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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74C60ECAAD3 for ; Mon, 19 Sep 2022 13:45:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230149AbiISNpv (ORCPT ); Mon, 19 Sep 2022 09:45:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229667AbiISNpt (ORCPT ); Mon, 19 Sep 2022 09:45:49 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1CA8517066; Mon, 19 Sep 2022 06:45:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=bjogngX1F/JZwA+k9RfkZhp88x9yf+GaiFwl+CZH6hg=; b=d4nxG+MzP54k7yWbKFQHdqhuGv ozyorpIIgc4NNC9rIw994EZtM6mjs1hztVHSPVx0bIG5bf2wtTh988madhgQtJGM3ytUd3pLN6Nsf 7MzV3Npvn+edwN/xTN4XEAVPVUU/tfjGeKs4EHIMgdaiynn5Lt8FqTIye5owf8vMn4xpy0CeeUAK8 TSbFhnqlzFxMKabPlf5uh6Mt5IdwNJxhvHB8gah14SkZun2E10bmeyq3usOtPdHhKLFgRNPd9qiwd Fm/2Z/pCv+mydapcnpDMHXuSw5tGuGQyjepzNCFwihAkcNWhF7zJWpe3a69ymybUjV/sPZAPOYsUa PQSlWAOA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1oaH5L-004k8i-9t; Mon, 19 Sep 2022 13:45:19 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 1CA95300202; Mon, 19 Sep 2022 15:45:15 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id ED5F02BAC75BE; Mon, 19 Sep 2022 15:45:14 +0200 (CEST) Date: Mon, 19 Sep 2022 15:45:14 +0200 From: Peter Zijlstra To: guoren@kernel.org Cc: arnd@arndb.de, palmer@rivosinc.com, tglx@linutronix.de, luto@kernel.org, conor.dooley@microchip.com, heiko@sntech.de, jszhang@kernel.org, lazyparser@gmail.com, falcon@tinylab.org, chenhuacai@kernel.org, apatel@ventanamicro.com, atishp@atishpatra.org, palmer@dabbelt.com, paul.walmsley@sifive.com, mark.rutland@arm.com, zouyipeng@huawei.com, bigeasy@linutronix.de, David.Laight@aculab.com, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org, Guo Ren , keescook@chromium.org Subject: Re: [PATCH V5 08/11] riscv: Support HAVE_IRQ_EXIT_ON_IRQ_STACK Message-ID: References: <20220918155246.1203293-1-guoren@kernel.org> <20220918155246.1203293-9-guoren@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220918155246.1203293-9-guoren@kernel.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Sep 18, 2022 at 11:52:43AM -0400, guoren@kernel.org wrote: > +ENTRY(call_on_stack) > + /* Create a frame record to save our ra and fp */ > + addi sp, sp, -RISCV_SZPTR > + REG_S ra, (sp) > + addi sp, sp, -RISCV_SZPTR > + REG_S fp, (sp) > + > + /* Save sp in fp */ > + move fp, sp > + > + /* Move to the new stack and call the function there */ > + li a3, IRQ_STACK_SIZE > + add sp, a1, a3 > + jalr a2 > + > + /* > + * Restore sp from prev fp, and fp, ra from the frame > + */ > + move sp, fp > + REG_L fp, (sp) > + addi sp, sp, RISCV_SZPTR > + REG_L ra, (sp) > + addi sp, sp, RISCV_SZPTR > + ret > +ENDPROC(call_on_stack) IIRC x86_64 moved away from a stack-switch function like this because it presents a convenient exploit gadget. I'm not much of an exploit writer and I've no idea how effective our inline stategy is, perhaps other can comment.