From patchwork Wed Nov 9 05:40:56 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guo Ren X-Patchwork-Id: 17345 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:6687:0:0:0:0:0 with SMTP id l7csp160631wru; Tue, 8 Nov 2022 21:46:42 -0800 (PST) X-Google-Smtp-Source: AMsMyM4O4IcrpNLPYuKIhY74rgulZGMdIgEXhwQHNA3ImmCbNsCDm5jOpaHM4AG4B5L5ObQMJNXh X-Received: by 2002:a05:6402:358e:b0:461:ea80:fb61 with SMTP id y14-20020a056402358e00b00461ea80fb61mr58123628edc.356.1667972802210; Tue, 08 Nov 2022 21:46:42 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1667972802; cv=none; d=google.com; s=arc-20160816; b=EmpZ/wECng1+INB9OweER9z+71VcXvKri4q550iN9teQ4cGxW6cfdvhJkXh4e+Y+Dz MvrpcepChgLN0WEf9B6QaLMZwWQ9NvQJhuckxAndTJH7euiTBXO4ogADThZYJP4yQB7R QLzRFe9+aggRWe+s6biTYr6vCXCheKM3FUATuEQMWGuqE8UVsXRxJBv3wlvM4abxBxtv m/t0uhYbHKwIdP0c+0mgicYaVNkTJKeAtcnP7iJgKdBTk7mySbUJ8QKYoQqyjshgZQPi GhPSjkbKiad571KWJ+iRGb1CVmc9Sg6c7+ppyA9no4ttngfirdq03uO66Rinu52PZdhF WRpQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from:dkim-signature; bh=bY5K1BRXh8iA5u3R4bSQ7NPMjoLRIbBQ8r0hh9D7Whk=; b=Y0Sb9EC8EraeMudvpnGn+M2m8Vq7nF8itMY+UJpmnsdLAO5LfkXAEn+HLrFE0nmj0G kDHc3hLxwByNUlpQtOmoRa7QG81dT/bPIPvRUjrULBrzdVXiWA0LWCGOt17RKZFfQDgc H+SmtipNpUHuX5VQiFm0ry4d9SeKRj2lXanhrgrlafgkEjcWJKoIrYWm6tXDab+0ynp3 yuuMomLQHyyMC8nCo+OObbTYmoEx1XSg0fFD79o5eVqv82d+FUQmTz5maf9AoxtNsYVT iz7Qbc+FoEXH2wveD+WoSVHLs4KFQ3FhaeuYFe3mFUscT1wGCv6lKMwqImXDib0iUANk fniA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=A6Aw7vrV; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id qk35-20020a1709077fa300b007ae6076db35si4030909ejc.315.2022.11.08.21.46.18; Tue, 08 Nov 2022 21:46:42 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=k20201202 header.b=A6Aw7vrV; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229578AbiKIFlM (ORCPT + 99 others); Wed, 9 Nov 2022 00:41:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51284 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229485AbiKIFlL (ORCPT ); Wed, 9 Nov 2022 00:41:11 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C9CAB1AD9C for ; Tue, 8 Nov 2022 21:41:09 -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 60B656188F for ; Wed, 9 Nov 2022 05:41:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id BDFE4C433D6; Wed, 9 Nov 2022 05:41:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667972468; bh=NcYwem+RG7CdaZySwWGMcxlQ4IDXuYGi+05zOMk3sqU=; h=From:To:Cc:Subject:Date:From; b=A6Aw7vrV1Qw79HjJWSBXybgU6SvB/JtjMlUsZDpNHtY2LEdXNSvGuJLFtGYcHGhEc aC3iMHT0hGIFvCiuBfXC9IkSOz8qFt93aDlipKpAM7d66Ly9Tx+3YlbcgZgmSYVmXw bp0M4sKs68iWYMdt6nRy9Y+7ffGBggcwDA/eqKNzTX1n5u9htXGntKqR8BxnCZ7TFx /eXUZwdqqzEXY0uwdZd0g004hvGz34Z6sHwIUmbQUINoITLqWHZqfFxLvDnwOwe2z/ /2RC24tKCtWD0jizM/3zT3YMU1oC1uE00dAqSEjtUkisUc3t1sw3Tg84vupN8VMloy h+uxN54KsUmhw== From: guoren@kernel.org To: anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, conor.dooley@microchip.com, heiko@sntech.de, philipp.tomsich@vrull.eu Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Guo Ren , Guo Ren , Anup Patel , Palmer Dabbelt Subject: [PATCH V2] riscv: asid: Fixup stale TLB entry cause application crash Date: Wed, 9 Nov 2022 00:40:56 -0500 Message-Id: <20221109054056.3618089-1-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 MIME-Version: 1.0 X-Spam-Status: No, score=-7.