Home | History | Annotate | Line # | Download | only in gdb
alpha-obsd-tdep.c revision 1.1.1.4 
      1 /* Target-dependent code for OpenBSD/alpha.
      2 
      3    Copyright (C) 2006-2023 Free Software Foundation, Inc.
      4 
      5    This file is part of GDB.
      6 
      7    This program is free software; you can redistribute it and/or modify
      8    it under the terms of the GNU General Public License as published by
      9    the Free Software Foundation; either version 3 of the License, or
     10    (at your option) any later version.
     11 
     12    This program is distributed in the hope that it will be useful,
     13    but WITHOUT ANY WARRANTY; without even the implied warranty of
     14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
     15    GNU General Public License for more details.
     16 
     17    You should have received a copy of the GNU General Public License
     18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
     19 
     20 #include "defs.h"
     21 #include "frame.h"
     22 #include "gdbcore.h"
     23 #include "osabi.h"
     24 
     25 #include "obsd-tdep.h"
     26 #include "alpha-tdep.h"
     27 #include "alpha-bsd-tdep.h"
     28 #include "solib-svr4.h"
     29 
     30 /* Signal trampolines.  */
     31 
     32 /* The OpenBSD kernel maps the signal trampoline at some random
     33    location in user space, which means that the traditional BSD way of
     34    detecting it won't work.
     35 
     36    The signal trampoline will be mapped at an address that is page
     37    aligned.  We recognize the signal trampoline by looking for the
     38    sigreturn system call.  */
     39 
     40 static const int alphaobsd_page_size = 8192;
     41 
     42 static LONGEST
     43 alphaobsd_sigtramp_offset (struct gdbarch *gdbarch, CORE_ADDR pc)
     44 {
     45   return (pc & (alphaobsd_page_size - 1));
     46 }
     47 
     48 static int
     49 alphaobsd_pc_in_sigtramp (struct gdbarch *gdbarch,
     50 			  CORE_ADDR pc, const char *name)
     51 {
     52   CORE_ADDR start_pc = (pc & ~(alphaobsd_page_size - 1));
     53   unsigned insn;
     54 
     55   if (name)
     56     return 0;
     57 
     58   /* Check for "".  */
     59   insn = alpha_read_insn (gdbarch, start_pc + 5 * ALPHA_INSN_SIZE);
     60   if (insn != 0x201f0067)
     61     return 0;
     62 
     63   /* Check for "".  */
     64   insn = alpha_read_insn (gdbarch, start_pc + 6 * ALPHA_INSN_SIZE);
     65   if (insn != 0x00000083)
     66     return 0;
     67 
     68   return 1;
     69 }
     70 
     71 static CORE_ADDR
     72 alphaobsd_sigcontext_addr (frame_info_ptr this_frame)
     73 {
     74   struct gdbarch *gdbarch = get_frame_arch (this_frame);
     75   CORE_ADDR pc = get_frame_pc (this_frame);
     76 
     77   if (alphaobsd_sigtramp_offset (gdbarch, pc) < 3 * ALPHA_INSN_SIZE)
     78     {
     79       /* On entry, a pointer the `struct sigcontext' is passed in %a2.  */
     80       return get_frame_register_unsigned (this_frame, ALPHA_A0_REGNUM + 2);
     81     }
     82   else if (alphaobsd_sigtramp_offset (gdbarch, pc) < 4 * ALPHA_INSN_SIZE)
     83     {
     84       /* It is stored on the stack Before calling the signal handler.  */
     85       CORE_ADDR sp;
     86       sp = get_frame_register_unsigned (this_frame, ALPHA_SP_REGNUM);
     87       return get_frame_memory_unsigned (this_frame, sp, 8);
     88     }
     89   else
     90     {
     91       /* It is reloaded into %a0 for the sigreturn(2) call.  */
     92       return get_frame_register_unsigned (this_frame, ALPHA_A0_REGNUM);
     93     }
     94 }
     95 
     96 
     98 static void
     99 alphaobsd_init_abi(struct gdbarch_info info, struct gdbarch *gdbarch)
    100 {
    101   alpha_gdbarch_tdep *tdep = gdbarch_tdep<alpha_gdbarch_tdep> (gdbarch);
    102 
    103   /* Hook into the DWARF CFI frame unwinder.  */
    104   alpha_dwarf2_init_abi (info, gdbarch);
    105 
    106   /* Hook into the MDEBUG frame unwinder.  */
    107   alpha_mdebug_init_abi (info, gdbarch);
    108 
    109   /* OpenBSD/alpha 3.0 and earlier does not provide single step
    110      support via ptrace(2); use software single-stepping for now.  */
    111   set_gdbarch_software_single_step (gdbarch, alpha_software_single_step);
    112 
    113   /* OpenBSD/alpha has SVR4-style shared libraries.  */
    114   set_solib_svr4_fetch_link_map_offsets
    115     (gdbarch, svr4_lp64_fetch_link_map_offsets);
    116   set_gdbarch_skip_solib_resolver (gdbarch, obsd_skip_solib_resolver);
    117 
    118   tdep->dynamic_sigtramp_offset = alphaobsd_sigtramp_offset;
    119   tdep->pc_in_sigtramp = alphaobsd_pc_in_sigtramp;
    120   tdep->sigcontext_addr = alphaobsd_sigcontext_addr;
    121 
    122   tdep->jb_pc = 2;
    123   tdep->jb_elt_size = 8;
    124 
    125   set_gdbarch_iterate_over_regset_sections
    126     (gdbarch, alphanbsd_iterate_over_regset_sections);
    127 }
    128 
    129 
    131 void _initialize_alphaobsd_tdep ();
    132 void
    133 _initialize_alphaobsd_tdep ()
    134 {
    135   gdbarch_register_osabi (bfd_arch_alpha, 0, GDB_OSABI_OPENBSD,
    136 			  alphaobsd_init_abi);
    137 }
    138