From patchwork Mon Apr 26 07:30:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 427837 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=-19.0 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=ham 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 67531C433ED for ; Mon, 26 Apr 2021 07:42:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 35F5E61402 for ; Mon, 26 Apr 2021 07:42:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233000AbhDZHnT (ORCPT ); Mon, 26 Apr 2021 03:43:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:56278 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232859AbhDZHkf (ORCPT ); Mon, 26 Apr 2021 03:40:35 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1865A611BF; Mon, 26 Apr 2021 07:38:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1619422720; bh=C5hji4FUmPrWScW47HD+P0j3mRsXZ4Sl6LrAKw74j8Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DRsT5EWQB+x4cJnPrqmjvjtyNkSd9uIHzkRkQXtZ4pBAX9zrKWzbLIq3/SwqEtDdf X9EcapRugzvcFHmTeEaQ7NfnHDLsXVTJjdPYLGIL1wA3fq+wuX3XUBe9MO+EJDSsbX dMSoDFbM7AslGUgDoba+QiOXPgKUgdOKo4dndtz8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sven Schnelle , Vasily Gorbik , Heiko Carstens , Sasha Levin Subject: [PATCH 5.4 14/20] s390/entry: save the caller of psw_idle Date: Mon, 26 Apr 2021 09:30:05 +0200 Message-Id: <20210426072817.152717905@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210426072816.686976183@linuxfoundation.org> References: <20210426072816.686976183@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vasily Gorbik [ Upstream commit a994eddb947ea9ebb7b14d9a1267001699f0a136 ] Currently psw_idle does not allocate a stack frame and does not save its r14 and r15 into the save area. Even though this is valid from call ABI point of view, because psw_idle does not make any calls explicitly, in reality psw_idle is an entry point for controlled transition into serving interrupts. So, in practice, psw_idle stack frame is analyzed during stack unwinding. Depending on build options that r14 slot in the save area of psw_idle might either contain a value saved by previous sibling call or complete garbage. [task 0000038000003c28] do_ext_irq+0xd6/0x160 [task 0000038000003c78] ext_int_handler+0xba/0xe8 [task *0000038000003dd8] psw_idle_exit+0x0/0x8 <-- pt_regs ([task 0000038000003dd8] 0x0) [task 0000038000003e10] default_idle_call+0x42/0x148 [task 0000038000003e30] do_idle+0xce/0x160 [task 0000038000003e70] cpu_startup_entry+0x36/0x40 [task 0000038000003ea0] arch_call_rest_init+0x76/0x80 So, to make a stacktrace nicer and actually point for the real caller of psw_idle in this frequently occurring case, make psw_idle save its r14. [task 0000038000003c28] do_ext_irq+0xd6/0x160 [task 0000038000003c78] ext_int_handler+0xba/0xe8 [task *0000038000003dd8] psw_idle_exit+0x0/0x6 <-- pt_regs ([task 0000038000003dd8] arch_cpu_idle+0x3c/0xd0) [task 0000038000003e10] default_idle_call+0x42/0x148 [task 0000038000003e30] do_idle+0xce/0x160 [task 0000038000003e70] cpu_startup_entry+0x36/0x40 [task 0000038000003ea0] arch_call_rest_init+0x76/0x80 Reviewed-by: Sven Schnelle Signed-off-by: Vasily Gorbik Signed-off-by: Heiko Carstens Signed-off-by: Sasha Levin --- arch/s390/kernel/entry.S | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/s390/kernel/entry.S b/arch/s390/kernel/entry.S index c544b7a11ebb..5cba1815b8f8 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -993,6 +993,7 @@ ENDPROC(ext_int_handler) * Load idle PSW. The second "half" of this function is in .Lcleanup_idle. */ ENTRY(psw_idle) + stg %r14,(__SF_GPRS+8*8)(%r15) stg %r3,__SF_EMPTY(%r15) larl %r1,.Lpsw_idle_lpsw+4 stg %r1,__SF_EMPTY+8(%r15)