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 18555C54E76 for ; Tue, 27 Dec 2022 20:47:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232793AbiL0Ur3 (ORCPT ); Tue, 27 Dec 2022 15:47:29 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60190 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232887AbiL0UqS (ORCPT ); Tue, 27 Dec 2022 15:46:18 -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 53CACDF9F; Tue, 27 Dec 2022 12:37:14 -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 A0003B811FC; Tue, 27 Dec 2022 20:35:59 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1F9A9C433D2; Tue, 27 Dec 2022 20:35:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672173358; bh=gLHa8wPVNasYI+GMR7fWgGDvdoezUkTB1n1PKg3VzD0=; h=From:To:Cc:Subject:Date:From; b=o/m4tllxY/wc4nQSF1hZCL5ejPlXlzGHNGiIRafN+eR5Meo7rar9UvDW95KSKxjAP PS5NYWYDn73O2kG9knPFEQVR0k9+nnOKzwpUlHFJoDj7CUJnEJc6CNqbGJRAhoRB/C YfxtvOyMQY4P041bYMK8/1uKu6cpZsGoYg3jpDY6bQApS5CQX5xbNS2hpEmCVMBrDW LaVL1AouubLrM+nbt7hxTHqKqAEz7UOPxxpiRZ06WDl9QyoCBvjmoccNqBuFYcbDgt zP2uTnYtyoM9fDb61EZVTdwoJkFp1YehGevCjtM4XXlkIi+lenhKE/dztEH05/myXm 4JizYWokHY2dg== 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, christophe.leroy@csgroup.eu, paulus@ozlabs.org, sourabhjain@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 4.19 1/4] powerpc/rtas: avoid device tree lookups in rtas_os_term() Date: Tue, 27 Dec 2022 15:35:50 -0500 Message-Id: <20221227203555.1214746-1-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 b492cb1c36fd..4c9ed28465b3 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -717,6 +717,7 @@ 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) { @@ -728,14 +729,13 @@ 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)); @@ -1332,6 +1332,13 @@ 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