From patchwork Fri Jan 21 16:36:05 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Heiko Stuebner X-Patchwork-Id: 533933 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 9FF42C4321E for ; Fri, 21 Jan 2022 16:37:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350422AbiAUQhJ (ORCPT ); Fri, 21 Jan 2022 11:37:09 -0500 Received: from gloria.sntech.de ([185.11.138.130]:35258 "EHLO gloria.sntech.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1349296AbiAUQhF (ORCPT ); Fri, 21 Jan 2022 11:37:05 -0500 Received: from p508fcef5.dip0.t-ipconnect.de ([80.143.206.245] helo=phil.fritz.box) by gloria.sntech.de with esmtpsa (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1nAwuF-0008GA-I7; Fri, 21 Jan 2022 17:36:55 +0100 From: Heiko Stuebner To: palmer@dabbelt.com, paul.walmsley@sifive.com, aou@eecs.berkeley.edu Cc: linux-riscv@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, robh+dt@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, dlustig@nvidia.com, gfavor@ventanamicro.com, andrea.mondelli@huawei.com, behrensj@mit.edu, xinhaoqu@huawei.com, huffman@cadence.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 Subject: [PATCH v5 01/14] riscv: only use IPIs to handle cache-flushes on remote cpus Date: Fri, 21 Jan 2022 17:36:05 +0100 Message-Id: <20220121163618.351934-2-heiko@sntech.de> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220121163618.351934-1-heiko@sntech.de> References: <20220121163618.351934-1-heiko@sntech.de> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Right now, the flush_icache functions always use the SBI remote-fence when SBI is available, leaving using IPIs as a fallback mechanism. IPIs on the other hand are more flexible, as the ipi_ops are initially set to go through SBI but later will be overwritten to go through the ACLINT/CLINT. In a discussion we had, Nick was of the opinion that "In general we should prefer doing IPIs on S-mode through CLINT instead of going through SBI/M-mode, so IMHO we should only be using on_each_cpu_mask(ipi_remote_fence_i) on flush_icache_all()/ flush_icache_mm() and remove any explicit calls to sbi_remote_fence_i(), because this way we continue using SBI for doing remote fences even after CLINT/ACLINT driver is registered, instead of using direct IPIs through CLINT/ACLINT." So follow this suggestion and just do ipi calls to have the proper kernel parts do them, This also fixes the null-ptr dereference happening when flush_icache_all() is called before sbi_init(). Suggested-by: Nick Kossifidis Signed-off-by: Heiko Stuebner --- arch/riscv/mm/cacheflush.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-) diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c index 6cb7d96ad9c7..c35375cd52ec 100644 --- a/arch/riscv/mm/cacheflush.c +++ b/arch/riscv/mm/cacheflush.c @@ -17,11 +17,7 @@ static void ipi_remote_fence_i(void *info) void flush_icache_all(void) { local_flush_icache_all(); - - if (IS_ENABLED(CONFIG_RISCV_SBI)) - sbi_remote_fence_i(NULL); - else - on_each_cpu(ipi_remote_fence_i, NULL, 1); + on_each_cpu(ipi_remote_fence_i, NULL, 1); } EXPORT_SYMBOL(flush_icache_all); @@ -66,8 +62,6 @@ void flush_icache_mm(struct mm_struct *mm, bool local) * with flush_icache_deferred(). */ smp_mb(); - } else if (IS_ENABLED(CONFIG_RISCV_SBI)) { - sbi_remote_fence_i(&others); } else { on_each_cpu_mask(&others, ipi_remote_fence_i, NULL, 1); }