From patchwork Wed Oct 19 15:47:27 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jisheng Zhang X-Patchwork-Id: 13012102 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 1A286C4332F for ; Wed, 19 Oct 2022 16:09:05 +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=rmAsfmXkK92MD7h2RgXzuVVgcCPynMRT/jHDhZ0eE8g=; b=1XoUjWq2OuBsDk YVaKwb3+aBHl9fP+oUfxGDQnWk81K4/RgtVVf+Z2L1hCsHJROCT+bSsXc/g5+sn9IN01ODvfWI5kk 3gF+2wJm374xunwU45WT2ldZbC9Wwe5Mypx3Is533ckd3uYSJtrxUVro+bN58M/6mkoTH98csoB3m DQJzFYT6K2RZfgDh8UrL9pF5noLMMzxCPMkcvZ4SnHPi5/sIyheb30PxZmpIluWSLfzjsXpGYaBOM oXnm8jWfK9opg2w+jm+N7J4h7VltGwsLnx2IPWZbSdqpSAOjdGh+9G2VqBqJ86/xsaB81GEse9tr9 cb434yEktHwSz02CGCtQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1olBcg-003jv5-Vw; Wed, 19 Oct 2022 16:08:51 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1olBRK-003Zgj-Pw for linux-riscv@lists.infradead.org; Wed, 19 Oct 2022 15:57:08 +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 795C06194D; Wed, 19 Oct 2022 15:57:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6EF9FC433C1; Wed, 19 Oct 2022 15:57:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1666195024; bh=tl/t0JSFx6B/W7U7U+lCNfIdDELRIvrRpnIkdxf7UO8=; h=From:To:Cc:Subject:Date:From; b=LXQ3DBXykd8cxJe+nDeTMuzZh2SioIauX440gB0kLifBqT436A3SwZ8AqZAu0d5Ks QaH7PcJ7Zc5hE1yZ2imldpdk31TSsBPmyqtqIUmi/FDTM7tlChYsG3UdkuAm43zcOZ RAvDnZZCtCzMzQWa2vGzAFjZlg84MC1gKhu9nK2YdtXDm2qiYt7ZuDVhgD6so4+eab ItBZ4nypwK6bA1YqZxImaHz4C5ugTj8o4tT4JXmFk+xq+iKF2uoHw9fPykRoMDNju8 p4Ah1KhNSiZSfM7VwAmm6T8F5k5PTyhH7sfIJdBw4ZMGoCPp3RMnU1QXuOVwaKr0tn j/GdetFOTgQsA== From: Jisheng Zhang To: Paul Walmsley , Palmer Dabbelt , Albert Ou Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Guo Ren Subject: [PATCH] riscv: fix race when vmap stack overflow Date: Wed, 19 Oct 2022 23:47:27 +0800 Message-Id: <20221019154727.2395-1-jszhang@kernel.org> X-Mailer: git-send-email 2.37.2 MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221019_085707_008426_14FE1D76 X-CRM114-Status: UNSURE ( 9.63 ) X-CRM114-Notice: Please train this message. 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 Currently, when detecting vmap stack overflow, riscv firstly switches to the so called shadow stack, then use this shadow stack to call the get_overflow_stack() to get the overflow stack. However, there's a race here if two or more harts use the same shadow stack at the same time. To solve this race, we introduce spin_shadow_stack atomic var, which will make the shadow stack usage serialized. Fixes: 31da94c25aea ("riscv: add VMAP_STACK overflow detection") Signed-off-by: Jisheng Zhang Suggested-by: Guo Ren Reviewed-by: Guo Ren --- arch/riscv/kernel/entry.S | 4 ++++ arch/riscv/kernel/traps.c | 4 ++++ 2 files changed, 8 insertions(+) diff --git a/arch/riscv/kernel/entry.S b/arch/riscv/kernel/entry.S index b9eda3fcbd6d..7b924b16792b 100644 --- a/arch/riscv/kernel/entry.S +++ b/arch/riscv/kernel/entry.S @@ -404,6 +404,10 @@ handle_syscall_trace_exit: #ifdef CONFIG_VMAP_STACK handle_kernel_stack_overflow: +1: la sp, spin_shadow_stack + amoswap.w sp, sp, (sp) + bnez sp, 1b + la sp, shadow_stack addi sp, sp, SHADOW_OVERFLOW_STACK_SIZE diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index f3e96d60a2ff..88a54947dffb 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -221,11 +221,15 @@ asmlinkage unsigned long get_overflow_stack(void) OVERFLOW_STACK_SIZE; } +atomic_t spin_shadow_stack; + asmlinkage void handle_bad_stack(struct pt_regs *regs) { unsigned long tsk_stk = (unsigned long)current->stack; unsigned long ovf_stk = (unsigned long)this_cpu_ptr(overflow_stack); + atomic_set_release(&spin_shadow_stack, 0); + console_verbose(); pr_emerg("Insufficient stack space to handle exception!\n");