| /* |
| * trace stack traces |
| * |
| * Copyright (C) 2004-2008, Soeren Sandmann |
| * Copyright (C) 2007 Steven Rostedt <srostedt@redhat.com> |
| * Copyright (C) 2008 Ingo Molnar <mingo@redhat.com> |
| */ |
| #include <linux/kallsyms.h> |
| #include <linux/debugfs.h> |
| #include <linux/hrtimer.h> |
| #include <linux/uaccess.h> |
| #include <linux/ftrace.h> |
| #include <linux/module.h> |
| #include <linux/irq.h> |
| #include <linux/fs.h> |
| |
| #include <asm/stacktrace.h> |
| |
| #include "trace.h" |
| |
| static struct trace_array *sysprof_trace; |
| static int __read_mostly tracer_enabled; |
| |
| /* |
| * 1 msec sample interval by default: |
| */ |
| static unsigned long sample_period = 1000000; |
| static const unsigned int sample_max_depth = 512; |
| |
| static DEFINE_MUTEX(sample_timer_lock); |
| /* |
| * Per CPU hrtimers that do the profiling: |
| */ |
| static DEFINE_PER_CPU(struct hrtimer, stack_trace_hrtimer); |
| |
| struct stack_frame_user { |
| const void __user *next_fp; |
| unsigned long return_address; |
| }; |
| |
| static int |
| copy_stack_frame(const void __user *fp, struct stack_frame_user *frame) |
| { |
| int ret; |
| |
| if (!access_ok(VERIFY_READ, fp, sizeof(*frame))) |
| return 0; |
| |
| ret = 1; |
| pagefault_disable(); |
| if (__copy_from_user_inatomic(frame, fp, sizeof(*frame))) |
| ret = 0; |
| pagefault_enable(); |
| |
| return ret; |
| } |
| |
| struct backtrace_info { |
| struct trace_array_cpu *data; |
| struct trace_array *tr; |
| int pos; |
| }; |
| |
| static void |
| backtrace_warning_symbol(void *data, char *msg, unsigned long symbol) |
| { |
| /* Ignore warnings */ |
| } |
| |
| static void backtrace_warning(void *data, char *msg) |
| { |
| /* Ignore warnings */ |
| } |
| |
| static int backtrace_stack(void *data, char *name) |
| { |
| /* Don't bother with IRQ stacks for now */ |
| return -1; |
| } |
| |
| static void backtrace_address(void *data, unsigned long addr, int reliable) |
| { |
| struct backtrace_info *info = data; |
| |
| if (info->pos < sample_max_depth && reliable) { |
| __trace_special(info->tr, info->data, 1, addr, 0); |
| |
| info->pos++; |
| } |
| } |
| |
| static const struct stacktrace_ops backtrace_ops = { |
| .warning = backtrace_warning, |
| .warning_symbol = backtrace_warning_symbol, |
| .stack = backtrace_stack, |
| .address = backtrace_address, |
| .walk_stack = print_context_stack, |
| }; |
| |
| static int |
| trace_kernel(struct pt_regs *regs, struct trace_array *tr, |
| struct trace_array_cpu *data) |
| { |
| struct backtrace_info info; |
| unsigned long bp; |
| char *stack; |
| |
| info.tr = tr; |
| info.data = data; |
| info.pos = 1; |
| |
| __trace_special(info.tr, info.data, 1, regs->ip, 0); |
| |
| stack = ((char *)regs + sizeof(struct pt_regs)); |
| #ifdef CONFIG_FRAME_POINTER |
| bp = regs->bp; |
| #else |
| bp = 0; |
| #endif |
| |
| dump_trace(NULL, regs, (void *)stack, bp, &backtrace_ops, &info); |
| |
| return info.pos; |
| } |
| |
| static void timer_notify(struct pt_regs *regs, int cpu) |
| { |
| struct trace_array_cpu *data; |
| struct stack_frame_user frame; |
| struct trace_array *tr; |
| const void __user *fp; |
| int is_user; |
| int i; |
| |
| if (!regs) |
| return; |
| |
| tr = sysprof_trace; |
| data = tr->data[cpu]; |
| is_user = user_mode(regs); |
| |
| if (!current || current->pid == 0) |
| return; |
| |
| if (is_user && current->state != TASK_RUNNING) |
| return; |
| |
| __trace_special(tr, data, 0, 0, current->pid); |
| |
| if (!is_user) |
| i = trace_kernel(regs, tr, data); |
| else |
| i = 0; |
| |
| /* |
| * Trace user stack if we are not a kernel thread |
| */ |
| if (current->mm && i < sample_max_depth) { |
| regs = (struct pt_regs *)current->thread.sp0 - 1; |
| |
| fp = (void __user *)regs->bp; |
| |
| __trace_special(tr, data, 2, regs->ip, 0); |
| |
