sysdeps/microblaze/backtrace_linux.c

   1 /* Copyright (C) 2005-2016 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 <stddef.h>
  20 #include <asm/sigcontext.h>
  21 #include <linux/signal.h>
  22 #include <asm-generic/ucontext.h>
  23 #include <asm/unistd.h>
  24
  25 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   unsigned long *tramp = 0;
  31   struct ucontext *uc;
  32
  33   if (*retaddr == 0)
  34     {
  35       /* Kernel inserts the tramp between the signal handler frame and the
  36          caller frame in signal handling.  */
  37       tramp = (unsigned long *) pc;
  38       tramp += 2;
  39       if ((*tramp == (0x31800000 | __NR_rt_sigreturn))
  40           && (*(tramp+1) == 0xb9cc0008))
  41         {
  42           /* Signal handler function argument are:
  43              int sig_num, siginfo_t * info, void * ucontext
  44              therefore ucontext is the 3rd argument.  */
  45           unsigned long ucptr = ((unsigned long) tramp
  46                                  - sizeof (struct ucontext));
  47           uc = (struct ucontext *) ucptr;
  48           *pprev_pc = uc->uc_mcontext.regs.pc;
  49           /* Need to record the return address since the return address of the
  50              function which causes this signal may not be recorded in the
  51              stack.  */
  52           *pprev_fp = uc->uc_mcontext.regs.r1;
  53           *retaddr = uc->uc_mcontext.regs.r15;
  54           /* It is a signal handler.  */
  55           return 1;
  56         }
  57     }
  58   return 0;
  59 }