From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932932AbdEKNDl (ORCPT ); Thu, 11 May 2017 09:03:41 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:50526 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755727AbdEKNDh (ORCPT ); Thu, 11 May 2017 09:03:37 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Arnd Bergmann , Nicolas Pitre , Ard Biesheuvel , Russell King Subject: [PATCH 3.18 04/39] ARM: 8452/3: PJ4: make coprocessor access sequences buildable in Thumb2 mode Date: Thu, 11 May 2017 15:02:39 +0200 Message-Id: <20170511130239.021725256@linuxfoundation.org> X-Mailer: git-send-email 2.12.2 In-Reply-To: <20170511130238.045434679@linuxfoundation.org> References: <20170511130238.045434679@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ard Biesheuvel commit 5008efc83bf85b647aa1cbc44718b1675bbb7444 upstream. The PJ4 inline asm sequence to write to cp15 cannot be built in Thumb-2 mode, due to the way it performs arithmetic on the program counter, so it is built in ARM mode instead. However, building C files in ARM mode under CONFIG_THUMB2_KERNEL is problematic, since the instrumentation performed by subsystems like ftrace does not expect having to deal with interworking branches. Since the sequence in question is simply a poor man's ISB instruction, let's use a straight 'isb' instead when building in Thumb2 mode. Thumb2 implies V7, so 'isb' should always be supported in that case. Acked-by: Arnd Bergmann Acked-by: Nicolas Pitre Signed-off-by: Ard Biesheuvel Signed-off-by: Russell King Signed-off-by: Greg Kroah-Hartman --- arch/arm/kernel/Makefile | 1 - arch/arm/kernel/pj4-cp0.c | 4 ++++ 2 files changed, 4 insertions(+), 1 deletion(-) --- a/arch/arm/kernel/Makefile +++ b/arch/arm/kernel/Makefile @@ -84,7 +84,6 @@ obj-$(CONFIG_CPU_PJ4B) += pj4-cp0.o obj-$(CONFIG_IWMMXT) += iwmmxt.o obj-$(CONFIG_PERF_EVENTS) += perf_regs.o obj-$(CONFIG_HW_PERF_EVENTS) += perf_event.o perf_event_cpu.o -CFLAGS_pj4-cp0.o := -marm AFLAGS_iwmmxt.o := -Wa,-mcpu=iwmmxt obj-$(CONFIG_ARM_CPU_TOPOLOGY) += topology.o --- a/arch/arm/kernel/pj4-cp0.c +++ b/arch/arm/kernel/pj4-cp0.c @@ -66,9 +66,13 @@ static void __init pj4_cp_access_write(u __asm__ __volatile__ ( "mcr p15, 0, %1, c1, c0, 2\n\t" +#ifdef CONFIG_THUMB2_KERNEL + "isb\n\t" +#else "mrc p15, 0, %0, c1, c0, 2\n\t" "mov %0, %0\n\t" "sub pc, pc, #4\n\t" +#endif : "=r" (temp) : "r" (value)); }