From patchwork Fri Feb 28 05:18:39 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: AKASHI Takahiro X-Patchwork-Id: 25505 Return-Path: X-Original-To: linaro@patches.linaro.org Delivered-To: linaro@patches.linaro.org Received: from mail-oa0-f72.google.com (mail-oa0-f72.google.com [209.85.219.72]) by ip-10-151-82-157.ec2.internal (Postfix) with ESMTPS id 951A72055D for ; Fri, 28 Feb 2014 05:19:54 +0000 (UTC) Received: by mail-oa0-f72.google.com with SMTP id g12sf5292744oah.11 for ; Thu, 27 Feb 2014 21:19:54 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:delivered-to:from:to:cc:subject :date:message-id:in-reply-to:references:sender:precedence:list-id :x-original-sender:x-original-authentication-results:mailing-list :list-post:list-help:list-archive:list-unsubscribe; bh=A0S3yrBDmH7puI/Ie2/miIUQz+nkUy4907KLiB4ls9I=; b=VYWRnX65ztCJh1oK5/LNLMKCZ+TdmNph5aMrixGL+lLWpTyKriFTR/+5vQbllwYLgN UJcG01KgjiMShusjTZWSbOJ/cpHgn52EZOY32533uwTRiIGxVMlXA1irozrLjj2PIj2u EVUC93dSFQEqqquDy3ysNOyzIx5zqSRE4PnaNfQc2Zq92uIhAPkur3HQ2APpuyBkOjQS IpUUpW1vpCu1IRQ1EHC9x+ZyI+acYYwV0sjh7xVVG8JVC3y6Az0qeCYigrA158kTkeWL 43UdxHSQ1G6O9C2Ke+sA9ZrsfIEUThPryMV9BFLoarQKKO7UvemHS9JBrrVKn+d/Q4gc Z7kA== X-Gm-Message-State: ALoCoQmMsBhVvpYSsUMp281jPHgOyMSdy5RxwEjHFcr60wvRBCKzkU/HaT2mt0ewuKLeST6uIoEF X-Received: by 10.182.74.226 with SMTP id x2mr5713093obv.1.1393564794200; Thu, 27 Feb 2014 21:19:54 -0800 (PST) MIME-Version: 1.0 X-BeenThere: patchwork-forward@linaro.org Received: by 10.140.106.165 with SMTP id e34ls1018811qgf.29.gmail; Thu, 27 Feb 2014 21:19:54 -0800 (PST) X-Received: by 10.221.55.199 with SMTP id vz7mr846237vcb.40.1393564794094; Thu, 27 Feb 2014 21:19:54 -0800 (PST) Received: from mail-vc0-f177.google.com (mail-vc0-f177.google.com [209.85.220.177]) by mx.google.com with ESMTPS id ys9si1221233vcb.17.2014.02.27.21.19.54 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 27 Feb 2014 21:19:54 -0800 (PST) Received-SPF: neutral (google.com: 209.85.220.177 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) client-ip=209.85.220.177; Received: by mail-vc0-f177.google.com with SMTP id if11so232258vcb.8 for ; Thu, 27 Feb 2014 21:19:54 -0800 (PST) X-Received: by 10.220.88.204 with SMTP id b12mr784046vcm.3.1393564794009; Thu, 27 Feb 2014 21:19:54 -0800 (PST) X-Forwarded-To: patchwork-forward@linaro.org X-Forwarded-For: patch@linaro.org patchwork-forward@linaro.org Delivered-To: patch@linaro.org Received: by 10.220.130.193 with SMTP id u1csp28916vcs; Thu, 27 Feb 2014 21:19:53 -0800 (PST) X-Received: by 10.66.246.229 with SMTP id xz5mr1115546pac.119.1393564793039; Thu, 27 Feb 2014 21:19:53 -0800 (PST) Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id qy5si592618pab.311.2014.02.27.21.19.52; Thu, 27 Feb 2014 21:19:52 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751998AbaB1FTg (ORCPT + 26 others); Fri, 28 Feb 2014 00:19:36 -0500 Received: from mail-pb0-f52.google.com ([209.85.160.52]:47198 "EHLO mail-pb0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751100AbaB1FTd (ORCPT ); Fri, 28 Feb 2014 00:19:33 -0500 Received: by mail-pb0-f52.google.com with SMTP id rr13so268018pbb.39 for ; Thu, 27 Feb 2014 21:19:33 -0800 (PST) X-Received: by 10.66.27.202 with SMTP id v10mr1094992pag.127.1393564773348; Thu, 27 Feb 2014 21:19:33 -0800 (PST) Received: from localhost.localdomain (KD182249084248.au-net.ne.jp. [182.249.84.248]) by mx.google.com with ESMTPSA id vn10sm1790978pbc.21.2014.02.27.21.19.28 for (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 27 Feb 2014 21:19:32 -0800 (PST) From: AKASHI Takahiro To: rostedt@goodmis.org, fweisbec@gmail.com, mingo@redhat.com, catalin.marinas@arm.com, will.deacon@arm.com, tim.bird@sonymobile.com Cc: gkulkarni@caviumnetworks.com, dsaxena@linaro.org, arndb@arndb.de, linux-arm-kernel@lists.infradead.org, linaro-kernel@lists.linaro.org, linux-kernel@vger.kernel.org, AKASHI Takahiro Subject: [PATCH v5 2/7] arm64: ftrace: Add dynamic ftrace support Date: Fri, 28 Feb 2014 14:18:39 +0900 Message-Id: <1393564724-3966-3-git-send-email-takahiro.akashi@linaro.org> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1393564724-3966-1-git-send-email-takahiro.akashi@linaro.org> References: <1393320196-2942-1-git-send-email-takahiro.akashi@linaro.org> <1393564724-3966-1-git-send-email-takahiro.akashi@linaro.