From nobody Wed Sep 3 01:54:02 2025 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 685D6C38145 for ; Fri, 2 Sep 2022 12:29:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236561AbiIBM3n (ORCPT ); Fri, 2 Sep 2022 08:29:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37222 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236515AbiIBM2V (ORCPT ); Fri, 2 Sep 2022 08:28:21 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E88CBD8E33; Fri, 2 Sep 2022 05:24:36 -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 4F9F0B82A9E; Fri, 2 Sep 2022 12:24:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9CC87C433C1; Fri, 2 Sep 2022 12:24:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1662121475; bh=GRY44WcHqY/SgymLIc9wHIjeXiuJ7rxdOZn+fozOfg8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HV2bL/CoKqKFL/f0QUPQjKRNxBdz76le4erdchl5u8oKYuFbBIDCmCuNkmZo3zzBp LaJ6TDsECzSRlEYMyh74CIr1WNcZLsEC/DOsQZAdtfZa5k3gw7TUNh80b26Zp1oSvr CGObnOK9b9EYSPfvu/5uPxpzVGPCwshUp4Jy767E= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Helge Deller Subject: [PATCH 4.19 02/56] parisc: Fix exception handler for fldw and fstw instructions Date: Fri, 2 Sep 2022 14:18:22 +0200 Message-Id: <20220902121400.299316707@linuxfoundation.org> X-Mailer: git-send-email 2.37.3 In-Reply-To: <20220902121400.219861128@linuxfoundation.org> References: <20220902121400.219861128@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Helge Deller commit 7ae1f5508d9a33fd58ed3059bd2d569961e3b8bd upstream. The exception handler is broken for unaligned memory acceses with fldw and fstw instructions, because it trashes or uses randomly some other floating point register than the one specified in the instruction word on loads and stores. The instruction "fldw 0(addr),%fr22L" (and the other fldw/fstw instructions) encode the target register (%fr22) in the rightmost 5 bits of the instruction word. The 7th rightmost bit of the instruction word defines if the left or right half of %fr22 should be used. While processing unaligned address accesses, the FR3() define is used to extract the offset into the local floating-point register set. But the calculation in FR3() was buggy, so that for example instead of %fr22, register %fr12 [((22 * 2) & 0x1f) =3D 12] was used. This bug has been since forever in the parisc kernel and I wonder why it wasn't detected earlier. Interestingly I noticed this bug just because the libime debian package failed to build on *native* hardware, while it successfully built in qemu. This patch corrects the bitshift and masking calculation in FR3(). Signed-off-by: Helge Deller Cc: Signed-off-by: Greg Kroah-Hartman --- arch/parisc/kernel/unaligned.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/arch/parisc/kernel/unaligned.c +++ b/arch/parisc/kernel/unaligned.c @@ -121,7 +121,7 @@ #define R1(i) (((i)>>21)&0x1f) #define R2(i) (((i)>>16)&0x1f) #define R3(i) ((i)&0x1f) -#define FR3(i) ((((i)<<1)&0x1f)|(((i)>>6)&1)) +#define FR3(i) ((((i)&0x1f)<<1)|(((i)>>6)&1)) #define IM(i,n) (((i)>>1&((1<<(n-1))-1))|((i)&1?((0-1L)<<(n-1)):0)) #define IM5_2(i) IM((i)>>16,5) #define IM5_3(i) IM((i),5)