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=-16.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 8989BC43463 for ; Fri, 18 Sep 2020 03:11:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4C0822083B for ; Fri, 18 Sep 2020 03:11:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600398673; bh=o1UIEffgkGVqT10VkWmZfxY3hxOMHLjiuAxTGUvbeMk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=tzwNkTsqJpixMsnwKh0VcOXMrhasR6BINcWO/ssyruQH7yyinXjAIFWHR35Jcsd4v RVrupC7Sn/aZLYGvUbiU9zh8GaRfvYUqd36FmO+sVeQyiXLk15IDiEwjWiNBT4ntmd 2ryl1QpU4aaklGoPtMXhMPFyRklTrtG+LnQrfhyE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726065AbgIRDLL (ORCPT ); Thu, 17 Sep 2020 23:11:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:47702 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726767AbgIRCCb (ORCPT ); Thu, 17 Sep 2020 22:02:31 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1B9152087D; Fri, 18 Sep 2020 02:02:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600394550; bh=o1UIEffgkGVqT10VkWmZfxY3hxOMHLjiuAxTGUvbeMk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=M3+iUEDhPIu4R3JWxS7MDedZRM7G05xKu4SZZhtSBIjUIBnOcRVRPZVmG+JVL+sq9 SnzHM4vR3oK4StZmZ/2ANj0aTODzWwjW0iEQDf+2dn4H6J8W+5SNzin2gA/Jxw6kd5 sjMUuTLmyUNzWx0oY/M3rdGArZU4nDvhsx81w1Hk= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Vasily Gorbik , Heiko Carstens , Sasha Levin , linux-s390@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 067/330] s390: avoid misusing CALL_ON_STACK for task stack setup Date: Thu, 17 Sep 2020 21:56:47 -0400 Message-Id: <20200918020110.2063155-67-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200918020110.2063155-1-sashal@kernel.org> References: <20200918020110.2063155-1-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: stable@vger.kernel.org From: Vasily Gorbik [ Upstream commit 7bcaad1f9fac889f5fcd1a383acf7e00d006da41 ] CALL_ON_STACK is intended to be used for temporary stack switching with potential return to the caller. When CALL_ON_STACK is misused to switch from nodat stack to task stack back_chain information would later lead stack unwinder from task stack into (per cpu) nodat stack which is reused for other purposes. This would yield confusing unwinding result or errors. To avoid that introduce CALL_ON_STACK_NORETURN to be used instead. It makes sure that back_chain is zeroed and unwinder finishes gracefully ending up at task pt_regs. Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin --- arch/s390/include/asm/stacktrace.h | 11 +++++++++++ arch/s390/kernel/setup.c | 9 +-------- arch/s390/kernel/smp.c | 2 +- 3 files changed, 13 insertions(+), 9 deletions(-) diff --git a/arch/s390/include/asm/stacktrace.h b/arch/s390/include/asm/stacktrace.h index 0ae4bbf7779c8..3679d224fd3c5 100644 --- a/arch/s390/include/asm/stacktrace.h +++ b/arch/s390/include/asm/stacktrace.h @@ -111,4 +111,15 @@ struct stack_frame { r2; \ }) +#define CALL_ON_STACK_NORETURN(fn, stack) \ +({ \ + asm volatile( \ + " la 15,0(%[_stack])\n" \ + " xc %[_bc](8,15),%[_bc](15)\n" \ + " brasl 14,%[_fn]\n" \ + ::[_bc] "i" (offsetof(struct stack_frame, back_chain)), \ + [_stack] "a" (stack), [_fn] "X" (fn)); \ + BUG(); \ +}) + #endif /* _ASM_S390_STACKTRACE_H */ diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c index 07b2b61a0289f..82ef081e7448e 100644 --- a/arch/s390/kernel/setup.c +++ b/arch/s390/kernel/setup.c @@ -356,7 +356,6 @@ early_initcall(async_stack_realloc); void __init arch_call_rest_init(void) { - struct stack_frame *frame; unsigned long stack; stack = stack_alloc(); @@ -369,13 +368,7 @@ void __init arch_call_rest_init(void) set_task_stack_end_magic(current); stack += STACK_INIT_OFFSET; S390_lowcore.kernel_stack = stack; - frame = (struct stack_frame *) stack; - memset(frame, 0, sizeof(*frame)); - /* Branch to rest_init on the new stack, never returns */ - asm volatile( - " la 15,0(%[_frame])\n" - " jg rest_init\n" - : : [_frame] "a" (frame)); + CALL_ON_STACK_NORETURN(rest_init, stack); } static void __init setup_lowcore_dat_off(void) diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index 66bf050d785cf..ad426cc656e56 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -878,7 +878,7 @@ static void __no_sanitize_address smp_start_secondary(void *cpuvoid) S390_lowcore.restart_source = -1UL; __ctl_load(S390_lowcore.cregs_save_area, 0, 15); __load_psw_mask(PSW_KERNEL_BITS | PSW_MASK_DAT); - CALL_ON_STACK(smp_init_secondary, S390_lowcore.kernel_stack, 0); + CALL_ON_STACK_NORETURN(smp_init_secondary, S390_lowcore.kernel_stack); } /* Upping and downing of CPUs */ -- 2.25.1