Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761617AbZCQByX (ORCPT ); Mon, 16 Mar 2009 21:54:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752087AbZCQByN (ORCPT ); Mon, 16 Mar 2009 21:54:13 -0400 Received: from tomts20-srv.bellnexxia.net ([209.226.175.74]:36209 "EHLO tomts20-srv.bellnexxia.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751877AbZCQByL (ORCPT ); Mon, 16 Mar 2009 21:54:11 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: ApQFAAOdvklMQW1W/2dsb2JhbACBTsRRji6DfwZh Date: Mon, 16 Mar 2009 21:53:59 -0400 From: Mathieu Desnoyers To: Jiaying Zhang Cc: Michael Rubin , linux-kernel@vger.kernel.org, Michael Davidson , Steven Rostedt , ltt-dev@lists.casi.polymtl.ca, Martin Bligh , Ingo Molnar Subject: Re: [ltt-dev] [RFC PATCH] Propose a new kernel tracing framework Message-ID: <20090317015359.GA23976@Krystal> References: <5df78e1d0902231610y615bcfb5hdbbc44736ecfce00@mail.gmail.com> <20090313170415.GE3354@Krystal> <5df78e1d0903161623s1d5d2a04h946668ac0c6a69f7@mail.gmail.com> <20090317000138.GA19848@Krystal> <5df78e1d0903161840o50becebcxe2378805049fee77@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline In-Reply-To: <5df78e1d0903161840o50becebcxe2378805049fee77@mail.gmail.com> X-Editor: vi X-Info: http://krystal.dyndns.org:8080 X-Operating-System: Linux/2.6.21.3-grsec (i686) X-Uptime: 21:47:01 up 16 days, 22:13, 1 user, load average: 0.63, 0.73, 0.54 User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 62224 Lines: 1438 * Jiaying Zhang (jiayingz@google.com) wrote: > On Mon, Mar 16, 2009 at 5:01 PM, Mathieu Desnoyers > wrote: > > * Jiaying Zhang (jiayingz@google.com) wrote: > >> Hi Mathieu, > >> > >> First, I apologize that I did not forward you my original email. I assumed > >> that the email would be noticed by interested people when it was sent > >> to lkml. Now I see that is a mistake. > >> > > > > Hi Jiaying, > > > > Apologies accepted, no hard feeling :) I have just been surprised when I > > found out about the numbers you posted. > > > >> On Fri, Mar 13, 2009 at 10:04 AM, Mathieu Desnoyers > >> wrote: > >> > Hi Jiaying, > >> > > >> > I'm very interested to hear about the details of your test-case, because > >> > what you are talking about here, and the numbers that you get, are, at > >> > the very least, not representative of the current LTTng. Perharps you > >> > used a version right after the kernel summit and stopped following the > >> > improvements we have done since then ? I also wonder about the instrumentation > >> > set you enabled in your tests, and whether it's exactly the same in the ktrace > >> > and LTTng runs (especially system call tracing). Please note that following the > >> > Kernel Summit 2008, a more active development cycle began, and the time was not > >> > right for optimisation. But since then a lot of improvement has been done on > >> > this side. > >> > >> Sorry that I omitted a lot of details in my test description. I did use an old > >> version of LTTng in my tests. The LTTng version I used was the 0.21 lttng > >> patches for 2.6.27 kernel. I used 2.6.26 kernel in my tests, with the ported > >> lttng-2.6.27-rc6-0.21 patches. > >> > >> I enabled the same set of trace events in ktrace and LTTng runs. Here is > >> the list of enabled events: syscall entry/exit, irq entry/exit, trap > >> entry/exit, > >> kernel_sched_switch, kernel_process_fork, kernel_process_wait, > >> kernel_process_free, kernel_process_exit. > >> > >> We are glad to see the improvements coming from the LTTng community. > >> I haven't got time to sync with the latest LTTng code and re-run my tests. > >> I will let you know when I have such data available. > >> > > > > On my side, with flight recorder activated, same instrumentation you > > use, with LTTng 0.111 : > > > > arm-google script : > > > > #!/bin/sh > > > > DIR=/mnt/debugfs/ltt/markers > > > > for a in \ > > syscall_entry syscall_exit \ > > irq_entry irq_exit \ > > trap_entry trap_exit \ > > page_fault_entry page_fault_exit \ > > page_fault_nosem_entry page_fault_nosem_exit \ > > page_fault_get_user_entry page_fault_get_user_exit \ > > sched_schedule process_fork process_wait \ > > process_free process_exit; > > do > > echo 1 > ${DIR}/kernel/$a/enable > > done > > > > running tbench -t 200 8 > > > > Vanilla kernel : 2070 MB/sec > > Flight recorder : 1693 MB/sec Performance impact : 18.2 % > > Normal : 1620 MB/sec Performance impact : 21.7 % (8 lttd threads) > > > > So now we are comparing apples with apples :-) > Looks like the performance of LTTng has improved a lot over the past > few months. I will run some tests with the latest LTTng patches and > let you know if I see any difference. Did you use 2.6.29-rc7 kernel in > your tests? > Yes, kernel 2.6.29-rc7, lttng 0.111. But lttng 0.112 for kernel 2.6.29-rc8 should also be close enough. > > > >> > > >> > First I'd like to express my concern about the way you posted your > >> > numbers : > >> > > >> > 1 - You did not CC anyone from the LTTng project. > >> > 2 - You did not tell which LTTng version you used as a comparison basis. > >> > 3 - You did not look at the current state of code before posting your > >> > comparison. (as shows the comment in your patch header) > >> That is indeed my mistake. > >> > >> > 4 - You did not tell the instrumentation set that you enabled from LTTng. Is it > >> > the default instrumentation ? Did you also enable system call tracing > >> > with your tracer using set_kernel_trace_flag_all_tasks() ? If not, this > >> > makes a huge difference on the amount of information gathered. > >> Yes. We also enable syscall tracing via set_kernel_trace_flag_all_tasks(). > >> > >> > > >> > So let's have a close look at them. I'm re-doing the benchmarks based on > >> > the current LTTng version below. > >> > > >> >> Hello All, > >> >> > >> >> We have been working on building a kernel tracer for a production environment. > >> >> We first considered to use the existing markers code, but found it a bit > >> >> heavyweight. > >> > > >> > Have you looked at : > >> > > >> > 1 - The tracepoints currently in the kernel > >> > 2 - The _current_ version of markers in the LTTng tree ? > >> > >> I looked at the tracepoints currently in the kernel. It is great to see that > >> some trace instrumentation code is finally available in the mainline kernel. > >> But I still don't like an additional tracepoint layer on top of the > >> actual tracing > >> (ktrace or markers or ftrace) layer. That seems to add unnecessary overhead. > >> The markers code I referred to in my email is the current code in the mainline > >> kernel. I had a look at the LTTng markers code but still saw that va_list > >> argument is used in marker_probe_func. It sounds