From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from metis.ext.pengutronix.de ([2001:6f8:1178:4:290:27ff:fe1d:cc33]) by merlin.infradead.org with esmtps (Exim 4.76 #1 (Red Hat Linux)) id 1SVJgQ-0007z0-Et for barebox@lists.infradead.org; Fri, 18 May 2012 09:41:15 +0000 Date: Fri, 18 May 2012 11:41:11 +0200 From: Sascha Hauer Message-ID: <20120518094110.GS30400@pengutronix.de> References: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: 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-bounces@lists.infradead.org Errors-To: barebox-bounces+u.kleine-koenig=pengutronix.de@lists.infradead.org Subject: Re: SVC32 and SP To: Carlo Caione Cc: barebox@lists.infradead.org On Fri, May 18, 2012 at 12:06:00AM +0200, Carlo Caione wrote: > Hi, > I was debugging the problem with barebox and qemu-linaro as I > described in a previous post. > This is what I have discovered. > > The problem is in the strlen function that seems to get corrupted > runtime during barebox initialization. The problem seems related to > the switch to SVC32 mode together with the __mmu_cache_flush > implementation. > Before setting the cpu to SVC32 mode, the Stack Pointer is correctly > set to 0x4020fcb0, but, immediately after the writing in the cpsr > register (__asm__ __volatile__("msr cpsr, %0" : : "r"(r));) the Stack > Pointer (now R13_SVC) is in 0x40205cb0 that is in the middle of the > .text section (and precisely in the middle of the strlen routine). > The problem is that in the __mmu_cache_flush disassembly I have a huge > push {r0, r1, r2, r3, r4, r5, r6, r7, r9, r10, r11} that overwrites > the strlen function and corrupts the code. Can you try and remove the call to __mmu_cache_flush in start.c? I think this call shouldn't be there at all. A (pre-) bootloader should always manage to call the next image with the caches properly flushed, otherwise we are doomed in barebox anyway. The problem with the armv7 __mmu_cache_flush implementation is that it uses the stack which we haven't configured at that time. I thought I had already wired up a patch for this, but it seems I haven't. Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 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