1 files changed, 324 insertions, 32 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index b6a80b98a3fb..d1ae2ba25274 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -13,10 +13,19 @@
  *  Copyright (C) 2004 William Lee Irwin III
  */
 
-#include <linux/module.h>
+#include <linux/stop_machine.h>
+#include <linux/clocksource.h>
+#include <linux/kallsyms.h>
+#include <linux/kthread.h>
+#include <linux/hardirq.h>
 #include <linux/ftrace.h>
+#include <linux/module.h>
+#include <linux/hash.h>
+#include <linux/list.h>
+
+#include "trace.h"
 
-static DEFINE_SPINLOCK(ftrace_func_lock);
+static DEFINE_SPINLOCK(ftrace_lock);
 static struct ftrace_ops ftrace_list_end __read_mostly =
 {
         .func = ftrace_stub,
@@ -44,21 +53,21 @@ notrace void ftrace_list_func(unsigned long ip, unsigned long parent_ip)
 }
 
 /**
- * register_ftrace_function - register a function for profiling
- * @ops - ops structure that holds the function for profiling.
- *
- * Register a function to be called by all functions in the
- * kernel.
+ * clear_ftrace_function - reset the ftrace function
  *
- * Note: @ops->func and all the functions it calls must be labeled
- *       with "notrace", otherwise it will go into a
- *       recursive loop.
+ * This NULLs the ftrace function and in essence stops
+ * tracing.  There may be lag
  */
-int register_ftrace_function(struct ftrace_ops *ops)
+void clear_ftrace_function(void)
 {
-        unsigned long flags;
+        ftrace_trace_function = ftrace_stub;
+}
+
+static int notrace __register_ftrace_function(struct ftrace_ops *ops)
+{
+        /* Should never be called by interrupts */
+        spin_lock(&ftrace_lock);
 
-        spin_lock_irqsave(&ftrace_func_lock, flags);
         ops->next = ftrace_list;
         /*
          * We are entering ops into the ftrace_list but another
@@ -68,6 +77,7 @@ int register_ftrace_function(struct ftrace_ops *ops)
          */
         smp_wmb();
         ftrace_list = ops;
+
         /*
          * For one func, simply call it directly.
          * For more than one func, call the chain.
@@ -76,28 +86,22 @@ int register_ftrace_function(struct ftrace_ops *ops)
                 ftrace_trace_function = ops->func;
         else
                 ftrace_trace_function = ftrace_list_func;
-        spin_unlock_irqrestore(&ftrace_func_lock, flags);
+
+        spin_unlock(&ftrace_lock);
 
         return 0;
 }
 
-/**
- * unregister_ftrace_function - unresgister a function for profiling.
- * @ops - ops structure that holds the function to unregister
- *
- * Unregister a function that was added to be called by ftrace profiling.
- */
-int unregister_ftrace_function(struct ftrace_ops *ops)
+static int notrace __unregister_ftrace_function(struct ftrace_ops *ops)
 {
-        unsigned long flags;
         struct ftrace_ops **p;
         int ret = 0;
 
-        spin_lock_irqsave(&ftrace_func_lock, flags);
+        spin_lock(&ftrace_lock);
 
         /*
-         * If we are the only function, then the ftrace pointer is
-         * pointing directly to that function.
+         * If we are removing the last function, then simply point
+         * to the ftrace_stub.
          */
         if (ftrace_list == ops && ops->next == &ftrace_list_end) {
                 ftrace_trace_function = ftrace_stub;
@@ -117,22 +121,310 @@ int unregister_ftrace_function(struct ftrace_ops *ops)
         *p = (*p)->next;
 
         /* If we only have one func left, then call that directly */
-        if (ftrace_list->next == &ftrace_list_end)
+        if (ftrace_list == &ftrace_list_end ||
+            ftrace_list->next == &ftrace_list_end)
                 ftrace_trace_function = ftrace_list->func;
 
