[PATCH 10/22 -v7] mcount based trace in the form of a header file library

Steven Rostedt
2008-01-30T03:21:10Z

[-- Attachment #1: mcount-function-tracer.patch --]
[-- Type: text/plain, Size: 38267 bytes --]

This is a simple trace that uses the mcount infrastructure. It is
designed to be fast and small, and easy to use. It is useful to
record things that happen over a very short period of time, and
not to analyze the system in general.

An interface is added to the debugfs

/debugfs/tracing/

This patch adds the following files:

available_tracers
list of available tracers. Currently only "function" is
available.

current_tracer
The trace that is currently active. Empty on start up.
To switch to a tracer simply echo one of the tracers that
are listed in available_tracers:

echo function > /debugfs/tracing/current_tracer

To disable the tracer:

echo disable > /debugfs/tracing/current_tracer

trace_ctrl
echoing "1" into this file starts the mcount function tracing
(if sysctl kernel.mcount_enabled=1)
echoing "0" turns it off.

latency_trace
This file is readonly and holds the result of the trace.

trace
This file outputs a easier to read version of the trace.

iter_ctrl
Controls the way the output of traces look.
So far there's two controls:
echoing in "symonly" will only show the kallsyms variables
without the addresses (if kallsyms was configured)
echoing in "verbose" will change the output to show
a lot more data, but not very easy to understand by
humans.
echoing in "nosymonly" turns off symonly.
echoing in "noverbose" turns off verbose.

The output of the function_trace file is as follows

"echo noverbose > /debugfs/tracing/iter_ctrl"

preemption latency trace v1.1.5 on 2.6.24-rc7-tst
--------------------------------------------------------------------
latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
-----------------
| task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------

_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
swapper-0 0d.h. 1595128us+: set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
swapper-0 0d.h. 1595131us+: _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)

Or with verbose turned on:

"echo verbose > /debugfs/tracing/iter_ctrl"

preemption latency trace v1.1.5 on 2.6.24-rc7-tst
--------------------------------------------------------------------
latency: 0 us, #419428/4361791, CPU#1 | (M:desktop VP:0, KP:0, SP:0 HP:0 #P:4)
-----------------
| task: -0 (uid:0 nice:0 policy:0 rt_prio:0)
-----------------

swapper 0 0 9 00000000 00000000 [f3675f41] 1595.128ms (+0.003ms): set_normalized_timespec+0x8/0x2d <c043841d> (ktime_get_ts+0x4a/0x4e <c04499d4>)
swapper 0 0 9 00000000 00000001 [f3675f45] 1595.131ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)
swapper 0 0 9 00000000 00000002 [f3675f48] 1595.135ms (+0.003ms): _spin_lock+0x8/0x18 <c0630690> (hrtimer_interrupt+0x6e/0x1b0 <c0449c56>)

The "trace" file is not affected by the verbose mode, but is by the symonly.

echo "nosymonly" > /debugfs/tracing/iter_ctrl

tracer:
[ 81.479967] CPU 0: bash:3154 register_mcount_function+0x5f/0x66 <ffffffff80337a4d> <-- _spin_unlock_irqrestore+0xe/0x5a <ffffffff8048cc8f>
[ 81.479967] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <ffffffff8048ccbf> <-- sub_preempt_count+0xc/0x7a <ffffffff80233d7b>
[ 81.479968] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <ffffffff80233d9f> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>
[ 81.479968] CPU 0: bash:3154 vfs_write+0x11d/0x155 <ffffffff8029a043> <-- dnotify_parent+0x12/0x78 <ffffffff802d54fb>
[ 81.479968] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <ffffffff802d5516> <-- _spin_lock+0xe/0x70 <ffffffff8048c910>
[ 81.479969] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <ffffffff8048c91d> <-- add_preempt_count+0xe/0x77 <ffffffff80233df7>
[ 81.479969] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <ffffffff80233e27> <-- in_lock_functions+0x9/0x24 <ffffffff8025a75d>

echo "symonly" > /debugfs/tracing/iter_ctrl

tracer:
[ 81.479913] CPU 0: bash:3154 register_mcount_function+0x5f/0x66 <-- _spin_unlock_irqrestore+0xe/0x5a
[ 81.479913] CPU 0: bash:3154 _spin_unlock_irqrestore+0x3e/0x5a <-- sub_preempt_count+0xc/0x7a
[ 81.479913] CPU 0: bash:3154 sub_preempt_count+0x30/0x7a <-- in_lock_functions+0x9/0x24
[ 81.479914] CPU 0: bash:3154 vfs_write+0x11d/0x155 <-- dnotify_parent+0x12/0x78
[ 81.479914] CPU 0: bash:3154 dnotify_parent+0x2d/0x78 <-- _spin_lock+0xe/0x70
[ 81.479914] CPU 0: bash:3154 _spin_lock+0x1b/0x70 <-- add_preempt_count+0xe/0x77
[ 81.479914] CPU 0: bash:3154 add_preempt_count+0x3e/0x77 <-- in_lock_functions+0x9/0x24

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
---
lib/Makefile | 1
lib/tracing/Kconfig | 15
lib/tracing/Makefile | 3
lib/tracing/trace_function.c | 72 ++
lib/tracing/tracer.c | 1160 +++++++++++++++++++++++++++++++++++++++++++
lib/tracing/tracer.h | 96 +++
6 files changed, 1347 insertions(+)