a nice improvement > >> if the LTTng markers avoids the use of va_arg whenever possible. > >> > > > > Yes, vs_args is only there as a commodity for slow paths. > > > >> > > >> >> So we developed a new kernel tracing prototype that shares > >> >> many similarities as markers but also includes several simplifications that > >> >> give us considerable performance benefits. For example, we pass the size of > >> >> trace event directly to the probe function instead of using va_arg as that > >> >> used in markers, which saves us the overhead of variable passing. > >> > > >> > The markers in the LTTng tree only use va_args for "debug-style" > >> > tracing. All the tracing fast paths are now done with custom probe > >> > functions which takes the arguments from the tracepoint and write them > >> > in the trace buffers directly in C. When the event payload size is already > >> > known statically, there is no dynamic computation cost at all : it's > >> > simply passed to the ltt-relay write function. > >> But this raises another concern that sub-system developers may need > >> to write a bunch of custom probe functions to avoid the argument parsing > >> overhead. Can you instead have a general probe function or macro that > >> does this work? > >> > > > > Well, considering the amount of care we have to take when we consider > > adding a tracepoint in the mainline kernel, I think it's even a *good* > > thing that someone has to stop and write a small callback to deal with > > the information he wants to export. I think debug-style tracing should > > be very, very quick and easy to add, but tracepoints meant to make it > > into the mainline does not share this requirement. > I agree that we need to be careful when adding tracepoints into the kernel, > but I still think it is good to simplify the process of adding/maintaining > tracepoints so sub-system maintainers don't feel it is a big burden. > Yes, we have to make sure it's not an impossible task. > > > >> > > >> >> Also, we > >> >> associate a single probe function to each event, so we can directly call the > >> >> probe function when tracing is enabled. > >> > > >> > You seem to imply that being stuck with a single probe function is > >> > somehow superior to have tiny per-event callbacks which then call into a > >> > buffer write function ? Why ? > >> That is indeed my thinking, because we saw that some platforms are > >> very sensitive to function call overhead and we haven't seen use cases > >> where multi probe functions prove necessary. > >> > > > > Hrm, so your plan is to embed the tracing code at the caller site, or to > > keep one single function call ? > We do have a general probe function that is called when tracing is enabled. > Other than that, the main tracing code is defined as an inline function that is > embed at the caller site. > You mean that you embed the main tracing code directly in the kernel instrumented functions ? Hrm, have you considered the calling site pollution impact that might have ? The compiler might start having difficulty optimising hot paths that would then become large functions. Or maybe I am not correctly understanding your approach. Mathieu > > Jiaying > > > > >> > > >> >> Our measurements show that our > >> >> current tracing prototype introduces much lower overhead compared with > >> >> lttng (we use lttng as a comparison because markers does not provide the > >> >> implementation to record trace data). > >> > > >> > Why LTTng version, kernel version, LTTng config and runtime options do > >> > you use ? > >> See above for LTTng and kernel versions. I was using the default LTTng > >> config options and 'normal' recorder mode. > >> > >> > > >> >> E.g., with dbench, lttng introduces > >> >> 20~80% overhead on our testing platforms while the overhead with our > >> >> kernel tracer is within 10%; with tbench, lttng usually adds more than 30% > >> >> overhead while the overhead added by our kernel tracer is usually within > >> >> 15%; with kernbench (time to compile a Linux kernel), the overhead > >> >> added by lttng is around 4%~18% while the overhead added by our > >> >> kernel tracer is within 2.5%. > >> >> > >> > > >> > I'm re-running the dbench and tbench tests : > >> > > >> > With LTTng 0.106, kernel 2.6.29-rc7 > >> > 8-cores Intel(R) Xeon(R) CPU E5405 @ 2.00GHz, 16GB ram > >> > > >> > Arming all the default LTTng instrumentation (168 tracepoints), > >> > Tracing in flight recorder mode, including system call entry/exit > >> > tracing and block I/O tracing (blktrace instrumentation), I get : > >> > > >> > Test / config | Vanilla kernel | LTTng 0.106 | slowdown > >> > dbench 8 -t 200 | 1361 MB/s | 1193 MB/s | 12.3 % > >> > > >> > As an example of the effect of custom probe vs va_args based probes, > >> > let's take the tbench example > >> > > >> > | Vanilla | LTTng 0.106 | slowdown > >> > tbench 8 -t 200 | 2074 MB/s | 997 MB/s | 52 % > >> > > >> > The LTTng trace statistics shows the top high event rate events : > >> > > >> > Some are usual (therefore lttng already implements custom probes for them) : > >> > > >> > 42004 sched_try_wakeup > >> > 79754 timer_set > >> > 83973 sched_schedule > >> > 84317 softirq_exit > >> > 84318 softirq_entry > >> > 95370 page_free > >> > 95412 page_alloc > >> > 267247 syscall_entry > >> > 267247 syscall_exit > >> > > >> > Some are more tbench workload-specific : > >> > > >> > 16915 socket_sendmsg > >> > 18911 napi_complete > >> > 18911 napi_schedule > >> > 18912 dev_receive > >> > 18914 dev_xmit > >> > 18920 napi_poll > >> > 33831 socket_recvmsg > >> > 59860 read > >> > > >> > > >> > So let's see what happens if I implement those as custom probes and do a bit of > >> > tuning in the tracer hot path : > >> Could you give more details about the custom probe you used? > > > > They are available in the lttng tree on git.kernel.org in > > ltt/probes/*-trace.c. Their API is in include/linux/ltt-type-serialize.h > > > >> Do you need to write a custom probe for each tracepoint? > >> > > > > Yes. But it's not such a big deal. It looks a bit like Steve's > > TRACE_EVENT macro-fu, but written in a simple C callback : > > > > void probe_sched_switch(struct rq *rq, struct task_struct *prev, > > struct task_struct *next); > > > > DEFINE_MARKER_TP(kernel, sched_schedule, sched_switch, probe_sched_switch, > > "prev_pid %d next_pid %d prev_state #2d%ld"); > > > > notrace void probe_sched_switch(struct rq *rq, struct task_struct *prev, > > struct task_struct *next) > > { > > struct marker *marker; > > struct serialize_int_int_short data; > > > > data.f1 = prev->pid; > > data.f2 = next->pid; > > data.f3 = prev->state; > > > > marker = &GET_MARKER(kernel, sched_schedule); > > ltt_specialized_trace(marker, marker->single.probe_private, > > &data, serialize_sizeof(data), sizeof(int)); > > } > > > > Best regards, > > > > Mathieu > > > >> Jiaying > >> > >> > > >> > | Vanilla | LTTng 0.107 | slowdown > >> > Custom probes : > >> > tbench 8 -t 200 | 2074 MB/s | 1275 MB/s | 38.5 % > >> > > >> > With tracer hot path tuning (inline hot path, function calls for slow path, will > >> > be in 0.108) : > >> > tbench 8 -t 200 | 2074 MB/s | 1335 MB/s | 35.6 % > >> > > >> > kernbench : > >> > Average Optimal load -j 32 Run > >> > > >> > Vanilla 2.6.29-rc7 : > >> > Elapsed Time 48.238 (0.117346) > >> > > >> > With flight recorder tracing, default lttng instrumentation, lttng 0.108 : > >> > Elapsed Time 50.226 (0.0750333) > >> > > >> > Slowdown : 4.1 % > >> > > >> > So except the tbench workload on LTTng 0.106, which still had a 52% performance > >> > impact (brought it down to 35 % for the next LTTng release) due to > >> > specific workload and not having specialized probes implemented, the > >> > dbench impact is well below your results (12.3 % vs 20-80%) > >> > > >> > So given the huge result discrepancies between your tests and mine, could you > >> > give us more detail about your benchmarks ? Especially knowing the enabled > >> > instrumentation set, and the amount of MB/s generated by both ktrace and LTTng > >> > runs (to make sure we are comparing the same traffic) and the LTTng versions you > >> > are using as a comparison basis would be good. > >> > > >> > Thanks, > >> > > >> > Mathieu > >> > > >> > > >> >> The patch below is the current prototype we have implemented. It uses > >> >> Steve's unified trace buffer code with some small extensions to support > >> >> buffer mmap. The patch is probably still buggy, but we would like to get > >> >> some early feedback from the community. > >> >> > >> >> Signed-off-by: Jiaying Zhang > >> >> > >> >> Index: git-linux/init/Kconfig > >> >> =================================================================== > >> >> --- git-linux.orig/init/Kconfig 2009-02-19 14:58:37.000000000 -0800 > >> >> +++ git-linux/init/Kconfig 2009-02-19 15:50:15.000000000 -0800 > >> >> @@ -950,6 +950,15 @@ > >> >> Place an empty function call at each marker site. Can be > >> >> dynamically changed for a probe function. > >> >> > >> >> +config KTRACE > >> >> + bool "Enable ktrace support" > >> >> + select DEBUG_FS > >> >> + select TRACING > >> >> + select RING_BUFFER > >> >> + help > >> >> + Ktrace is a kernel tracing tool that allows you to trace > >> >> + kernel events by inserting trace points at proper places. > >> >> + > >> >> source "arch/Kconfig" > >> >> > >> >> endmenu # General setup > >> >> Index: git-linux/kernel/Makefile > >> >> =================================================================== > >> >> --- git-linux.orig/kernel/Makefile 2009-02-19 14:58:37.000000000 -0800 > >> >> +++ git-linux/kernel/Makefile 2009-02-19 14:58:39.000000000 -0800 > >> >> @@ -86,6 +86,7 @@ > >> >> obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o > >> >> obj-$(CONFIG_TASKSTATS) += taskstats.o tsacct.o > >> >> obj-$(CONFIG_MARKERS) += marker.o > >> >> +obj-$(CONFIG_KTRACE) += ktrace.o > >> >> obj-$(CONFIG_TRACEPOINTS) += tracepoint.o > >> >> obj-$(CONFIG_LATENCYTOP) += latencytop.o > >> >> obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o > >> >> Index: git-linux/include/asm-generic/vmlinux.lds.h > >> >> =================================================================== > >> >> --- git-linux.orig/include/asm-generic/vmlinux.lds.h 2009-02-19 > >> >> 14:58:37.000000000 -0800 > >> >> +++ git-linux/include/asm-generic/vmlinux.lds.h 2009-02-19 > >> >> 14:58:39.000000000 -0800 > >> >> @@ -73,6 +73,9 @@ > >> >> MEM_KEEP(init.data) \ > >> >> MEM_KEEP(exit.data) \ > >> >> . = ALIGN(8); \ > >> >> + VMLINUX_SYMBOL(__start___ktraces) = .; \ > >> >> + *(__ktrace) \ > >> >> + VMLINUX_SYMBOL(__stop___ktraces) = .; \ > >> >> VMLINUX_SYMBOL(__start___markers) = .; \ > >> >> *(__markers) \ > >> >> VMLINUX_SYMBOL(__stop___markers) = .; \ > >> >> @@ -89,6 +92,7 @@ > >> >> VMLINUX_SYMBOL(__start_rodata) = .; \ > >> >> *(.rodata) *(.rodata.*) \ > >> >> *(__vermagic) /* Kernel version magic */ \ > >> >> + *(__ktrace_strings) /* Ktrace: strings */ \ > >> >> *(__markers_strings) /* Markers: strings */ \ > >> >> *(__tracepoints_strings)/* Tracepoints: strings */ \ > >> >> } \ > >> >> Index: git-linux/kernel/module.c > >> >> =================================================================== > >> >> --- git-linux.orig/kernel/module.c 2009-02-19 14:58:37.000000000 -0800 > >> >> +++ git-linux/kernel/module.c 2009-02-19 14:58:39.000000000 -0800 > >> >> @@ -50,6 +50,7 @@ > >> >> #include > >> >> #include > >> >> #include > >> >> +#include > >> >> #include > >> >> > >> >> #if 0 > >> >> @@ -2145,6 +2146,10 @@ > >> >> sizeof(*mod->tracepoints), > >> >> &mod->num_tracepoints); > >> >> #endif > >> >> +#ifdef CONFIG_KTRACE > >> >> + mod->ktrace = section_objs(hdr, sechdrs, secstrings, "__ktrace", > >> >> + sizeof(*mod->ktrace), &mod->num_ktrace); > >> >> +#endif > >> >> > >> >> #ifdef CONFIG_MODVERSIONS > >> >> if ((mod->num_syms && !mod->crcs) > >> >> Index: git-linux/include/linux/module.h > >> >> =================================================================== > >> >> --- git-linux.orig/include/linux/module.h 2009-02-19 > >> >> 14:58:37.000000000 -0800 > >> >> +++ git-linux/include/linux/module.h 2009-02-19 14:58:39.000000000 -0800 > >> >> @@ -44,6 +44,7 @@ > >> >> }; > >> >> > >> >> struct module; > >> >> +struct kernel_trace; > >> >> > >> >> struct module_attribute { > >> >> struct attribute attr; > >> >> @@ -347,6 +348,11 @@ > >> >> /* Reference counts */ > >> >> struct module_ref ref[NR_CPUS]; > >> >> #endif > >> >> +#ifdef CONFIG_KTRACE > >> >> + struct kernel_trace *ktrace; > >> >> + unsigned int num_ktrace; > >> >> +#endif > >> >> + > >> >> }; > >> >> #ifndef MODULE_ARCH_INIT > >> >> #define MODULE_ARCH_INIT {} > >> >> Index: git-linux/include/linux/ktrace.h > >> >> =================================================================== > >> >> --- /dev/null 1970-01-01 00:00:00.000000000 +0000 > >> >> +++ git-linux/include/linux/ktrace.h 2009-02-19 15:36:39.000000000 -0800 > >> >> @@ -0,0 +1,83 @@ > >> >> +#ifndef _LINUX_KTRACE_H > >> >> +#define _LINUX_KTRACE_H > >> >> + > >> >> +#include > >> >> + > >> >> +struct kernel_trace; > >> >> + > >> >> +typedef void ktrace_probe_func(struct kernel_trace *, void *, size_t); > >> >> + > >> >> +struct kernel_trace { > >> >> + const char *name; > >> >> + const char *format; /* format string describing variable list */ > >> >> + size_t *stroff; /* offsets of string variables */ > >> >> + /* 31 bit event_id is converted to 16 bit when entering to the buffer */ > >> >> + u32 enabled:1, event_id:31; > >> >> + ktrace_probe_func *func; /* probe function */ > >> >> + struct list_head list; /* list head linked to the hash table entry */ > >> >> +} __attribute__((aligned(8))); > >> >> + > >> >> +extern int ktrace_enabled; > >> >> + > >> >> +/* > >> >> + * Make sure the alignment of the structure in the __ktrace section will > >> >> + * not add unwanted padding between the beginning of the section and the > >> >> + * structure. Force alignment to the same alignment as the section start. > >> >> + */ > >> >> + > >> >> +#define DEFINE_KTRACE_STRUCT(name) \ > >> >> + struct __attribute__((packed)) ktrace_struct_##name > >> >> + > >> >> +#ifdef CONFIG_KTRACE > >> >> +/* > >> >> + * DO_TRACE is the macro that is called from each trace point. Each trace > >> >> + * point is associated with a static ktrace object that is located in a > >> >> + * special __ktrace section and is uniquely identified by the event name and > >> >> + * event format. Take a look at the files under include/trace for example > >> >> + * usage. Note that we call the trace probe function only if the global > >> >> + * tracing is enabled and the tracing for the associated event is enabled, > >> >> + * so we only introduce the overhead of a predicted condition judge when > >> >> + * tracing is disabled. > >> >> + */ > >> >> +#define DO_TRACE(name, format, args...) > >> >> \ > >> >> + do { \ > >> >> + static const char __kstrtab_##name[] \ > >> >> + __attribute__((section("__ktrace_strings"))) \ > >> >> + = #name "\0" format; \ > >> >> + static struct kernel_trace __ktrace_##name \ > >> >> + __attribute__((section("__ktrace"), aligned(8))) = \ > >> >> + { __kstrtab_##name, &__kstrtab_##name[sizeof(#name)], \ > >> >> + NULL, 0, 0, NULL, LIST_HEAD_INIT(__ktrace_##name.list) }; \ > >> >> + __ktrace_check_format(format, ## args); \ > >> >> + if (unlikely(ktrace_enabled) && \ > >> >> + unlikely(__ktrace_##name.enabled)) { \ > >> >> + struct ktrace_struct_##name karg = { args }; \ > >> >> + (*__ktrace_##name.func) \ > >> >> + (&__ktrace_##name, &karg, sizeof(karg)); \ > >> >> + } \ > >> >> + } while (0) > >> >> + > >> >> +#else /* !CONFIG_KTRACE */ > >> >> +#define DO_TRACE(name, format, args...) > >> >> +#endif > >> >> + > >> >> +/* To be used for string format validity checking with gcc */ > >> >> +static inline void __printf(1, 2) ___ktrace_check_format(const char *fmt, ...) > >> >> +{ > >> >> +} > >> >> + > >> >> +#define __ktrace_check_format(format, args...) \ > >> >> + do { \ > >> >> + if (0) \ > >> >> + ___ktrace_check_format(format, ## args); \ > >> >> + } while (0) > >> >> + > >> >> + > >> >> +/* get the trace buffer information */ > >> >> +#define KTRACE_BUF_GET_SIZE _IOR(0xF5, 0x00, __u32) > >> >> +#define KTRACE_BUF_GET_PRODUCED _IOR(0xF5, 0x01, __u32) > >> >> +#define KTRACE_BUF_GET_CONSUMED _IOR(0xF5, 0x02, __u32) > >> >> +#define KTRACE_BUF_PUT_PRODUCED _IOW(0xF5, 0x03, __u32) > >> >> +#define KTRACE_BUF_PUT_CONSUMED _IOW(0xF5, 0x04, __u32) > >> >> + > >> >> +#endif > >> >> Index: git-linux/kernel/ktrace.c > >> >> =================================================================== > >> >> --- /dev/null 1970-01-01 00:00:00.000000000 +0000 > >> >> +++ git-linux/kernel/ktrace.c 2009-02-19 15:45:20.000000000 -0800 > >> >> @@ -0,0 +1,872 @@ > >> >> +/* > >> >> + * kernel/ktrace.c > >> >> + * > >> >> + * Implementation of the kernel tracing for linux kernel 2.6. > >> >> + * > >> >> + * Copyright 2008- Google Inc. > >> >> + * Original Author: Jiaying Zhang > >> >> + */ > >> >> + > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> +#include > >> >> + > >> >> +static char *ktrace_version = "1.0.0"; > >> >> +int ktrace_enabled; > >> >> +EXPORT_SYMBOL(ktrace_enabled); > >> >> +static uint16_t ktrace_next_id; > >> >> + > >> >> +extern struct kernel_trace __start___ktraces[]; > >> >> +extern struct kernel_trace __stop___ktraces[]; > >> >> + > >> >> +static DEFINE_MUTEX(ktrace_mutex); > >> >> + > >> >> +/* ktrace hash table entry structure and variables */ > >> >> +struct ktrace_entry { > >> >> + struct hlist_node hlist; > >> >> + char *name; > >> >> + char *format; > >> >> + size_t *stroff; > >> >> + ktrace_probe_func *func; > >> >> + u32 enabled:1, event_id:31; > >> >> + struct list_head klist; /* list of loaded ktraces */ > >> >> +}; > >> >> + > >> >> +#define KTRACE_HASH_BITS 6 > >> >> +#define KTRACE_HASH_SIZE (1 << KTRACE_HASH_BITS) > >> >> +static struct hlist_head ktrace_table[KTRACE_HASH_SIZE]; > >> >> + > >> >> +/* debugfs directory variables */ > >> >> +static struct dentry *tracedir; > >> >> +static struct dentry *eventdir; > >> >> +typedef void tracecontrol_handle_func(struct file *, unsigned long, size_t *); > >> >> + > >> >> +/* ring buffer code */ > >> >> +static unsigned long trace_buf_size = 65536UL; > >> >> +struct ring_buffer *trace_buffer; > >> >> +static DECLARE_WAIT_QUEUE_HEAD(trace_wait); /* waitqueue for trace_data_poll */ > >> >> +static struct timer_list trace_timer; /* reader wake-up timer */ > >> >> +#define TRACEREAD_WAKEUP_INTERVAL 1000 /* time interval in jiffies */ > >> >> +static struct kref ktrace_kref; > >> >> + > >> >> +static void > >> >> +ring_buffer_probe(struct kernel_trace *kt, void *data, size_t event_size) > >> >> +{ > >> >> + struct ring_buffer_event *event; > >> >> + void *trace_event; > >> >> + unsigned long flag; > >> >> + > >> >> + event = ring_buffer_lock_reserve(trace_buffer, > >> >> + sizeof(uint16_t) + event_size, &flag); > >> >> + if (!event) > >> >> + return; > >> >> + trace_event = ring_buffer_event_data(event); > >> >> + *(uint16_t *) trace_event = (uint16_t) kt->event_id; > >> >> + memcpy(trace_event + sizeof(uint16_t), data, event_size); > >> >> + ring_buffer_unlock_commit(trace_buffer, event, flag); > >> >> +} > >> >> + > >> >> +/* special probe function for events that contain string arguments */ > >> >> +static void > >> >> +string_probe(struct kernel_trace *kt, void *data, size_t event_size) > >> >> +{ > >> >> + struct ring_buffer_event *event; > >> >> + void *trace_event, *p; > >> >> + unsigned long flag; > >> >> + size_t *offset, scanned; > >> >> + char *string; > >> >> + > >> >> + /* > >> >> + * Get the real length of the event, i.e., we use stroff array to > >> >> + * locate string variables in the passed-in trace data and use their > >> >> + * length to replace the size of the string pointers. > >> >> + */ > >> >> + for (offset = kt->stroff; *offset != -1; offset++) { > >> >> + string = *(char **) (data + *offset); > >> >> + event_size += strlen(string) + 1 - sizeof(char *); > >> >> + } > >> >> + event = ring_buffer_lock_reserve(trace_buffer, > >> >> + sizeof(uint16_t) + event_size, &flag); > >> >> + if (!event) > >> >> + return; > >> >> + trace_event = ring_buffer_event_data(event); > >> >> + *(uint16_t *) trace_event = (uint16_t) kt->event_id; > >> >> + p = trace_event + sizeof(uint16_t); > >> >> + /* > >> >> + * Copy the trace data into buffer. For string variables, we enter the > >> >> + * string into the buffer. Otherwise, the passed in data is copied. > >> >> + */ > >> >> + for (offset = kt->stroff, scanned = 0; *offset != -1; offset++) { > >> >> + memcpy(p, data + scanned, *offset - scanned); > >> >> + p += *offset - scanned; > >> >> + string = *(char **) (data + *offset); > >> >> + memcpy(p, string, strlen(string) + 1); > >> >> + p += strlen(string) + 1; > >> >> + scanned = *offset + sizeof(char *); > >> >> + } > >> >> + memcpy(p, data + scanned, > >> >> + trace_event + sizeof(uint16_t) + event_size - p); > >> >> + ring_buffer_unlock_commit(trace_buffer, event, flag); > >> >> +} > >> >> + > >> >> +/* timer function used to defer ring buffer reader waking */ > >> >> +static void wakeup_readers(unsigned long data) > >> >> +{ > >> >> + if (trace_buffer && !ring_buffer_empty(trace_buffer)) > >> >> + wake_up_interruptible(&trace_wait); > >> >> + mod_timer(&trace_timer, jiffies + TRACEREAD_WAKEUP_INTERVAL); > >> >> +} > >> >> + > >> >> +/* function for reading ktrace metadata info */ > >> >> +static void *tracing_info_start(struct seq_file *seq, loff_t *pos) > >> >> +{ > >> >> + seq_printf(seq, "version %s\n", ktrace_version); > >> >> + return (*pos >= KTRACE_HASH_SIZE) ? NULL : &ktrace_table[*pos]; > >> >> +} > >> >> + > >> >> +static void *tracing_info_next(struct seq_file *seq, void *v, loff_t *pos) > >> >> +{ > >> >> + ++*pos; > >> >> + return (*pos >= KTRACE_HASH_SIZE) ? NULL : &ktrace_table[*pos]; > >> >> +} > >> >> + > >> >> +static int tracing_info_show(struct seq_file *seq, void *v) > >> >> +{ > >> >> + struct hlist_head *head = v; > >> >> + struct hlist_node *node; > >> >> + struct ktrace_entry *entry; > >> >> + hlist_for_each_entry(entry, node, head, hlist) > >> >> + seq_printf(seq, "name '%s' format '%s' id %u %s\n", > >> >> + entry->name, entry->format, entry->event_id, > >> >> + entry->enabled ? "enabled" : "disabled"); > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static void tracing_info_stop(struct seq_file *seq, void *v) > >> >> +{ > >> >> +} > >> >> + > >> >> +static const struct seq_operations tracing_info_seq_ops = { > >> >> + .start = tracing_info_start, > >> >> + .next = tracing_info_next, > >> >> + .show = tracing_info_show, > >> >> + .stop = tracing_info_stop, > >> >> +}; > >> >> + > >> >> +static int tracing_info_open(struct inode *inode, struct file *file) > >> >> +{ > >> >> + return seq_open(file, &tracing_info_seq_ops); > >> >> +} > >> >> + > >> >> +static const struct file_operations traceinfo_file_operations = { > >> >> + .open = tracing_info_open, > >> >> + .read = seq_read, > >> >> + .llseek = seq_lseek, > >> >> + .release = seq_release, > >> >> +}; > >> >> + > >> >> +/* > >> >> + * wrapper function used by debugfs write operation. > >> >> + * func: handling function that does real work > >> >> + */ > >> >> +static ssize_t trace_debugfs_write(struct file *filp, const char __user *ubuf, > >> >> + size_t cnt, loff_t *ppos, tracecontrol_handle_func *func) > >> >> +{ > >> >> + int ret; > >> >> + char buf[64]; > >> >> + unsigned long val; > >> >> + > >> >> + if (cnt >= sizeof(buf)) > >> >> + return -EINVAL; > >> >> + if (copy_from_user(&buf, ubuf, cnt)) > >> >> + return -EFAULT; > >> >> + buf[cnt] = 0; > >> >> + > >> >> + ret = strict_strtoul(buf, 10, &val); > >> >> + if (ret < 0) > >> >> + return ret; > >> >> + val = !!val; > >> >> + > >> >> + func(filp, val, &cnt); > >> >> + > >> >> + filp->f_pos += cnt; > >> >> + return cnt; > >> >> +} > >> >> + > >> >> +/* functions for reading/writing the global 'enabled' control file */ > >> >> +static ssize_t tracing_control_read(struct file *filp, char __user *ubuf, > >> >> + size_t cnt, loff_t *ppos) > >> >> +{ > >> >> + int ret; > >> >> + char buf[64]; > >> >> + ret = snprintf(buf, 64, "%u\n", ktrace_enabled); > >> >> + return simple_read_from_buffer(ubuf, cnt, ppos, buf, ret); > >> >> +} > >> >> + > >> >> +static void __tracing_control_write(struct file *filp, > >> >> + unsigned long val, size_t *cnt) > >> >> +{ > >> >> + if (val ^ ktrace_enabled) { > >> >> + if (val) { > >> >> + trace_timer.expires = > >> >> + jiffies + TRACEREAD_WAKEUP_INTERVAL; > >> >> + add_timer(&trace_timer); > >> >> + ktrace_enabled = 1; > >> >> + } else { > >> >> + ktrace_enabled = 0; > >> >> + del_timer_sync(&trace_timer); > >> >> + if (trace_buffer && !ring_buffer_empty(trace_buffer)) > >> >> + wake_up_interruptible(&trace_wait); > >> >> + } > >> >> + } > >> >> +} > >> >> + > >> >> +static ssize_t tracing_control_write(struct file *filp, const char > >> >> __user *ubuf, > >> >> + size_t cnt, loff_t *ppos) > >> >> +{ > >> >> + return trace_debugfs_write(filp, ubuf, cnt, ppos, > >> >> + __tracing_control_write); > >> >> +} > >> >> + > >> >> +static const struct file_operations tracecontrol_file_operations = { > >> >> + .read = tracing_control_read, > >> >> + .write = tracing_control_write, > >> >> +}; > >> >> + > >> >> +/* functions for reading/writing a trace event file */ > >> >> +static int update_ktrace(struct ktrace_entry *entry, > >> >> + ktrace_probe_func *func, int enabled) > >> >> +{ > >> >> + struct kernel_trace *iter; > >> >> + /* no need to update the list if the tracing is not initialized */ > >> >> + if (!tracedir) > >> >> + return 0; > >> >> + entry->enabled = enabled; > >> >> + entry->func = func; > >> >> + list_for_each_entry(iter, &entry->klist, list) { > >> >> + iter->stroff = entry->stroff; > >> >> + iter->func = func; > >> >> + iter->enabled = enabled; > >> >> + } > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static int ktrace_probe_register(struct ktrace_entry *entry, > >> >> + ktrace_probe_func *probefunc) > >> >> +{ > >> >> + return update_ktrace(entry, probefunc, 1); > >> >> +} > >> >> + > >> >> +static int ktrace_probe_unregister(struct ktrace_entry *entry) > >> >> +{ > >> >> + return update_ktrace(entry, NULL, 0); > >> >> +} > >> >> + > >> >> +static int ktrace_control_open(struct inode *inode, struct file *filp) > >> >> +{ > >> >> + filp->private_data = inode->i_private; > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static ssize_t ktrace_control_read(struct file *filp, char __user *ubuf, > >> >> + size_t cnt, loff_t *ppos) > >> >> +{ > >> >> + int ret; > >> >> + char buf[64]; > >> >> + struct ktrace_entry *entry = filp->private_data; > >> >> + > >> >> + ret = snprintf(buf, 64, "%u\n", entry->enabled); > >> >> + return simple_read_from_buffer(ubuf, cnt, ppos, buf, ret); > >> >> +} > >> >> + > >> >> +/* > >> >> + * Check