From mboxrd@z Thu Jan 1 00:00:00 1970 Delivery-date: Fri, 14 Jan 2022 10:30:31 +0100 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by lore.white.stw.pengutronix.de with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1n8Iul-001um1-HU for lore@lore.pengutronix.de; Fri, 14 Jan 2022 10:30:31 +0100 Received: from bombadil.infradead.org ([2607:7c80:54:e::133]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1n8Iuk-00089t-7n for lore@pengutronix.de; Fri, 14 Jan 2022 10:30:30 +0100 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:From:In-Reply-To:MIME-Version: References:Message-ID:Subject:Cc:To:Date:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Owner; bh=fdnf4GPJHEnuKvQKoMPlQuUG5xVtbj1Or07CVNBqd6Q=; b=okogV5L4tD1K2Kq61a+5Gl3R7T sJI2ulpKQFP3/2TEQMsD9H8KeMVyp2ShSWm5SW8Cw5FTkvmiKIhoKP994Vr7EkhOsMMR1EU/GpVnb 7Yc9+ku4h/nZG7f3npSE/K0yD+3/KZT3AwVLOUne8ioAtFIHmGkhjARB5RoNWXG5EgHHYRWh5ZAuy QZQRGO5L1GcM9+om/P3Lkd/aCJeMYjkrgl7Hj4AfeWadsjW9TnKifFIl/K/kqYtCVnBKqYUnjIux/ xrha1Mo+rOwwlAG8KuQqzEUVgg98PmaX6MkPkKxFhCoAMYCAvbKM9wvOVLxmMAKbplaJ1mhNDEgwA Zazu9ttQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1n8ItR-008VXS-I9; Fri, 14 Jan 2022 09:29:09 +0000 Received: from metis.ext.pengutronix.de ([2001:67c:670:201:290:27ff:fe1d:cc33]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1n8ItM-008VWR-2I for barebox@lists.infradead.org; Fri, 14 Jan 2022 09:29:05 +0000 Received: from ptx.hi.pengutronix.de ([2001:67c:670:100:1d::c0]) by metis.ext.pengutronix.de with esmtps (TLS1.3:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1n8ItK-0007ww-SJ; Fri, 14 Jan 2022 10:29:02 +0100 Received: from sha by ptx.hi.pengutronix.de with local (Exim 4.92) (envelope-from ) id 1n8ItK-0001h9-Jo; Fri, 14 Jan 2022 10:29:02 +0100 Date: Fri, 14 Jan 2022 10:29:02 +0100 To: Ahmad Fatoum Cc: barebox@lists.infradead.org Message-ID: <20220114092902.GU26619@pengutronix.de> References: <20220114084227.308804-1-a.fatoum@pengutronix.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220114084227.308804-1-a.fatoum@pengutronix.de> X-Sent-From: Pengutronix Hildesheim X-URL: http://www.pengutronix.de/ X-IRC: #ptxdist @freenode X-Accept-Language: de,en X-Accept-Content-Type: text/plain X-Uptime: 10:28:36 up 34 days, 18:14, 79 users, load average: 0.01, 0.06, 0.09 User-Agent: Mutt/1.10.1 (2018-07-13) From: Sascha Hauer X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220114_012904_134368_04ABD2E7 X-CRM114-Status: GOOD ( 30.18 ) X-BeenThere: barebox@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: "barebox" X-SA-Exim-Connect-IP: 2607:7c80:54:e::133 X-SA-Exim-Mail-From: barebox-bounces+lore=pengutronix.de@lists.infradead.org X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on metis.ext.pengutronix.de X-Spam-Level: X-Spam-Status: No, score=-4.9 required=4.0 tests=AWL,BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_NONE autolearn=unavailable autolearn_force=no version=3.4.2 Subject: Re: [PATCH v2 1/3] ARM: implement ENTRY_FUNCTION_WITHSTACK X-SA-Exim-Version: 4.2.1 (built Wed, 08 May 2019 21:11:16 +0000) X-SA-Exim-Scanned: Yes (on metis.ext.pengutronix.de) On Fri, Jan 14, 2022 at 09:42:25AM +0100, Ahmad Fatoum wrote: > The point of ENTRY_FUNCTION is to write the entry point in C. Due to > lack of __naked on ARM64, the start of the entry point will have prologue > using stack and it's not possible to set up the stack safely without > branching into non-inline assembly[0]. On ARM32, where we got __naked, we > have the potential for a different problem: If BootROM sets up stack for > us and we branch to a naked function, which doesn't set up its own > stack, compiler may decide to spill local variables overwriting > instructions it had already run[1]. > > For code reuse between ARM and ARM64, it would be nice to use the same > entry point structure for both. Currently, the only way is to write it > in non-inline assembly using the ENTRY_PROC macro. > > This introduces another way: the ARM64 barebox header has enough space > for 8 instructions of which 5 are unused (2 instructions compiler prologue > + 1 instruction to jump after the header), we could place a stack setup > routine there to avoid having to write a separate assembly file. > For ARM32, we just call arm_setup_stack and branch out directly after, > freeing board porters of the burden of getting it right. > > Add a new ENTRY_FUNCTION_WITHSTACK to realize this. > > [0]: 76bced6fe146 ("ARM: document arm_setup_stack() pitfalls"), > [1]: b51b15ba1738 ("RISC-V: board-dt-2nd: move low level init into nonnaked function") > > Signed-off-by: Ahmad Fatoum > --- > v1 -> v2: > - add __ARM_SETUP_STACK(0) to normal ENTRY_FUNCTION. On ARM32, it's a > no-op, but on ARM64, it ensures the header isn't shifted > --- > arch/arm/include/asm/barebox-arm-head.h | 6 +--- > arch/arm/include/asm/barebox-arm.h | 46 +++++++++++++++++++++++++ > arch/arm/lib/pbl.lds.S | 1 + > 3 files changed, 48 insertions(+), 5 deletions(-) Applied, thanks Sascha -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@lists.infradead.org http://lists.infradead.org/mailman/listinfo/barebox