From patchwork Tue Nov 8 09:02:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Guo Ren X-Patchwork-Id: 13036029 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 52C4CC4332F for ; Tue, 8 Nov 2022 09:02:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-Id:Date:Subject:Cc :To:From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References: List-Owner; bh=RBs9dbH6GnB7LGECnT5mAsw1c79Hv1GZ09svWz5T0iw=; b=ncpeNEZ8HkvEol 44/7wR0NNVxS5TtwOSXiXl7j4xvUdRO/+EU+ChKc/oAAQPmvmrf6XGduPatHx+L30yLUlD4WpZxe0 aJZX/idC0coVnR6VAUwx21vu/PnkFBFRQvk8+fuYMZF5+sSCzrfFcojlb6XDAUxh+t+vmW89njArk kw8X9FfCuk3FxzNeegoi2mHOVXLLMq9F1VH2V8QwdIyCgLcKW5UGWRgShXiqacotEjCR1AgRXxVZF MosogaUxqIIJHVfJmBdimYRIfgKwdWBAHUSB4mTt8d0sxO548GN0AoDzPvWnq/xHZjCODH8Ob+fl9 /o5Bd8q1ZabAC7Kph5jw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1osKV5-003tq0-BF; Tue, 08 Nov 2022 09:02:31 +0000 Received: from dfw.source.kernel.org ([139.178.84.217]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1osKV2-003tQE-Qs for linux-riscv@lists.infradead.org; Tue, 08 Nov 2022 09:02:30 +0000 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 C7F81614C4; Tue, 8 Nov 2022 09:02:27 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id F38E7C433C1; Tue, 8 Nov 2022 09:02:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1667898147; bh=40as9zy58r8i/rJfR7Z6TRRJsKNmmDmW8cmLv1ORktE=; h=From:To:Cc:Subject:Date:From; b=pkfJDph7m26p588lRvKtcu20kjCZlELls26LoNAh2HMA5oPn4okhu+02A9B5HV3wA B6jM2Tx5CPm9N/P5lhalCJiQt42kptl2J5hRuWT6HjMUqjW08sO3Em22n0jZyCU3gJ 3y9HFKaL+e090LM91K1PI1j8enY9F0ucXaXMlQ25o6WheVnYeHLtcWhY9C7SyVvLV3 T5jrQqwTCPLZXTF3Ul4a7NHJKrq3Wu5wN/ILrFsxine91hKQh6vZkmLS5IKP41nWYk 0BcrifcoSpgRNaQ4cHm2cr3ey405LJ8I60X1f5QlJcKSat60uEUcgeT/9qfz17kjmd 95rwf8jqrAZfA== From: guoren@kernel.org To: anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, alexandre.ghiti@canonical.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] riscv: asid: Fixup stale TLB entry cause application crash Date: Tue, 8 Nov 2022 04:02:19 -0500 Message-Id: <20221108090219.3285030-1-guoren@kernel.org> X-Mailer: git-send-email 2.36.1 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221108_010228_940650_E3132182 X-CRM114-Status: GOOD ( 13.65 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org From: Guo Ren When use_asid_allocator is enabled, the userspace application would crash by stale tlb entry. Because only using cpumask_clear_cpu without local_flush_tlb_all couldn't guarantee CPU's tlb contains fresh mapping entry. Then set_mm_asid would cause user space application 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/16 0x3fd6d92490 0x3fd6d92490: 0xd80ac8a8 0x0000003f The core dump file show us the value of register s0 is wrong, but the value in memory is right. When task run on CPU0, the task loaded/speculative-loaded the value of address-0x3fd6d92490, the first version tlb mapping enter in CPU0's tlb. When the task switched from CPU0 to CPU1 without local_tlb_flush_all (because of asid), the task happened to write a value on address: 0x3fd6d92490 that caused do_page_fault -> wp_page_copy -> ptep_clear_flush -> ptep_get_and_clear & flush_tlb_page. The flush_tlb_page would use mm_cpumask(mm) to determine which CPUs need tlb flush, but CPU0 cleared the CPU0's mm_cpumask in previous switch_mm. So we only flushed the CPU1's tlb entry, and setted second version mapping of the pte. When the task switch from CPU1 to CPU0 again, it still used a stale tlb entry on CPU0 which contained a wrong target physical address. When the task happened to read that value, the bug would be raised. Fixes: 65d4b9c53017 ("RISC-V: Implement ASID allocator") Signed-off-by: Guo Ren Signed-off-by: Guo Ren Cc: Anup Patel Cc: Palmer Dabbelt --- arch/riscv/mm/context.c | 1 - 1 file changed, 1 deletion(-) diff --git a/arch/riscv/mm/context.c b/arch/riscv/mm/context.c index 7acbfbd14557..843e86b63532 100644 --- a/arch/riscv/mm/context.c +++ b/arch/riscv/mm/context.c @@ -317,7 +317,6 @@ void switch_mm(struct mm_struct *prev, struct mm_struct *next, */ cpu = smp_processor_id(); - cpumask_clear_cpu(cpu, mm_cpumask(prev)); cpumask_set_cpu(cpu, mm_cpumask(next)); set_mm(next, cpu);