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 000000000000..74c5d9a3afae
--- /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);