Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754809Ab3IZCrr (ORCPT ); Wed, 25 Sep 2013 22:47:47 -0400 Received: from mail-wi0-f181.google.com ([209.85.212.181]:45249 "EHLO mail-wi0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752591Ab3IZCrq (ORCPT ); Wed, 25 Sep 2013 22:47:46 -0400 MIME-Version: 1.0 In-Reply-To: <20130925111605.7437f70f@gandalf.local.home> References: <1380105868-31985-1-git-send-email-liuj97@gmail.com> <1380105868-31985-3-git-send-email-liuj97@gmail.com> <20130925103535.2249f617@gandalf.local.home> <20130925111605.7437f70f@gandalf.local.home> Date: Thu, 26 Sep 2013 08:17:45 +0530 Message-ID: Subject: Re: [PATCH v1 2/7] arm64: introduce interfaces to hotpatch kernel and module code From: Sandeepa Prabhu To: Steven Rostedt Cc: Jiang Liu , Catalin Marinas , Will Deacon , Jiang Liu , "linux-arm-kernel@lists.infradead.org" , linux-kernel@vger.kernel.org Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1099 Lines: 30 On 25 September 2013 20:46, Steven Rostedt wrote: > On Wed, 25 Sep 2013 20:12:17 +0530 > Sandeepa Prabhu wrote: > > >> > On aarch64, are instructions always word aligned? If not, it should be >> > safe for stop machine to modify non word aligned instructions, but this >> > patch looks like it doesn't allow stop_machine() to do so. >> Steve, >> >> Yes, aarch64 instructions must be word-aligned, else instruction fetch >> would generate Misaligned PC fault. >> > > Thanks for clarifying, as IIUC, there's ARM architectures that allow > for 2 and 4 byte instructions. Yes, ARM 32-bit mode would support both 32-bit and 16-bit alignment based on ARM or Thumb mode, whereas AArch64 (in arch/arm64/) is always 32-bit instructions and PC need to be aligned to 32-bit address. Thanks, Sandeepa > > -- Steve -- 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/