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 992B1C46467 for ; Mon, 2 Jan 2023 11:30:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236148AbjABLa0 (ORCPT ); Mon, 2 Jan 2023 06:30:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50060 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236147AbjABLaA (ORCPT ); Mon, 2 Jan 2023 06:30:00 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A4DFB6364 for ; Mon, 2 Jan 2023 03:29:45 -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 5BC7FB80D1C for ; Mon, 2 Jan 2023 11:29:44 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7B495C433D2; Mon, 2 Jan 2023 11:29:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1672658983; bh=0wY3rcBMiKqya1495ZaBY5wlc8cLBa4SQUoFWG6M7h8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=A3I8UMbm9PAjSCSZMeG/ix1+BiPznnohqbgl/TgE005XFKmnY3xzHDWESjNWMAn0Q ILzRVjAPVxnSWvh3lJW0Hxy3PlMKJZPcWmfBaVTZawx6Duvwc8iF0U1DRpgkIjlwXd YEKd/h9F842kt1bJAjGKCDieBqzbXqgk1mZfgkVg= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nathan Lynch , Nicholas Piggin , Andrew Donnellan , Michael Ellerman , Sasha Levin Subject: [PATCH 6.0 41/74] powerpc/rtas: avoid device tree lookups in rtas_os_term() Date: Mon, 2 Jan 2023 12:22:14 +0100 Message-Id: <20230102110553.859954996@linuxfoundation.org> X-Mailer: git-send-email 2.39.0 In-Reply-To: <20230102110552.061937047@linuxfoundation.org> References: <20230102110552.061937047@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@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 0b8a858aa847..082b0c9e0c8a 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -875,6 +875,7 @@ 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) { @@ -886,14 +887,13 @@ 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)); @@ -1255,6 +1255,13 @@ 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