Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934336Ab2KZRQ5 (ORCPT ); Mon, 26 Nov 2012 12:16:57 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:48342 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934272Ab2KZRQe (ORCPT ); Mon, 26 Nov 2012 12:16:34 -0500 From: Herton Ronaldo Krzesinski To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Paul Walmsley , Tony Lindgren , Catalin Marinas , Dave Martin , =?UTF-8?q?M=C3=A5ns=20Rullg=C3=A5rd?= , Russell King , Herton Ronaldo Krzesinski Subject: [PATCH 266/270] ARM: 7566/1: vfp: fix save and restore when running on pre-VFPv3 and CONFIG_VFPv3 set Date: Mon, 26 Nov 2012 14:59:16 -0200 Message-Id: <1353949160-26803-267-git-send-email-herton.krzesinski@canonical.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1353949160-26803-1-git-send-email-herton.krzesinski@canonical.com> References: <1353949160-26803-1-git-send-email-herton.krzesinski@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5043 Lines: 129 3.5.7u1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Paul Walmsley commit 39141ddfb63a664f26d3f42f64ee386e879b492c upstream. 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 Måns to clarify the name of the HWCAP flag. Signed-off-by: Paul Walmsley Cc: Tony Lindgren Cc: Catalin Marinas Cc: Dave Martin Cc: Måns Rullgård Signed-off-by: Russell King [ herton: no uapi directory on 3.5 ] Signed-off-by: Herton Ronaldo Krzesinski --- arch/arm/include/asm/hwcap.h | 3 ++- arch/arm/include/asm/vfpmacros.h | 12 ++++++------ arch/arm/vfp/vfpmodule.c | 9 ++++++--- 3 files changed, 14 insertions(+), 10 deletions(-) diff --git a/arch/arm/include/asm/hwcap.h b/arch/arm/include/asm/hwcap.h index 9176261..a2fe893 100644 --- a/arch/arm/include/asm/hwcap.h +++ b/arch/arm/include/asm/hwcap.h @@ -18,11 +18,12 @@ #define HWCAP_THUMBEE (1 << 11) #define HWCAP_NEON (1 << 12) #define HWCAP_VFPv3 (1 << 13) -#define HWCAP_VFPv3D16 (1 << 14) +#define HWCAP_VFPv3D16 (1 << 14) /* also set for VFPv4-D16 */ #define HWCAP_TLS (1 << 15) #define HWCAP_VFPv4 (1 << 16) #define HWCAP_IDIVA (1 << 17) #define HWCAP_IDIVT (1 << 18) +#define HWCAP_VFPD32 (1 << 19) /* set if VFP has 32 regs (not 16) */ #define HWCAP_IDIV (HWCAP_IDIVA | HWCAP_IDIVT) #if defined(__KERNEL__) diff --git a/arch/arm/include/asm/vfpmacros.h b/arch/arm/include/asm/vfpmacros.h index bf53047..c49c8f7 100644 --- a/arch/arm/include/asm/vfpmacros.h +++ b/arch/arm/include/asm/vfpmacros.h @@ -27,9 +27,9 @@ #if __LINUX_ARM_ARCH__ <= 6 ldr \tmp, =elf_hwcap @ may not have MVFR regs ldr \tmp, [\tmp, #0] - tst \tmp, #HWCAP_VFPv3D16 - ldceql p11, cr0, [\base],#32*4 @ FLDMIAD \base!, {d16-d31} - addne \base, \base, #32*4 @ step over unused register space + tst \tmp, #HWCAP_VFPD32 + ldcnel p11, cr0, [\base],#32*4 @ FLDMIAD \base!, {d16-d31} + addeq \base, \base, #32*4 @ step over unused register space #else VFPFMRX \tmp, MVFR0 @ Media and VFP Feature Register 0 and \tmp, \tmp, #MVFR0_A_SIMD_MASK @ A_SIMD field @@ -51,9 +51,9 @@ #if __LINUX_ARM_ARCH__ <= 6 ldr \tmp, =elf_hwcap @ may not have MVFR regs ldr \tmp, [\tmp, #0] - tst \tmp, #HWCAP_VFPv3D16 - stceql p11, cr0, [\base],#32*4 @ FSTMIAD \base!, {d16-d31} - addne \base, \base, #32*4 @ step over unused register space + tst \tmp, #HWCAP_VFPD32 + stcnel p11, cr0, [\base],#32*4 @ FSTMIAD \base!, {d16-d31} + addeq \base, \base, #32*4 @ step over unused register space #else VFPFMRX \tmp, MVFR0 @ Media and VFP Feature Register 0 and \tmp, \tmp, #MVFR0_A_SIMD_MASK @ A_SIMD field diff --git a/arch/arm/vfp/vfpmodule.c b/arch/arm/vfp/vfpmodule.c index c834b32..3b44e0d 100644 --- a/arch/arm/vfp/vfpmodule.c +++ b/arch/arm/vfp/vfpmodule.c @@ -701,11 +701,14 @@ static int __init vfp_init(void) elf_hwcap |= HWCAP_VFPv3; /* - * Check for VFPv3 D16. CPUs in this configuration - * only have 16 x 64bit registers. + * Check for VFPv3 D16 and VFPv4 D16. CPUs in + * this configuration only have 16 x 64bit + * registers. */ if (((fmrx(MVFR0) & MVFR0_A_SIMD_MASK)) == 1) - elf_hwcap |= HWCAP_VFPv3D16; + elf_hwcap |= HWCAP_VFPv3D16; /* also v4-D16 */ + else + elf_hwcap |= HWCAP_VFPD32; } #endif /* -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/