From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CF5C9C433EF for ; Tue, 5 Apr 2022 13:23:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1345928AbiDENF0 (ORCPT ); Tue, 5 Apr 2022 09:05:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41936 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242459AbiDEJIA (ORCPT ); Tue, 5 Apr 2022 05:08:00 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 18BBF6C95C; Tue, 5 Apr 2022 01:56:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 3F9EEB81C19; Tue, 5 Apr 2022 08:56:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96A41C385A1; Tue, 5 Apr 2022 08:56:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1649149010; bh=Fuaowa36LZmZrZwM9VAhTPo1a9kG2y7HWx+kfZ1HWT4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ffeACz8ziiDBheGrw1WTvTP8rTCFNmlnMSuUet4m9JhuxzMlevEFXo5QyBtBrRcFe 9idsxDTdmOIAP0ukA8Crpui/yub9Mvt6Z21Wsm5VR3YcTKPchOOz4D3YyiBaYPrs0R Xdq0+FZhS9Lw9N7xdIKeU0jmSEIR2Zd3w7g2puho= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Michael Ellerman , Sasha Levin Subject: [PATCH 5.16 0562/1017] powerpc/Makefile: Dont pass -mcpu=powerpc64 when building 32-bit Date: Tue, 5 Apr 2022 09:24:35 +0200 Message-Id: <20220405070410.962528069@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220405070354.155796697@linuxfoundation.org> References: <20220405070354.155796697@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Michael Ellerman [ Upstream commit 2863dd2db23e0407f6c50b8ba5c0e55abef894f1 ] When CONFIG_GENERIC_CPU=y (true for all our defconfigs) we pass -mcpu=powerpc64 to the compiler, even when we're building a 32-bit kernel. This happens because we have an ifdef CONFIG_PPC_BOOK3S_64/else block in the Makefile that was written before 32-bit supported GENERIC_CPU. Prior to that the else block only applied to 64-bit Book3E. The GCC man page says -mcpu=powerpc64 "[specifies] a pure ... 64-bit big endian PowerPC ... architecture machine [type], with an appropriate, generic processor model assumed for scheduling purposes." It's unclear how that interacts with -m32, which we are also passing, although obviously -m32 is taking precedence in some sense, as the 32-bit kernel only contains 32-bit instructions. This was noticed by inspection, not via any bug reports, but it does affect code generation. Comparing before/after code generation, there are some changes to instruction scheduling, and the after case (with -mcpu=powerpc64 removed) the compiler seems more keen to use r8. Fix it by making the else case only apply to Book3E 64, which excludes 32-bit. Fixes: 0e00a8c9fd92 ("powerpc: Allow CPU selection also on PPC32") Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20220215112858.304779-1-mpe@ellerman.id.au Signed-off-by: Sasha Levin --- arch/powerpc/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index e02568f17334..3d2e74ebc014 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -171,7 +171,7 @@ else CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mtune=power7,$(call cc-option,-mtune=power5)) CFLAGS-$(CONFIG_GENERIC_CPU) += $(call cc-option,-mcpu=power5,-mcpu=power4) endif -else +else ifdef CONFIG_PPC_BOOK3E_64 CFLAGS-$(CONFIG_GENERIC_CPU) += -mcpu=powerpc64 endif -- 2.34.1