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: list List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Removed-Original-Auth: Dkim didn't pass. X-Original-Sender: takahiro.akashi@linaro.org X-Original-Authentication-Results: mx.google.com; spf=neutral (google.com: 209.85.220.177 is neither permitted nor denied by best guess record for domain of patch+caf_=patchwork-forward=linaro.org@linaro.org) smtp.mail=patch+caf_=patchwork-forward=linaro.org@linaro.org Mailing-list: list patchwork-forward@linaro.org; contact patchwork-forward+owners@linaro.org X-Google-Group-Id: 836684582541 List-Post: , List-Help: , List-Archive: List-Unsubscribe: , This patch allows "dynamic ftrace" if CONFIG_DYNAMIC_FTRACE is enabled. Here we can turn on and off tracing dynamically per-function base. On arm64, this is done by patching single branch instruction to _mcount() inserted by gcc -pg option. The branch is replaced to NOP initially at kernel start up, and later on, NOP to branch to ftrace_caller() when enabled or branch to NOP when disabled. Please note that ftrace_caller() is a counterpart of _mcount() in case of 'static' ftrace. More details on architecture specific requirements are described in Documentation/trace/ftrace-design.txt. Signed-off-by: AKASHI Takahiro --- arch/arm64/Kconfig | 1 + arch/arm64/include/asm/ftrace.h | 15 +++++ arch/arm64/kernel/entry-ftrace.S | 43 +++++++++++++++ arch/arm64/kernel/ftrace.c | 113 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 172 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 5783641..b176bc0 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -32,6 +32,7 @@ config ARM64 select HAVE_DMA_API_DEBUG select HAVE_DMA_ATTRS select HAVE_DMA_CONTIGUOUS + select HAVE_DYNAMIC_FTRACE select HAVE_EFFICIENT_UNALIGNED_ACCESS select HAVE_FUNCTION_TRACER select HAVE_FUNCTION_GRAPH_TRACER diff --git a/arch/arm64/include/asm/ftrace.h b/arch/arm64/include/asm/ftrace.h index 58ea595..ed5c448 100644 --- a/arch/arm64/include/asm/ftrace.h +++ b/arch/arm64/include/asm/ftrace.h @@ -18,6 +18,21 @@ #ifndef __ASSEMBLY__ extern void _mcount(unsigned long); + +struct dyn_arch_ftrace { + /* No extra data needed for arm64 */ +}; + +extern unsigned long ftrace_graph_call; + +static inline unsigned long ftrace_call_adjust(unsigned long addr) +{ + /* + * addr is the address of the mcount call instruction. + * recordmcount does the necessary offset calculation. + */ + return addr; +} #endif /* __ASSEMBLY__ */ #endif /* __ASM_FTRACE_H */ diff --git a/arch/arm64/kernel/entry-ftrace.S b/arch/arm64/kernel/entry-ftrace.S index 0e5b8b0..c012cf0 100644 --- a/arch/arm64/kernel/entry-ftrace.S +++ b/arch/arm64/kernel/entry-ftrace.S @@ -85,6 +85,7 @@ add \reg, \reg, #8 .endm +#ifndef CONFIG_DYNAMIC_FTRACE /* * void _mcount(unsigned long return_address) * @return_address: return address to instrumented function @@ -133,6 +134,48 @@ skip_ftrace_call: #endif /* CONFIG_FUNCTION_GRAPH_TRACER */ ENDPROC(_mcount) +#else /* CONFIG_DYNAMIC_FTRACE */ +/* + * _mcount() is used to build the kernel with -pg option, but all the branch + * instructions to _mcount() are replaced to NOP initially at kernel start up, + * and later on, NOP to branch to ftrace_caller() when enabled or branch to + * NOP when disabled per-function base. + */ +ENTRY(_mcount) + ret +ENDPROC(_mcount) + +/* + * void ftrace_caller(unsigned long return_address) + * @return_address: return address to instrumented function + * + * This function is a counterpart of _mcount() in 'static' ftrace, and + * makes