Index: linux-mcount.git/lib/tracing/Kconfig
===================================================================
--- linux-mcount.git.orig/lib/tracing/Kconfig 2008-01-29 17:26:18.000000000 -0500
+++ linux-mcount.git/lib/tracing/Kconfig 2008-01-29 18:06:25.000000000 -0500
@@ -8,3 +8,18 @@ config HAVE_MCOUNT
config MCOUNT
bool
select FRAME_POINTER
+
+config TRACING
+ bool
+ select DEBUG_FS
+
+config FUNCTION_TRACER
+ bool "Profiler instrumentation based tracer"
+ depends on DEBUG_KERNEL && HAVE_MCOUNT
+ select MCOUNT
+ select TRACING
+ help
+ Use profiler instrumentation, adding -pg to CFLAGS. This will
+ insert a call to an architecture specific __mcount routine,
+ that the debugging mechanism using this facility will hook by
+ providing a set of inline routines.
Index: linux-mcount.git/lib/tracing/Makefile
===================================================================
--- linux-mcount.git.orig/lib/tracing/Makefile 2008-01-29 17:26:18.000000000 -0500
+++ linux-mcount.git/lib/tracing/Makefile 2008-01-29 18:06:25.000000000 -0500
@@ -1,3 +1,6 @@
obj-$(CONFIG_MCOUNT) += libmcount.o

