/kernel/trace/trace_stack.c
C | 380 lines | 280 code | 96 blank | 4 comment | 37 complexity | d81a675105e584e2bb1629ef15d4951e MD5 | raw file
Possible License(s): GPL-2.0
- /*
- * Copyright (C) 2008 Steven Rostedt <srostedt@redhat.com>
- *
- */
- #include <linux/stacktrace.h>
- #include <linux/kallsyms.h>
- #include <linux/seq_file.h>
- #include <linux/spinlock.h>
- #include <linux/uaccess.h>
- #include <linux/debugfs.h>
- #include <linux/ftrace.h>
- #include <linux/module.h>
- #include <linux/sysctl.h>
- #include <linux/init.h>
- #include <linux/fs.h>
- #include <asm/setup.h>
- #include "trace.h"
- #define STACK_TRACE_ENTRIES 500
- static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES+1] =
- { [0 ... (STACK_TRACE_ENTRIES)] = ULONG_MAX };
- static unsigned stack_dump_index[STACK_TRACE_ENTRIES];
- static struct stack_trace max_stack_trace = {
- .max_entries = STACK_TRACE_ENTRIES,
- .entries = stack_dump_trace,
- };
- static unsigned long max_stack_size;
- static arch_spinlock_t max_stack_lock =
- (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
- static int stack_trace_disabled __read_mostly;
- static DEFINE_PER_CPU(int, trace_active);
- static DEFINE_MUTEX(stack_sysctl_mutex);
- int stack_tracer_enabled;
- static int last_stack_tracer_enabled;
- static inline void check_stack(void)
- {
- unsigned long this_size, flags;
- unsigned long *p, *top, *start;
- int i;
- this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1);
- this_size = THREAD_SIZE - this_size;
- if (this_size <= max_stack_size)
- return;
-
- if (!object_is_on_stack(&this_size))
- return;
- local_irq_save(flags);
- arch_spin_lock(&max_stack_lock);
-
- if (this_size <= max_stack_size)
- goto out;
- max_stack_size = this_size;
- max_stack_trace.nr_entries = 0;
- max_stack_trace.skip = 3;
- save_stack_trace(&max_stack_trace);
- i = 0;
- start = &this_size;
- top = (unsigned long *)
- (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
- while (i < max_stack_trace.nr_entries) {
- int found = 0;
- stack_dump_index[i] = this_size;
- p = start;
- for (; p < top && i < max_stack_trace.nr_entries; p++) {
- if (*p == stack_dump_trace[i]) {
- this_size = stack_dump_index[i++] =
- (top - p) * sizeof(unsigned long);
- found = 1;
-
- start = p + 1;
- }
- }
- if (!found)
- i++;
- }
- out:
- arch_spin_unlock(&max_stack_lock);
- local_irq_restore(flags);
- }
- static void
- stack_trace_call(unsigned long ip, unsigned long parent_ip)
- {
- int cpu;
- if (unlikely(!ftrace_enabled || stack_trace_disabled))
- return;
- preempt_disable_notrace();
- cpu = raw_smp_processor_id();
-
- if (per_cpu(trace_active, cpu)++ != 0)
- goto out;
- check_stack();
- out:
- per_cpu(trace_active, cpu)--;
-
- preempt_enable_notrace();
- }
- static struct ftrace_ops trace_ops __read_mostly =
- {
- .func = stack_trace_call,
- };
- static ssize_t
- stack_max_size_read(struct file *filp, char __user *ubuf,
- size_t count, loff_t *ppos)
- {
- unsigned long *ptr = filp->private_data;
- char buf[64];
- int r;
- r = snprintf(buf, sizeof(buf), "%ld\n", *ptr);
- if (r > sizeof(buf))
- r = sizeof(buf);
- return simple_read_from_buffer(ubuf, count, ppos, buf, r);
- }
- static ssize_t
- stack_max_size_write(struct file *filp, const char __user *ubuf,
- size_t count, loff_t *ppos)
- {
- long *ptr = filp->private_data;
- unsigned long val, flags;
- int ret;
- int cpu;
- ret = kstrtoul_from_user(ubuf, count, 10, &val);
- if (ret)
- return ret;
- local_irq_save(flags);
- cpu = smp_processor_id();
- per_cpu(trace_active, cpu)++;
- arch_spin_lock(&max_stack_lock);
- *ptr = val;
- arch_spin_unlock(&max_stack_lock);
- per_cpu(trace_active, cpu)--;
- local_irq_restore(flags);
- return count;
- }
- static const struct file_operations stack_max_size_fops = {
- .open = tracing_open_generic,
- .read = stack_max_size_read,
- .write = stack_max_size_write,
- .llseek = default_llseek,
- };
- static void *
- __next(struct seq_file *m, loff_t *pos)
- {
- long n = *pos - 1;
- if (n >= max_stack_trace.nr_entries || stack_dump_trace[n] == ULONG_MAX)
- return NULL;
