From nobody Tue Dec 2 00:44:27 2025 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1475A2A1C7 for ; Mon, 24 Nov 2025 14:25:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763994331; cv=none; b=mB7YwNmA4xNU/sIftIykQHQFmqE+Hs7imgG1QASWgAafyBfEE1Wgxano1ZHavmyFGT2Phgyc53TVQrp9dlB1vZIfvpQqM65iLBExDjUp3JeX7metIoGrH749wW7AC0ys6QjXGr1aV/GNSHlppgrJiEdSvS66VTAJnxN+lKLX7OE= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763994331; c=relaxed/simple; bh=L/XbNw+4Ugcjx/J4Mai31cTuDAtYkM88zPyJ4ltrlgY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=H0lK4mX1OQSyf188z/t405JSTt+Q4upiZinXE6SnxvBYFxntFQ8L89i94S1DanHUs/brAiCtJrCaQjbPS/tV0HmOgBbI4trFPvgP8demEL0LKWiOJTzRjzh6xC5dhrMus+KtbkvvuYBC+HKK3dc4XgN8BzXjdvyE3D0FhVUGI4s= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=sYHIteKi; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b=sYHIteKi; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="sYHIteKi"; dkim=pass (1024-bit key) header.d=suse.com header.i=@suse.com header.b="sYHIteKi" Received: from imap1.dmz-prg2.suse.org (unknown [10.150.64.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 534425BD39; Mon, 24 Nov 2025 14:25:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1763994327; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=haavHNAGdu2Jadk1TzWiSsMC3NtXgH1OWZQ0Sj8vclQ=; b=sYHIteKiCsMfpxeM3neKOG7Ww6zq3Xg5yxyTqgygEBfBnlvACD1oc0banmPA3cKmkYgmY6 RInqXOdJMnML0HhBaaxGthMwCMY2YMybB8wIuXdnC+5TWlEQ81wPqLl16uP/ioBk8eDOk9 K/R2rkw+tCx96+whfulQXm2c0aNr0QE= Authentication-Results: smtp-out2.suse.de; none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1763994327; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=haavHNAGdu2Jadk1TzWiSsMC3NtXgH1OWZQ0Sj8vclQ=; b=sYHIteKiCsMfpxeM3neKOG7Ww6zq3Xg5yxyTqgygEBfBnlvACD1oc0banmPA3cKmkYgmY6 RInqXOdJMnML0HhBaaxGthMwCMY2YMybB8wIuXdnC+5TWlEQ81wPqLl16uP/ioBk8eDOk9 K/R2rkw+tCx96+whfulQXm2c0aNr0QE= Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id F08323EA63; Mon, 24 Nov 2025 14:25:26 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id yadDONZqJGm7DgAAD6G6ig (envelope-from ); Mon, 24 Nov 2025 14:25:26 +0000 From: Nikolay Borisov To: linux-edac@vger.kernel.org Cc: linux-kernel@vger.kernel.org, bp@alien8.de, Yazen.Ghannam@amd.com, Nikolay Borisov Subject: [PATCH] RAS/AMD/ATL: Replace bitwise_xor_bits() with hweight16() Date: Mon, 24 Nov 2025 16:25:17 +0200 Message-ID: <20251124142517.1708451-1-nik.borisov@suse.com> X-Mailer: git-send-email 2.52.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Spam-Level: X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; ARC_NA(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.com:email,suse.com:mid]; RCVD_VIA_SMTP_AUTH(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; FUZZY_RATELIMITED(0.00)[rspamd.com]; DKIM_SIGNED(0.00)[suse.com:s=susede1]; RCPT_COUNT_FIVE(0.00)[5]; RCVD_TLS_ALL(0.00)[] X-Spam-Flag: NO X-Spam-Score: -2.80 Content-Type: text/plain; charset="utf-8" Doing hweight16 and checking whether the lsb is set is functionally equivalent to what bitwise_xor_bits() does. In addition it results in better generated code as before gcc would inline the function 4 times. With hweight, the resulting code boils down to 2 instructions - popcnt and andl as all cpus we care about has popcnt. No functional changes. An alternative would have been to use the __builtin_parity() function provi= ded by both Clang/GCC, however under some circumstances the compiler can choose= not to inline it but generate a library call which is unsupported in the kernel. Signed-off-by: Nikolay Borisov --- drivers/ras/amd/atl/umc.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-) diff --git a/drivers/ras/amd/atl/umc.c b/drivers/ras/amd/atl/umc.c index 6e072b7667e9..8d1363237eee 100644 --- a/drivers/ras/amd/atl/umc.c +++ b/drivers/ras/amd/atl/umc.c @@ -49,17 +49,6 @@ static u8 get_coh_st_inst_id_mi300(struct atl_err *err) return i; } -/* XOR the bits in @val. */ -static u16 bitwise_xor_bits(u16 val) -{ - u16 tmp =3D 0; - u8 i; - - for (i =3D 0; i < 16; i++) - tmp ^=3D (val >> i) & 0x1; - - return tmp; -} struct xor_bits { bool xor_enable; @@ -250,17 +239,17 @@ static unsigned long convert_dram_to_norm_addr_mi300(= unsigned long addr) if (!addr_hash.bank[i].xor_enable) continue; - temp =3D bitwise_xor_bits(col & addr_hash.bank[i].col_xor); - temp ^=3D bitwise_xor_bits(row & addr_hash.bank[i].row_xor); + temp =3D hweight16(col & addr_hash.bank[i].col_xor) & 1; + temp ^=3D hweight16(row & addr_hash.bank[i].row_xor) & 1; bank ^=3D temp << i; } /* Calculate hash for PC bit. */ if (addr_hash.pc.xor_enable) { - temp =3D bitwise_xor_bits(col & addr_hash.pc.col_xor); - temp ^=3D bitwise_xor_bits(row & addr_hash.pc.row_xor); + temp =3D hweight16(col & addr_hash.pc.col_xor) & 1; + temp ^=3D hweight16(row & addr_hash.pc.row_xor) & 1; /* Bits SID[1:0] act as Bank[5:4] for PC hash, so apply them here. */ - temp ^=3D bitwise_xor_bits((bank | sid << NUM_BANK_BITS) & addr_hash.ban= k_xor); + temp ^=3D hweight16((bank | sid << NUM_BANK_BITS) & addr_hash.bank_xor) = & 1; pc ^=3D temp; } -- 2.52.0