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-rw-r--r--kernel/trace/trace_stack.c310
1 files changed, 310 insertions, 0 deletions
diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
new file mode 100644
index 0000000..74c5d9a
--- /dev/null
+++ b/kernel/trace/trace_stack.c
@@ -0,0 +1,310 @@
+/*
+ * 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+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 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, 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;
+
+ 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 = 3;
+
+ save_stack_trace(&max_stack_trace);
+
+ /*
+ * Now find where in the stack these are.
+ */
+ i = 0;
+ start = &this_size;
+ top = (unsigned long *)
+ (((unsigned long)start & ~(THREAD_SIZE-1)) + THREAD_SIZE);
+
+ /*
+ * Loop through all the entries. One of the entries may
+ * for some reason be missed on the stack, so we may
+ * have to account for them. If they are all there, this
+ * loop will only happen once. This code only takes place
+ * on a new max, so it is far from a fast path.
+ */
+ while (i < max_stack_trace.nr_entries) {
+
+ 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);
+ /* Start the search from here */
+ start = p + 1;
+ }
+ }
+
+ i++;
+ }
+
+ 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)
+{
+ long i = (long)m->private;
+
+ (*pos)++;
+
+ i++;
+
+ if (i >= max_stack_trace.nr_entries ||
+ stack_dump_trace[i] == ULONG_MAX)
+ return NULL;
+
+ m->private = (void *)i;
+
+ return &m->private;
+}
+
+static void *t_start(struct seq_file *m, loff_t *pos)
+{
+ void *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, long i)
+{
+ unsigned long addr = stack_dump_trace[i];
+#ifdef CONFIG_KALLSYMS
+ char str[KSYM_SYMBOL_LEN];
+
+ sprint_symbol(str, addr);
+
+ return seq_printf(m, "%s\n", str);
+#else
+ return seq_printf(m, "%p\n", (void*)addr);
+#endif
+}
+
+static int t_show(struct seq_file *m, void *v)
+{
+ long i = *(long *)v;
+ int size;
+
+ if (i < 0) {
+ seq_printf(m, " Depth Size Location"
+ " (%d entries)\n"
+ " ----- ---- --------\n",
+ max_stack_trace.nr_entries);
+ return 0;
+ }
+
+ 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 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 = (void *)-1;
+ }
+
+ 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);