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 X-Spam-Level: X-Spam-Status: No, score=-17.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37E1AC433EF for ; Sat, 18 Sep 2021 16:05:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 153AE60EE9 for ; Sat, 18 Sep 2021 16:05:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238005AbhIRQGu (ORCPT ); Sat, 18 Sep 2021 12:06:50 -0400 Received: from relay3-d.mail.gandi.net ([217.70.183.195]:47949 "EHLO relay3-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234157AbhIRQGn (ORCPT ); Sat, 18 Sep 2021 12:06:43 -0400 Received: (Authenticated sender: alex@ghiti.fr) by relay3-d.mail.gandi.net (Postfix) with ESMTPSA id 3CA9160002; Sat, 18 Sep 2021 16:05:12 +0000 (UTC) Subject: Re: [PATCH] riscv: Flush current cpu icache before other cpus To: Paul Walmsley , Palmer Dabbelt , Albert Ou , Anup Patel , Atish Patra , linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org References: <20210918160221.111902-1-alex@ghiti.fr> Cc: stable@vger.kernel.org From: Alex Ghiti Message-ID: <66013f6b-e3d0-2fbf-c02b-93899c2b4696@ghiti.fr> Date: Sat, 18 Sep 2021 18:05:09 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: <20210918160221.111902-1-alex@ghiti.fr> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Language: fr Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org (+cc stable) Le 18/09/2021 à 18:02, Alexandre Ghiti a écrit : > On SiFive Unmatched, I recently fell onto the following BUG when booting: > > [ 0.000000] ftrace: allocating 36610 entries in 144 pages > [ 0.000000] Oops - illegal instruction [#1] > [ 0.000000] Modules linked in: > [ 0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 5.13.1+ #5 > [ 0.000000] Hardware name: SiFive HiFive Unmatched A00 (DT) > [ 0.000000] epc : riscv_cpuid_to_hartid_mask+0x6/0xae > [ 0.000000] ra : __sbi_rfence_v02+0xc8/0x10a > [ 0.000000] epc : ffffffff80007240 ra : ffffffff80009964 sp : ffffffff81803e10 > [ 0.000000] gp : ffffffff81a1ea70 tp : ffffffff8180f500 t0 : ffffffe07fe30000 > [ 0.000000] t1 : 0000000000000004 t2 : 0000000000000000 s0 : ffffffff81803e60 > [ 0.000000] s1 : 0000000000000000 a0 : ffffffff81a22238 a1 : ffffffff81803e10 > [ 0.000000] a2 : 0000000000000000 a3 : 0000000000000000 a4 : 0000000000000000 > [ 0.000000] a5 : 0000000000000000 a6 : ffffffff8000989c a7 : 0000000052464e43 > [ 0.000000] s2 : ffffffff81a220c8 s3 : 0000000000000000 s4 : 0000000000000000 > [ 0.000000] s5 : 0000000000000000 s6 : 0000000200000100 s7 : 0000000000000001 > [ 0.000000] s8 : ffffffe07fe04040 s9 : ffffffff81a22c80 s10: 0000000000001000 > [ 0.000000] s11: 0000000000000004 t3 : 0000000000000001 t4 : 0000000000000008 > [ 0.000000] t5 : ffffffcf04000808 t6 : ffffffe3ffddf188 > [ 0.000000] status: 0000000200000100 badaddr: 0000000000000000 cause: 0000000000000002 > [ 0.000000] [] riscv_cpuid_to_hartid_mask+0x6/0xae > [ 0.000000] [] sbi_remote_fence_i+0x1e/0x26 > [ 0.000000] [] flush_icache_all+0x12/0x1a > [ 0.000000] [] patch_text_nosync+0x26/0x32 > [ 0.000000] [] ftrace_init_nop+0x52/0x8c > [ 0.000000] [] ftrace_process_locs.isra.0+0x29c/0x360 > [ 0.000000] [] ftrace_init+0x80/0x130 > [ 0.000000] [] start_kernel+0x5c4/0x8f6 > [ 0.000000] ---[ end trace f67eb9af4d8d492b ]--- > [ 0.000000] Kernel panic - not syncing: Attempted to kill the idle task! > [ 0.000000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]--- > > While ftrace is looping over a list of addresses to patch, it always failed > when patching the same function: riscv_cpuid_to_hartid_mask. Looking at the > backtrace, the illegal instruction is encountered in this same function. > However, patch_text_nosync, after patching the instructions, calls > flush_icache_range. But looking at what happens in this function: > > flush_icache_range -> flush_icache_all > -> sbi_remote_fence_i > -> __sbi_rfence_v02 > -> riscv_cpuid_to_hartid_mask > > The icache and dcache of the current cpu are never synchronized between the > patching of riscv_cpuid_to_hartid_mask and calling this same function. > > So fix this by flushing the current cpu's icache before asking for the other > cpus to do the same. > > Signed-off-by: Alexandre Ghiti > --- > arch/riscv/mm/cacheflush.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/riscv/mm/cacheflush.c b/arch/riscv/mm/cacheflush.c > index 094118663285..89f81067e09e 100644 > --- a/arch/riscv/mm/cacheflush.c > +++ b/arch/riscv/mm/cacheflush.c > @@ -16,6 +16,8 @@ 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 >