+obj-$(CONFIG_TRACING) += tracer.o
+obj-$(CONFIG_FUNCTION_TRACER) += trace_function.o
+
libmcount-y := mcount.o
Index: linux-mcount.git/lib/tracing/tracer.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-mcount.git/lib/tracing/tracer.c 2008-01-29 18:07:38.000000000 -0500
@@ -0,0 +1,1160 @@
+/*
+ * ring buffer based mcount tracer
+ *
+ * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
+ *
+ * Originally taken from the RT patch by:
+ * Arnaldo Carvalho de Melo <acme@redhat.com>
+ *
+ * Based on code from the latency_tracer, that is:
+ * Copyright (C) 2004-2006 Ingo Molnar
+ * Copyright (C) 2004 William Lee Irwin III
+ */
+
+#include <linux/fs.h>
+#include <linux/gfp.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/linkage.h>
+#include <linux/seq_file.h>
+#include <linux/percpu.h>
+#include <linux/ctype.h>
+#include <linux/debugfs.h>
+#include <linux/kallsyms.h>
+#include <linux/utsrelease.h>
+#include <linux/uaccess.h>
+#include <linux/hardirq.h>
+#include <linux/mcount.h>
+
+#include "tracer.h"
+
+static struct tracing_trace tracer_trace __read_mostly;
+static DEFINE_PER_CPU(struct tracing_trace_cpu, tracer_trace_cpu);
+static int trace_enabled __read_mostly;
+static unsigned long trace_nr_entries = (65536UL);
+
+static struct trace_types_struct *trace_types __read_mostly;
+static struct trace_types_struct *current_trace __read_mostly;
+static int max_tracer_type_len;
+
+static DEFINE_MUTEX(trace_types_lock);
+
+static int __init set_nr_entries(char *str)
+{
+ if (!str)
+ return 0;
+ trace_nr_entries = simple_strtoul(str, &str, 0);
+ return 1;
+}
+__setup("trace_entries=", set_nr_entries);
+
+enum trace_type {
+ __TRACE_FIRST_TYPE = 0,
+
+ TRACE_FN,
+
+ __TRACE_LAST_TYPE
+};
+
+enum trace_flag_type {
+ TRACE_FLAG_IRQS_OFF = 0x01,
+ TRACE_FLAG_NEED_RESCHED = 0x02,
+ TRACE_FLAG_HARDIRQ = 0x04,
+ TRACE_FLAG_SOFTIRQ = 0x08,
+};
+
+int register_trace(struct trace_types_struct *type)
+{
+ struct trace_types_struct *t;
+ int len;
+ int ret = 0;
+
+ if (!type->name) {
+ pr_info("Tracer must have a name\n");
+ return -1;
+ }
+
+ mutex_lock(&trace_types_lock);
+ for (t = trace_types; t; t = t->next) {
+ if (strcmp(type->name, t->name) == 0) {
+ /* already found */
+ pr_info("Trace %s already registered\n",
+ type->name);
+ ret = -1;
+ goto out;
+ }
+ }
+
+ type->next = trace_types;
+ trace_types = type;
+ len = strlen(type->name);
+ if (len > max_tracer_type_len)
+ max_tracer_type_len = len;
+ out:
+ mutex_unlock(&trace_types_lock);
+
+ return ret;
+}
+
+void unregister_trace(struct trace_types_struct *type)
+{
+ struct trace_types_struct **t;
+ int len;
+
+ mutex_lock(&trace_types_lock);
+ for (t = &trace_types; *t; t = &(*t)->next) {
+ if (*t == type)
+ goto found;
+ }
+ pr_info("Trace %s not registered\n", type->name);
+ goto out;
+
+ found:
+ *t = (*t)->next;
+ if (strlen(type->name) != max_tracer_type_len)
+ goto out;
+
+ max_tracer_type_len = 0;
+ for (t = &trace_types; *t; t = &(*t)->next) {
+ len = strlen((*t)->name);
+ if (len > max_tracer_type_len)
+ max_tracer_type_len = len;
+ }
+ out:
+ mutex_unlock(&trace_types_lock);
+}
+
+void notrace tracing_reset(struct tracing_trace_cpu *data)
+{
+ data->trace_idx = 0;
+ atomic_set(&data->underrun, 0);
+}
+
+#ifdef CONFIG_MCOUNT
+static void notrace function_trace_call(unsigned long ip,
+ unsigned long parent_ip)
+{
+ struct tracing_trace *tr = &tracer_trace;
+ struct tracing_trace_cpu *data;
+ unsigned long flags;
+ int cpu;
+
+ if (unlikely(!trace_enabled))
+ return;
+
+ raw_local_irq_save(flags);
+ cpu = raw_smp_processor_id();
+ data = tr->data[cpu];
+ atomic_inc(&data->disabled);
+
+ if (likely(atomic_read(&data->disabled) == 1))
+ tracing_function_trace(tr, data, ip, parent_ip, flags);
+
+ atomic_dec(&data->disabled);
+ raw_local_irq_restore(flags);
+}
+
+static struct mcount_ops trace_ops __read_mostly =
+{
+ .func = function_trace_call,
+};
+#endif
+
+void tracing_start_function_trace(void)
+{
+ register_mcount_function(&trace_ops);
+}
+
+void tracing_stop_function_trace(void)
+{
+ unregister_mcount_function(&trace_ops);
+}
+
+static inline notrace struct tracing_entry *
+tracing_get_trace_entry(struct tracing_trace *tr,
+ struct tracing_trace_cpu *data)
+{
+ unsigned long idx, idx_next;
+ struct tracing_entry *entry;
+
+ idx = data->trace_idx;
+ idx_next = idx + 1;
+
+ if (unlikely(idx_next >= tr->entries)) {
+ atomic_inc(&data->underrun);
+ idx_next = 0;
+ }
+
+ data->trace_idx = idx_next;
+
+ if (unlikely(idx_next != 0 && atomic_read(&data->underrun)))
+ atomic_inc(&data->underrun);
+
+ entry = data->trace + idx * TRACING_ENTRY_SIZE;
+
+ return entry;
+}
+
+static inline notrace void
+tracing_generic_entry_update(struct tracing_entry *entry,
+ unsigned long flags)
+{
+ struct task_struct *tsk = current;
+ unsigned long pc;
+
+ pc = preempt_count();
+
+ entry->preempt_count = pc & 0xff;
+ entry->pid = tsk->pid;
+ entry->t = now();
+ entry->flags = (irqs_disabled_flags(flags) ? TRACE_FLAG_IRQS_OFF : 0) |
+ ((pc & HARDIRQ_MASK) ? TRACE_FLAG_HARDIRQ : 0) |
+ ((pc & SOFTIRQ_MASK) ? TRACE_FLAG_SOFTIRQ : 0) |
+ (need_resched() ? TRACE_FLAG_NEED_RESCHED : 0);
+ memcpy(entry->comm, tsk->comm, TASK_COMM_LEN);
+}
+
+notrace void tracing_function_trace(struct tracing_trace *tr,
+ struct tracing_trace_cpu *data,
+ unsigned long ip,
+ unsigned long parent_ip,
+ unsigned long flags)
+{
+ struct tracing_entry *entry;
+
+ entry = tracing_get_trace_entry(tr, data);
+ tracing_generic_entry_update(entry, flags);
+ entry->type = TRACE_FN;
+ entry->fn.ip = ip;
+ entry->fn.parent_ip = parent_ip;
+}
+
+enum trace_iterator {
+ TRACE_ITER_SYM_ONLY = 1,
+ TRACE_ITER_VERBOSE = 2,
+};
+
+/* These must match the bit postions above */
+static const char *trace_options[] = {