- m->private = (void *)n;
- return &m->private;
- }
- static void *
- t_next(struct seq_file *m, void *v, loff_t *pos)
- {
- (*pos)++;
- return __next(m, pos);
- }
- static void *t_start(struct seq_file *m, loff_t *pos)
- {
- int cpu;
- local_irq_disable();
- cpu = smp_processor_id();
- per_cpu(trace_active, cpu)++;
- arch_spin_lock(&max_stack_lock);
- if (*pos == 0)
- return SEQ_START_TOKEN;
- return __next(m, pos);
- }
- static void t_stop(struct seq_file *m, void *p)
- {
- int cpu;
- arch_spin_unlock(&max_stack_lock);
- cpu = smp_processor_id();
- per_cpu(trace_active, cpu)--;
- local_irq_enable();
- }
- static int trace_lookup_stack(struct seq_file *m, long i)
- {
- unsigned long addr = stack_dump_trace[i];
- return seq_printf(m, "%pS\n", (void *)addr);
- }
- static void print_disabled(struct seq_file *m)
- {
- seq_puts(m, "#\n"
- "# Stack tracer disabled\n"
- "#\n"
- "# To enable the stack tracer, either add 'stacktrace' to the\n"
- "# kernel command line\n"
- "# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'\n"
- "#\n");
- }
- static int t_show(struct seq_file *m, void *v)
- {
- long i;
- int size;
- if (v == SEQ_START_TOKEN) {
- seq_printf(m, " Depth Size Location"
- " (%d entries)\n"
- " ----- ---- --------\n",
- max_stack_trace.nr_entries - 1);
- if (!stack_tracer_enabled && !max_stack_size)
- print_disabled(m);
- return 0;
- }
- i = *(long *)v;
- if (i >= max_stack_trace.nr_entries ||
- stack_dump_trace[i] == ULONG_MAX)
- return 0;
- if (i+1 == max_stack_trace.nr_entries ||
- stack_dump_trace[i+1] == ULONG_MAX)
- size = stack_dump_index[i];
- else
- size = stack_dump_index[i] - stack_dump_index[i+1];
- seq_printf(m, "%3ld) %8d %5d ", i, stack_dump_index[i], size);
- trace_lookup_stack(m, i);
- return 0;
- }
- static const struct seq_operations stack_trace_seq_ops = {
- .start = t_start,
- .next = t_next,
- .stop = t_stop,
- .show = t_show,
- };
- static int stack_trace_open(struct inode *inode, struct file *file)
- {
- return seq_open(file, &stack_trace_seq_ops);
- }
- static const struct file_operations stack_trace_fops = {
- .open = stack_trace_open,
- .read = seq_read,
- .llseek = seq_lseek,
- .release = seq_release,
- };
- static int
- stack_trace_filter_open(struct inode *inode, struct file *file)
- {
- return ftrace_regex_open(&trace_ops, FTRACE_ITER_FILTER,
- inode, file);
- }
- static const struct file_operations stack_trace_filter_fops = {
- .open = stack_trace_filter_open,
- .read = seq_read,
- .write = ftrace_filter_write,
- .llseek = ftrace_regex_lseek,
- .release = ftrace_regex_release,
- };
- int
- stack_trace_sysctl(struct ctl_table *table, int write,
- void __user *buffer, size_t *lenp,
- loff_t *ppos)
- {
- int ret;
- mutex_lock(&stack_sysctl_mutex);
- ret = proc_dointvec(table, write, buffer, lenp, ppos);
- if (ret || !write ||
- (last_stack_tracer_enabled == !!stack_tracer_enabled))
- goto out;
- last_stack_tracer_enabled = !!stack_tracer_enabled;
- if (stack_tracer_enabled)
- register_ftrace_function(&trace_ops);
- else
- unregister_ftrace_function(&trace_ops);
- out:
- mutex_unlock(&stack_sysctl_mutex);
- return ret;
- }
- static char stack_trace_filter_buf[COMMAND_LINE_SIZE+1] __initdata;
- static __init int enable_stacktrace(char *str)
- {
- if (strncmp(str, "_filter=", 8) == 0)
- strncpy(stack_trace_filter_buf, str+8, COMMAND_LINE_SIZE);
- stack_tracer_enabled = 1;
- last_stack_tracer_enabled = 1;
- return 1;
- }
- __setup("stacktrace", enable_stacktrace);
- static __init int stack_trace_init(void)
- {
- struct dentry *d_tracer;
- d_tracer = tracing_init_dentry();
- trace_create_file("stack_max_size", 0644, d_tracer,
- &max_stack_size, &stack_max_size_fops);
- trace_create_file("stack_trace", 0444, d_tracer,
- NULL, &stack_trace_fops);
- trace_create_file("stack_trace_filter", 0444, d_tracer,
- NULL, &stack_trace_filter_fops);
- if (stack_trace_filter_buf[0])
- ftrace_set_early_filter(&trace_ops, stack_trace_filter_buf, 1);
- if (stack_tracer_enabled)
- register_ftrace_function(&trace_ops);
- return 0;
- }
- device_initcall(stack_trace_init);