arch/x86/kernel/stacktrace.c

   1 /*
   2  * Stack trace management functions
   3  *
   4  *  Copyright (C) 2006-2009 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
   5  */
   6 #include <linux/sched.h>
   7 #include <linux/stacktrace.h>
   8 #include <linux/module.h>
   9 #include <linux/uaccess.h>
  10 #include <asm/stacktrace.h>
  11
  12 static void save_stack_warning(void *data, char *msg)
  13 {
  14 }
  15
  16 static void
  17 save_stack_warning_symbol(void *data, char *msg, unsigned long symbol)
  18 {
  19 }
  20
  21 static int save_stack_stack(void *data, char *name)
  22 {
  23         return 0;
  24 }
  25
  26 static void save_stack_address(void *data, unsigned long addr, int reliable)
  27 {
  28         struct stack_trace *trace = data;
  29         if (!reliable)
  30                 return;
  31         if (trace->skip > 0) {
  32                 trace->skip--;
  33                 return;
  34         }
  35         if (trace->nr_entries < trace->max_entries)
  36                 trace->entries[trace->nr_entries++] = addr;
  37 }
  38
  39 static void
  40 save_stack_address_nosched(void *data, unsigned long addr, int reliable)
  41 {
  42         struct stack_trace *trace = (struct stack_trace *)data;
  43         if (!reliable)
  44                 return;
  45         if (in_sched_functions(addr))
  46                 return;
  47         if (trace->skip > 0) {
  48                 trace->skip--;
  49                 return;
  50         }
  51         if (trace->nr_entries < trace->max_entries)
  52                 trace->entries[trace->nr_entries++] = addr;
  53 }
  54
  55 static const struct stacktrace_ops save_stack_ops = {
  56         .warning        = save_stack_warning,
  57         .warning_symbol = save_stack_warning_symbol,
  58         .stack          = save_stack_stack,
  59         .address        = save_stack_address,
  60         .walk_stack     = print_context_stack,
  61 };
  62
  63 static const struct stacktrace_ops save_stack_ops_nosched = {
  64         .warning        = save_stack_warning,
  65         .warning_symbol = save_stack_warning_symbol,
  66         .stack          = save_stack_stack,
  67         .address        = save_stack_address_nosched,
  68         .walk_stack     = print_context_stack,
  69 };
  70
  71 /*
  72  * Save stack-backtrace addresses into a stack_trace buffer.
  73  */
  74 void save_stack_trace(struct stack_trace *trace)
  75 {
  76         dump_trace(current, NULL, NULL, 0, &save_stack_ops, trace);
  77         if (trace->nr_entries < trace->max_entries)
  78                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  79 }
  80 EXPORT_SYMBOL_GPL(save_stack_trace);
  81
  82 void save_stack_trace_bp(struct stack_trace *trace, unsigned long bp)
  83 {
  84         dump_trace(current, NULL, NULL, bp, &save_stack_ops, trace);
  85         if (trace->nr_entries < trace->max_entries)
  86                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  87 }
  88
  89 void save_stack_trace_tsk(struct task_struct *tsk, struct stack_trace *trace)
  90 {
  91         dump_trace(tsk, NULL, NULL, 0, &save_stack_ops_nosched, trace);
  92         if (trace->nr_entries < trace->max_entries)
  93                 trace->entries[trace->nr_entries++] = ULONG_MAX;
  94 }
  95 EXPORT_SYMBOL_GPL(save_stack_trace_tsk);
  96
  97 /* Userspace stacktrace - based on kernel/trace/trace_sysprof.c */
  98
  99 struct stack_frame {
 100         const void __user       *next_fp;
 101         unsigned long           ret_addr;
 102 };
 103
 104 static int copy_stack_frame(const void __user *fp, struct stack_frame *frame)
 105 {
 106         int ret;
 107
 108         if (!access_ok(VERIFY_READ, fp, sizeof(*frame)))
 109                 return 0;
 110
 111         ret = 1;
 112         pagefault_disable();
 113         if (__copy_from_user_inatomic(frame, fp, sizeof(*frame)))
 114                 ret = 0;
 115         pagefault_enable();
 116
 117         return ret;
 118 }
 119
 120 static inline void __save_stack_trace_user(struct stack_trace *trace)
 121 {
 122         const struct pt_regs *regs = task_pt_regs(current);
 123         const void __user *fp = (const void __user *)regs->bp;
 124
 125         if (trace->nr_entries < trace->max_entries)
 126                 trace->entries[trace->nr_entries++] = regs->ip;
 127
 128         while (trace->nr_entries < trace->max_entries) {
 129                 struct stack_frame frame;
 130
 131                 frame.next_fp = NULL;
 132                 frame.ret_addr = 0;
 133                 if (!copy_stack_frame(fp, &frame))
 134                         break;
 135                 if ((unsigned long)fp < regs->sp)
 136                         break;
 137                 if (frame.ret_addr) {
 138                         trace->entries[trace->nr_entries++] =
 139                                 frame.ret_addr;
 140                 }
 141                 if (fp == frame.next_fp)
 142                         break;
 143                 fp = frame.next_fp;
 144         }
 145 }
 146
 147 void save_stack_trace_user(struct stack_trace *trace)
 148 {
 149         /*
 150          * Trace user stack if we are not a kernel thread
 151          */
 152         if (current->mm) {
 153                 __save_stack_trace_user(trace);
 154         }
 155         if (trace->nr_entries < trace->max_entries)
 156                 trace->entries[trace->nr_entries++] = ULONG_MAX;
 157 }
 158