calls to: + * - tracer function to probe instrumented function's entry, + * - ftrace_graph_caller to set up an exit hook + */ +ENTRY(ftrace_caller) + mcount_enter + + mcount_get_pc0 x0 // function's pc + mcount_get_lr x1 // function's lr + + .global ftrace_call +ftrace_call: // tracer(pc, lr); + nop // This will be replaced with "bl xxx" + // where xxx can be any kind of tracer. + +#ifdef CONFIG_FUNCTION_GRAPH_TRACER + .global ftrace_graph_call +ftrace_graph_call: // ftrace_graph_caller(); + nop // If enabled, this will be replaced + // "b ftrace_graph_caller" +#endif + + mcount_exit +ENDPROC(ftrace_caller) +#endif /* CONFIG_DYNAMIC_FTRACE */ + ENTRY(ftrace_stub) ret ENDPROC(ftrace_stub) diff --git a/arch/arm64/kernel/ftrace.c b/arch/arm64/kernel/ftrace.c index a559ab8..8c26476 100644 --- a/arch/arm64/kernel/ftrace.c +++ b/arch/arm64/kernel/ftrace.c @@ -17,6 +17,89 @@ #include #include +#ifdef CONFIG_DYNAMIC_FTRACE +/* + * Replace a single instruction, which may be a branch or NOP. + * If @validate == true, a replaced instruction is checked against 'old'. + */ +static int ftrace_modify_code(unsigned long pc, unsigned int old, + unsigned int new, bool validate) +{ + unsigned int replaced; + + /* + * Note: + * Due to modules and __init, code can disappear and change, + * we need to protect against faulting as well as code changing. + * We do this by aarch64_insn_*() which use the probe_kernel_*(). + * + * No lock is held here because all the modifications are run + * through stop_machine(). + */ + if (validate) { + if (aarch64_insn_read((void *)pc, &replaced)) + return -EFAULT; + + if (replaced != old) + return -EINVAL; + } + if (aarch64_insn_patch_text_nosync((void *)pc, new)) + return -EPERM; + + return 0; +} + +/* + * Replace tracer function in ftrace_caller() + */ +int ftrace_update_ftrace_func(ftrace_func_t func) +{ + unsigned long pc; + unsigned int new; + + pc = (unsigned long)&ftrace_call; + new = aarch64_insn_gen_branch_imm(pc, (unsigned long)func, true); + + return ftrace_modify_code(pc, 0, new, false); +} + +/* + * Turn on the call to ftrace_caller() in instrumented function + */ +int ftrace_make_call(struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned long pc = rec->ip; + unsigned int old, new; + + old = aarch64_insn_gen_nop(); + new = aarch64_insn_gen_branch_imm(pc, addr, true); + + return ftrace_modify_code(pc, old, new, true); +} + +/* + * Turn off the call to ftrace_caller() in instrumented function + */ +int ftrace_make_nop(struct module *mod, + struct dyn_ftrace *rec, unsigned long addr) +{ + unsigned long pc = rec->ip; + unsigned int old, new; + + old = aarch64_insn_gen_branch_imm(pc, addr, true); + new = aarch64_insn_gen_nop(); + + return ftrace_modify_code(pc, old, new, true); +} + +int __init ftrace_dyn_arch_init(void *data) +{ + *(unsigned long *)data = 0; + + return 0; +} +#endif /* CONFIG_DYNAMIC_FTRACE */ + #ifdef CONFIG_FUNCTION_GRAPH_TRACER /* * function_graph tracer expects ftrace_return_to_handler() to be called @@ -61,4 +144,34 @@ void prepare_ftrace_return(unsigned long *parent, unsigned long self_addr, return; } } + +#ifdef CONFIG_DYNAMIC_FTRACE +/* + * Turn on/off the call to ftrace_graph_caller() in ftrace_caller() + * depending on @enable. + */ +static int ftrace_modify_graph_caller(bool enable) +{ + unsigned long pc = (unsigned long)&ftrace_graph_call; + unsigned int branch, nop, old, new; + + branch = aarch64_insn_gen_branch_imm(pc, + (unsigned long)ftrace_graph_caller, false); + nop = aarch64_insn_gen_nop(); + old = enable ? nop : branch; + new = enable ? branch : nop; + + return ftrace_modify_code(pc, old, new, true); +} + +int ftrace_enable_ftrace_graph_caller(void) +{ + return ftrace_modify_graph_caller(true); +} + +int ftrace_disable_ftrace_graph_caller(void) +{ + return ftrace_modify_graph_caller(false); +} +#endif /* CONFIG_DYNAMIC_FTRACE */ #endif /* CONFIG_FUNCTION_GRAPH_TRACER */