From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tony Lindgren Subject: Re: [PATCH v3] ARM: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set Date: Mon, 15 Oct 2012 10:53:18 -0700 Message-ID: <20121015175317.GE15569@atomide.com> References: <20121013090255.GT28061@n2100.arm.linux.org.uk> <20121013133654.GU28061@n2100.arm.linux.org.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from mho-03-ewr.mailhop.org ([204.13.248.66]:17056 "EHLO mho-01-ewr.mailhop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753819Ab2JORx0 (ORCPT ); Mon, 15 Oct 2012 13:53:26 -0400 Content-Disposition: inline In-Reply-To: Sender: linux-omap-owner@vger.kernel.org List-Id: linux-omap@vger.kernel.org To: Paul Walmsley Cc: Mans Rullgard , Russell King - ARM Linux , linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, Catalin Marinas , Dave Martin * Paul Walmsley [121014 22:26]: >=20 > After commit 846a136881b8f73c1f74250bf6acfaa309cab1f2 ("ARM: vfp: fix > saving d16-d31 vfp registers on v6+ kernels"), the OMAP 2430SDP board > started crashing during boot with omap2plus_defconfig: >=20 > [ 3.875122] mmcblk0: mmc0:e624 SD04G 3.69 GiB > [ 3.915954] mmcblk0: p1 > [ 4.086639] Internal error: Oops - undefined instruction: 0 [#1] S= MP 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 >=20 > It turns out that the context save/restore fix unmasked a latent bug > in commit 5aaf254409f8d58229107b59507a8235b715a960 ("ARM: 6203/1: Mak= e > VFPv3 usable on ARMv6"). When CONFIG_VFPv3 is set, but the kernel is > booted on a pre-VFPv3 core, the code attempts to save and restore the > 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. >=20 > Fix by implementing a request from Russell King to add a new HWCAP > flag that affirmatively indicates the presence of the d16-d31 > registers: >=20 > http://marc.info/?l=3Dlinux-arm-kernel&m=3D135013547905283&w=3D2 >=20 > and some feedback from M=C3=A5ns to clarify the name of the HWCAP fla= g. >=20 > Signed-off-by: Paul Walmsley > Cc: Tony Lindgren > Cc: Russell King > Cc: Catalin Marinas > Cc: Dave Martin > Cc: M=C3=A5ns Rullg=C3=A5rd This fixes the error above on my 2430sdp: Tested-by: Tony Lindgren -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 From: tony@atomide.com (Tony Lindgren) Date: Mon, 15 Oct 2012 10:53:18 -0700 Subject: [PATCH v3] ARM: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set In-Reply-To: References: <20121013090255.GT28061@n2100.arm.linux.org.uk> <20121013133654.GU28061@n2100.arm.linux.org.uk> Message-ID: <20121015175317.GE15569@atomide.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org * Paul Walmsley [121014 22:26]: > > After commit 846a136881b8f73c1f74250bf6acfaa309cab1f2 ("ARM: vfp: fix > saving d16-d31 vfp registers on v6+ kernels"), the OMAP 2430SDP board > 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: Make > VFPv3 usable on ARMv6"). When CONFIG_VFPv3 is set, but the kernel is > booted on a pre-VFPv3 core, the code attempts to save and restore the > 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=linux-arm-kernel&m=135013547905283&w=2 > > and some feedback from M?ns 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?ns Rullg?rd This fixes the error above on my 2430sdp: Tested-by: Tony Lindgren