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