  out:
-        spin_unlock_irqrestore(&ftrace_func_lock, flags);
+        spin_unlock(&ftrace_lock);
+
+        return ret;
+}
+
+#ifdef CONFIG_DYNAMIC_FTRACE
+
+static struct hlist_head ftrace_hash[FTRACE_HASHSIZE];
+
+static DEFINE_PER_CPU(int, ftrace_shutdown_disable_cpu);
+
+static DEFINE_SPINLOCK(ftrace_shutdown_lock);
+static DEFINE_MUTEX(ftraced_lock);
+
+static int ftraced_trigger;
+static int ftraced_suspend;
+
+static int ftrace_record_suspend;
+
+static inline int
+notrace ftrace_ip_in_hash(unsigned long ip, unsigned long key)
+{
+        struct dyn_ftrace *p;
+        struct hlist_node *t;
+        int found = 0;
+
+        hlist_for_each_entry(p, t, &ftrace_hash[key], node) {
+                if (p->ip == ip) {
+                        found = 1;
+                        break;
+                }
+        }
+
+        return found;
+}
+
+static inline void notrace
+ftrace_add_hash(struct dyn_ftrace *node, unsigned long key)
+{
+        hlist_add_head(&node->node, &ftrace_hash[key]);
+}
+
+static void notrace
+ftrace_record_ip(unsigned long ip, unsigned long parent_ip)
+{
+        struct dyn_ftrace *node;
+        unsigned long flags;
+        unsigned long key;
+        int resched;
+        int atomic;
+
+        resched = need_resched();
+        preempt_disable_notrace();
+
+        /* We simply need to protect against recursion */
+        __get_cpu_var(ftrace_shutdown_disable_cpu)++;
+        if (__get_cpu_var(ftrace_shutdown_disable_cpu) != 1)
+                goto out;
+
+        if (unlikely(ftrace_record_suspend))
+                goto out;
+
+        key = hash_long(ip, FTRACE_HASHBITS);
+
+        WARN_ON_ONCE(key >= FTRACE_HASHSIZE);
+
+        if (ftrace_ip_in_hash(ip, key))
+                goto out;
+
+        atomic = irqs_disabled();
+
+        spin_lock_irqsave(&ftrace_shutdown_lock, flags);
+
+        /* This ip may have hit the hash before the lock */
+        if (ftrace_ip_in_hash(ip, key))
+                goto out_unlock;
+
+        /*
+         * There's a slight race that the ftraced will update the
+         * hash and reset here. The arch alloc is responsible
+         * for seeing if the IP has already changed, and if
+         * it has, the alloc will fail.
+         */
+        node = ftrace_alloc_shutdown_node(ip);
+        if (!node)
+                goto out_unlock;
+
+        node->ip = ip;
+
+        ftrace_add_hash(node, key);
+
+        ftraced_trigger = 1;
+
+ out_unlock:
+        spin_unlock_irqrestore(&ftrace_shutdown_lock, flags);
+ out:
+        __get_cpu_var(ftrace_shutdown_disable_cpu)--;
+
+        /* prevent recursion with scheduler */
+        if (resched)
+                preempt_enable_no_resched_notrace();
+        else
+                preempt_enable_notrace();
+}
+
+static struct ftrace_ops ftrace_shutdown_ops __read_mostly =
+{
+        .func = ftrace_record_ip,
+};
+
+
+static int notrace __ftrace_modify_code(void *data)
+{
+        void (*func)(void) = data;
+
+        func();
+        return 0;
+}
+
+static void notrace ftrace_run_startup_code(void)
+{
+        stop_machine_run(__ftrace_modify_code, ftrace_startup_code, NR_CPUS);
+}
+
+static void notrace ftrace_run_shutdown_code(void)
+{
+        stop_machine_run(__ftrace_modify_code, ftrace_shutdown_code, NR_CPUS);
+}
+
+static void notrace ftrace_startup(void)
+{
+        mutex_lock(&ftraced_lock);
+        ftraced_suspend++;
+        if (ftraced_suspend != 1)
+                goto out;
+        __unregister_ftrace_function(&ftrace_shutdown_ops);
+
+        ftrace_run_startup_code();
+ out:
+        mutex_unlock(&ftraced_lock);
+}
+
+static void notrace ftrace_shutdown(void)
+{
+        mutex_lock(&ftraced_lock);
+        ftraced_suspend--;
+        if (ftraced_suspend)
+                goto out;
+
+        ftrace_run_shutdown_code();
+
+        __register_ftrace_function(&ftrace_shutdown_ops);
+ out:
+        mutex_unlock(&ftraced_lock);
+}
+
+static cycle_t          ftrace_update_time;
+static unsigned long    ftrace_update_cnt;
+unsigned long           ftrace_update_tot_cnt;
+
+static int notrace __ftrace_update_code(void *ignore)
+{
+        struct dyn_ftrace *p;
+        struct hlist_head head;
+        struct hlist_node *t;
+        cycle_t start, stop;
+        int i;
+
+        /* Don't be calling ftrace ops now */
+        __unregister_ftrace_function(&ftrace_shutdown_ops);
+
+        start = now(raw_smp_processor_id());
+        ftrace_update_cnt = 0;
+
+        /* No locks needed, the machine is stopped! */
+        for (i = 0; i < FTRACE_HASHSIZE; i++) {
+                if (hlist_empty(&ftrace_hash[i]))
+                        continue;
+
+                head = ftrace_hash[i];
+                INIT_HLIST_HEAD(&ftrace_hash[i]);
+
+                /* all CPUS are stopped, we are safe to modify code */
+                hlist_for_each_entry(p, t, &head, node) {
+                        ftrace_code_disable(p);
+                        ftrace_update_cnt++;
+                }
+
+        }
+
+        stop = now(raw_smp_processor_id());
+        ftrace_update_time = stop - start;
+        ftrace_update_tot_cnt += ftrace_update_cnt;
+
+        __register_ftrace_function(&ftrace_shutdown_ops);
 
