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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 8885AC4167B for ; Tue, 27 Dec 2022 20:37:01 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4NhRK81FLcz3cCP for ; Wed, 28 Dec 2022 07:37:00 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=VxD9h5mP; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=2604:1380:4601:e00::1; helo=ams.source.kernel.org; envelope-from=sashal@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=VxD9h5mP; dkim-atps=neutral Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4NhRG26v4Nz3c7K for ; Wed, 28 Dec 2022 07:34:18 +1100 (AEDT) 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 A3B6CB811FE; Tue, 27 Dec 2022 20:34:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39F3FC433F2; Tue, 27 Dec 2022 20:34:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672173255; bh=0wY3rcBMiKqya1495ZaBY5wlc8cLBa4SQUoFWG6M7h8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VxD9h5mP3ounRZv7JmLgluHD+tDHaF9abeIYMTXiJingJm1aBS4Dhdp4CCZUQydoq pTTWFgnbaKqGjSk8aIqXHOXDn5XPEDty+mr2E40ThQU4Su6V757+BmtTdjztnUDjZA XA8zE2hiaqBx6E6J7t64DkZ7m2pTd3jnecsZ75nzWBygvvVNEC7VsvE+Dz1RGtazHr l76LwmFY2lkXcMVkgOWFyGcJMk5codYb1BJ4aP8CXYEcCuHUydB/HsY6hOV902FWzO C47MAp1nW/SrvhvFFWaAnX7+9FrtgzzZhWwBazcQOqi0iLoMbj6xSYVq7hQP41EZX5 MSFsDjFYrpoSg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH AUTOSEL 6.0 21/27] powerpc/rtas: avoid device tree lookups in rtas_os_term() Date: Tue, 27 Dec 2022 15:33:36 -0500 Message-Id: <20221227203342.1213918-21-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221227203342.1213918-1-sashal@kernel.org> References: <20221227203342.1213918-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Nathan Lynch , Sasha Levin , Andrew Donnellan , Nicholas Piggin , sourabhjain@linux.ibm.com, ldufour@linux.ibm.com, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" 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 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 5A2A8C4167B for ; Tue, 27 Dec 2022 20:38:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232651AbiL0UiX (ORCPT ); Tue, 27 Dec 2022 15:38:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232340AbiL0UhT (ORCPT ); Tue, 27 Dec 2022 15:37:19 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 74A5BDFF3; Tue, 27 Dec 2022 12:34:16 -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 dfw.source.kernel.org (Postfix) with ESMTPS id 0D7B76123C; Tue, 27 Dec 2022 20:34:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 39F3FC433F2; Tue, 27 Dec 2022 20:34:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1672173255; bh=0wY3rcBMiKqya1495ZaBY5wlc8cLBa4SQUoFWG6M7h8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VxD9h5mP3ounRZv7JmLgluHD+tDHaF9abeIYMTXiJingJm1aBS4Dhdp4CCZUQydoq pTTWFgnbaKqGjSk8aIqXHOXDn5XPEDty+mr2E40ThQU4Su6V757+BmtTdjztnUDjZA XA8zE2hiaqBx6E6J7t64DkZ7m2pTd3jnecsZ75nzWBygvvVNEC7VsvE+Dz1RGtazHr l76LwmFY2lkXcMVkgOWFyGcJMk5codYb1BJ4aP8CXYEcCuHUydB/HsY6hOV902FWzO C47MAp1nW/SrvhvFFWaAnX7+9FrtgzzZhWwBazcQOqi0iLoMbj6xSYVq7hQP41EZX5 MSFsDjFYrpoSg== 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, sourabhjain@linux.ibm.com, paulus@ozlabs.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 6.0 21/27] powerpc/rtas: avoid device tree lookups in rtas_os_term() Date: Tue, 27 Dec 2022 15:33:36 -0500 Message-Id: <20221227203342.1213918-21-sashal@kernel.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20221227203342.1213918-1-sashal@kernel.org> References: <20221227203342.1213918-1-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: 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