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
  20 static int backtrace_stack(void *data, char *name)
  21 {
  22         /* Yes, we want all stacks */
  23         return 0;
  24 }
  25
  26 static int backtrace_address(void *data, unsigned long addr, int reliable)
  27 {
  28         unsigned int *depth = data;
  29
  30         if ((*depth)--)
  31                 oprofile_add_trace(addr);
  32         return 0;
  33 }
  34
  35 static struct stacktrace_ops backtrace_ops = {
  36         .stack          = backtrace_stack,
  37         .address        = backtrace_address,
  38         .walk_stack     = print_context_stack,
  39 };
  40
  41 #ifdef CONFIG_COMPAT
  42 static struct stack_frame_ia32 *
  43 dump_user_backtrace_32(struct stack_frame_ia32 *head)
  44 {
  45         /* Also check accessibility of one struct frame_head beyond: */
  46         struct stack_frame_ia32 bufhead[2];
  47         struct stack_frame_ia32 *fp;
  48         unsigned long bytes;
  49
  50         bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
  51         if (bytes != 0)
  52                 return NULL;
  53
  54         fp = (struct stack_frame_ia32 *) compat_ptr(bufhead[0].next_frame);
  55
  56         oprofile_add_trace(bufhead[0].return_address);
  57
  58         /* frame pointers should strictly progress back up the stack
  59         * (towards higher addresses) */
  60         if (head >= fp)
  61                 return NULL;
  62
  63         return fp;
  64 }
  65
  66 static inline int
  67 x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
  68 {
  69         struct stack_frame_ia32 *head;
  70
  71         /* User process is IA32 */
  72         if (!current || !test_thread_flag(TIF_IA32))
  73                 return 0;
  74
  75         head = (struct stack_frame_ia32 *) regs->bp;
  76         while (depth-- && head)
  77                 head = dump_user_backtrace_32(head);
  78
  79         return 1;
  80 }
  81
  82 #else
  83 static inline int
  84 x86_backtrace_32(struct pt_regs * const regs, unsigned int depth)
  85 {
  86         return 0;
  87 }
  88 #endif /* CONFIG_COMPAT */
  89
  90 static struct stack_frame *dump_user_backtrace(struct stack_frame *head)
  91 {
  92         /* Also check accessibility of one struct frame_head beyond: */
  93         struct stack_frame bufhead[2];
  94         unsigned long bytes;
  95
  96         bytes = copy_from_user_nmi(bufhead, head, sizeof(bufhead));
  97         if (bytes != 0)
  98                 return NULL;
  99
 100         oprofile_add_trace(bufhead[0].return_address);
 101
 102         /* frame pointers should strictly progress back up the stack
 103          * (towards higher addresses) */
 104         if (head >= bufhead[0].next_frame)
 105                 return NULL;
 106
 107         return bufhead[0].next_frame;
 108 }
 109
 110 void
 111 x86_backtrace(struct pt_regs * const regs, unsigned int depth)
 112 {
 113         struct stack_frame *head = (struct stack_frame *)frame_pointer(regs);
 114
 115         if (!user_mode(regs)) {
 116                 unsigned long stack = kernel_stack_pointer(regs);
 117                 if (depth)
 118                         dump_trace(NULL, regs, (unsigned long *)stack, 0,
 119                                    &backtrace_ops, &depth);
 120                 return;
 121         }
 122
 123         if (x86_backtrace_32(regs, depth))
 124                 return;
 125
 126         while (depth-- && head)
 127                 head = dump_user_backtrace(head);
 128 }