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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 54826C43462 for ; Mon, 19 Apr 2021 20:46:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 28846613B4 for ; Mon, 19 Apr 2021 20:46:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240700AbhDSUq7 (ORCPT ); Mon, 19 Apr 2021 16:46:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:54296 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239839AbhDSUpS (ORCPT ); Mon, 19 Apr 2021 16:45:18 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 0771F613C7; Mon, 19 Apr 2021 20:44:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1618865076; bh=/MryeiTXYPA/GZQ2I/xwcA7zqnRSNepmGJPr4dTkBoI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZnG555YWAM/wO2PedfqY9x/JPBwHqDWi7Xg7/Qla9tJzeqMkyr6mJS2yB3rsywBo+ 3dJQ7FcLMdRUoGMNypumId7sZ1zQn5fRaDouq+rd48PEQwY610oug+oLgs4wwmJ44q XHHGH/iRVJuMJp09P3HQFjur/Ko5/rGItQ5pB+GM1Wgcq3PIwxRj0Jri/Scc6tyYac rGjUYzkZ1jvLGfkEFWiw24pW65lQQcl2APrdBdz/7YFWI0cnPcFjqxZb4JrVhE2+y/ kCpixGDXXvKPYbpFymI443wHpVphEkSkpfOqPKdrJMvMB3xPTeY4fmkECasstf9kqu sTOwo0TVpb+dg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vasily Gorbik , Sven Schnelle , Heiko Carstens , Sasha Levin , linux-s390@vger.kernel.org Subject: [PATCH AUTOSEL 5.10 11/21] s390/entry: save the caller of psw_idle Date: Mon, 19 Apr 2021 16:44:09 -0400 Message-Id: <20210419204420.6375-11-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210419204420.6375-1-sashal@kernel.org> References: <20210419204420.6375-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 71203324ff42..81c458e996d9 100644 --- a/arch/s390/kernel/entry.S +++ b/arch/s390/kernel/entry.S @@ -994,6 +994,7 @@ ENDPROC(ext_int_handler) * Load idle PSW. */ ENTRY(psw_idle) + stg %r14,(__SF_GPRS+8*8)(%r15) stg %r3,__SF_EMPTY(%r15) larl %r1,.Lpsw_idle_exit stg %r1,__SF_EMPTY+8(%r15) -- 2.30.2