1# This shell script emits a C file. -*- C -*-
2#   Copyright 2006
3#   Free Software Foundation, Inc.
4#
5# This file is part of GLD, the Gnu Linker.
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 2 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, write to the Free Software
19# Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston, 
20# MA 02110-1301 USA.
21
22# This file is sourced from elf32.em, and defines extra avr-elf
23# specific routines.  It is used to generate the trampolines for the avr6
24# family devices where one needs to address the issue that it is not possible
25# to reach the whole program memory by using 16 bit pointers.
26
27cat >>e${EMULATION_NAME}.c <<EOF
28
29#include "elf32-avr.h"
30#include "ldctor.h"
31
32/* The fake file and it's corresponding section meant to hold 
33   the linker stubs if needed.  */
34
35static lang_input_statement_type *stub_file;
36static asection *avr_stub_section;
37
38/* Variables set by the command-line parameters and transfered
39   to the bfd without use of global shared variables.  */
40
41static bfd_boolean avr_no_stubs = FALSE;
42static bfd_boolean avr_debug_relax = FALSE;
43static bfd_boolean avr_debug_stubs = FALSE;
44static bfd_boolean avr_replace_call_ret_sequences = TRUE;
45static bfd_vma avr_pc_wrap_around = 0x10000000;
46
47/* Transfers information to the bfd frontend.  */
48
49static void
50avr_elf_set_global_bfd_parameters (void)
51{
52  elf32_avr_setup_params (& link_info,
53                          stub_file->the_bfd,
54                          avr_stub_section,
55                          avr_no_stubs,
56                          avr_debug_stubs,
57                          avr_debug_relax,
58                          avr_pc_wrap_around,
59                          avr_replace_call_ret_sequences);
60}
61
62
63/* Makes a conservative estimate of the trampoline section size that could
64   be corrected later on.  */
65
66static void
67avr_elf_${EMULATION_NAME}_before_allocation (void)
68{
69  int ret;
70
71  gld${EMULATION_NAME}_before_allocation ();
72
73  /* We only need stubs for the avr6 family.  */
74  if (strcmp ("${EMULATION_NAME}","avr6"))
75    avr_no_stubs = TRUE;
76
77  avr_elf_set_global_bfd_parameters ();
78
79  /* If generating a relocatable output file, then
80     we don't  have to generate the trampolines.  */
81  if (link_info.relocatable)
82    avr_no_stubs = TRUE;
83
84  if (avr_no_stubs)
85    return;
86
87  ret = elf32_avr_setup_section_lists (output_bfd, &link_info);
88
89  if (ret < 0)
90    einfo ("%X%P: can not setup the input section list: %E\n");
91
92  if (ret <= 0)
93    return;
94
95  /* Call into the BFD backend to do the real "stub"-work.  */
96  if (! elf32_avr_size_stubs (output_bfd, &link_info, TRUE))
97    einfo ("%X%P: can not size stub section: %E\n");
98}
99
100/* This is called before the input files are opened.  We create a new
101   fake input file to hold the stub section and generate the section itself.  */
102
103static void
104avr_elf_create_output_section_statements (void)
105{
106  flagword flags;
107
108  stub_file = lang_add_input_file ("linker stubs",
109                                   lang_input_file_is_fake_enum,
110                                   NULL);
111
112  stub_file->the_bfd = bfd_create ("linker stubs", output_bfd);
113  if (stub_file->the_bfd == NULL
114      || !bfd_set_arch_mach (stub_file->the_bfd,
115                             bfd_get_arch (output_bfd),
116                             bfd_get_mach (output_bfd)))
117    {
118      einfo ("%X%P: can not create stub BFD %E\n");
119      return;
120    }
121
122  /* Now we add the stub section.  */
123
124  avr_stub_section = bfd_make_section_anyway (stub_file->the_bfd,
125                                              ".trampolines");
126  if (avr_stub_section == NULL)
127    goto err_ret;
128  
129  flags = (SEC_ALLOC | SEC_LOAD | SEC_READONLY | SEC_CODE
130           | SEC_HAS_CONTENTS | SEC_RELOC | SEC_IN_MEMORY | SEC_KEEP);
131  if (!bfd_set_section_flags (stub_file->the_bfd, avr_stub_section, flags))
132    goto err_ret;
133
134  avr_stub_section->alignment_power = 1;
135  
136  ldlang_add_file (stub_file);
137
138  return;
139
140  err_ret:
141   einfo ("%X%P: can not make stub section: %E\n");
142   return;
143}
144
145/* Re-calculates the size of the stubs so that we won't waste space.  */
146
147static void
148avr_elf_finish (void)
149{ 
150  if (!avr_no_stubs)
151    {
152      /* Now build the linker stubs.  */
