From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jon Hunter Subject: Re: [PATCH v3] ARM: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set Date: Tue, 16 Oct 2012 12:13:22 -0500 Message-ID: <507D95B2.3020506@ti.com> References: <20121013090255.GT28061@n2100.arm.linux.org.uk> <20121013133654.GU28061@n2100.arm.linux.org.uk> <20121015175317.GE15569@atomide.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from devils.ext.ti.com ([198.47.26.153]:42161 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753977Ab2JPRNk (ORCPT ); Tue, 16 Oct 2012 13:13:40 -0400 In-Reply-To: <20121015175317.GE15569@atomide.com> Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Tony Lindgren Cc: Paul Walmsley , Dave Martin , Russell King - ARM Linux , Catalin Marinas , linux-omap@vger.kernel.org, Mans Rullgard , linux-arm-kernel@lists.infradead.org On 10/15/2012 12:53 PM, Tony Lindgren wrote: > * Paul Walmsley [121014 22:26]: >> >> After commit 846a136881b8f73c1f74250bf6acfaa309cab1f2 ("ARM: vfp: fi= x >> saving d16-d31 vfp registers on v6+ kernels"), the OMAP 2430SDP boar= d >> started crashing during boot with omap2plus_defconfig: >> >> [ 3.875122] mmcblk0: mmc0:e624 SD04G 3.69 GiB >> [ 3.915954] mmcblk0: p1 >> [ 4.086639] Internal error: Oops - undefined instruction: 0 [#1] = SMP ARM >> [ 4.093719] Modules linked in: >> [ 4.096954] CPU: 0 Not tainted (3.6.0-02232-g759e00b #570) >> [ 4.103149] PC is at vfp_reload_hw+0x1c/0x44 >> [ 4.107666] LR is at __und_usr_fault_32+0x0/0x8 >> >> It turns out that the context save/restore fix unmasked a latent bug >> in commit 5aaf254409f8d58229107b59507a8235b715a960 ("ARM: 6203/1: Ma= ke >> VFPv3 usable on ARMv6"). When CONFIG_VFPv3 is set, but the kernel i= s >> booted on a pre-VFPv3 core, the code attempts to save and restore th= e >> d16-d31 VFP registers. These are only present on non-D16 VFPv3+, so >> this results in an undefined instruction exception. The code didn't >> crash before commit 846a136 because the save and restore code was >> only touching d0-d15, present on all VFP. >> >> Fix by implementing a request from Russell King to add a new HWCAP >> flag that affirmatively indicates the presence of the d16-d31 >> registers: >> >> http://marc.info/?l=3Dlinux-arm-kernel&m=3D135013547905283&w=3D2 >> >> and some feedback from M=E5ns to clarify the name of the HWCAP flag. >> >> Signed-off-by: Paul Walmsley >> Cc: Tony Lindgren >> Cc: Russell King >> Cc: Catalin Marinas >> Cc: Dave Martin >> Cc: M=E5ns Rullg=E5rd >=20 > This fixes the error above on my 2430sdp: >=20 > Tested-by: Tony Lindgren =46ixes same error on 2420 H4. Tested-by: Jon Hunter Cheers Jon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html