From patchwork Sat Mar 15 05:45:51 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: AKASHI Takahiro X-Patchwork-Id: 3836411 Return-Path: X-Original-To: patchwork-linux-arm@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork1.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.19.201]) by patchwork1.web.kernel.org (Postfix) with ESMTP id 60A2C9F2BB for ; Sat, 15 Mar 2014 05:48:28 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 5584C2035C for ; Sat, 15 Mar 2014 05:48:27 +0000 (UTC) Received: from casper.infradead.org (casper.infradead.org [85.118.1.10]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 3463420295 for ; Sat, 15 Mar 2014 05:48:26 +0000 (UTC) Received: from merlin.infradead.org ([2001:4978:20e::2]) by casper.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WOhRr-0003Pd-VG; Sat, 15 Mar 2014 05:47:56 +0000 Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1WOhRk-0008Gt-Jk; Sat, 15 Mar 2014 05:47:48 +0000 Received: from mail-pa0-f50.google.com ([209.85.220.50]) by merlin.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1WOhRV-0008Dd-QD for linux-arm-kernel@lists.infradead.org; Sat, 15 Mar 2014 05:47:36 +0000 Received: by mail-pa0-f50.google.com with SMTP id kq14so3521584pab.37 for ; Fri, 14 Mar 2014 22:47:12 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=8OqOtbD9goU60JgSFwcTQ6xuef1xviju7zH4cU/UT7w=; b=U7AhDm1p8U8qJUn+6zGJczYitc3PveI5KCQaWwHIiwdztnnu4gAqJj0SH5h4/6dibA oGZNvX84OOodMsGXT1nvDifM/NzKvxsSBLrKRK8CUqzztelG7VzeW7veW4p1M2Q83lXh fxeeRql+eQMOzTZTNFtRy2W07yvg5yVBoZdJdRizNyFEGR5ou+mx2zYd40qqKWr2mcxr /WFtUBZIztApz+6/Ul6kGNq6OdJ2sTn/u9axhTUROvJo0wx5bx3tOCbb92XYwlrMp91m gespKvNZJp4RHw0LRUh5Y/NkbuAlWtpEIt+Tb/VmvvhGYpNyn+bRRDpWY1w9gZnA51+F rfYQ== X-Gm-Message-State: ALoCoQkvD/odLWm3VD407NbihbqZdv6g9JLXQIArCGo6qw7YLpXr2Lv8YqTOZZgS0o6d5PPmvXSP X-Received: by 10.66.25.203 with SMTP id e11mr13182263pag.76.1394862432384; Fri, 14 Mar 2014 22:47:12 -0700 (PDT) Received: from localhost.localdomain (pdddd29.tkyoac00.ap.so-net.ne.jp. [218.221.221.41]) by mx.google.com with ESMTPSA id eb5sm36044899pad.22.2014.03.14.22.47.07 for (version=TLSv1.1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Fri, 14 Mar 2014 22:47:10 -0700 (PDT) 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 Subject: [PATCH v7 5/7] arm64: ftrace: Add dynamic ftrace support Date: Sat, 15 Mar 2014 14:45:51 +0900 Message-Id: <1394862353-28963-6-git-send-email-takahiro.akashi@linaro.org> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1394705630-12384-1-git-send-email-takahiro.akashi@linaro.org> References: <1394705630-12384-1-git-send-email-takahiro.akashi@linaro.org> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20140315_014734_084062_3A62C3CF X-CRM114-Status: GOOD ( 20.59 ) X-Spam-Score: -2.6 (--) Cc: linaro-kernel@lists.linaro.org, arndb@arndb.de, linux-kernel@vger.kernel.org, AKASHI Takahiro , dsaxena@linaro.org, gkulkarni@caviumnetworks.com, linux-arm-kernel@lists.infradead.org X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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 | 114 +++++++++++++++++++++++++++++++++++++++ 4 files changed, 173 insertions(+) diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 6b3fef6..6954959 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -33,6 +33,7 @@ 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_FTRACE_MCOUNT_RECORD select HAVE_FUNCTION_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 622846f..d0cad6d 100644 --- a/arch/arm64/kernel/entry-ftrace.S +++ b/arch/arm64/kernel/entry-ftrace.S @@ -86,6 +86,7 @@ add \reg, \reg, #8 .endm +#ifndef CONFIG_DYNAMIC_FTRACE /* * void _mcount(unsigned long return_address) * @return_address: return address to instrumented function @@ -134,6 +135,48 @@ 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..9f708e7 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, u32 old, u32 new, + bool validate) +{ + u32 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; + u32 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; + u32 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; + u32 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 +144,35 @@ 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; + u32 branch, nop; + + branch = aarch64_insn_gen_branch_imm(pc, + (unsigned long)ftrace_graph_caller, false); + nop = aarch64_insn_gen_nop(); + + if (enable) + return ftrace_modify_code(pc, nop, branch, true); + else + return ftrace_modify_code(pc, branch, nop, 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 */