153      if (stub_file->the_bfd->sections != NULL)
154       {
155         /* Call again the trampoline analyzer to initialize the trampoline
156            stubs with the correct symbol addresses.  Since there could have
157            been relaxation, the symbol addresses that were found during
158            first call may no longer be correct.  */
159         if (!elf32_avr_size_stubs (output_bfd, &link_info, FALSE))
160           {
161             einfo ("%X%P: can not size stub section: %E\n");
162             return;
163           }
164
165         if (!elf32_avr_build_stubs (&link_info))
166           einfo ("%X%P: can not build stubs: %E\n");
167       }
168    }
169
170  gld${EMULATION_NAME}_finish ();
171}
172
173
174EOF
175
176
177PARSE_AND_LIST_PROLOGUE='
178
179#define OPTION_NO_CALL_RET_REPLACEMENT 301
180#define OPTION_PMEM_WRAP_AROUND        302
181#define OPTION_NO_STUBS                303
182#define OPTION_DEBUG_STUBS             304
183#define OPTION_DEBUG_RELAX             305
184'
185
186PARSE_AND_LIST_LONGOPTS='
187  { "no-call-ret-replacement", no_argument, 
188     NULL, OPTION_NO_CALL_RET_REPLACEMENT},
189  { "pmem-wrap-around", required_argument, 
190    NULL, OPTION_PMEM_WRAP_AROUND},
191  { "no-stubs", no_argument, 
192    NULL, OPTION_NO_STUBS},
193  { "debug-stubs", no_argument, 
194    NULL, OPTION_DEBUG_STUBS},
195  { "debug-relax", no_argument, 
196    NULL, OPTION_DEBUG_RELAX},
197'
198
199PARSE_AND_LIST_OPTIONS='
200  fprintf (file, _("     --pmem-wrap-around=<val> "
201                           "Make the linker relaxation machine assume that a\n"
202                   "                              "
203                           "program counter wrap-around occures at address\n"
204                   "                              "
205                           "<val>. Supported values are 8k, 16k, 32k and 64k.\n"));
206  fprintf (file, _("     --no-call-ret-replacement "
207                           "The relaxation machine normally will\n"
208                   "                               "
209                           "substitute two immediately following call/ret\n"
210                   "                               "
211                           "instructions by a single jump instruction.\n"
212                   "                               "
213                           "This option disables this optimization.\n"));
214  fprintf (file, _("     --no-stubs "
215                           "If the linker detects to attempt to access\n"
216                   "                               "
217                           "an instruction beyond 128k by a reloc that\n"
218                   "                               "
219                           "is limited to 128k max, it inserts a jump\n"
220                   "                               "
221                           "stub. You can de-active this with this switch.\n"));
222  fprintf (file, _("     --debug-stubs Used for debugging avr-ld.\n"));
223  fprintf (file, _("     --debug-relax Used for debugging avr-ld.\n"));
224'
225
226PARSE_AND_LIST_ARGS_CASES='
227
228    case OPTION_PMEM_WRAP_AROUND:
229      { 
230        /* This variable is defined in the bfd library.  */
231        if ((!strcmp (optarg,"32k"))      || (!strcmp (optarg,"32K")))
232          avr_pc_wrap_around = 32768;
233        else if ((!strcmp (optarg,"8k")) || (!strcmp (optarg,"8K")))
234          avr_pc_wrap_around = 8192;
235        else if ((!strcmp (optarg,"16k")) || (!strcmp (optarg,"16K")))
236          avr_pc_wrap_around = 16384;
237        else if ((!strcmp (optarg,"64k")) || (!strcmp (optarg,"64K")))
238          avr_pc_wrap_around = 0x10000;
239        else
240          return FALSE;
241      }
242      break;
243
244    case OPTION_DEBUG_STUBS:
245      avr_debug_stubs = TRUE;
246      break;
247
248    case OPTION_DEBUG_RELAX:
249      avr_debug_relax = TRUE;
250      break;
251
252    case OPTION_NO_STUBS:
253      avr_no_stubs = TRUE;
254      break;
255
256    case OPTION_NO_CALL_RET_REPLACEMENT:
257      {
258        /* This variable is defined in the bfd library.  */
259        avr_replace_call_ret_sequences = FALSE;
260      }
261      break;
262'
263
264#
265# Put these extra avr-elf routines in ld_${EMULATION_NAME}_emulation
266#
267LDEMUL_BEFORE_ALLOCATION=avr_elf_${EMULATION_NAME}_before_allocation
268LDEMUL_FINISH=avr_elf_finish
269LDEMUL_CREATE_OUTPUT_SECTION_STATEMENTS=avr_elf_create_output_section_statements
270