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 <asm/ptrace.h>
  15 #include <asm/uaccess.h>
  16 #include <asm/stacktrace.h>
  17
  18 static void backtrace_warning_symbol(void *data, char *msg,
  19                                      unsigned long symbol)
  20 {
  21         /* Ignore warnings */
  22 }
  23
  24 static void backtrace_warning(void *data, char *msg)
  25 {
  26         /* Ignore warnings */
  27 }
  28
  29 static int backtrace_stack(void *data, char *name)
  30 {
  31         /* Yes, we want all stacks */
  32         return 0;
  33 }
  34
  35 static void backtrace_address(void *data, unsigned long addr, int reliable)
  36 {
  37         unsigned int *depth = data;
  38
  39         if ((*depth)--)
  40                 oprofile_add_trace(addr);
  41 }
  42
  43 static struct stacktrace_ops backtrace_ops = {
  44         .warning = backtrace_warning,
  45         .warning_symbol = backtrace_warning_symbol,
  46         .stack = backtrace_stack,
  47         .address = backtrace_address,
  48 };
  49
  50 struct frame_head {
  51         struct frame_head *bp;
  52         unsigned long ret;
  53 } __attribute__((packed));
  54
  55 static struct frame_head *dump_user_backtrace(struct frame_head *head)
  56 {
  57         struct frame_head bufhead[2];
  58
  59         /* Also check accessibility of one struct frame_head beyond */
  60         if (!access_ok(VERIFY_READ, head, sizeof(bufhead)))
  61                 return NULL;
  62         if (__copy_from_user_inatomic(bufhead, head, sizeof(bufhead)))
  63                 return NULL;
  64
  65         oprofile_add_trace(bufhead[0].ret);
  66
  67         /* frame pointers should strictly progress back up the stack
  68          * (towards higher addresses) */
  69         if (head >= bufhead[0].bp)
  70                 return NULL;
  71
  72         return bufhead[0].bp;
  73 }
  74
  75 void
  76 x86_backtrace(struct pt_regs * const regs, unsigned int depth)
  77 {
  78         struct frame_head *head = (struct frame_head *)frame_pointer(regs);
  79
  80         if (!user_mode_vm(regs)) {
  81                 unsigned long stack = kernel_stack_pointer(regs);
  82                 if (depth)
  83                         dump_trace(NULL, regs, (unsigned long *)stack, 0,
  84                                    &backtrace_ops, &depth);
  85                 return;
  86         }
  87
  88         while (depth-- && head)
  89                 head = dump_user_backtrace(head);
  90 }