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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4C7A0C54EBC for ; Tue, 27 Dec 2022 20:47:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232937AbiL0Urg (ORCPT ); Tue, 27 Dec 2022 15:47:36 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:32928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233115AbiL0Uq7 (ORCPT ); Tue, 27 Dec 2022 15:46:59 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EBF0611C1C; Tue, 27 Dec 2022 12:37:32 -0800 (PST) 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 1BE51B81204; Tue, 27 Dec 2022 20:36:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A9719C433EF; Tue, 27 Dec 2022 20:36:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672173373; bh=0RYqncs2ZL/H6FL0nDtlJt+7AGOQWobMQhZOuyEIovY=; h=From:To:Cc:Subject:Date:From; b=YjPze8ySW5E/2G+74EAuTlXzrefFiFSrQpXjrIatHyL3qo1PW7Pi3O/DTui++M4C8 KwQKYbhCcVFgBHu+l9jOYI6bbbteg2IU73PcWRhqX+vxjvSErxdk5Zppk3VKskiejH c193IX6wtxmhisNynyZklJYQmKVamnx1UzFy40igh7ZRGI2+N0Ooqojf3mgRGuzL0R 10SyA+9Hz4QrtltMNY0+dJVu6ejsRQ6i15sJCvBIpgSbB4b6nYuJoaJOQPvJ1UeBf8 CojbB/dc4Kr4nd5uRMxy6k92h9zDeo6U41iL0vZbK68sJkyZy8/JX+3LFs1D+2tQUH HuGtmT3QYpuLA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Nathan Lynch , Nicholas Piggin , Andrew Donnellan , Michael Ellerman , Sasha Levin , ldufour@linux.ibm.com, paulus@ozlabs.org, christophe.leroy@csgroup.eu, sourabhjain@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 4.14 1/4] powerpc/rtas: avoid device tree lookups in rtas_os_term() Date: Tue, 27 Dec 2022 15:36:06 -0500 Message-Id: <20221227203611.1214818-1-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 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: Nathan Lynch [ Upstream commit ed2213bfb192ab51f09f12e9b49b5d482c6493f3 ] rtas_os_term() is called during panic. Its behavior depends on a couple of conditions in the /rtas node of the device tree, the traversal of which entails locking and local IRQ state changes. If the kernel panics while devtree_lock is held, rtas_os_term() as currently written could hang. Instead of discovering the relevant characteristics at panic time, cache them in file-static variables at boot. Note the lookup for "ibm,extended-os-term" is converted to of_property_read_bool() since it is a boolean property, not an RTAS function token. Signed-off-by: Nathan Lynch Reviewed-by: Nicholas Piggin Reviewed-by: Andrew Donnellan [mpe: Incorporate suggested change from Nick] Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20221118150751.469393-4-nathanl@linux.ibm.com Signed-off-by: Sasha Levin --- arch/powerpc/kernel/rtas.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index dd20e87f18f2..914d71879536 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -716,6 +716,7 @@ void __noreturn rtas_halt(void) /* Must be in the RMO region, so we place it here */ static char rtas_os_term_buf[2048]; +static s32 ibm_os_term_token = RTAS_UNKNOWN_SERVICE; void rtas_os_term(char *str) { @@ -727,14 +728,13 @@ void rtas_os_term(char *str) * this property may terminate the partition which we want to avoid * since it interferes with panic_timeout. */ - if (RTAS_UNKNOWN_SERVICE == rtas_token("ibm,os-term") || - RTAS_UNKNOWN_SERVICE == rtas_token("ibm,extended-os-term")) + if (ibm_os_term_token == RTAS_UNKNOWN_SERVICE) return; snprintf(rtas_os_term_buf, 2048, "OS panic: %s", str); do { - status = rtas_call(rtas_token("ibm,os-term"), 1, 1, NULL, + status = rtas_call(ibm_os_term_token, 1, 1, NULL, __pa(rtas_os_term_buf)); } while (rtas_busy_delay(status)); @@ -1331,6 +1331,13 @@ void __init rtas_initialize(void) no_entry = of_property_read_u32(rtas.dev, "linux,rtas-entry", &entry); rtas.entry = no_entry ? rtas.base : entry; + /* + * Discover these now to avoid device tree lookups in the + * panic path. + */ + if (of_property_read_bool(rtas.dev, "ibm,extended-os-term")) + ibm_os_term_token = rtas_token("ibm,os-term"); + /* If RTAS was found, allocate the RMO buffer for it and look for * the stop-self token if any */ -- 2.35.1