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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 E9CF5C388F9 for ; Thu, 12 Nov 2020 01:42:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9FF03206F1 for ; Thu, 12 Nov 2020 01:42:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729638AbgKLBlV (ORCPT ); Wed, 11 Nov 2020 20:41:21 -0500 Received: from mail.kernel.org ([198.145.29.99]:52396 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728222AbgKLBSS (ORCPT ); Wed, 11 Nov 2020 20:18:18 -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 0DA002067D; Thu, 12 Nov 2020 01:18:17 +0000 (UTC) Received: from rostedt by gandalf.local.home with local (Exim 4.94) (envelope-from ) id 1kd1Ff-0002LS-Dt; Wed, 11 Nov 2020 20:18:15 -0500 Message-ID: <20201112011516.589846126@goodmis.org> User-Agent: quilt/0.66 Date: Wed, 11 Nov 2020 20:15:16 -0500 From: Steven Rostedt To: linux-kernel@vger.kernel.org Cc: Ingo Molnar , Andrew Morton , Miroslav Benes , Peter Zijlstra , Thomas Gleixner , Masami Hiramatsu Subject: [PATCH 0/3 v5] ftrace: Add access to function arguments for all callbacks Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is something I wanted to implement a long time ago, but held off until there was a good reason to do so. Now it appears that having access to the arguments of the function by default is very useful. As a bonus, because arguments must be saved regardless before calling a callback, because they need to be restored before returning back to the start of the traced function, there's not much work to do to have them always be there for normal function callbacks. The basic idea is that if CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS is set, then all callbacks registered to ftrace can use the regs parameter for the stack and arguments (kernel_stack_pointer(regs), regs_get_kernel_argument(regs, n)), without the need to set REGS that causes overhead by saving all registers as REGS simulates a breakpoint. This could be extended to move the REGS portion to kprobes itself, and remove the SAVE_REGS flag completely, but for now, kprobes still uses the full SAVE_REGS support. The last patch extends the WITH_ARGS to allow default function tracing to modify the instruction pointer, where livepatching for x86 no longer needs to save all registers. The idea of this approach is to give enough information to a callback that it could retrieve all arguments, which includes the stack pointer and instruction pointer. This can also be extended to modify the function graph tracer to use the function tracer instead of having a separate trampoline. Changes since v4: - Fixed compile error for !CONFIG_FUNCTION_TRACER - Fixed prototype of pstore ftrace callback function. This also passed all my tests, and I will probably add this to my for-next soon if there's no complaints. Steven Rostedt (VMware) (3): ftrace: Have the callbacks receive a struct ftrace_regs instead of pt_regs ftrace/x86: Allow for arguments to be passed in to ftrace_regs by default livepatch: Use the default ftrace_ops instead of REGS when ARGS is available ---- arch/powerpc/include/asm/livepatch.h | 4 +++- arch/s390/include/asm/livepatch.h | 5 ++++- arch/x86/Kconfig | 1 + arch/x86/include/asm/ftrace.h | 18 ++++++++++++++++++ arch/x86/include/asm/livepatch.h | 4 ++-- arch/x86/kernel/ftrace_64.S | 15 +++++++++++++-- arch/x86/kernel/kprobes/ftrace.c | 3 ++- fs/pstore/ftrace.c | 2 +- include/linux/ftrace.h | 28 ++++++++++++++++++++++++++-- include/linux/kprobes.h | 2 +- kernel/livepatch/Kconfig | 2 +- kernel/livepatch/patch.c | 10 ++++++---- kernel/trace/Kconfig | 9 +++++++++ kernel/trace/ftrace.c | 27 +++++++++++++++------------ kernel/trace/trace_event_perf.c | 2 +- kernel/trace/trace_events.c | 2 +- kernel/trace/trace_functions.c | 9 ++++----- kernel/trace/trace_irqsoff.c | 2 +- kernel/trace/trace_sched_wakeup.c | 2 +- kernel/trace/trace_selftest.c | 20 +++++++++++--------- kernel/trace/trace_stack.c | 2 +- 21 files changed, 122 insertions(+), 47 deletions(-)