzRkQsjSHwlTI73GlNW8C2SL6VfXYoHKYCzj075I09ayNvmpjKzn6CV7NQej73EWcMRfmvdN/NVfO/EoM+5x5Lj9kf1s46Wwf7PvORqXfL2y3fv9TpJAS6nfkXRJVpgJmbJD64= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1720806110; c=relaxed/simple; bh=sOx2tSu8bAAxd9gUAzNhIGOVI80chdfx8Kmj7OkUkO8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ilso52reLRCduaJUPGOPeu6h6XS0bsyDaF2TidcSMP2U+gFysGwAc9GE1d1BZGOpNO0t8ZAUib5NXSOi6XlzIjnmZ6Xw8AGYxppHY02rr5bWbZYimXLtDZKTj1E3rfV0IvPAToktXkcwkJl7GPFJtu6LV73oEbTjNb88TIa64kM= ARC-Authentication-Results:i=1; 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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=L/YySgvgRGoUVSk4bxDAdYYTzQmVs++/qjN74kRvBkawQ4jO2R0EoXxPteff7PxKG P1IyEjSPRlKhfcTc6QyOFbEDvUJjORY0ChRbqqy7s499ISfuFLwpaSCWMx6l400UGS ysgda1m8Y3/PCGnhUGlHCShOZyZjj3VZhKVx3v50L6X7owkpufUu85JU3+K7+qqkHk fCiHH5Lhmztm/TCG+HL2j53j0Ix0qwfmHUZ6iEUHEbIBdrMxpql5D2OgPxGyDHKA9i AOG0ohWRvdedVhTPGmKcv9y1AB0b1Lxb7dvL64mZaDxYwFiM3cy2Z7ZrWswu9KDgSA 0proXA2dtqt0w== Message-ID: <7fad52e6-83cf-4c17-9b3f-4dfa087f8fc4@zytor.com> Date: Fri, 12 Jul 2024 10:40:48 -0700 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 v2 1/3] x86/fred: Parse cmdline param "fred=" in cpu_parse_early_param() To: Nikolay Borisov , linux-kernel@vger.kernel.org Cc: hpa@zytor.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, peterz@infradead.org, andrew.cooper3@citrix.com, houwenlong.hwl@antgroup.com References: <20240709154048.3543361-1-xin@zytor.com> <20240709154048.3543361-2-xin@zytor.com> <98b2d56f-767f-4074-a9f2-4d993880e2a5@suse.com> Content-Language: en-US From: Xin Li Autocrypt: addr=xin@zytor.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 7/10/2024 11:53 AM, Nikolay Borisov wrote: > On 9.07.24 г. 18:40 ч., Xin Li (Intel) wrote: >> @@ -1510,6 +1510,11 @@ static void __init cpu_parse_early_param(void) >>       if (cmdline_find_option_bool(boot_command_line, "nousershstk")) >>           setup_clear_cpu_cap(X86_FEATURE_USER_SHSTK); >> +    /* Minimize the gap between FRED is available and available but >> disabled. */ >> +    arglen = cmdline_find_option(boot_command_line, "fred", arg, >> sizeof(arg)); >> +    if (arglen != 2 || strncmp(arg, "on", 2)) > > I'm confused why you keep perverting the calling convention of > cmdline_find_option. The doc clearly states: > >     * Returns the position of that @option (starts counting with 1) >     * or 0 on not found.  @option will only be found if it is found >     * as an entire word in @cmdline.  For instance, if @option="car" >     * then a cmdline which contains "cart" will not match. > > You should only care if arglen is non 0, which if it is you check if its > value equal 'on', why bother with its starting position? > Well, just look at how it is used in match_option() in arch/x86/kernel/cpu/bugs.c and arch/x86/kernel/cpu/intel.c. This is a short version and it will be expanded once we have more option strings well defined (match_option() should be a common lib function then).