+ "symonly",
+ "verbose",
+ NULL
+};
+
+static unsigned trace_flags;
+
+enum trace_file_type {
+ TRACE_FILE_LAT_FMT = 1,
+};
+
+static struct tracing_entry *tracing_entry_idx(struct tracing_trace *tr,
+ unsigned long idx,
+ int cpu)
+{
+ struct tracing_entry *array = tr->data[cpu]->trace;
+ unsigned long underrun;
+
+ if (idx >= tr->entries)
+ return NULL;
+
+ underrun = atomic_read(&tr->data[cpu]->underrun);
+ if (underrun)
+ idx = ((underrun - 1) + idx) % tr->entries;
+ else if (idx >= tr->data[cpu]->trace_idx)
+ return NULL;
+
+ return &array[idx];
+}
+
+static struct notrace tracing_entry *
+find_next_entry(struct tracing_iterator *iter, int *ent_cpu)
+{
+ struct tracing_trace *tr = iter->tr;
+ struct tracing_entry *ent, *next = NULL;
+ int next_cpu = -1;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ if (!tr->data[cpu]->trace)
+ continue;
+ ent = tracing_entry_idx(tr, iter->next_idx[cpu], cpu);
+ if (ent && (!next || next->t > ent->t)) {
+ next = ent;
+ next_cpu = cpu;
+ }
+ }
+
+ if (ent_cpu)
+ *ent_cpu = next_cpu;
+
+ return next;
+}
+
+static void *find_next_entry_inc(struct tracing_iterator *iter)
+{
+ struct tracing_entry *next;
+ int next_cpu = -1;
+
+ next = find_next_entry(iter, &next_cpu);
+
+ if (next) {
+ iter->next_idx[next_cpu]++;
+ iter->idx++;
+ }
+ iter->ent = next;
+ iter->cpu = next_cpu;
+
+ return next ? iter : NULL;
+}
+
+static void notrace *
+s_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ struct tracing_iterator *iter = m->private;
+ void *ent;
+ void *last_ent = iter->ent;
+ int i = (int)*pos;
+
+ (*pos)++;
+
+ /* can't go backwards */
+ if (iter->idx > i)
+ return NULL;
+
+ if (iter->idx < 0)
+ ent = find_next_entry_inc(iter);
+ else
+ ent = iter;
+
+ while (ent && iter->idx < i)
+ ent = find_next_entry_inc(iter);
+
+ iter->pos = *pos;
+
+ if (last_ent && !ent)
+ seq_puts(m, "\n\nvim:ft=help\n");
+
+ return ent;
+}
+
+static void *s_start(struct seq_file *m, loff_t *pos)
+{
+ struct tracing_iterator *iter = m->private;
+ void *p = NULL;
+ loff_t l = 0;
+ int i;
+
+ mutex_lock(&trace_types_lock);
+
+ if (!current_trace || current_trace != iter->trace)
+ return NULL;
+
+ /* let the tracer grab locks here if needed */
+ if (current_trace->start)
+ current_trace->start(iter);
+
+ if (*pos != iter->pos) {
+ iter->ent = NULL;
+ iter->cpu = 0;
+ iter->idx = -1;
+
+ for (i = 0; i < NR_CPUS; i++)
+ iter->next_idx[i] = 0;
+
+ for (p = iter; p && l < *pos; p = s_next(m, p, &l))
+ ;
+
+ } else {
+ l = *pos;
+ p = s_next(m, p, &l);
+ }
+
+ return p;
+}
+
+static void s_stop(struct seq_file *m, void *p)
+{
+ struct tracing_iterator *iter = m->private;
+
+ /* let the tracer release locks here if needed */
+ if (current_trace && current_trace == iter->trace && iter->trace->stop)
+ iter->trace->stop(iter);
+
+ mutex_unlock(&trace_types_lock);
+}
+
+#ifdef CONFIG_KALLSYMS
+static void seq_print_symbol(struct seq_file *m,
+ const char *fmt, unsigned long address)
+{
+ char buffer[KSYM_SYMBOL_LEN];
+
+ sprint_symbol(buffer, address);
+ seq_printf(m, fmt, buffer);
+}
+#else
+# define seq_print_symbol(m, fmt, address) do { } while (0)
+#endif
+
+#ifndef CONFIG_64BIT
+# define IP_FMT "%08lx"
+#else
+# define IP_FMT "%016lx"
+#endif
+
+static void notrace seq_print_ip_sym(struct seq_file *m,
+ unsigned long ip, int sym_only)
+{
+ if (!ip) {
+ seq_printf(m, "0");
+ return;
+ }
+
+ seq_print_symbol(m, "%s", ip);
+ if (!sym_only)
+ seq_printf(m, " <" IP_FMT ">", ip);
+}
+
+static void notrace print_help_header(struct seq_file *m)
+{
+ seq_puts(m, " _------=> CPU# \n");
+ seq_puts(m, " / _-----=> irqs-off \n");
+ seq_puts(m, " | / _----=> need-resched \n");
+ seq_puts(m, " || / _---=> hardirq/softirq \n");
+ seq_puts(m, " ||| / _--=> preempt-depth \n");
+ seq_puts(m, " |||| / \n");
+ seq_puts(m, " ||||| delay \n");
+ seq_puts(m, " cmd pid ||||| time | caller \n");
+ seq_puts(m, " \\ / ||||| \\ | / \n");
+}
+
+static void notrace print_trace_header(struct seq_file *m,
+ struct tracing_iterator *iter)
+{
+ struct tracing_trace *tr = iter->tr;
+ struct tracing_trace_cpu *data = tr->data[tr->cpu];
+ struct trace_types_struct *type = current_trace;
+ unsigned long underruns = 0;
+ unsigned long underrun;
+ unsigned long entries = 0;
+ int sym_only = !!(trace_flags & TRACE_ITER_SYM_ONLY);
+ int cpu;
+ const char *name = "preemption";
+
+ if (type)
+ name = type->name;
+
+ for_each_possible_cpu(cpu) {
+ if (tr->data[cpu]->trace) {
+ underrun = atomic_read(&tr->data[cpu]->underrun);
+ if (underrun) {
+ underruns += underrun;
+ entries += tr->entries;
+ } else
+ entries += tr->data[cpu]->trace_idx;
+ }
+ }
+
+ seq_printf(m, "%s latency trace v1.1.5 on %s\n",
+ name, UTS_RELEASE);
+ seq_puts(m, "-----------------------------------"
+ "---------------------------------\n");
+ seq_printf(m, " latency: %lu us, #%lu/%lu, CPU#%d |"
+ " (M:%s VP:%d, KP:%d, SP:%d HP:%d",
+ cycles_to_usecs(data->saved_latency),
+ entries,
+ (entries + underruns),
+ tr->cpu,
+#if defined(CONFIG_PREEMPT_NONE)
+ "server",
+#elif defined(CONFIG_PREEMPT_VOLUNTARY)
+ "desktop",
+#elif defined(CONFIG_PREEMPT_DESKTOP)
+ "preempt",
+#else
+ "unknown",
+#endif
+ /* These are reserved for later use */
+ 0, 0, 0, 0);
+#ifdef CONFIG_SMP
+ seq_printf(m, " #P:%d)\n", num_online_cpus());
+#else
+ seq_puts(m, ")\n");
+#endif
+ seq_puts(m, " -----------------\n");
+ seq_printf(m, " | task: %.16s-%d "
+ "(uid:%d nice:%ld policy:%ld rt_prio:%ld)\n",
+ data->comm, data->pid, data->uid, data->nice,
+ data->policy, data->rt_priority);
+ seq_puts(m, " -----------------\n");
+
+ if (data->critical_start) {
+ seq_puts(m, " => started at: ");
+ seq_print_ip_sym(m, data->critical_start, sym_only);
+ seq_puts(m, "\n => ended at: ");
