ftrace: add stack tracer (e5a81b62) · Commits · 戴 / test

kernel/trace/Kconfig

+9 −0

Original line number	Diff line number	Diff line
		@@ -106,6 +106,15 @@ config CONTEXT_SWITCH_TRACER
		This tracer gets called from the context switch and records
		all switching of tasks.

		config STACK_TRACER
		bool "Trace max stack"
		depends on HAVE_FTRACE
		select FTRACE
		select STACKTRACE
		help
		This tracer records the max stack of the kernel, and displays
		it in debugfs/tracing/stack_trace

		config DYNAMIC_FTRACE
		bool "enable/disable ftrace tracepoints dynamically"
		depends on FTRACE

kernel/trace/Makefile

+1 −0

Original line number	Diff line number	Diff line
		@@ -19,6 +19,7 @@ obj-$(CONFIG_FTRACE) += trace_functions.o
		obj-$(CONFIG_IRQSOFF_TRACER) += trace_irqsoff.o
		obj-$(CONFIG_PREEMPT_TRACER) += trace_irqsoff.o
		obj-$(CONFIG_SCHED_TRACER) += trace_sched_wakeup.o
		obj-$(CONFIG_STACK_TRACER) += trace_stack.o
		obj-$(CONFIG_MMIOTRACE) += trace_mmiotrace.o

		libftrace-y := ftrace.o

kernel/trace/trace_stack.c

0 → 100644

+254 −0

Original line number	Diff line number	Diff line
		/*
		* 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/init.h>
		#include <linux/fs.h>
		#include "trace.h"

		#define STACK_TRACE_ENTRIES 500

		static unsigned long stack_dump_trace[STACK_TRACE_ENTRIES] =
		{ [0 ... (STACK_TRACE_ENTRIES-1)] = ULONG_MAX };
		static struct stack_trace max_stack_trace = {
		.max_entries = STACK_TRACE_ENTRIES,
		.entries = stack_dump_trace,
		};

		static unsigned long max_stack_size;
		static raw_spinlock_t max_stack_lock =
		(raw_spinlock_t)__RAW_SPIN_LOCK_UNLOCKED;

		static int stack_trace_disabled __read_mostly;
		static DEFINE_PER_CPU(int, trace_active);

		static inline void check_stack(void)
		{
		unsigned long this_size;
		unsigned long flags;

		this_size = ((unsigned long)&this_size) & (THREAD_SIZE-1);
		this_size = THREAD_SIZE - this_size;

		if (this_size <= max_stack_size)
		return;

		raw_local_irq_save(flags);
		__raw_spin_lock(&max_stack_lock);

		/* a race could have already updated it */
		if (this_size <= max_stack_size)
		goto out;

		max_stack_size = this_size;

		max_stack_trace.nr_entries = 0;
		max_stack_trace.skip = 1;

		save_stack_trace(&max_stack_trace);

		out:
		__raw_spin_unlock(&max_stack_lock);
		raw_local_irq_restore(flags);
		}

		static void
		stack_trace_call(unsigned long ip, unsigned long parent_ip)
		{
		int cpu, resched;

		if (unlikely(!ftrace_enabled \|\| stack_trace_disabled))
		return;

		resched = need_resched();
		preempt_disable_notrace();

		cpu = raw_smp_processor_id();
		/* no atomic needed, we only modify this variable by this cpu */
		if (per_cpu(trace_active, cpu)++ != 0)
		goto out;

		check_stack();

		out:
		per_cpu(trace_active, cpu)--;
		/* prevent recursion in schedule */
		if (resched)
		preempt_enable_no_resched_notrace();
		else
		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;
		char buf[64];
		int ret;

		if (count >= sizeof(buf))
		return -EINVAL;

		if (copy_from_user(&buf, ubuf, count))
		return -EFAULT;

		buf[count] = 0;

		ret = strict_strtoul(buf, 10, &val);
		if (ret < 0)
		return ret;

		raw_local_irq_save(flags);
		__raw_spin_lock(&max_stack_lock);
		*ptr = val;
		__raw_spin_unlock(&max_stack_lock);
		raw_local_irq_restore(flags);

		return count;
		}

		static struct file_operations stack_max_size_fops = {
		.open = tracing_open_generic,
		.read = stack_max_size_read,
		.write = stack_max_size_write,
		};

		static void *
		t_next(struct seq_file m, void v, loff_t *pos)
		{
		unsigned long *t = m->private;

		(*pos)++;

		if (!t \|\| *t == ULONG_MAX)
		return NULL;

		t++;
		m->private = t;

		return t;
		}

		static void t_start(struct seq_file m, loff_t *pos)
		{
		unsigned long *t = m->private;
		loff_t l = 0;

		local_irq_disable();
		__raw_spin_lock(&max_stack_lock);

		for (; t && l < *pos; t = t_next(m, t, &l))
		;

		return t;
		}

		static void t_stop(struct seq_file m, void p)
		{
		__raw_spin_unlock(&max_stack_lock);
		local_irq_enable();
		}

		static int trace_lookup_stack(struct seq_file *m, unsigned long addr)
		{
		#ifdef CONFIG_KALLSYMS
		char str[KSYM_SYMBOL_LEN];

		sprint_symbol(str, addr);

		return seq_printf(m, "[<%p>] %s\n", (void*)addr, str);
		#else
		return seq_printf(m, "%p\n", (void*)addr);
		#endif
		}

		static int t_show(struct seq_file m, void v)
		{
		unsigned long *t = v;

		if (!t \|\| *t == ULONG_MAX)
		return 0;

		trace_lookup_stack(m, *t);

		return 0;
		}

		static 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)
		{
		int ret;

		ret = seq_open(file, &stack_trace_seq_ops);
		if (!ret) {
		struct seq_file *m = file->private_data;
		m->private = stack_dump_trace;
		}

		return ret;
		}

		static struct file_operations stack_trace_fops = {
		.open = stack_trace_open,
		.read = seq_read,
		.llseek = seq_lseek,
		};

		static __init int stack_trace_init(void)
		{
		struct dentry *d_tracer;
		struct dentry *entry;

		d_tracer = tracing_init_dentry();

		entry = debugfs_create_file("stack_max_size", 0644, d_tracer,
		&max_stack_size, &stack_max_size_fops);
		if (!entry)
		pr_warning("Could not create debugfs 'stack_max_size' entry\n");

		entry = debugfs_create_file("stack_trace", 0444, d_tracer,
		NULL, &stack_trace_fops);
		if (!entry)
		pr_warning("Could not create debugfs 'stack_trace' entry\n");

		register_ftrace_function(&trace_ops);

		return 0;
		}

		device_initcall(stack_trace_init);

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