arch/x86/oprofile/backtrace.c

   1 /**
   2  * @file backtrace.c
   3  *
   4  * @remark Copyright 2002 OProfile authors
   5  * @remark Read the file COPYING
   6  *
   7  * @author John Levon
   8  * @author David Smith
   9  */
  10
  11 #include <linux/oprofile.h>
  12 #include <linux/sched.h>
  13 #include <linux/mm.h>
  14 #include <linux/compat.h>
  15 #include <linux/uaccess.h>
  16
  17 #include <asm/ptrace.h>
  18 #include <asm/stacktrace.h>
  19 #include <asm/unwind.h>
  20
  21 #ifdef CONFIG_COMPAT
  22 static struct stack_frame_ia32 *
  23 dump_user_backtrace_32(struct stack_frame_ia32 *head)
  24 {
  25         /* Also check accessibility of one struct frame_head beyond: */
  26         struct stack_frame_ia32 bufhead[2];
  27         struct stack_frame_ia32 *fp;
  28         unsigned long bytes;
  29
  30         bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
  31         if (bytes != 0)
  32                 return NULL;
  33
  34         fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);
  35
  36         oprofile_add_trace(bufhead[0].return_address);
  37
  38         /* frame pointers should strictly progress back up the stack
  39         * (towards higher addresses) */
  40         if (head >= fp)
  41                 return NULL;
  42
  43         return fp;
  44 }
  45
  46 static inline int
  47 x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
  48 {
  49         struct stack_frame_ia32 *head;
  50
  51         /* User process is IA32 */
  52         if (!current || !test_thread_flag(TIF_IA32))
  53                 return 0;
  54
  55         head = (struct stack_frame_ia32 *) regs->bp;
  56         while (depth-- && head)
  57                 head = dump_user_backtrace_32(head);
  58
  59         return 1;
  60 }
  61
  62 #else
  63 static inline int
  64 x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
  65 {
  66         return 0;
  67 }
  68 #endif /* CONFIG_COMPAT */
  69
  70 static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
  71 {
  72         /* Also check accessibility of one struct frame_head beyond: */
  73         struct stack_frame bufhead[2];
  74         unsigned long bytes;
  75
  76         bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
  77         if (bytes != 0)
  78                 return NULL;
  79
  80         oprofile_add_trace(bufhead[0].return_address);
  81
  82         /* frame pointers should strictly progress back up the stack
  83          * (towards higher addresses) */
  84         if (head >= bufhead[0].next_frame)
  85                 return NULL;
  86
  87         return bufhead[0].next_frame;
  88 }
  89
  90 void
  91 x86_backtrace(struct pt_regs * const regs, unsigned int depth)
  92 {
  93         struct stack_frame *head = (struct stack_frame *)frame_pointer(regs);
  94
  95         if (!user_mode(regs)) {
  96                 struct unwind_state state;
  97                 unsigned long addr;
  98
  99                 if (!depth)
 100                         return;
 101
 102                 oprofile_add_trace(regs->ip);
 103
 104                 if (!--depth)
 105                         return;
 106
 107                 for (unwind_start(&state, current, regs, NULL);
 108                      !unwind_done(&state); unwind_next_frame(&state)) {
 109                         addr = unwind_get_return_address(&state);
 110                         if (!addr)
 111                                 break;
 112
 113                         oprofile_add_trace(addr);
 114
 115                         if (!--depth)
 116                                 break;
 117                 }
 118
 119                 return;
 120         }
 121
 122         if (x86_backtrace_32(regs, depth))
 123                 return;
 124
 125         while (depth-- && head)
 126                 head = dump_user_backtrace(head);
 127 }