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 X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 320BFC07E9C for ; Fri, 9 Jul 2021 13:20:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1E6E3613BC for ; Fri, 9 Jul 2021 13:20:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232473AbhGINXR (ORCPT ); Fri, 9 Jul 2021 09:23:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:54376 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232457AbhGINXO (ORCPT ); Fri, 9 Jul 2021 09:23:14 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3777B6128A; Fri, 9 Jul 2021 13:20:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1625836829; bh=xGKGHbBAKfbQJlJpTH9BBsLPG5SPFOPOHzQMjy9TGG8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y69avIQJYi5guUiv4ZTnmv43AjqrtqUMLKgCtoT+FBu7+yH+M7/A3nRx/EbhqlnFE yCeUMEccytIbqUNdJT8u8Tu1AFg60YrWLLr8gbchxhESA4B2yD7q/RAkP0YsiUvFLH ixHsaAHt8JqBIEWsHa5em4J5o2NXcDdoL2UFhkvE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vasily Gorbik , Heiko Carstens , stable@kernel.org Subject: [PATCH 5.4 2/4] s390/stack: fix possible register corruption with stack switch helper Date: Fri, 9 Jul 2021 15:20:16 +0200 Message-Id: <20210709131534.397822619@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210709131531.277334979@linuxfoundation.org> References: <20210709131531.277334979@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: Heiko Carstens commit 67147e96a332b56c7206238162771d82467f86c0 upstream. The CALL_ON_STACK macro is used to call a C function from inline assembly, and therefore must consider the C ABI, which says that only registers 6-13, and 15 are non-volatile (restored by the called function). The inline assembly incorrectly marks all registers used to pass parameters to the called function as read-only input operands, instead of operands that are read and written to. This might result in register corruption depending on usage, compiler, and compile options. Fix this by marking all operands used to pass parameters as read/write operands. To keep the code simple even register 6, if used, is marked as read-write operand. Fixes: ff340d2472ec ("s390: add stack switch helper") Cc: # 4.20 Reviewed-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman --- arch/s390/include/asm/stacktrace.h | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) --- a/arch/s390/include/asm/stacktrace.h +++ b/arch/s390/include/asm/stacktrace.h @@ -79,12 +79,16 @@ struct stack_frame { CALL_ARGS_4(arg1, arg2, arg3, arg4); \ register unsigned long r4 asm("6") = (unsigned long)(arg5) -#define CALL_FMT_0 "=&d" (r2) : -#define CALL_FMT_1 "+&d" (r2) : -#define CALL_FMT_2 CALL_FMT_1 "d" (r3), -#define CALL_FMT_3 CALL_FMT_2 "d" (r4), -#define CALL_FMT_4 CALL_FMT_3 "d" (r5), -#define CALL_FMT_5 CALL_FMT_4 "d" (r6), +/* + * To keep this simple mark register 2-6 as being changed (volatile) + * by the called function, even though register 6 is saved/nonvolatile. + */ +#define CALL_FMT_0 "=&d" (r2) +#define CALL_FMT_1 "+&d" (r2) +#define CALL_FMT_2 CALL_FMT_1, "+&d" (r3) +#define CALL_FMT_3 CALL_FMT_2, "+&d" (r4) +#define CALL_FMT_4 CALL_FMT_3, "+&d" (r5) +#define CALL_FMT_5 CALL_FMT_4, "+&d" (r6) #define CALL_CLOBBER_5 "0", "1", "14", "cc", "memory" #define CALL_CLOBBER_4 CALL_CLOBBER_5 @@ -105,7 +109,7 @@ struct stack_frame { " brasl 14,%[_fn]\n" \ " la 15,0(%[_prev])\n" \ : [_prev] "=&a" (prev), CALL_FMT_##nr \ - [_stack] "a" (stack), \ + : [_stack] "a" (stack), \ [_bc] "i" (offsetof(struct stack_frame, back_chain)), \ [_fn] "X" (fn) : CALL_CLOBBER_##nr); \ r2; \