sysdeps/microblaze/backtrace.c

   1 /* Copyright (C) 2005-2015 Free Software Foundation, Inc.
   2
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <string.h>
  21 #include <sysdep.h>
  22 #include <signal.h>
  23 #include <execinfo.h>
  24
  25 extern int
  26 _identify_sighandler (unsigned long fp, unsigned long pc,
  27                       unsigned long *pprev_fp, unsigned long *pprev_pc,
  28                       unsigned long *retaddr);
  29
  30 inline long
  31 get_frame_size (unsigned long instr)
  32 {
  33   return abs ((short signed) (instr & 0xFFFF));
  34 }
  35
  36 static unsigned long *
  37 find_frame_creation (unsigned long *pc)
  38 {
  39   int i;
  40
  41   /* NOTE: Distance to search is arbitrary.
  42      250 works well for most things,
  43      750 picks up things like tcp_recvmsg,
  44      1000 needed for fat_fill_super.  */
  45   for (i = 0; i < 1000; i++, pc--)
  46     {
  47       unsigned long instr;
  48       unsigned long frame_size;
  49
  50       instr = *pc;
  51
  52       /* Is the instruction of the form
  53          addik r1, r1, foo ? */
  54       if ((instr & 0xFFFF0000) != 0x30210000)
  55         continue;
  56
  57       frame_size = get_frame_size (instr);
  58
  59       if ((frame_size < 8) || (frame_size & 3))
  60         return NULL;
  61
  62       return pc;
  63     }
  64   return NULL;
  65 }
  66
  67 static int
  68 lookup_prev_stack_frame (unsigned long fp, unsigned long pc,
  69                          unsigned long *pprev_fp, unsigned long *pprev_pc,
  70                          unsigned long *retaddr)
  71 {
  72   unsigned long *prologue = NULL;
  73
  74   int is_signalhandler = _identify_sighandler (fp, pc, pprev_fp,
  75                                                pprev_pc, retaddr);
  76
  77   if (!is_signalhandler)
  78     {
  79       prologue = find_frame_creation ((unsigned long *) pc);
  80
  81       if (prologue)
  82         {
  83           long frame_size = get_frame_size (*prologue);
  84           *pprev_fp = fp + frame_size;
  85           if (*retaddr != 0)
  86             *pprev_pc = *retaddr;
  87           else
  88             *pprev_pc = *(unsigned long *) fp;
  89
  90           *retaddr = 0;
  91           if (!*pprev_pc || (*pprev_pc & 3))
  92             prologue=0;
  93         }
  94       else
  95         {
  96           *pprev_pc = 0;
  97           *pprev_fp = fp;
  98           *retaddr = 0;
  99         }
 100     }
 101     return (!*pprev_pc || (*pprev_pc & 3)) ? -1 : 0;
 102 }
 103
 104 int
 105 __backtrace (void **array, int size)
 106 {
 107   unsigned long pc, fp;
 108   unsigned long ppc, pfp;
 109   /* Return address(r15) is required in the signal handler case, since the
 110      return address of the function which causes the signal may not be
 111      recorded in the stack.  */
 112   unsigned long retaddr;
 113
 114   int count;
 115   int rc = 0;
 116
 117   __asm__ __volatile__ ("mfs %0, rpc"
 118                         : "=r"(pc));
 119
 120   __asm__ __volatile__ ("add %0, r1, r0"
 121                         : "=r"(fp));
 122
 123   array[0] = (void *) pc;
 124   retaddr = 0;
 125   for (count = 1; count < size; count++)
 126     {
 127       rc = lookup_prev_stack_frame (fp, pc, &pfp, &ppc, &retaddr);
 128
 129       fp = pfp;
 130       pc = ppc;
 131       array[count] = (void *) pc;
 132       if (rc)
 133         return count;
 134     }
 135   return count;
 136 }
 137
 138 weak_alias (__backtrace, backtrace)
 139 libc_hidden_def (__backtrace)