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 0A010C433EF for ; Thu, 24 Mar 2022 00:07:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346627AbiCXAJN (ORCPT ); Wed, 23 Mar 2022 20:09:13 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38134 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240367AbiCXAJK (ORCPT ); Wed, 23 Mar 2022 20:09:10 -0400 Received: from gloria.sntech.de (gloria.sntech.de [185.11.138.130]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 206C28CCD1 for ; Wed, 23 Mar 2022 17:07:38 -0700 (PDT) Received: from ip5b412258.dynamic.kabel-deutschland.de ([91.65.34.88] helo=phil.lan) by gloria.sntech.de with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nXB0k-00055s-Ts; Thu, 24 Mar 2022 01:07:30 +0100 From: Heiko Stuebner To: palmer@dabbelt.com, paul.walmsley@sifive.com, aou@eecs.berkeley.edu Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, wefu@redhat.com, liush@allwinnertech.com, guoren@kernel.org, atishp@atishpatra.org, anup@brainfault.org, drew@beagleboard.org, hch@lst.de, arnd@arndb.de, wens@csie.org, maxime@cerno.tech, gfavor@ventanamicro.com, andrea.mondelli@huawei.com, behrensj@mit.edu, xinhaoqu@huawei.com, mick@ics.forth.gr, allen.baum@esperantotech.com, jscheid@ventanamicro.com, rtrauben@gmail.com, samuel@sholland.org, cmuellner@linux.com, philipp.tomsich@vrull.eu, Heiko Stuebner , Atish Patra Subject: [PATCH v8 01/14] riscv: prevent null-pointer dereference with sbi_remote_fence_i Date: Thu, 24 Mar 2022 01:06:57 +0100 Message-Id: <20220324000710.575331-2-heiko@sntech.de> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220324000710.575331-1-heiko@sntech.de> References: <20220324000710.575331-1-heiko@sntech.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The callback used inside sbi_remote_fence_i is set at sbi probe time to the needed variant. Before that it is a NULL pointer. Some users like the flush_icache_*() functions suggest a generic functionality, that doesn't depend on a specific boot-stage but uses sbi_remote_fence_i as one option to flush other cpu cores. So they definitely shouldn't run into null-pointer dereference issues when called "too early" during boot. So introduce an empty function to be the standard for the __sbi_rfence function pointer until sbi_init has run. Users of sbi_remote_fence_i will have separate code for the local cpu and sbi_init() is called before other cpus are brought up. So there are no other cpus present at the time when the issue might happen. Signed-off-by: Heiko Stuebner Reviewed-by: Atish Patra --- arch/riscv/kernel/sbi.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c index 775d3322b422..5a60a458c0b7 100644 --- a/arch/riscv/kernel/sbi.c +++ b/arch/riscv/kernel/sbi.c @@ -16,11 +16,19 @@ unsigned long sbi_spec_version __ro_after_init = SBI_SPEC_VERSION_DEFAULT; EXPORT_SYMBOL(sbi_spec_version); +static int __sbi_rfence_none(int fid, const struct cpumask *cpu_mask, + unsigned long start, unsigned long size, + unsigned long arg4, unsigned long arg5) +{ + return -EOPNOTSUPP; +} + static void (*__sbi_set_timer)(uint64_t stime) __ro_after_init; static int (*__sbi_send_ipi)(const struct cpumask *cpu_mask) __ro_after_init; static int (*__sbi_rfence)(int fid, const struct cpumask *cpu_mask, unsigned long start, unsigned long size, - unsigned long arg4, unsigned long arg5) __ro_after_init; + unsigned long arg4, unsigned long arg5) + __ro_after_init = __sbi_rfence_none; struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0, unsigned long arg1, unsigned long arg2, -- 2.35.1