+ seq_print_ip_sym(m, data->critical_end, sym_only);
+ seq_puts(m, "\n");
+ }
+
+ seq_puts(m, "\n");
+}
+
+
+static void notrace
+lat_print_generic(struct seq_file *m, struct tracing_entry *entry, int cpu)
+{
+ int hardirq, softirq;
+
+ seq_printf(m, "%8.8s-%-5d ", entry->comm, entry->pid);
+ seq_printf(m, "%d", cpu);
+ seq_printf(m, "%c%c",
+ (entry->flags & TRACE_FLAG_IRQS_OFF) ? 'd' : '.',
+ ((entry->flags & TRACE_FLAG_NEED_RESCHED) ? 'N' : '.'));
+
+ hardirq = entry->flags & TRACE_FLAG_HARDIRQ;
+ softirq = entry->flags & TRACE_FLAG_SOFTIRQ;
+ if (hardirq && softirq)
+ seq_putc(m, 'H');
+ else {
+ if (hardirq)
+ seq_putc(m, 'h');
+ else {
+ if (softirq)
+ seq_putc(m, 's');
+ else
+ seq_putc(m, '.');
+ }
+ }
+
+ if (entry->preempt_count)
+ seq_printf(m, "%x", entry->preempt_count);
+ else
+ seq_puts(m, ".");
+}
+
+unsigned long preempt_mark_thresh = 100;
+
+static void notrace
+lat_print_timestamp(struct seq_file *m, unsigned long long abs_usecs,
+ unsigned long rel_usecs)
+{
+ seq_printf(m, " %4lldus", abs_usecs);
+ if (rel_usecs > preempt_mark_thresh)
+ seq_puts(m, "!: ");
+ else if (rel_usecs > 1)
+ seq_puts(m, "+: ");
+ else
+ seq_puts(m, " : ");
+}
+
+static void notrace
+print_lat_fmt(struct seq_file *m, struct tracing_iterator *iter,
+ unsigned int trace_idx, int cpu)
+{
+ struct tracing_entry *entry = iter->ent;
+ struct tracing_entry *next_entry = find_next_entry(iter, NULL);
+ unsigned long abs_usecs;
+ unsigned long rel_usecs;
+ int sym_only = !!(trace_flags & TRACE_ITER_SYM_ONLY);
+ int verbose = !!(trace_flags & TRACE_ITER_VERBOSE);
+
+ if (!next_entry)
+ next_entry = entry;
+ rel_usecs = cycles_to_usecs(next_entry->t - entry->t);
+ abs_usecs = cycles_to_usecs(entry->t - iter->tr->time_start);
+
+ if (verbose) {
+ seq_printf(m, "%16s %5d %d %d %08x %08x [%08lx]"
+ " %ld.%03ldms (+%ld.%03ldms): ",
+ entry->comm,
+ entry->pid, cpu, entry->flags,
+ entry->preempt_count, trace_idx,
+ cycles_to_usecs(entry->t),
+ abs_usecs/1000,
+ abs_usecs % 1000, rel_usecs/1000, rel_usecs % 1000);
+ } else {
+ lat_print_generic(m, entry, cpu);
+ lat_print_timestamp(m, abs_usecs, rel_usecs);
+ }
+ switch (entry->type) {
+ case TRACE_FN:
+ seq_print_ip_sym(m, entry->fn.ip, sym_only);
+ seq_puts(m, " (");
+ seq_print_ip_sym(m, entry->fn.parent_ip, sym_only);
+ seq_puts(m, ")\n");
+ break;
+ }
+}
+
+static void notrace print_trace_fmt(struct seq_file *m,
+ struct tracing_iterator *iter)
+{
+ struct tracing_entry *entry = iter->ent;
+ unsigned long usec_rem;
+ unsigned long secs;
+ int sym_only = !!(trace_flags & TRACE_ITER_SYM_ONLY);
+ unsigned long long t;
+
+ t = cycles_to_usecs(entry->t);
+ usec_rem = do_div(t, 1000000ULL);
+ secs = (unsigned long)t;
+
+ seq_printf(m, "[%5lu.%06lu] ", secs, usec_rem);
+ seq_printf(m, "CPU %d: ", iter->cpu);
+ seq_printf(m, "%s:%d ", entry->comm,
+ entry->pid);
+ switch (entry->type) {
+ case TRACE_FN:
+ seq_print_ip_sym(m, entry->fn.ip, sym_only);
+ if (entry->fn.parent_ip) {
+ seq_printf(m, " <-- ");
+ seq_print_ip_sym(m, entry->fn.parent_ip,
+ sym_only);
+ }
+ break;
+ }
+ seq_printf(m, "\n");
+}
+
+static int trace_empty(struct tracing_iterator *iter)
+{
+ struct tracing_trace_cpu *data;
+ int cpu;
+
+ for_each_possible_cpu(cpu) {
+ data = iter->tr->data[cpu];
+
+ if (data->trace &&
+ (data->trace_idx ||
+ atomic_read(&data->underrun)))
+ return 0;
+ }
+ return 1;
+}
+
+static int s_show(struct seq_file *m, void *v)
+{
+ struct tracing_iterator *iter = v;
+
+ if (iter->ent == NULL) {
+ if (iter->iter_flags & TRACE_FILE_LAT_FMT) {
+ /* print nothing if the buffers are empty */
+ if (trace_empty(iter))
+ return 0;
+ print_trace_header(m, iter);
+ if (!(trace_flags & TRACE_ITER_VERBOSE))
+ print_help_header(m);
+ } else
+ seq_printf(m, "tracer:\n");
+ } else {
+ if (iter->iter_flags & TRACE_FILE_LAT_FMT)
+ print_lat_fmt(m, iter, iter->idx, iter->cpu);
+ else
+ print_trace_fmt(m, iter);
+ }
+
+ return 0;
+}
+
+static struct seq_operations tracer_seq_ops = {
+ .start = s_start,
+ .next = s_next,
+ .stop = s_stop,
+ .show = s_show,
+};
+
+static struct tracing_iterator notrace *
+__tracing_open(struct inode *inode, struct file *file, int *ret)
+{
+ struct tracing_iterator *iter;
+
+ iter = kzalloc(sizeof(*iter), GFP_KERNEL);
+ if (!iter) {
+ *ret = -ENOMEM;
+ goto out;
+ }
+
+ iter->tr = inode->i_private;
+ iter->trace = current_trace;
+ iter->pos = -1;
+
+ /* TODO stop tracer */
+ *ret = seq_open(file, &tracer_seq_ops);
+ if (!*ret) {
+ struct seq_file *m = file->private_data;
+ m->private = iter;
+
+ /* stop the trace while dumping */
+ if (iter->tr->ctrl)
+ trace_enabled = 0;
+
+ if (iter->trace && iter->trace->open)
+ iter->trace->open(iter);
+ } else {
+ kfree(iter);
+ iter = NULL;
+ }
+
+ out:
+ return iter;
+}
+
+int tracing_open_generic(struct inode *inode, struct file *filp)
+{
+ filp->private_data = inode->i_private;
+ return 0;
+}
+
+int tracing_release(struct inode *inode, struct file *file)
+{
+ struct seq_file *m = (struct seq_file *)file->private_data;
+ struct tracing_iterator *iter = m->private;
+
+ if (iter->trace && iter->trace->close)
+ iter->trace->close(iter);
+
+ /* reenable tracing if it was previously enabled */
+ if (iter->tr->ctrl)
+ trace_enabled = 1;
+
+ seq_release(inode, file);
+ kfree(iter);
+ return 0;
+}
+
+static int tracing_open(struct inode *inode, struct file *file)
+{
+ int ret;
+
+ __tracing_open(inode, file, &ret);
+
+ return ret;
+}
+
+static int tracing_lt_open(struct inode *inode, struct file *file)
+{
+ struct tracing_iterator *iter;
+ int ret;
+
+ iter = __tracing_open(inode, file, &ret);
+
+ if (!ret)
+ iter->iter_flags |= TRACE_FILE_LAT_FMT;
+
+ return ret;
+}
+
+
+static void notrace *
+t_next(struct seq_file *m, void *v, loff_t *pos)
+{
