From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0020DC5519F for ; Thu, 12 Nov 2020 14:59:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 997F82224A for ; Thu, 12 Nov 2020 14:59:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728198AbgKLO7S (ORCPT ); Thu, 12 Nov 2020 09:59:18 -0500 Received: from mail.kernel.org ([198.145.29.99]:33780 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727035AbgKLO7S (ORCPT ); Thu, 12 Nov 2020 09:59:18 -0500 Received: from gandalf.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 518E622201; Thu, 12 Nov 2020 14:59:16 +0000 (UTC) Date: Thu, 12 Nov 2020 09:59:14 -0500 From: Steven Rostedt To: Peter Zijlstra Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Miroslav Benes , Thomas Gleixner , Masami Hiramatsu , Josh Poimboeuf , Jiri Kosina , live-patching@vger.kernel.org Subject: Re: [PATCH 3/3 v5] livepatch: Use the default ftrace_ops instead of REGS when ARGS is available Message-ID: <20201112095914.61bb8a3e@gandalf.local.home> In-Reply-To: <20201112082144.GS2628@hirez.programming.kicks-ass.net> References: <20201112011516.589846126@goodmis.org> <20201112011815.755256598@goodmis.org> <20201112082144.GS2628@hirez.programming.kicks-ass.net> X-Mailer: Claws Mail 3.17.3 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: live-patching@vger.kernel.org On Thu, 12 Nov 2020 09:21:44 +0100 Peter Zijlstra wrote: > On Wed, Nov 11, 2020 at 08:15:19PM -0500, Steven Rostedt wrote: > > > diff --git a/arch/x86/include/asm/ftrace.h b/arch/x86/include/asm/ftrace.h > > index e00fe88146e0..235385a38bd9 100644 > > --- a/arch/x86/include/asm/ftrace.h > > +++ b/arch/x86/include/asm/ftrace.h > > @@ -54,6 +54,9 @@ arch_ftrace_get_regs(struct ftrace_regs *fregs) > > return NULL; > > return &fregs->regs; > > } > > + > > +#define ftrace_regs_set_ip(fregs, _ip) \ > > + do { (fregs)->regs.ip = (_ip); } while (0) > > #endif > > > > #ifdef CONFIG_DYNAMIC_FTRACE > > diff --git a/arch/x86/include/asm/livepatch.h b/arch/x86/include/asm/livepatch.h > > index 1fde1ab6559e..59a08d5c6f1d 100644 > > --- a/arch/x86/include/asm/livepatch.h > > +++ b/arch/x86/include/asm/livepatch.h > > @@ -12,9 +12,9 @@ > > #include > > #include > > > > -static inline void klp_arch_set_pc(struct pt_regs *regs, unsigned long ip) > > +static inline void klp_arch_set_pc(struct ftrace_regs *fregs, unsigned long ip) > > { > > - regs->ip = ip; > > + ftrace_regs_set_ip(fregs, ip); > > } > > > > The normal variant is called instruction_pointer_set(), should this be > called ftrace_instruction_pointer_set() ? Sure, I can change that. > > (and yes, I hate the long name too). ftrace_regs_ip_set()? ;-) > > Also, do you want something like: > > unsigned long ftrace_regs_get_register(struct ftrace_regs *regs, unsigned int offset) > { I haven't gotten this far yet. I'm looking at generic use cases on how to get args across archs. Each arch will have its own method. > switch (offset / sizeof(long)) { > case 4: /* RBP */ > > case 8: /* R9 */ > case 9: /* R8 */ > case 10: /* RAX */ > case 11: /* RCX */ > case 12: /* RDX */ > case 13: /* RSI */ > case 14: /* RDI */ > case 15: /* ORIG_RAX */ > case 16: /* RIP */ > return *(unsigned long *)regs->regs + offset; > > default: > WARN_ON_ONCE(1); Not sure we even want to warn. Perhaps have this as: bool ftrace_regs_get_register(struct ftrace_regs *regs, unsigned int offset, unsigned long *val) { if (regs->cs) { *val = regs_get_register(regs->regs, offset); return true; } switch (offset / sizeof(long)) { case ...: *val = *(unsigned long *)regs->regs + offset; return true; default; return false; > } -- Steve