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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CA3D6C433FE for ; Thu, 3 Nov 2022 17:06:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231601AbiKCRGm (ORCPT ); Thu, 3 Nov 2022 13:06:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231947AbiKCRF5 (ORCPT ); Thu, 3 Nov 2022 13:05:57 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 10E406276 for ; Thu, 3 Nov 2022 10:05:29 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 533C61FB; Thu, 3 Nov 2022 10:05:35 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8B1683F5A1; Thu, 3 Nov 2022 10:05:27 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, mark.rutland@arm.com, mhiramat@kernel.org, revest@chromium.org, rostedt@goodmis.org, will@kernel.org Subject: [PATCH v2 0/4] arm64/ftrace: move to DYNAMIC_FTRACE_WITH_ARGS Date: Thu, 3 Nov 2022 17:05:16 +0000 Message-Id: <20221103170520.931305-1-mark.rutland@arm.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This series replaces arm64's support for FTRACE_WITH_REGS with support for FTRACE_WITH_ARGS. This removes some overhead and complexity, and removes some latent issues with inconsistent presentation of struct pt_regs (which can only be reliably saved/restored at exception boundaries). The existing FTRACE_WITH_REGS support was added for two major reasons: (1) To make it possible to use the ftrace graph tracer with pointer authentication, where it's necessary to snapshot/manipulate the LR before it is signed by the instrumented function. (2) To make it possible to implement LIVEPATCH in future, where we need to hook function entry before an instrumented function manipulates the stack or argument registers. Practically speaking, we need to preserve the argument/return registers, PC, LR, and SP. Neither of these requires the full set of pt_regs, and only requires us to save/restore a subset of registers used for passing arguments/return-values and context/return information (which is the minimum set we always need to save/restore today). As there is no longer a need to save different sets of registers for different features, we no longer need distinct `ftrace_caller` and `ftrace_regs_caller` trampolines. This allows the trampoline assembly to be simpler, and simplifies code which previously had to handle the two trampolines. I've tested this with the ftrace selftests, where there are no unexpected failures. I plan to build atop this with subsequent patches to add per-callsite ftrace_ops, and I'm sending these patches on their own as I think they make sense regardless. Since v1 [1]: * Change ifdeferry per Steve's request * Add ftrace_regs_query_register_offset() per Masami's request * Fix a bunch of typos [1] https://lore.kernel.org/lkml/20221024140846.3555435-1-mark.rutland@arm.com This series can be found in my 'arm64/ftrace/minimal-regs' branch on kernel.org: https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/ git://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git This version is tagged as: arm64-ftrace-minimal-regs-20221103 Thanks, Mark. Mark Rutland (4): ftrace: pass fregs to arch_ftrace_set_direct_caller() ftrace: rename ftrace_instruction_pointer_set() -> ftrace_regs_set_instruction_pointer() ftrace: abstract DYNAMIC_FTRACE_WITH_ARGS accesses ftrace: arm64: move from REGS to ARGS arch/arm64/Kconfig | 18 +++-- arch/arm64/Makefile | 2 +- arch/arm64/include/asm/ftrace.h | 72 ++++++++++++++++-- arch/arm64/kernel/asm-offsets.c | 13 ++++ arch/arm64/kernel/entry-ftrace.S | 117 ++++++++++++------------------ arch/arm64/kernel/ftrace.c | 82 ++++++++++++--------- arch/arm64/kernel/module.c | 3 - arch/powerpc/include/asm/ftrace.h | 24 +++++- arch/s390/include/asm/ftrace.h | 29 +++++++- arch/x86/include/asm/ftrace.h | 49 +++++++++---- include/linux/ftrace.h | 47 +++++++++--- kernel/livepatch/patch.c | 2 +- kernel/trace/Kconfig | 6 +- kernel/trace/ftrace.c | 3 +- 14 files changed, 309 insertions(+), 158 deletions(-) -- 2.30.2