+ struct trace_types_struct *t = m->private;
+
+ (*pos)++;
+
+ if (t)
+ t = t->next;
+
+ m->private = t;
+
+ return t;
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+ struct trace_types_struct *t = m->private;
+ loff_t l = 0;
+
+ mutex_lock(&trace_types_lock);
+ for (; t && l < *pos; t = t_next(m, t, &l))
+ ;
+
+ return t;
+}
+
+static void t_stop(struct seq_file *m, void *p)
+{
+ mutex_unlock(&trace_types_lock);
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+ struct trace_types_struct *t = v;
+
+ if (!t)
+ return 0;
+
+ seq_printf(m, "%s", t->name);
+ if (t->next)
+ seq_putc(m, ' ');
+ else
+ seq_putc(m, '\n');
+
+ return 0;
+}
+
+static struct seq_operations show_traces_seq_ops = {
+ .start = t_start,
+ .next = t_next,
+ .stop = t_stop,
+ .show = t_show,
+};
+
+static int show_traces_open(struct inode *inode, struct file *file)
+{
+ int ret;
+
+ ret = seq_open(file, &show_traces_seq_ops);
+ if (!ret) {
+ struct seq_file *m = file->private_data;
+ m->private = trace_types;
+ }
+
+ return ret;
+}
+
+static struct file_operations tracing_fops = {
+ .open = tracing_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = tracing_release,
+};
+
+static struct file_operations tracing_lt_fops = {
+ .open = tracing_lt_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = tracing_release,
+};
+
+static struct file_operations show_traces_fops = {
+ .open = show_traces_open,
+ .read = seq_read,
+ .release = seq_release,
+};
+
+static ssize_t tracing_iter_ctrl_read(struct file *filp, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char *buf;
+ int r = 0;
+ int len = 0;
+ int i;
+
+ /* calulate max size */
+ for (i = 0; trace_options[i]; i++) {
+ len += strlen(trace_options[i]);
+ len += 3; /* "no" and space */
+ }
+
+ /* +2 for \n and \0 */
+ buf = kmalloc(len + 2, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ for (i = 0; trace_options[i]; i++) {
+ if (trace_flags & (1 << i))
+ r += sprintf(buf + r, "%s ", trace_options[i]);
+ else
+ r += sprintf(buf + r, "no%s ", trace_options[i]);
+ }
+
+ r += sprintf(buf + r, "\n");
+ WARN_ON(r >= len + 2);
+
+ r = simple_read_from_buffer(ubuf, cnt, ppos,
+ buf, r);
+
+ kfree(buf);
+
+ return r;
+}
+
+static ssize_t tracing_iter_ctrl_write(struct file *filp,
+ const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char buf[64];
+ char *cmp = buf;
+ int neg = 0;
+ int i;
+
+ if (cnt > 63)
+ cnt = 63;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = 0;
+
+ if (strncmp(buf, "no", 2) == 0) {
+ neg = 1;
+ cmp += 2;
+ }
+
+ for (i = 0; trace_options[i]; i++) {
+ int len = strlen(trace_options[i]);
+
+ if (strncmp(cmp, trace_options[i], len) == 0) {
+ if (neg)
+ trace_flags &= ~(1 << i);
+ else
+ trace_flags |= (1 << i);
+ break;
+ }
+ }
+
+ filp->f_pos += cnt;
+
+ return cnt;
+}
+
+static struct file_operations tracing_iter_fops = {
+ .open = tracing_open_generic,
+ .read = tracing_iter_ctrl_read,
+ .write = tracing_iter_ctrl_write,
+};
+
+static ssize_t tracing_ctrl_read(struct file *filp, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct tracing_trace *tr = filp->private_data;
+ char buf[64];
+ int r;
+
+ r = sprintf(buf, "%ld\n", tr->ctrl);
+ return simple_read_from_buffer(ubuf, cnt, ppos,
+ buf, r);
+}
+
+static ssize_t tracing_ctrl_write(struct file *filp,
+ const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct tracing_trace *tr = filp->private_data;
+ long val;
+ char buf[64];
+
+ if (cnt > 63)
+ cnt = 63;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = 0;
+
+ val = simple_strtoul(buf, NULL, 10);
+
+ val = !!val;
+
+ if (tr->ctrl ^ val) {
+ if (val)
+ trace_enabled = 1;
+ else
+ trace_enabled = 0;
+
+ tr->ctrl = val;
+
+ mutex_lock(&trace_types_lock);
+ if (current_trace->ctrl_update)
+ current_trace->ctrl_update(tr);
+ mutex_unlock(&trace_types_lock);
+ }
+
+ filp->f_pos += cnt;
+
+ return cnt;
+}
+
+static ssize_t tracing_set_trace_read(struct file *filp, char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ char buf[max_tracer_type_len+2];
+ int r;
+
+ mutex_lock(&trace_types_lock);
+ if (current_trace)
+ r = sprintf(buf, "%s\n", current_trace->name);
+ else
+ r = sprintf(buf, "\n");
+ mutex_unlock(&trace_types_lock);
+
+ return simple_read_from_buffer(ubuf, cnt, ppos,
+ buf, r);
+}
+
+static ssize_t tracing_set_trace_write(struct file *filp,
+ const char __user *ubuf,
+ size_t cnt, loff_t *ppos)
+{
+ struct tracing_trace *tr = &tracer_trace;
+ struct trace_types_struct *t;
+ char buf[max_tracer_type_len+1];
+ int i;
+
+ if (cnt > max_tracer_type_len)
+ cnt = max_tracer_type_len;
+
+ if (copy_from_user(&buf, ubuf, cnt))
+ return -EFAULT;
+
+ buf[cnt] = 0;
+
+ /* strip ending whitespace. */
+ for (i = cnt - 1; i > 0 && isspace(buf[i]); i--)
+ buf[i] = 0;
+
+ mutex_lock(&trace_types_lock);
+ for (t = trace_types; t; t = t->next) {
+ if (strcmp(t->name, buf) == 0)
+ break;
+ }
+ if (!t || t == current_trace)
+ goto out;
+
+ if (current_trace && current_trace->reset)
+ current_trace->reset(tr);
+
+ current_trace = t;
+ if (t->init)
+ t->init(tr);
+
+ out:
+ mutex_unlock(&trace_types_lock);
+
+ filp->f_pos += cnt;
+
+ return cnt;
+}
+
+static struct file_operations tracing_ctrl_fops = {
+ .open = tracing_open_generic,
+ .read = tracing_ctrl_read,
+ .write = tracing_ctrl_write,
+};
+
+static struct file_operations set_tracer_fops = {
+ .open = tracing_open_generic,
+ .read = tracing_set_trace_read,
+ .write = tracing_set_trace_write,
+};
+
+static struct dentry *d_tracer;
+
+struct dentry *tracing_init_dentry(void)
+{
+ static int once;
+
+ if (d_tracer)
+ return d_tracer;
+
+ d_tracer = debugfs_create_dir("tracing", NULL);
+
+ if (!d_tracer && !once) {
+ once = 1;
+ pr_warning("Could not create debugfs directory 'tracing'\n");
+ return NULL;
