1 files changed, 49 insertions, 43 deletions

diff --git a/kernel/trace/trace_stack.c b/kernel/trace/trace_stack.c
index 8abf1ba18085..dda9e6742950 100644
--- a/kernel/trace/trace_stack.c
+++ b/kernel/trace/trace_stack.c
@@ -16,24 +16,22 @@
 
 #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];
+unsigned stack_trace_index[STACK_TRACE_ENTRIES];
 
 /*
  * Reserve one entry for the passed in ip. This will allow
  * us to remove most or all of the stack size overhead
  * added by the stack tracer itself.
  */
-static struct stack_trace max_stack_trace = {
+struct stack_trace stack_trace_max = {
         .max_entries            = STACK_TRACE_ENTRIES - 1,
         .entries                = &stack_dump_trace[0],
 };
 
-static unsigned long max_stack_size;
-static arch_spinlock_t max_stack_lock =
+unsigned long stack_trace_max_size;
+arch_spinlock_t stack_trace_max_lock =
         (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
 
 static DEFINE_PER_CPU(int, trace_active);
@@ -42,30 +40,38 @@ static DEFINE_MUTEX(stack_sysctl_mutex);
 int stack_tracer_enabled;
 static int last_stack_tracer_enabled;
 
-static inline void print_max_stack(void)
+void stack_trace_print(void)
 {
         long i;
         int size;
 
         pr_emerg("        Depth    Size   Location    (%d entries)\n"
                            "        -----    ----   --------\n",
-                           max_stack_trace.nr_entries);
+                           stack_trace_max.nr_entries);
 
-        for (i = 0; i < max_stack_trace.nr_entries; i++) {
+        for (i = 0; i < stack_trace_max.nr_entries; i++) {
                 if (stack_dump_trace[i] == ULONG_MAX)
                         break;
-                if (i+1 == max_stack_trace.nr_entries ||
+                if (i+1 == stack_trace_max.nr_entries ||
                                 stack_dump_trace[i+1] == ULONG_MAX)
-                        size = stack_dump_index[i];
+                        size = stack_trace_index[i];
                 else
-                        size = stack_dump_index[i] - stack_dump_index[i+1];
+                        size = stack_trace_index[i] - stack_trace_index[i+1];
 
-                pr_emerg("%3ld) %8d   %5d   %pS\n", i, stack_dump_index[i],
+                pr_emerg("%3ld) %8d   %5d   %pS\n", i, stack_trace_index[i],
                                 size, (void *)stack_dump_trace[i]);
         }
 }
 
-static inline void
+/*
+ * When arch-specific code overides this function, the following
+ * data should be filled up, assuming stack_trace_max_lock is held to
+ * prevent concurrent updates.
+ *     stack_trace_index[]
+ *     stack_trace_max
+ *     stack_trace_max_size
+ */
+void __weak
 check_stack(unsigned long ip, unsigned long *stack)
 {
         unsigned long this_size, flags; unsigned long *p, *top, *start;
@@ -78,7 +84,7 @@ check_stack(unsigned long ip, unsigned long *stack)
         /* Remove the frame of the tracer */
         this_size -= frame_size;
 
-        if (this_size <= max_stack_size)
+        if (this_size <= stack_trace_max_size)
                 return;
 
         /* we do not handle interrupt stacks yet */
@@ -90,7 +96,7 @@ check_stack(unsigned long ip, unsigned long *stack)
                 return;
 
         local_irq_save(flags);
-        arch_spin_lock(&max_stack_lock);
+        arch_spin_lock(&stack_trace_max_lock);
 
         /*
          * RCU may not be watching, make it see us.
@@ -103,18 +109,18 @@ check_stack(unsigned long ip, unsigned long *stack)
                 this_size -= tracer_frame;
 
         /* a race could have already updated it */
-        if (this_size <= max_stack_size)
+        if (this_size <= stack_trace_max_size)
                 goto out;
 
-        max_stack_size = this_size;
+        stack_trace_max_size = this_size;
 
-        max_stack_trace.nr_entries = 0;
-        max_stack_trace.skip = 3;
+        stack_trace_max.nr_entries = 0;
+        stack_trace_max.skip = 3;
 
-        save_stack_trace(&max_stack_trace);
+        save_stack_trace(&stack_trace_max);
 
         /* Skip over the overhead of the stack tracer itself */
-        for (i = 0; i < max_stack_trace.nr_entries; i++) {
+        for (i = 0; i < stack_trace_max.nr_entries; i++) {
                 if (stack_dump_trace[i] == ip)
                         break;
         }
@@ -134,18 +140,18 @@ check_stack(unsigned long ip, unsigned long *stack)
          * 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) {
+        while (i < stack_trace_max.nr_entries) {
                 int found = 0;
 
-                stack_dump_index[x] = this_size;
+                stack_trace_index[x] = this_size;
                 p = start;
 