| while (i < sample_max_depth) { |
| frame.next_fp = NULL; |
| frame.return_address = 0; |
| if (!copy_stack_frame(fp, &frame)) |
| break; |
| if ((unsigned long)fp < regs->sp) |
| break; |
| |
| __trace_special(tr, data, 2, frame.return_address, |
| (unsigned long)fp); |
| fp = frame.next_fp; |
| |
| i++; |
| } |
| |
| } |
| |
| /* |
| * Special trace entry if we overflow the max depth: |
| */ |
| if (i == sample_max_depth) |
| __trace_special(tr, data, -1, -1, -1); |
| |
| __trace_special(tr, data, 3, current->pid, i); |
| } |
| |
| static enum hrtimer_restart stack_trace_timer_fn(struct hrtimer *hrtimer) |
| { |
| /* trace here */ |
| timer_notify(get_irq_regs(), smp_processor_id()); |
| |
| hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period)); |
| |
| return HRTIMER_RESTART; |
| } |
| |
| static void start_stack_timer(void *unused) |
| { |
| struct hrtimer *hrtimer = &__get_cpu_var(stack_trace_hrtimer); |
| |
| hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL); |
| hrtimer->function = stack_trace_timer_fn; |
| |
| hrtimer_start(hrtimer, ns_to_ktime(sample_period), |
| HRTIMER_MODE_REL_PINNED); |
| } |
| |
| static void start_stack_timers(void) |
| { |
| on_each_cpu(start_stack_timer, NULL, 1); |
| } |
| |
| static void stop_stack_timer(int cpu) |
| { |
| struct hrtimer *hrtimer = &per_cpu(stack_trace_hrtimer, cpu); |
| |
| hrtimer_cancel(hrtimer); |
| } |
| |
| static void stop_stack_timers(void) |
| { |
| int cpu; |
| |
| for_each_online_cpu(cpu) |
| stop_stack_timer(cpu); |
| } |
| |
| static void stop_stack_trace(struct trace_array *tr) |
| { |
| mutex_lock(&sample_timer_lock); |
| stop_stack_timers(); |
| tracer_enabled = 0; |
| mutex_unlock(&sample_timer_lock); |
| } |
| |
| static int stack_trace_init(struct trace_array *tr) |
| { |
| sysprof_trace = tr; |
| |
| tracing_start_cmdline_record(); |
| |
| mutex_lock(&sample_timer_lock); |
| start_stack_timers(); |
| tracer_enabled = 1; |
| mutex_unlock(&sample_timer_lock); |
| return 0; |
| } |
| |
| static void stack_trace_reset(struct trace_array *tr) |
| { |
| tracing_stop_cmdline_record(); |
| stop_stack_trace(tr); |
| } |
| |
| static struct tracer stack_trace __read_mostly = |
| { |
| .name = "sysprof", |
| .init = stack_trace_init, |
| .reset = stack_trace_reset, |
| #ifdef CONFIG_FTRACE_SELFTEST |
| .selftest = trace_selftest_startup_sysprof, |
| #endif |
| }; |
| |
| __init static int init_stack_trace(void) |
| { |
| return register_tracer(&stack_trace); |
| } |
| device_initcall(init_stack_trace); |
| |
| #define MAX_LONG_DIGITS 22 |
| |
| static ssize_t |
| sysprof_sample_read(struct file *filp, char __user *ubuf, |
| size_t cnt, loff_t *ppos) |
| { |
| char buf[MAX_LONG_DIGITS]; |
| int r; |
| |
| r = sprintf(buf, "%ld\n", nsecs_to_usecs(sample_period)); |
| |
| return simple_read_from_buffer(ubuf, cnt, ppos, buf, r); |
| } |
| |
| static ssize_t |
| sysprof_sample_write(struct file *filp, const char __user *ubuf, |
| size_t cnt, loff_t *ppos) |
| { |
| char buf[MAX_LONG_DIGITS]; |
| unsigned long val; |
| |
| if (cnt > MAX_LONG_DIGITS-1) |
| cnt = MAX_LONG_DIGITS-1; |
| |
| if (copy_from_user(&buf, ubuf, cnt)) |
| return -EFAULT; |
| |
| buf[cnt] = 0; |
| |
| val = simple_strtoul(buf, NULL, 10); |
| /* |
| * Enforce a minimum sample period of 100 usecs: |
| */ |
| if (val < 100) |
| val = 100; |
| |
| mutex_lock(&sample_timer_lock); |
| stop_stack_timers(); |
| sample_period = val * 1000; |
| start_stack_timers(); |
| mutex_unlock(&sample_timer_lock); |
| |
| return cnt; |
| } |
| |
| static const struct file_operations sysprof_sample_fops = { |
| .read = sysprof_sample_read, |
| .write = sysprof_sample_write, |
| }; |
| |
| void init_tracer_sysprof_debugfs(struct dentry *d_tracer) |
| { |
| |
| trace_create_file("sysprof_sample_period", 0644, |
| d_tracer, NULL, &sysprof_sample_fops); |
| } |