+ }
+
+ return d_tracer;
+}
+
+static __init void tracer_init_debugfs(void)
+{
+ struct dentry *d_tracer;
+ struct dentry *entry;
+
+ d_tracer = tracing_init_dentry();
+
+ entry = debugfs_create_file("trace_ctrl", 0644, d_tracer,
+ &tracer_trace, &tracing_ctrl_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs 'trace_ctrl' entry\n");
+
+ entry = debugfs_create_file("iter_ctrl", 0644, d_tracer,
+ NULL, &tracing_iter_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs 'iter_ctrl' entry\n");
+
+ entry = debugfs_create_file("latency_trace", 0444, d_tracer,
+ &tracer_trace, &tracing_lt_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs 'latency_trace' entry\n");
+
+ entry = debugfs_create_file("trace", 0444, d_tracer,
+ &tracer_trace, &tracing_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs 'trace' entry\n");
+
+ entry = debugfs_create_file("available_tracers", 0444, d_tracer,
+ &tracer_trace, &show_traces_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs 'trace' entry\n");
+
+ entry = debugfs_create_file("current_tracer", 0444, d_tracer,
+ &tracer_trace, &set_tracer_fops);
+ if (!entry)
+ pr_warning("Could not create debugfs 'trace' entry\n");
+}
+
+/* dummy trace to disable tracing */
+static struct trace_types_struct disable_trace __read_mostly =
+{
+ .name = "disable",
+};
+
+static inline notrace int page_order(const unsigned long size)
+{
+ const unsigned long nr_pages = DIV_ROUND_UP(size, PAGE_SIZE);
+ return ilog2(roundup_pow_of_two(nr_pages));
+}
+
+__init static int tracer_alloc_buffers(void)
+{
+ const int order = page_order(trace_nr_entries * TRACING_ENTRY_SIZE);
+ const unsigned long size = (1UL << order) << PAGE_SHIFT;
+ struct tracing_entry *array;
+ int i;
+
+ for_each_possible_cpu(i) {
+ tracer_trace.data[i] = &per_cpu(tracer_trace_cpu, i);
+ array = (struct tracing_entry *)
+ __get_free_pages(GFP_KERNEL, order);
+ if (array == NULL) {
+ printk(KERN_ERR "tracer: failed to allocate"
+ " %ld bytes for trace buffer!\n", size);
+ goto free_buffers;
+ }
+ tracer_trace.data[i]->trace = array;
+ }
+
+ /*
+ * Since we allocate by orders of pages, we may be able to
+ * round up a bit.
+ */
+ tracer_trace.entries = size / TRACING_ENTRY_SIZE;
+
+ pr_info("tracer: %ld bytes allocated for %ld",
+ size, trace_nr_entries);
+ pr_info(" entries of %ld bytes\n", (long)TRACING_ENTRY_SIZE);
+ pr_info(" actual entries %ld\n", tracer_trace.entries);
+
+ tracer_init_debugfs();
+
+ register_trace(&disable_trace);
+
+ return 0;
+
+ free_buffers:
+ for (i-- ; i >= 0; i--) {
+ struct tracing_trace_cpu *data = tracer_trace.data[i];
+
+ if (data && data->trace) {
+ free_pages((unsigned long)data->trace, order);
+ data->trace = NULL;
+ }
+ }
+ return -ENOMEM;
+}
+
+device_initcall(tracer_alloc_buffers);
Index: linux-mcount.git/lib/tracing/tracer.h
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-mcount.git/lib/tracing/tracer.h 2008-01-29 18:06:25.000000000 -0500
@@ -0,0 +1,96 @@
+#ifndef _LINUX_MCOUNT_TRACER_H
+#define _LINUX_MCOUNT_TRACER_H
+
+#include <asm/atomic.h>
+#include <linux/sched.h>
+#include <linux/clocksource.h>
+
+struct tracing_function {
+ unsigned long ip;
+ unsigned long parent_ip;
+};
+
+struct tracing_entry {
+ char type;
+ char cpu; /* who will want to trace more than 256 CPUS? */
+ char flags;
+ char preempt_count; /* assumes PREEMPT_MASK is 8 bits or less */
+ int pid;
+ cycle_t t;
+ char comm[TASK_COMM_LEN];
+ struct tracing_function fn;
+};
+
+struct tracing_trace_cpu {
+ void *trace;
+ unsigned long trace_idx;
+ atomic_t disabled;
+ atomic_t underrun;
+ unsigned long saved_latency;
+ unsigned long critical_start;
+ unsigned long critical_end;
+ unsigned long critical_sequence;
+ unsigned long nice;
+ unsigned long policy;
+ unsigned long rt_priority;
+ cycle_t preempt_timestamp;
+ pid_t pid;
+ uid_t uid;
+ char comm[TASK_COMM_LEN];
+};
+
+struct tracing_iterator;
+
+struct tracing_trace {
+ unsigned long entries;
+ long ctrl;
+ int cpu;
+ cycle_t time_start;
+ struct tracing_trace_cpu *data[NR_CPUS];
+};
+
+struct trace_types_struct {
+ const char *name;
+ void (*init)(struct tracing_trace *tr);
+ void (*reset)(struct tracing_trace *tr);
+ void (*open)(struct tracing_iterator *iter);
+ void (*close)(struct tracing_iterator *iter);
+ void (*start)(struct tracing_iterator *iter);
+ void (*stop)(struct tracing_iterator *iter);
+ void (*ctrl_update)(struct tracing_trace *tr);
+ struct trace_types_struct *next;
+};
+
+struct tracing_iterator {
+ struct tracing_trace *tr;
+ struct trace_types_struct *trace;
+ struct tracing_entry *ent;
+ unsigned long iter_flags;
+ loff_t pos;
+ unsigned long next_idx[NR_CPUS];
+ int cpu;
+ int idx;
+};
+
+#define TRACING_ENTRY_SIZE sizeof(struct tracing_entry)
+
+void notrace tracing_reset(struct tracing_trace_cpu *data);
+int tracing_open_generic(struct inode *inode, struct file *filp);
+struct dentry *tracing_init_dentry(void);
+void tracing_function_trace(struct tracing_trace *tr,
+ struct tracing_trace_cpu *data,
+ unsigned long ip,
+ unsigned long parent_ip,
+ unsigned long flags);
+
+void tracing_start_function_trace(void);
+void tracing_stop_function_trace(void);
+int register_trace(struct trace_types_struct *type);
+void unregister_trace(struct trace_types_struct *type);
+
+static inline notrace cycle_t now(void)
+{
+ return get_monotonic_cycles();
+}
+
+#endif /* _LINUX_MCOUNT_TRACER_H */
Index: linux-mcount.git/lib/Makefile
===================================================================
--- linux-mcount.git.orig/lib/Makefile 2008-01-29 17:26:18.000000000 -0500
+++ linux-mcount.git/lib/Makefile 2008-01-29 17:26:43.000000000 -0500
@@ -68,6 +68,7 @@ obj-$(CONFIG_SWIOTLB) += swiotlb.o
obj-$(CONFIG_FAULT_INJECTION) += fault-inject.o