-                for (; p < top && i < max_stack_trace.nr_entries; p++) {
+                for (; p < top && i < stack_trace_max.nr_entries; p++) {
                         if (stack_dump_trace[i] == ULONG_MAX)
                                 break;
                         if (*p == stack_dump_trace[i]) {
                                 stack_dump_trace[x] = stack_dump_trace[i++];
-                                this_size = stack_dump_index[x++] =
+                                this_size = stack_trace_index[x++] =
                                         (top - p) * sizeof(unsigned long);
                                 found = 1;
                                 /* Start the search from here */
@@ -160,7 +166,7 @@ check_stack(unsigned long ip, unsigned long *stack)
                                 if (unlikely(!tracer_frame)) {
                                         tracer_frame = (p - stack) *
                                                 sizeof(unsigned long);
-                                        max_stack_size -= tracer_frame;
+                                        stack_trace_max_size -= tracer_frame;
                                 }
                         }
                 }
@@ -169,18 +175,18 @@ check_stack(unsigned long ip, unsigned long *stack)
                         i++;
         }
 
-        max_stack_trace.nr_entries = x;
+        stack_trace_max.nr_entries = x;
         for (; x < i; x++)
                 stack_dump_trace[x] = ULONG_MAX;
 
         if (task_stack_end_corrupted(current)) {
-                print_max_stack();
+                stack_trace_print();
                 BUG();
         }
 
  out:
         rcu_irq_exit();
-        arch_spin_unlock(&max_stack_lock);
+        arch_spin_unlock(&stack_trace_max_lock);
         local_irq_restore(flags);
 }
 
@@ -251,9 +257,9 @@ stack_max_size_write(struct file *filp, const char __user *ubuf,
         cpu = smp_processor_id();
         per_cpu(trace_active, cpu)++;
 
-        arch_spin_lock(&max_stack_lock);
+        arch_spin_lock(&stack_trace_max_lock);
         *ptr = val;
-        arch_spin_unlock(&max_stack_lock);
+        arch_spin_unlock(&stack_trace_max_lock);
 
         per_cpu(trace_active, cpu)--;
         local_irq_restore(flags);
@@ -273,7 +279,7 @@ __next(struct seq_file *m, loff_t *pos)
 {
         long n = *pos - 1;
 
-        if (n > max_stack_trace.nr_entries || stack_dump_trace[n] == ULONG_MAX)
+        if (n > stack_trace_max.nr_entries || stack_dump_trace[n] == ULONG_MAX)
                 return NULL;
 
         m->private = (void *)n;
@@ -296,7 +302,7 @@ static void *t_start(struct seq_file *m, loff_t *pos)
         cpu = smp_processor_id();
         per_cpu(trace_active, cpu)++;
 
-        arch_spin_lock(&max_stack_lock);
+        arch_spin_lock(&stack_trace_max_lock);
 
         if (*pos == 0)
                 return SEQ_START_TOKEN;
@@ -308,7 +314,7 @@ static void t_stop(struct seq_file *m, void *p)
 {
         int cpu;
 
-        arch_spin_unlock(&max_stack_lock);
+        arch_spin_unlock(&stack_trace_max_lock);
 
         cpu = smp_processor_id();
         per_cpu(trace_active, cpu)--;
@@ -343,9 +349,9 @@ static int t_show(struct seq_file *m, void *v)
                 seq_printf(m, "        Depth    Size   Location"
                            "    (%d entries)\n"
                            "        -----    ----   --------\n",
-                           max_stack_trace.nr_entries);
+                           stack_trace_max.nr_entries);
 
-                if (!stack_tracer_enabled && !max_stack_size)
+                if (!stack_tracer_enabled && !stack_trace_max_size)
                         print_disabled(m);
 
                 return 0;
@@ -353,17 +359,17 @@ static int t_show(struct seq_file *m, void *v)
 
         i = *(long *)v;
 
-        if (i >= max_stack_trace.nr_entries ||
+        if (i >= stack_trace_max.nr_entries ||
             stack_dump_trace[i] == ULONG_MAX)
                 return 0;
 
-        if (i+1 == max_stack_trace.nr_entries ||
+        if (i+1 == stack_trace_max.nr_entries ||
             stack_dump_trace[i+1] == ULONG_MAX)
-                size = stack_dump_index[i];
+                size = stack_trace_index[i];
         else
-                size = stack_dump_index[i] - stack_dump_index[i+1];
+                size = stack_trace_index[i] - stack_trace_index[i+1];
 
-        seq_printf(m, "%3ld) %8d   %5d   ", i, stack_dump_index[i], size);
+        seq_printf(m, "%3ld) %8d   %5d   ", i, stack_trace_index[i], size);
 
         trace_lookup_stack(m, i);
 
@@ -453,7 +459,7 @@ static __init int stack_trace_init(void)
                 return 0;
 
         trace_create_file("stack_max_size", 0644, d_tracer,
-                        &max_stack_size, &stack_max_size_fops);
+                        &stack_trace_max_size, &stack_max_size_fops);
 
         trace_create_file("stack_trace", 0444, d_tracer,
                         NULL, &stack_trace_fops);