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1748996248989055823?= X-GMAIL-MSGID: =?utf-8?q?1748996248989055823?= From: Guo Ren After use_asid_allocator is enabled, the userspace application will crash by stale TLB entries. Because only using cpumask_clear_cpu without local_flush_tlb_all couldn't guarantee CPU's TLB entries were fresh. Then set_mm_asid would cause the user space application to get a stale value by stale TLB entry, but set_mm_noasid is okay. Here is the symptom of the bug: unhandled signal 11 code 0x1 (coredump) 0x0000003fd6d22524 <+4>: auipc s0,0x70 0x0000003fd6d22528 <+8>: ld s0,-148(s0) # 0x3fd6d92490 => 0x0000003fd6d2252c <+12>: ld a5,0(s0) (gdb) i r s0 s0 0x8082ed1cc3198b21 0x8082ed1cc3198b21 (gdb) x /2x 0x3fd6d92490 0x3fd6d92490: 0xd80ac8a8 0x0000003f The core dump file shows that register s0 is wrong, but the value in memory is correct. Because 'ld s0, -148(s0)' used a stale mapping entry in TLB and got a wrong result from an incorrect physical address. When the task ran on CPU0, which loaded/speculative-loaded the value of address(0x3fd6d92490), then the first version of the mapping entry was PTWed into CPU0's TLB. When the task switched from CPU0 to CPU1 (No local_tlb_flush_all here by asid), it happened to write a value on the address (0x3fd6d92490). It caused do_page_fault -> wp_page_copy -> ptep_clear_flush -> ptep_get_and_clear & flush_tlb_page. The flush_tlb_page used mm_cpumask(mm) to determine which CPUs need TLB flush, but CPU0 had cleared the CPU0's mm_cpumask in the previous switch_mm. So we only flushed the CPU1 TLB and set the second version mapping of the PTE. When the task switched from CPU1 to CPU0 again, CPU0 still used a stale TLB mapping entry which contained a wrong target physical address. It raised a bug when the task happened to read that value. The solution is to keep all CPUs' footmarks of cpumask(mm) in switch_mm, which could prevent losing pieces of stuff during TLB flush. Fixes: 65d4b9c53017 ("RISC-V: Implement ASID allocator") Signed-off-by: Guo Ren Signed-off-by: Guo Ren Cc: Anup Patel Cc: Palmer Dabbelt --- Changes in v2: - Fixup nommu compile problem (Thx Conor, Also Reported-by: kernel test robot ) - Keep cpumask_clear_cpu for noasid --- arch/riscv/mm/context.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c index 7acbfbd14557..f58e4b211595 100644 --- a/arch/riscv/mm/context.c +++ b/arch/riscv/mm/context.c @@ -317,7 +317,11 @@ void switch_mm(struct mm_struct *prev, struct mm_struct *next, */ cpu = smp_processor_id(); - cpumask_clear_cpu(cpu, mm_cpumask(prev)); +#ifdef CONFIG_MMU + if (!static_branch_unlikely(&use_asid_allocator)) +#endif + cpumask_clear_cpu(cpu, mm_cpumask(prev)); + cpumask_set_cpu(cpu, mm_cpumask(next)); set_mm(next, cpu);