whether the event contains string arguments. Return 0 if not; > >> >> + * otherwise record the offsets of the string arguments in the ktrace > >> >> + * structure according to the event format and return 1. > >> >> + * The offset info is later used to store the string arguments into > >> >> + * the trace buffer during trace probe. > >> >> + */ > >> >> +static int contain_string_arguments(struct ktrace_entry *entry) > >> >> +{ > >> >> + int count = 0; > >> >> + char *fmt; > >> >> + int qualifier; /* 'h', 'l', or 'L' for integer fields */ > >> >> + size_t offset = 0; > >> >> + > >> >> + for (fmt = strstr(entry->format, "%s"); fmt; fmt = strstr(++fmt, "%s")) > >> >> + count++; > >> >> + if (!count) > >> >> + return 0; > >> >> + entry->stroff = kmalloc(sizeof(size_t) * (count + 1), GFP_KERNEL); > >> >> + if (!entry->stroff) > >> >> + return -ENOMEM; > >> >> + > >> >> + for (fmt = entry->format, count = 0; *fmt ; ++fmt) { > >> >> + if (*fmt != '%') > >> >> + continue; > >> >> +repeat: > >> >> + ++fmt; > >> >> + switch (*fmt) { > >> >> + case '-': > >> >> + case '+': > >> >> + case ' ': > >> >> + case '#': > >> >> + case '0': > >> >> + ++fmt; > >> >> + goto repeat; > >> >> + } > >> >> + > >> >> + while (isdigit(*fmt)) > >> >> + fmt++; > >> >> + > >> >> + /* get the conversion qualifier */ > >> >> + qualifier = -1; > >> >> + if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L') { > >> >> + qualifier = *fmt; > >> >> + ++fmt; > >> >> + if (qualifier == 'l' && *fmt == 'l') { > >> >> + qualifier = 'L'; > >> >> + ++fmt; > >> >> + } > >> >> + } > >> >> + > >> >> + switch (*fmt) { > >> >> + case 'c': > >> >> + offset += sizeof(char); > >> >> + continue; > >> >> + case 's': > >> >> + entry->stroff[count] = offset; > >> >> + count++; > >> >> + offset += sizeof(char *); > >> >> + continue; > >> >> + case 'p': > >> >> + offset += sizeof(void *); > >> >> + continue; > >> >> + case 'd': > >> >> + case 'i': > >> >> + case 'o': > >> >> + case 'u': > >> >> + case 'x': > >> >> + case 'X': > >> >> + switch (qualifier) { > >> >> + case 'L': > >> >> + offset += sizeof(long long); > >> >> + break; > >> >> + case 'l': > >> >> + offset += sizeof(long); > >> >> + break; > >> >> + case 'h': > >> >> + offset += sizeof(short); > >> >> + break; > >> >> + default: > >> >> + offset += sizeof(int); > >> >> + break; > >> >> + } > >> >> + break; > >> >> + default: > >> >> + printk(KERN_WARNING "unknown format '%c'", *fmt); > >> >> + continue; > >> >> + } > >> >> + } > >> >> + entry->stroff[count] = -1; > >> >> + return 1; > >> >> +} > >> >> + > >> >> +static void __ktrace_control_write(struct file *filp, > >> >> + unsigned long val, size_t *cnt) > >> >> +{ > >> >> + struct ktrace_entry *entry = filp->private_data; > >> >> + int ret; > >> >> + > >> >> + mutex_lock(&ktrace_mutex); > >> >> + if (val ^ entry->enabled) { > >> >> + if (val) { > >> >> + ret = contain_string_arguments(entry); > >> >> + if (ret == 0) > >> >> + ktrace_probe_register(entry, ring_buffer_probe); > >> >> + else if (ret > 0) > >> >> + ktrace_probe_register(entry, string_probe); > >> >> + else > >> >> + *cnt = ret; > >> >> + } else > >> >> + ktrace_probe_unregister(entry); > >> >> + } > >> >> + mutex_unlock(&ktrace_mutex); > >> >> +} > >> >> + > >> >> +static ssize_t ktrace_control_write(struct file *filp, const char __user *ubuf, > >> >> + size_t cnt, loff_t *ppos) > >> >> +{ > >> >> + return trace_debugfs_write(filp, ubuf, cnt, ppos, > >> >> + __ktrace_control_write); > >> >> +} > >> >> + > >> >> +static const struct file_operations ktracecontrol_file_operations = { > >> >> + .open = ktrace_control_open, > >> >> + .read = ktrace_control_read, > >> >> + .write = ktrace_control_write, > >> >> +}; > >> >> + > >> >> +/* functions for adding/removing a trace event. Protected by mutex lock. > >> >> + * Called during initialization or after loading a module */ > >> >> +static struct ktrace_entry *add_ktrace(struct kernel_trace *ktrace) > >> >> +{ > >> >> + struct ktrace_entry *entry; > >> >> + size_t name_len = strlen(ktrace->name) + 1; > >> >> + u32 hash = jhash(ktrace->name, name_len-1, 0); > >> >> + struct hlist_head *head; > >> >> + struct hlist_node *node; > >> >> + struct dentry *dentry; > >> >> + > >> >> + if (!tracedir) > >> >> + return 0; > >> >> + head = &ktrace_table[hash & ((1 << KTRACE_HASH_BITS)-1)]; > >> >> + hlist_for_each_entry(entry, node, head, hlist) { > >> >> + if (!strcmp(ktrace->name, entry->name)) { > >> >> + if (strcmp(ktrace->format, entry->format)) { > >> >> + printk(KERN_WARNING "the format of tracepoint " > >> >> + "\'%s\' changes from \'%s\' to \'%s\'." > >> >> + "Dynamic changing of trace format is " > >> >> + "not supported yet!\n", > >> >> + ktrace->name, entry->format, > >> >> + ktrace->format); > >> >> + return ERR_PTR(-EINVAL); > >> >> + } > >> >> + ktrace->enabled = entry->enabled; > >> >> + ktrace->func = entry->func; > >> >> + ktrace->event_id = entry->event_id; > >> >> + if (list_empty(&entry->klist)) > >> >> + goto add_head; > >> >> + list_add_tail(&ktrace->list, &entry->klist); > >> >> + return entry; > >> >> + } > >> >> + } > >> >> + entry = kmalloc(sizeof(struct ktrace_entry), GFP_KERNEL); > >> >> + if (!entry) > >> >> + return ERR_PTR(-ENOMEM); > >> >> + entry->name = kmalloc(name_len, GFP_KERNEL); > >> >> + if (!entry->name) { > >> >> + kfree(entry); > >> >> + return ERR_PTR(-ENOMEM); > >> >> + } > >> >> + memcpy(entry->name, ktrace->name, name_len); > >> >> + if (ktrace->format) { > >> >> + size_t format_len = strlen(ktrace->format) + 1; > >> >> + entry->format = kmalloc(format_len, GFP_KERNEL); > >> >> + if (!entry->format) { > >> >> + kfree(entry->name); > >> >> + kfree(entry); > >> >> + return ERR_PTR(-ENOMEM); > >> >> + } > >> >> + memcpy(entry->format, ktrace->format, format_len); > >> >> + } else > >> >> + entry->format = NULL; > >> >> + entry->func = ktrace->func; > >> >> + entry->enabled = 0; > >> >> + ktrace->event_id = entry->event_id = ktrace_next_id++; > >> >> + entry->stroff = NULL; > >> >> + INIT_LIST_HEAD(&entry->klist); > >> >> + hlist_add_head(&entry->hlist, head); > >> >> +add_head: > >> >> + list_add(&ktrace->list, &entry->klist); > >> >> + dentry = debugfs_create_file(entry->name, 0660, eventdir, > >> >> + entry, &ktracecontrol_file_operations); > >> >> + if (!dentry) > >> >> + printk(KERN_WARNING "Couldn't create debugfs '%s' entry\n", > >> >> + entry->name); > >> >> + return entry; > >> >> +} > >> >> + > >> >> +static int remove_ktrace(struct kernel_trace *ktrace, int free) > >> >> +{ > >> >> + struct ktrace_entry *entry; > >> >> + size_t name_len = strlen(ktrace->name) + 1; > >> >> + u32 hash = jhash(ktrace->name, name_len-1, 0); > >> >> + struct hlist_head *head; > >> >> + struct hlist_node *node, *temp; > >> >> + struct dentry *dentry; > >> >> + > >> >> + if (!tracedir) > >> >> + return 0; > >> >> + list_del(&ktrace->list); > >> >> + head = &ktrace_table[hash & ((1 << KTRACE_HASH_BITS)-1)]; > >> >> + hlist_for_each_entry_safe(entry, node, temp, head, hlist) > >> >> + if (!strcmp(ktrace->name, entry->name)) { > >> >> + if (list_empty(&entry->klist)) { > >> >> + dentry = lookup_one_len(entry->name, > >> >> + eventdir, strlen(entry->name)); > >> >> + if (dentry && !IS_ERR(dentry)) { > >> >> + debugfs_remove(dentry); > >> >> + dput(dentry); > >> >> + } > >> >> + entry->enabled = 0; > >> >> + if (free) { > >> >> + hlist_del(&entry->hlist); > >> >> + kfree(entry->name); > >> >> + kfree(entry->format); > >> >> + kfree(entry->stroff); > >> >> + kfree(entry); > >> >> + } > >> >> + } > >> >> + return 0; > >> >> + } > >> >> + return -1; > >> >> +} > >> >> + > >> >> +/* Add/remove tracepoints contained in a module to the ktrace hash table. > >> >> + * Called at the end of module load/unload. */ > >> >> +static int ktrace_module_notify(struct notifier_block *self, > >> >> + unsigned long val, void *data) > >> >> +{ > >> >> +#ifdef CONFIG_MODULES > >> >> + struct kernel_trace *iter; > >> >> + struct module *mod = data; > >> >> + > >> >> + if (val != MODULE_STATE_COMING && val != MODULE_STATE_GOING) > >> >> + return 0; > >> >> + mutex_lock(&ktrace_mutex); > >> >> + for (iter = mod->ktrace; iter < mod->ktrace + mod->num_ktrace; iter++) > >> >> + if (val == MODULE_STATE_COMING) > >> >> + add_ktrace(iter); > >> >> + else > >> >> + remove_ktrace(iter, 0); > >> >> + mutex_unlock(&ktrace_mutex); > >> >> +#endif > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static struct notifier_block ktrace_module_nb = { > >> >> + .notifier_call = ktrace_module_notify, > >> >> +}; > >> >> + > >> >> +/* functions for user-space programs to read data from tracing buffer */ > >> >> +static int trace_data_open(struct inode *inode, struct file *filp) > >> >> +{ > >> >> + filp->private_data = inode->i_private; > >> >> + kref_get(&ktrace_kref); > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static void release_trace_buffer(struct kref *kref) > >> >> +{ > >> >> + ring_buffer_free(trace_buffer); > >> >> + trace_buffer = NULL; > >> >> +} > >> >> + > >> >> +static int trace_data_release(struct inode *inode, struct file *filp) > >> >> +{ > >> >> + kref_put(&ktrace_kref, release_trace_buffer); > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static unsigned int trace_data_poll(struct file *filp, poll_table *poll_table) > >> >> +{ > >> >> + struct ring_buffer_per_cpu *cpu_buffer = filp->private_data; > >> >> + if (filp->f_mode & FMODE_READ) { > >> >> + if (!ring_buffer_per_cpu_empty(cpu_buffer)) > >> >> + return POLLIN | POLLRDNORM; > >> >> + poll_wait(filp, &trace_wait, poll_table); > >> >> + if (!ring_buffer_per_cpu_empty(cpu_buffer)) > >> >> + return POLLIN | POLLRDNORM; > >> >> + } > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static int trace_buf_fault(struct vm_area_struct *vma, struct vm_fault *vmf) > >> >> +{ > >> >> + struct ring_buffer_per_cpu *cpu_buffer = vma->vm_private_data; > >> >> + pgoff_t pgoff = vmf->pgoff; > >> >> + struct page *page; > >> >> + > >> >> + if (!trace_buffer) > >> >> + return VM_FAULT_OOM; > >> >> + page = ring_buffer_get_page(cpu_buffer, pgoff); > >> >> + if (page == NULL) > >> >> + return VM_FAULT_SIGBUS; > >> >> + get_page(page); > >> >> + vmf->page = page; > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static struct vm_operations_struct trace_data_mmap_ops = { > >> >> + .fault = trace_buf_fault, > >> >> +}; > >> >> + > >> >> +static int trace_data_mmap(struct file *filp, struct vm_area_struct *vma) > >> >> +{ > >> >> + struct ring_buffer_per_cpu *cpu_buffer = filp->private_data; > >> >> + > >> >> + vma->vm_ops = &trace_data_mmap_ops; > >> >> + vma->vm_flags |= VM_DONTEXPAND; > >> >> + vma->vm_private_data = cpu_buffer; > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static int trace_data_ioctl(struct inode *inode, struct file *filp, > >> >> + unsigned int cmd, unsigned long arg) > >> >> +{ > >> >> + u32 __user *argp = (u32 __user *)arg; > >> >> + struct ring_buffer_per_cpu *cpu_buffer = filp->private_data; > >> >> + > >> >> + if (!trace_buffer || !tracedir) > >> >> + return -EINVAL; > >> >> + switch (cmd) { > >> >> + case KTRACE_BUF_GET_SIZE: > >> >> + { > >> >> + unsigned long bufsize; > >> >> + bufsize = ring_buffer_size(trace_buffer); > >> >> + return put_user((u32)bufsize, argp); > >> >> + } > >> >> + case KTRACE_BUF_GET_PRODUCED: > >> >> + return put_user(ring_buffer_get_produced(cpu_buffer), argp); > >> >> + case KTRACE_BUF_GET_CONSUMED: > >> >> + return put_user(ring_buffer_get_consumed(cpu_buffer), argp); > >> >> + case KTRACE_BUF_PUT_CONSUMED: > >> >> + { > >> >> + u32 consumed, consumed_old; > >> >> + int ret; > >> >> + > >> >> + ret = get_user(consumed, argp); > >> >> + if (ret) { > >> >> + printk(KERN_WARNING > >> >> + "error getting consumed value: %d\n", ret); > >> >> + return ret; > >> >> + } > >> >> + consumed_old = ring_buffer_get_consumed(cpu_buffer); > >> >> + if (consumed == consumed_old) > >> >> + return 0; > >> >> + ring_buffer_advance_reader(cpu_buffer, consumed - consumed_old); > >> >> + return 0; > >> >> + } > >> >> + default: > >> >> + return -ENOIOCTLCMD; > >> >> + } > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static const struct file_operations tracedata_file_operations = { > >> >> + .open = trace_data_open, > >> >> + .poll = trace_data_poll, > >> >> + .mmap = trace_data_mmap, > >> >> + .ioctl = trace_data_ioctl, > >> >> + .release = trace_data_release, > >> >> +}; > >> >> + > >> >> +/* function to report the number of lost events due to buffer overflow */ > >> >> +static ssize_t trace_overflow_read(struct file *filp, char __user *ubuf, > >> >> + size_t cnt, loff_t *ppos) > >> >> +{ > >> >> + int ret; > >> >> + char buf[64]; > >> >> + ret = snprintf(buf, 64, "%lu\n", ring_buffer_overruns(trace_buffer)); > >> >> + return simple_read_from_buffer(ubuf, cnt, ppos, buf, ret); > >> >> +} > >> >> + > >> >> +static const struct file_operations traceoverflow_file_operations = { > >> >> + .read = trace_overflow_read, > >> >> +}; > >> >> + > >> >> +/* function to re-initialize trace buffer */ > >> >> +static void __trace_buffer_reset(struct file *filp, > >> >> + unsigned long val, size_t *cnt) > >> >> +{ > >> >> + if (val && trace_buffer) > >> >> + ring_buffer_reset(trace_buffer); > >> >> +} > >> >> + > >> >> +static ssize_t trace_buffer_reset(struct file *filp, const char __user *ubuf, > >> >> + size_t cnt, loff_t *ppos) > >> >> +{ > >> >> + return