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