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 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 0AB94C4332F for ; Fri, 18 Nov 2022 14:11:04 +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:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=VicBTjVA7xtvNIQAv6u84nEyuukVaXIS20+XADv+EC0=; b=BgzqR8fIiMC3dD agocvRDrFiNao0hoo7FOTFsCYhg5Za78xgyJQbrcLiiXwK2QvskCCNXRMnvnwVwiHuKviNnyz4RtT LxW5jWn8LCJFJF10g8qbmdfvsmUZNOPAToxQaWTMo6AYAbK67ACgyP4+5oOc0Su8kPJb3oXxA2lC6 jr3rk5zpDE39w774k/Rqk4f0zFsdKZjdIJERShvY00+kRtvgP9uEocOY+DP0zZE9RGRg+POZuZPyO 57xxZlisOfPKH/k/QZW2/kMFfN59qnbFlYhrKAPx5Bp1xncxZ5CoFUUcChTiATpk6HFLUkmqFHhSV UDzmF6pSpKnkmDAWFMNA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ow24B-004Jkv-Dn; Fri, 18 Nov 2022 14:10:03 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ow248-004JjI-HH for linux-arm-kernel@lists.infradead.org; Fri, 18 Nov 2022 14:10:01 +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 ams.source.kernel.org (Postfix) with ESMTPS id EFDB5B8240D; Fri, 18 Nov 2022 14:09:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 35637C433C1; Fri, 18 Nov 2022 14:09:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668780597; bh=YlqOyLJmIJmPUAIiq8dJcBPhanVtu3o0KNlHKw+/3bs=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=rGLEFppErUJSp8zXdsG5EEFU9xNMZm/+sI72TaPWUdMOj+KBpAlL0FJMvOm7YRzx7 tz/4jw+/O0g1qohJ2QSNCehqag+Xjzks8GC5MbOulByYnzvH+7RluaH5aph1eiX3QH TPHNYNSRMmYEMf8LV3rEKka+1ExVA2x5L2tDbkQ//ZNr6WroguvqZSt/pT2mVHKa/2 n0zkrAbi3QAUg1dNcLn6E4zzWGaFQnjy7V1zIGUikMOub7IffqL3gEktHWYx5rK+TF Bxm8U7rQRmoFg9HDv8Vbk7JWwIjGt7qSjXW3crWtQ1idvSbzup8wHOg4/7JBW3vpbf MSOpGDpudMaIA== Date: Fri, 18 Nov 2022 14:09:52 +0000 From: Will Deacon To: Mark Rutland Cc: linux-kernel@vger.kernel.org, catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, mhiramat@kernel.org, revest@chromium.org, rostedt@goodmis.org Subject: Re: [PATCH v2 4/4] ftrace: arm64: move from REGS to ARGS Message-ID: <20221118140951.GE4046@willie-the-truck> References: <20221103170520.931305-1-mark.rutland@arm.com> <20221103170520.931305-5-mark.rutland@arm.com> <20221115112701.GB32523@willie-the-truck> <20221118123149.GB3697@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221118_061000_735226_FF13E4DD X-CRM114-Status: GOOD ( 21.94 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Nov 18, 2022 at 01:57:52PM +0000, Mark Rutland wrote: > On Fri, Nov 18, 2022 at 12:31:50PM +0000, Will Deacon wrote: > > On Thu, Nov 17, 2022 at 10:52:15AM +0000, Mark Rutland wrote: > > > On Tue, Nov 15, 2022 at 11:27:03AM +0000, Will Deacon wrote: > > > > On Thu, Nov 03, 2022 at 05:05:20PM +0000, Mark Rutland wrote: > > > > > +static __always_inline unsigned long > > > > > +ftrace_regs_get_argument(struct ftrace_regs *fregs, unsigned int n) > > > > > +{ > > > > > + if (n < 8) > > > > > + return fregs->regs[n]; > > > > > > > > Where does this '8' come from? > > > > > > Because in AAPCS64 the arguments are in x0 to x7, as mentioned in the commit > > > message: > > > > > > | Per AAPCS64, all function call argument and return values are held in > > > | the following GPRs: > > > | > > > | * X0 - X7 : parameter / result registers > > > | * X8 : indirect result location register > > > | * SP : stack pointer (AKA SP) > > > > > > The 'indirect result location register' would be used when returning large > > > structures, and isn't a function argument as such. > > > > Ah gotcha, I was mainly wondering about the role of x8 in 'struct > > ftrace_regs', but now I see that the FETCH_OP_REG might want to get at that. > > Ah, I see. Should I just add the bits above from the commit message into a > comment block above the definition of struct ftrace_regs ? Nah, it's ok, mainly just me learning what this is doing and I've queued it locally now. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel