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 280B1E56A; Thu, 27 Jun 2024 16:46:34 +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=1719506797; cv=none; b=IE+1OUVVDhRnwxQjh6FQU36U+4e6J6svPtc1/TuOefQpvuSbXI2zwoPFreij7AZN3DYIU4CzCiIjaO0YsEMXXqTYti5k3XHCP7GMshqShPKjmJCKSFyoiv3UMJTbC/KkUIljq4PyIlICJ/56ECkv8uveT6yEVjJZ6higNvo5LZE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719506797; c=relaxed/simple; bh=FqoNRjT+cb9LRUsdU5RLE5nL8EwzbdO7DYD57enR6t4=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=IaKQPkpZPElxOXK6/FvLgzxoHW5x4araMHe2watgk/D+TsylH60W6QDMWqLOz7XDwVGKlhBe3B/QfxJCNS18PwT9kAtw0wDSWaLoBUqLLlE26BM9qGzLDGIZrMIdNzNDKD2NonLN+IIi7dJtrmMof0v2A1gdt2ENGCy0NiXCy2A= ARC-Authentication-Results:i=1; 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h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=oi4MYhw9IMUnJw9uB+nb7xC2JIVq24CV4Mx4jzzg+Hwaiq3r6+wE+Z2aEGm9O5gHA AVgIiqDKFzx6qGNjaJ2UU3niH2aXb3h3uO5OMk6IGLHAB/KlAXJywTwk3va3/OXUG8 l5PYbYOtlqsxY/H7vouPESGWsn4Lc9aEV4Ag/H6lHOAEjDvxP2aDXxAtbZBR2OBdyg h431EMcAaNPN2qTjecVGT0z2oHPQcFCG4xy2Ag3ERv7TPP/yBPyD0MJbRtipWEHRlA Tt6lJYEr8l01l/R55DusJwYM+gK4/rTowEPBMZ8Txiqo8FkfJZnN8cvrbn2aEkd1/f AD6wtZvi72wQQ== Message-ID: Date: Thu, 27 Jun 2024 09:45:34 -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 v3 2/4] x86/cpufeatures: Generate a feature mask header based on build config To: Nikolay Borisov , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, will@kernel.org, peterz@infradead.org, akpm@linux-foundation.org, acme@kernel.org, namhyung@kernel.org, brgerst@gmail.com References: <20240622171435.3725548-1-xin@zytor.com> <20240622171435.3725548-3-xin@zytor.com> <5aeaaecf-0eb6-4934-b14e-2285eff6cc62@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 6/26/2024 4:36 AM, Nikolay Borisov wrote: > > > On 22.06.24 г. 20:14 ч., Xin Li (Intel) wrote: >> From: "H. Peter Anvin (Intel)" >> >> Introduce an AWK script to auto-generate a header with required and >> disabled feature masks based on and current build >> config. Thus for any CPU feature with a build config, e.g., X86_FRED, >> simply add >> >> config X86_DISABLED_FEATURE_FRED >>     def_bool y >>     depends on !X86_FRED >> >> to arch/x86/Kconfig.cpufeatures, instead of adding a conditional CPU >> feature disable flag, e.g., DISABLE_FRED. >> >> Lastly the generated required and disabled feature masks will be added >> to their corresponding feature masks for this particular compile-time >> configuration. >> >> [ Xin: build integration improvements ] >> >> Signed-off-by: H. Peter Anvin (Intel) >> Signed-off-by: Xin Li (Intel) > > Overall LGTM, some minor points below. > > > Reviewed-by: Nikolay Borisov Thanks! > > > > >> diff --git a/arch/x86/tools/featuremasks.awk >> b/arch/x86/tools/featuremasks.awk >> new file mode 100755 >> index 000000000000..989b021e73d3 >> --- /dev/null >> +++ b/arch/x86/tools/featuremasks.awk >> @@ -0,0 +1,84 @@ >> +#!/usr/bin/awk >> +# >> +# Convert cpufeatures.h to a list of compile-time masks >> +# Note: this blithly assumes that each word has at least one >> +# feature defined in it; if not, something else is wrong! >> +# >> + >> +BEGIN { >> +    printf "#ifndef _ASM_X86_FEATUREMASKS_H\n"; >> +    printf "#define _ASM_X86_FEATUREMASKS_H\n\n"; >> + >> +    file = 0 >> +} >> + >> +BEGINFILE { >> +    switch (++file) { >> +    case 1:            # cpufeatures.h >> +        FPAT = "#[ \t]*[a-z]+|[A-Za-z0-9_]+|[^ \t]"; >> +        break; >> +    case 2:            # .config >> +        FPAT = "CONFIG_[A-Z0-9_]+|is not set|[yn]"; >> +        break; >> +    } >> +} >> + > > IMO this script could use a bit of high-level comments. Something like: > > > # Create a dictionary of sorts, containing all defined feature bits >> +file == 1 && $1 ~ /^#[ \t]*define$/ && $2 ~ /^X86_FEATURE_/ && >> +$3 == "(" && $5 == "*" && $7 == "+" && $9 == ")" { >> +    nfeat = $4 * $6 + $8; >> +    feat = $2; >> +    sub(/^X86_FEATURE_/, "", feat); >> +    feats[nfeat] = feat; >> +} > >> +file == 1 && $1 ~ /^#[ \t]*define$/ && $2 == "NCAPINTS" { >> +    ncapints = strtonum($3); >> +} >> + > > # Create a dictionary featstat[REQUIRED|DISABLED, FEATURE_NAME] = on | off > >> +file == 2 && $1 ~ /^CONFIG_X86_[A-Z]*_FEATURE_/ { >> +    on = ($2 == "y"); >> +    if (split($1, fs, "CONFIG_X86_|_FEATURE_") == 3) >> +        featstat[fs[2], fs[3]] = on; >> +} >> + >> +END { >> +    sets[1] = "REQUIRED"; >> +    sets[2] = "DISABLED"; >> + >> +    for (ns in sets) { >> +        s = sets[ns]; >> + >> +        printf "/*\n"; >> +        printf " * %s features:\n", s; >> +        printf " *\n"; >> +        fstr = ""; >> +        for (i = 0; i < ncapints; i++) { >> +            mask = 0; >> +            for (j = 0; j < 32; j++) { >> +                nfeat = i*32 + j; >> +                feat = feats[nfeat]; >> +                if (feat) { >> +                    st = !!featstat[s, feat]; >> +                    if (st) { >> +                        nfstr = fstr " " feat; >> +                        if (length(nfstr) > 72) { >> +                            printf " *   %s\n", fstr; >> +                            nfstr = " " feat; >> +                        } >> +                        fstr = nfstr; >> +                    } >> +                    mask += st * (2 ^ j); > > nit: This expression can be changed to mask += (2 ^j) and moved inside > the 'if (st)' branch. Essentially only add a bit iff that status of the > relevant feature in the kconfig is y, which is signified by the value of > 'st' variable. I will do a polish and send v4. > >> +                } >> +            } >> +            masks[i] = mask; >> +        } >> +        printf " *   %s\n */\n\n", fstr; >> + >> +        for (i = 0; i < ncapints; i++) { >> +            printf "#define %s_MASK%d\t0x%08x\n", s, i, masks[i]; I should append 'U' here too. >> +        } >> + >> +        printf "#define %s_MASK_CHECK BUILD_BUG_ON_ZERO(NCAPINTS != >> %d)\n\n", s, ncapints; >> +    } >> + >> +    printf "#endif /* _ASM_X86_FEATUREMASKS_H */\n"; >> +} >