obj-$(CONFIG_MCOUNT) += tracing/
+obj-$(CONFIG_TRACING) += tracing/

lib-$(CONFIG_GENERIC_BUG) += bug.o

Index: linux-mcount.git/lib/tracing/trace_function.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-mcount.git/lib/tracing/trace_function.c 2008-01-29 18:06:24.000000000 -0500
@@ -0,0 +1,72 @@
+/*
+ * ring buffer based mcount tracer
+ *
+ * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com>
+ *
+ * Based on code from the latency_tracer, that is:
+ *
+ * Copyright (C) 2004-2006 Ingo Molnar
+ * Copyright (C) 2004 William Lee Irwin III
+ */
+#include <linux/fs.h>
+#include <linux/debugfs.h>
+#include <linux/uaccess.h>
+#include <linux/mcount.h>
+
+#include "tracer.h"
+
+static notrace void function_reset(struct tracing_trace *tr)
+{
+ int cpu;
+
+ tr->time_start = now();
+
+ for_each_online_cpu(cpu)
+ tracing_reset(tr->data[cpu]);
+}
+
+static notrace void start_function_trace(struct tracing_trace *tr)
+{
+ function_reset(tr);
+ tracing_start_function_trace();
+}
+
+static notrace void stop_function_trace(struct tracing_trace *tr)
+{
+ tracing_stop_function_trace();
+}
+
+static notrace void function_trace_init(struct tracing_trace *tr)
+{
+ if (tr->ctrl)
+ start_function_trace(tr);
+}
+
+static notrace void function_trace_reset(struct tracing_trace *tr)
+{
+ if (tr->ctrl)
+ stop_function_trace(tr);
+}
+
+static notrace void function_trace_ctrl_update(struct tracing_trace *tr)
+{
+ if (tr->ctrl)
+ start_function_trace(tr);
+ else
+ stop_function_trace(tr);
+}
+
+static struct trace_types_struct function_trace __read_mostly =
+{
+ .name = "function",
+ .init = function_trace_init,
+ .reset = function_trace_reset,
+ .ctrl_update = function_trace_ctrl_update,
+};
+
+static __init int init_function_trace(void)
+{
+ return register_trace(&function_trace);
+}
+
+device_initcall(init_function_trace);

--