1/* Target-dependent code for Windows CE running on ARM processors,
2   for GDB.
3
4   Copyright (C) 2007-2020 Free Software Foundation, Inc.
5
6   This file is part of GDB.
7
8   This program is free software; you can redistribute it and/or modify
9   it under the terms of the GNU General Public License as published by
10   the Free Software Foundation; either version 3 of the License, or
11   (at your option) any later version.
12
13   This program is distributed in the hope that it will be useful,
14   but WITHOUT ANY WARRANTY; without even the implied warranty of
15   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16   GNU General Public License for more details.
17
18   You should have received a copy of the GNU General Public License
19   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
20
21#include "defs.h"
22#include "osabi.h"
23#include "gdbcore.h"
24#include "target.h"
25#include "frame.h"
26
27#include "arch/arm.h"
28#include "arm-tdep.h"
29#include "windows-tdep.h"
30
31static const gdb_byte arm_wince_le_breakpoint[] = { 0x10, 0x00, 0x00, 0xe6 };
32static const gdb_byte arm_wince_thumb_le_breakpoint[] = { 0xfe, 0xdf };
33
34/* Description of the longjmp buffer.  */
35#define ARM_WINCE_JB_ELEMENT_SIZE	ARM_INT_REGISTER_SIZE
36#define ARM_WINCE_JB_PC			10
37
38static CORE_ADDR
39arm_pe_skip_trampoline_code (struct frame_info *frame, CORE_ADDR pc)
40{
41  struct gdbarch *gdbarch = get_frame_arch (frame);
42  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
43  ULONGEST indirect;
44  struct bound_minimal_symbol indsym;
45  const char *symname;
46  CORE_ADDR next_pc;
47
48  /* The format of an ARM DLL trampoline is:
49
50       ldr  ip, [pc]
51       ldr  pc, [ip]
52       .dw __imp_<func>
53
54  */
55
56  if (pc == 0
57      || read_memory_unsigned_integer (pc + 0, 4, byte_order) != 0xe59fc000
58      || read_memory_unsigned_integer (pc + 4, 4, byte_order) != 0xe59cf000)
59    return 0;
60
61  indirect = read_memory_unsigned_integer (pc + 8, 4, byte_order);
62  if (indirect == 0)
63    return 0;
64
65  indsym = lookup_minimal_symbol_by_pc (indirect);
66  if (indsym.minsym == NULL)
67    return 0;
68
69  symname = indsym.minsym->linkage_name ();
70  if (symname == NULL || !startswith (symname, "__imp_"))
71    return 0;
72
73  next_pc = read_memory_unsigned_integer (indirect, 4, byte_order);
74  if (next_pc != 0)
75    return next_pc;
76
77  /* Check with the default arm gdbarch_skip_trampoline.  */
78  return arm_skip_stub (frame, pc);
79}
80
81/* GCC emits a call to __gccmain in the prologue of main.
82
83   The function below examines the code pointed at by PC and checks to
84   see if it corresponds to a call to __gccmain.  If so, it returns
85   the address of the instruction following that call.  Otherwise, it
86   simply returns PC.  */
87
88static CORE_ADDR
89arm_wince_skip_main_prologue (struct gdbarch *gdbarch, CORE_ADDR pc)
90{
91  enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
92  ULONGEST this_instr;
93
94  this_instr = read_memory_unsigned_integer (pc, 4, byte_order);
95
96  /* bl offset <__gccmain> */
97  if ((this_instr & 0xfff00000) == 0xeb000000)
98    {
99#define sign_extend(V, N) \
100  (((long) (V) ^ (1L << ((N) - 1))) - (1L << ((N) - 1)))
101
102      long offset = sign_extend (this_instr & 0x000fffff, 23) << 2;
103      CORE_ADDR call_dest = (pc + 8 + offset) & 0xffffffffU;
104      struct bound_minimal_symbol s = lookup_minimal_symbol_by_pc (call_dest);
105
106      if (s.minsym != NULL
107	  && s.minsym->linkage_name () != NULL
108	  && strcmp (s.minsym->linkage_name (), "__gccmain") == 0)
109	pc += 4;
110    }
111
112  return pc;
113}
114
115static void
116arm_wince_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
117{
118  struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
119
120  windows_init_abi (info, gdbarch);
121
122  tdep->arm_breakpoint = arm_wince_le_breakpoint;
123  tdep->arm_breakpoint_size = sizeof (arm_wince_le_breakpoint);
124  tdep->thumb_breakpoint = arm_wince_thumb_le_breakpoint;
125  tdep->thumb_breakpoint_size = sizeof (arm_wince_thumb_le_breakpoint);
126  tdep->struct_return = pcc_struct_return;
127
128  tdep->fp_model = ARM_FLOAT_SOFT_VFP;
129
130  tdep->jb_pc = ARM_WINCE_JB_PC;
131  tdep->jb_elt_size = ARM_WINCE_JB_ELEMENT_SIZE;
132
133  /* On ARM WinCE char defaults to signed.  */
134  set_gdbarch_char_signed (gdbarch, 1);
135
136  /* Shared library handling.  */
137  set_gdbarch_skip_trampoline_code (gdbarch, arm_pe_skip_trampoline_code);
138
139  /* Single stepping.  */
140  set_gdbarch_software_single_step (gdbarch, arm_software_single_step);
141
142  /* Skip call to __gccmain that gcc places in main.  */
143  set_gdbarch_skip_main_prologue (gdbarch, arm_wince_skip_main_prologue);
144}
145
146static enum gdb_osabi
147arm_wince_osabi_sniffer (bfd *abfd)
148{
149  const char *target_name = bfd_get_target (abfd);
150
151  if (strcmp (target_name, "pei-arm-wince-little") == 0)
152    return GDB_OSABI_WINCE;
153
154  return GDB_OSABI_UNKNOWN;
155}
156
157void _initialize_arm_wince_tdep ();
158void
159_initialize_arm_wince_tdep ()
160{
161  gdbarch_register_osabi_sniffer (bfd_arch_arm, bfd_target_coff_flavour,
162                                  arm_wince_osabi_sniffer);
163
164  gdbarch_register_osabi (bfd_arch_arm, 0, GDB_OSABI_WINCE,
165                          arm_wince_init_abi);
166}
167