From patchwork Sat Oct 13 04:46:18 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Walmsley X-Patchwork-Id: 1588951 Return-Path: X-Original-To: patchwork-linux-omap@patchwork.kernel.org Delivered-To: patchwork-process-083081@patchwork2.kernel.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by patchwork2.kernel.org (Postfix) with ESMTP id 74F29DF238 for ; Sat, 13 Oct 2012 04:46:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751410Ab2JMEqT (ORCPT ); Sat, 13 Oct 2012 00:46:19 -0400 Received: from utopia.booyaka.com ([74.50.51.50]:38539 "EHLO utopia.booyaka.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751384Ab2JMEqT (ORCPT ); Sat, 13 Oct 2012 00:46:19 -0400 Received: (qmail 14049 invoked by uid 1019); 13 Oct 2012 04:46:18 -0000 Date: Sat, 13 Oct 2012 04:46:18 +0000 (UTC) From: Paul Walmsley To: linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org cc: Tony Lindgren , Catalin Marinas , Russell King , Dave Martin Subject: [PATCH] ARM: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set Message-ID: User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Sender: linux-omap-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-omap@vger.kernel.org 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 the kernel dies with an undefined instruction exception. The kernel didn't crash before commit 846a136 because the save and restore code only touched d0-d15, present on all VFP. Fix to save and restore the d16-d31 registers only if they are present. Signed-off-by: Paul Walmsley Cc: Tony Lindgren Cc: Russell King Cc: Catalin Marinas Cc: Dave Martin --- arch/arm/include/asm/vfp.h | 6 ++++++ arch/arm/include/asm/vfpmacros.h | 8 ++++---- arch/arm/vfp/vfpmodule.c | 10 ++++++++++ 3 files changed, 20 insertions(+), 4 deletions(-) diff --git a/arch/arm/include/asm/vfp.h b/arch/arm/include/asm/vfp.h index f4ab34f..5689798 100644 --- a/arch/arm/include/asm/vfp.h +++ b/arch/arm/include/asm/vfp.h @@ -82,3 +82,9 @@ #define VFPOPDESC_UNUSED_BIT (24) #define VFPOPDESC_UNUSED_MASK (0xFF << VFPOPDESC_UNUSED_BIT) #define VFPOPDESC_OPDESC_MASK (~(VFPOPDESC_LENGTH_MASK | VFPOPDESC_UNUSED_MASK)) + +#ifndef __ASSEMBLER__ +#include + +extern u32 vfp_has_d16_d31; +#endif diff --git a/arch/arm/include/asm/vfpmacros.h b/arch/arm/include/asm/vfpmacros.h index 6a6f1e4..11496a9 100644 --- a/arch/arm/include/asm/vfpmacros.h +++ b/arch/arm/include/asm/vfpmacros.h @@ -25,9 +25,9 @@ #endif #ifdef CONFIG_VFPv3 #if __LINUX_ARM_ARCH__ <= 6 - ldr \tmp, =elf_hwcap @ may not have MVFR regs + ldr \tmp, =vfp_has_d16_d31 @ have VFP regs d16-d31? ldr \tmp, [\tmp, #0] - tst \tmp, #HWCAP_VFPv3D16 + cmp \tmp, #1 ldceql p11, cr0, [\base],#32*4 @ FLDMIAD \base!, {d16-d31} addne \base, \base, #32*4 @ step over unused register space #else @@ -49,9 +49,9 @@ #endif #ifdef CONFIG_VFPv3 #if __LINUX_ARM_ARCH__ <= 6 - ldr \tmp, =elf_hwcap @ may not have MVFR regs + ldr \tmp, =vfp_has_d16_d31 @ have VFP regs d16-d31? ldr \tmp, [\tmp, #0] - tst \tmp, #HWCAP_VFPv3D16 + cmp \tmp, #1 stceql p11, cr0, [\base],#32*4 @ FSTMIAD \base!, {d16-d31} addne \base, \base, #32*4 @ step over unused register space #else diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index c834b32..929b53b 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -58,6 +58,12 @@ unsigned int VFP_arch; union vfp_state *vfp_current_hw_state[NR_CPUS]; /* + * If the VFP on this ARM core has registers d16-d31, vfp_has_d16_d31 will + * be set to 1; otherwise, 0. Only valid after startup. + */ +u32 vfp_has_d16_d31; + +/* * Is 'thread's most up to date state stored in this CPUs hardware? * Must be called from non-preemptible context. */ @@ -691,6 +697,8 @@ static int __init vfp_init(void) thread_register_notifier(&vfp_notifier_block); vfp_pm_init(); + vfp_has_d16_d31 = 0; + /* * We detected VFP, and the support code is * in place; report VFP support to userspace. @@ -706,6 +714,8 @@ static int __init vfp_init(void) */ if (((fmrx(MVFR0) & MVFR0_A_SIMD_MASK)) == 1) elf_hwcap |= HWCAP_VFPv3D16; + else + vfp_has_d16_d31 = 1; } #endif /*