trace_debugfs_write(filp, ubuf, cnt, ppos, > >> >> + __trace_buffer_reset); > >> >> +} > >> >> + > >> >> +static const struct file_operations tracereset_file_operations = { > >> >> + .write = trace_buffer_reset, > >> >> +}; > >> >> + > >> >> +/* > >> >> + * We use debugfs for kernel-user communication. All of the control/info > >> >> + * files are under debugfs/ktrace directory. > >> >> + */ > >> >> +static int create_debugfs(void) > >> >> +{ > >> >> + struct dentry *entry, *bufdir; > >> >> + struct ring_buffer_per_cpu *cpu_buffer; > >> >> + char *tmpname; > >> >> + int cpu; > >> >> + > >> >> + tracedir = debugfs_create_dir("ktrace", NULL); > >> >> + if (!tracedir) { > >> >> + printk(KERN_WARNING "Couldn't create debugfs directory\n"); > >> >> + return -ENOMEM; > >> >> + } > >> >> + > >> >> + /* 'buffers' is the directory that holds trace buffer debugfs files */ > >> >> + bufdir = debugfs_create_dir("buffers", tracedir); > >> >> + if (!bufdir) { > >> >> + printk(KERN_WARNING "Couldn't create 'buffers' directory\n"); > >> >> + return -ENOMEM; > >> >> + } > >> >> + > >> >> + tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); > >> >> + if (!tmpname) > >> >> + return -ENOMEM; > >> >> + /* create a debugfs file for each cpu buffer */ > >> >> + for_each_possible_cpu(cpu) { > >> >> + snprintf(tmpname, NAME_MAX, "%s%d", "cpu", cpu); > >> >> + cpu_buffer = ring_buffer_cpu(trace_buffer, cpu); > >> >> + entry = debugfs_create_file(tmpname, 0440, bufdir, cpu_buffer, > >> >> + &tracedata_file_operations); > >> >> + if (!entry) { > >> >> + printk(KERN_WARNING > >> >> + "Couldn't create debugfs \'%s\' entry\n", > >> >> + tmpname); > >> >> + return -ENOMEM; > >> >> + } > >> >> + } > >> >> + kfree(tmpname); > >> >> + > >> >> + /* the control file for users to enable/disable global tracing. */ > >> >> + entry = debugfs_create_file("enabled", 0664, tracedir, NULL, > >> >> + &tracecontrol_file_operations); > >> >> + if (!entry) { > >> >> + printk(KERN_WARNING > >> >> + "Couldn't create debugfs 'enabled' entry\n"); > >> >> + return -ENOMEM; > >> >> + } > >> >> + > >> >> + /* > >> >> + * the debugfs file that displays the name, format etc. of every > >> >> + * supported trace event. The file is to be used by the user-space > >> >> + * trace parser to analyze the collected trace data. > >> >> + */ > >> >> + entry = debugfs_create_file("info", 0444, tracedir, NULL, > >> >> + &traceinfo_file_operations); > >> >> + if (!entry) { > >> >> + printk(KERN_WARNING "Couldn't create debugfs 'info' entry\n"); > >> >> + return -ENOMEM; > >> >> + } > >> >> + > >> >> + /* > >> >> + * the debugfs file that reports the number of events > >> >> + * lost due to buffer overflow > >> >> + */ > >> >> + entry = debugfs_create_file("overflow", 0444, tracedir, NULL, > >> >> + &traceoverflow_file_operations); > >> >> + if (!entry) { > >> >> + printk(KERN_WARNING > >> >> + "Couldn't create debugfs 'overflow' entry\n"); > >> >> + return -ENOMEM; > >> >> + } > >> >> + > >> >> + /* the debugfs file that resets trace buffer upon write */ > >> >> + entry = debugfs_create_file("reset", 0220, tracedir, NULL, > >> >> + &tracereset_file_operations); > >> >> + if (!entry) { > >> >> + printk(KERN_WARNING "Couldn't create debugfs 'reset' entry\n"); > >> >> + return -ENOMEM; > >> >> + } > >> >> + > >> >> + /* create the directory that holds the control files for every event */ > >> >> + eventdir = debugfs_create_dir("events", tracedir); > >> >> + if (!eventdir) { > >> >> + printk(KERN_WARNING "Couldn't create 'events' directory\n"); > >> >> + return -ENOMEM; > >> >> + } > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static void remove_debugfs_file(struct dentry *dir, char *name) > >> >> +{ > >> >> + struct dentry *dentry; > >> >> + dentry = lookup_one_len(name, dir, strlen(name)); > >> >> + if (dentry && !IS_ERR(dentry)) { > >> >> + debugfs_remove(dentry); > >> >> + dput(dentry); > >> >> + } > >> >> +} > >> >> + > >> >> +static int remove_debugfs(void) > >> >> +{ > >> >> + struct dentry *bufdir; > >> >> + char *tmpname; > >> >> + int cpu; > >> >> + > >> >> + bufdir = lookup_one_len("buffers", tracedir, strlen("buffers")); > >> >> + if (!bufdir || IS_ERR(bufdir)) > >> >> + return -EIO; > >> >> + tmpname = kzalloc(NAME_MAX + 1, GFP_KERNEL); > >> >> + if (!tmpname) > >> >> + return -ENOMEM; > >> >> + for_each_possible_cpu(cpu) { > >> >> + snprintf(tmpname, NAME_MAX, "%s%d", "cpu", cpu); > >> >> + remove_debugfs_file(bufdir, tmpname); > >> >> + } > >> >> + kfree(tmpname); > >> >> + debugfs_remove(bufdir); > >> >> + > >> >> + remove_debugfs_file(tracedir, "enabled"); > >> >> + remove_debugfs_file(tracedir, "info"); > >> >> + debugfs_remove(eventdir); > >> >> + debugfs_remove(tracedir); > >> >> + return 0; > >> >> +} > >> >> + > >> >> +static int __init init_ktrace(void) > >> >> +{ > >> >> + struct kernel_trace *iter; > >> >> + int i, err; > >> >> + > >> >> + ktrace_next_id = 0; > >> >> + kref_set(&ktrace_kref, 1); > >> >> + trace_buffer = ring_buffer_alloc(trace_buf_size, RB_FL_OVERWRITE); > >> >> + if (trace_buffer == NULL) > >> >> + return -ENOMEM; > >> >> + setup_timer(&trace_timer, wakeup_readers, 0); > >> >> + for (i = 0; i < KTRACE_HASH_SIZE; i++) > >> >> + INIT_HLIST_HEAD(&ktrace_table[i]); > >> >> + > >> >> + mutex_lock(&ktrace_mutex); > >> >> + err = create_debugfs(); > >> >> + if (err != 0) > >> >> + goto out; > >> >> + for (iter = __start___ktraces; iter < __stop___ktraces; iter++) > >> >> + add_ktrace(iter); > >> >> + err = register_module_notifier(&ktrace_module_nb); > >> >> +out: > >> >> + mutex_unlock(&ktrace_mutex); > >> >> + return err; > >> >> +} > >> >> +module_init(init_ktrace); > >> >> + > >> >> +static void __exit exit_ktrace(void) > >> >> +{ > >> >> + struct kernel_trace *iter; > >> >> + > >> >> + if (ktrace_enabled) { > >> >> + ktrace_enabled = 0; > >> >> + del_timer_sync(&trace_timer); > >> >> + } > >> >> + mutex_lock(&ktrace_mutex); > >> >> + for (iter = __start___ktraces; iter < __stop___ktraces; iter++) > >> >> + remove_ktrace(iter, 1); > >> >> + unregister_module_notifier(&ktrace_module_nb); > >> >> + remove_debugfs(); > >> >> + mutex_unlock(&ktrace_mutex); > >> >> + > >> >> + kref_put(&ktrace_kref, release_trace_buffer); > >> >> +} > >> > > >> > -- > >> > Mathieu Desnoyers > >> > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 > >> > > > > > -- > > Mathieu Desnoyers > > OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 > > > > _______________________________________________ > ltt-dev mailing list > ltt-dev@lists.casi.polymtl.ca > http://lists.casi.polymtl.ca/cgi-bin/mailman/listinfo/ltt-dev > -- Mathieu Desnoyers OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F BA06 3F25 A8FE 3BAE 9A68 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/