         return 0;
 }
 
+static void notrace ftrace_update_code(void)
+{
+        stop_machine_run(__ftrace_update_code, NULL, NR_CPUS);
+}
+
+static int notrace ftraced(void *ignore)
+{
+        unsigned long usecs;
+
+        set_current_state(TASK_INTERRUPTIBLE);
+
+        while (!kthread_should_stop()) {
+
+                /* check once a second */
+                schedule_timeout(HZ);
+
+                mutex_lock(&ftraced_lock);
+                if (ftraced_trigger && !ftraced_suspend) {
+                        ftrace_record_suspend++;
+                        ftrace_update_code();
+                        usecs = nsecs_to_usecs(ftrace_update_time);
+                        if (ftrace_update_tot_cnt > 100000) {
+                                ftrace_update_tot_cnt = 0;
+                                pr_info("hm, dftrace overflow: %lu change%s"
+                                         " (%lu total) in %lu usec%s\n",
+                                        ftrace_update_cnt,
+                                        ftrace_update_cnt != 1 ? "s" : "",
+                                        ftrace_update_tot_cnt,
+                                        usecs, usecs != 1 ? "s" : "");
+                                WARN_ON_ONCE(1);
+                        }
+                        ftraced_trigger = 0;
+                        ftrace_record_suspend--;
+                }
+                mutex_unlock(&ftraced_lock);
+
+                ftrace_shutdown_replenish();
+
+                set_current_state(TASK_INTERRUPTIBLE);
+        }
+        __set_current_state(TASK_RUNNING);
+        return 0;
+}
+
+static int __init notrace ftrace_shutdown_init(void)
+{
+        struct task_struct *p;
+        int ret;
+
+        ret = ftrace_shutdown_arch_init();
+        if (ret)
+                return ret;
+
+        p = kthread_run(ftraced, NULL, "ftraced");
+        if (IS_ERR(p))
+                return -1;
+
+        __register_ftrace_function(&ftrace_shutdown_ops);
+
+        return 0;
+}
+
+core_initcall(ftrace_shutdown_init);
+#else
+# define ftrace_startup()       do { } while (0)
+# define ftrace_shutdown()      do { } while (0)
+#endif /* CONFIG_DYNAMIC_FTRACE */
+
 /**
- * clear_ftrace_function - reset the ftrace function
+ * register_ftrace_function - register a function for profiling
+ * @ops - ops structure that holds the function for profiling.
  *
- * This NULLs the ftrace function and in essence stops
- * tracing.  There may be lag
+ * Register a function to be called by all functions in the
+ * kernel.
+ *
+ * Note: @ops->func and all the functions it calls must be labeled
+ *       with "notrace", otherwise it will go into a
+ *       recursive loop.
  */
-void clear_ftrace_function(void)
+int register_ftrace_function(struct ftrace_ops *ops)
 {
-        ftrace_trace_function = ftrace_stub;
+        ftrace_startup();
+
+        return __register_ftrace_function(ops);
+}
+
+/**
+ * unregister_ftrace_function - unresgister a function for profiling.
+ * @ops - ops structure that holds the function to unregister
+ *
+ * Unregister a function that was added to be called by ftrace profiling.
+ */
+int unregister_ftrace_function(struct ftrace_ops *ops)
+{
+        int ret;
+
+        ret = __unregister_ftrace_function(ops);
+
+        if (ftrace_list == &ftrace_list_end)
+                ftrace_shutdown();
+
+        return ret;
 }