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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0CC5FC433EF for ; Wed, 17 Nov 2021 14:08:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E1B5E61BA2 for ; Wed, 17 Nov 2021 14:08:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238250AbhKQOLO (ORCPT ); Wed, 17 Nov 2021 09:11:14 -0500 Received: from foss.arm.com ([217.140.110.172]:57356 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238187AbhKQOLL (ORCPT ); Wed, 17 Nov 2021 09:11:11 -0500 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 31DE31435; Wed, 17 Nov 2021 06:08:13 -0800 (PST) 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 A39EE3F70D; Wed, 17 Nov 2021 06:08:10 -0800 (PST) From: Mark Rutland To: linux-arm-kernel@lists.infradead.org Cc: aou@eecs.berkeley.edu, borntraeger@de.ibm.com, bp@alien8.de, broonie@kernel.org, catalin.marinas@arm.com, dave.hansen@linux.intel.com, gor@linux.ibm.com, hca@linux.ibm.com, linux-kernel@vger.kernel.org, madvenka@linux.microsoft.com, mark.rutland@arm.com, mhiramat@kernel.org, mingo@redhat.com, mpe@ellerman.id.au, palmer@dabbelt.com, paul.walmsley@sifive.com, peterz@infradead.org, rostedt@goodmis.org, tglx@linutronix.de, will@kernel.org Subject: [PATCH 7/9] arm64: Make profile_pc() use arch_stack_walk() Date: Wed, 17 Nov 2021 14:07:35 +0000 Message-Id: <20211117140737.44420-8-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20211117140737.44420-1-mark.rutland@arm.com> References: <20211117140737.44420-1-mark.rutland@arm.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Madhavan T. Venkataraman" To enable RELIABLE_STACKTRACE and LIVEPATCH on arm64, we need to substantially rework arm64's unwinding code. As part of this, we want to minimize the set of unwind interfaces we expose, and avoid open-coding of unwind logic outside of stacktrace.c. Currently profile_pc() walks the stack of an interrupted context by calling start_backtrace() with the context's PC and FP, and iterating unwind steps using walk_stackframe(). This is functionally equivalent to calling arch_stack_walk() with the interrupted context's pt_regs, which will start with the PC and FP from the regs. Make profile_pc() use arch_stack_walk(). This simplifies profile_pc(), and in future will alow us to make walk_stackframe() private to stacktrace.c. At the same time, we remove the early return for when regs->pc is not in lock functions, as this will be handled by the first call to the profile_pc_cb() callback. There should be no functional change as a result of this patch. Signed-off-by: Madhavan T. Venkataraman Reviewed-by: Mark Rutland [Mark: remove unnecessary early return, elaborate commit message] Signed-off-by: Mark Rutland --- arch/arm64/kernel/time.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/arch/arm64/kernel/time.c b/arch/arm64/kernel/time.c index eebbc8d7123e..070d4427327f 100644 --- a/arch/arm64/kernel/time.c +++ b/arch/arm64/kernel/time.c @@ -32,22 +32,23 @@ #include #include -unsigned long profile_pc(struct pt_regs *regs) +static bool profile_pc_cb(void *arg, unsigned long pc) { - struct stackframe frame; + unsigned long *prof_pc = arg; - if (!in_lock_functions(regs->pc)) - return regs->pc; + if (in_lock_functions(pc)) + return true; + *prof_pc = pc; + return false; +} - start_backtrace(&frame, regs->regs[29], regs->pc); +unsigned long profile_pc(struct pt_regs *regs) +{ + unsigned long prof_pc = 0; - do { - int ret = unwind_frame(NULL, &frame); - if (ret < 0) - return 0; - } while (in_lock_functions(frame.pc)); + arch_stack_walk(profile_pc_cb, &prof_pc, current, regs); - return frame.pc; + return prof_pc; } EXPORT_SYMBOL(profile_pc); -- 2.11.0