sysdeps/microblaze/backtrace.c

   1 /* Copyright (C) 2005-2024 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    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <sysdep.h>
  23 #include <signal.h>
  24 #include <execinfo.h>
  25
  26 extern int
  27 _identify_sighandler (unsigned long fp, unsigned long pc,
  28                       unsigned long *pprev_fp, unsigned long *pprev_pc,
  29                       unsigned long *retaddr);
  30
  31 static inline long
  32 get_frame_size (unsigned long instr)
  33 {
  34   return abs ((short signed) (instr & 0xFFFF));
  35 }
  36
  37 static unsigned long *
  38 find_frame_creation (unsigned long *pc)
  39 {
  40   int i;
  41
  42   /* NOTE: Distance to search is arbitrary.
  43      250 works well for most things,
  44      750 picks up things like tcp_recvmsg,
  45      1000 needed for fat_fill_super.  */
  46   for (i = 0; i < 1000; i++, pc--)
  47     {
  48       unsigned long instr;
  49       unsigned long frame_size;
  50
  51       instr = *pc;
  52
  53       /* Is the instruction of the form
  54          addik r1, r1, foo ? */
  55       if ((instr & 0xFFFF0000) != 0x30210000)
  56         continue;
  57
  58       frame_size = get_frame_size (instr);
  59
  60       if ((frame_size < 8) || (frame_size & 3))
  61         return NULL;
  62
  63       return pc;
  64     }
  65   return NULL;
  66 }
  67
  68 static int
  69 lookup_prev_stack_frame (unsigned long fp, unsigned long pc,
  70                          unsigned long *pprev_fp, unsigned long *pprev_pc,
  71                          unsigned long *retaddr)
  72 {
  73   unsigned long *prologue = NULL;
  74
  75   int is_signalhandler = _identify_sighandler (fp, pc, pprev_fp,
  76                                                pprev_pc, retaddr);
  77
  78   if (!is_signalhandler)
  79     {
  80       prologue = find_frame_creation ((unsigned long *) pc);
  81
  82       if (prologue)
  83         {
  84           long frame_size = get_frame_size (*prologue);
  85           *pprev_fp = fp + frame_size;
  86           if (*retaddr != 0)
  87             *pprev_pc = *retaddr;
  88           else
  89             *pprev_pc = *(unsigned long *) fp;
  90
  91           *retaddr = 0;
  92           if (!*pprev_pc || (*pprev_pc & 3))
  93             prologue=0;
  94         }
  95       else
  96         {
  97           *pprev_pc = 0;
  98           *pprev_fp = fp;
  99           *retaddr = 0;
 100         }
 101     }
 102     return (!*pprev_pc || (*pprev_pc & 3)) ? -1 : 0;
 103 }
 104
 105 int
 106 __backtrace (void **array, int size)
 107 {
 108   unsigned long pc, fp;
 109   unsigned long ppc, pfp;
 110   /* Return address(r15) is required in the signal handler case, since the
 111      return address of the function which causes the signal may not be
 112      recorded in the stack.  */
 113   unsigned long retaddr;
 114
 115   int count;
 116   int rc = 0;
 117
 118   if (size <= 0)
 119     return 0;
 120
 121   __asm__ __volatile__ ("mfs %0, rpc"
 122                         : "=r"(pc));
 123
 124   __asm__ __volatile__ ("add %0, r1, r0"
 125                         : "=r"(fp));
 126
 127   array[0] = (void *) pc;
 128   retaddr = 0;
 129   for (count = 1; count < size; count++)
 130     {
 131       rc = lookup_prev_stack_frame (fp, pc, &pfp, &ppc, &retaddr);
 132
 133       fp = pfp;
 134       pc = ppc;
 135       array[count] = (void *) pc;
 136       if (rc)
 137         return count;
 138     }
 139   return count;
 140 }
 141
 142 weak_alias (__backtrace, backtrace)
 143 libc_hidden_def (__backtrace)