1 /* Motorola m68k target-dependent support for GNU/Linux.
2
3 Copyright (C) 1996-2021 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 "gdbcore.h"
22 #include "frame.h"
23 #include "target.h"
24 #include "gdbtypes.h"
25 #include "osabi.h"
26 #include "regcache.h"
27 #include "objfiles.h"
28 #include "symtab.h"
29 #include "m68k-tdep.h"
30 #include "trad-frame.h"
31 #include "frame-unwind.h"
32 #include "glibc-tdep.h"
33 #include "solib-svr4.h"
34 #include "auxv.h"
35 #include "observable.h"
36 #include "elf/common.h"
37 #include "linux-tdep.h"
38 #include "regset.h"
39
40 /* Offsets (in target ints) into jmp_buf. */
41
42 #define M68K_LINUX_JB_ELEMENT_SIZE 4
43 #define M68K_LINUX_JB_PC 7
44
45 /* Check whether insn1 and insn2 are parts of a signal trampoline. */
46
47 #define IS_SIGTRAMP(insn1, insn2) \
48 (/* addaw #20,sp; moveq #119,d0; trap #0 */ \
49 (insn1 == 0xdefc0014 && insn2 == 0x70774e40) \
50 /* moveq #119,d0; trap #0 */ \
51 || insn1 == 0x70774e40)
52
53 #define IS_RT_SIGTRAMP(insn1, insn2) \
54 (/* movel #173,d0; trap #0 */ \
55 (insn1 == 0x203c0000 && insn2 == 0x00ad4e40) \
56 /* moveq #82,d0; notb d0; trap #0 */ \
57 || (insn1 == 0x70524600 && (insn2 >> 16) == 0x4e40))
58
59 /* Return non-zero if THIS_FRAME corresponds to a signal trampoline. For
60 the sake of m68k_linux_get_sigtramp_info we also distinguish between
61 non-RT and RT signal trampolines. */
62
63 static int
m68k_linux_pc_in_sigtramp(struct frame_info * this_frame)64 m68k_linux_pc_in_sigtramp (struct frame_info *this_frame)
65 {
66 struct gdbarch *gdbarch = get_frame_arch (this_frame);
67 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
68 gdb_byte buf[12];
69 unsigned long insn0, insn1, insn2;
70 CORE_ADDR pc = get_frame_pc (this_frame);
71
72 if (!safe_frame_unwind_memory (this_frame, pc - 4, {buf, sizeof (buf)}))
73 return 0;
74 insn1 = extract_unsigned_integer (buf + 4, 4, byte_order);
75 insn2 = extract_unsigned_integer (buf + 8, 4, byte_order);
76 if (IS_SIGTRAMP (insn1, insn2))
77 return 1;
78 if (IS_RT_SIGTRAMP (insn1, insn2))
79 return 2;
80
81 insn0 = extract_unsigned_integer (buf, 4, byte_order);
82 if (IS_SIGTRAMP (insn0, insn1))
83 return 1;
84 if (IS_RT_SIGTRAMP (insn0, insn1))
85 return 2;
86
87 insn0 = ((insn0 << 16) & 0xffffffff) | (insn1 >> 16);
88 insn1 = ((insn1 << 16) & 0xffffffff) | (insn2 >> 16);
89 if (IS_SIGTRAMP (insn0, insn1))
90 return 1;
91 if (IS_RT_SIGTRAMP (insn0, insn1))
92 return 2;
93
94 return 0;
95 }
96
97 /* From <asm/sigcontext.h>. */
98 static int m68k_linux_sigcontext_reg_offset[M68K_NUM_REGS] =
99 {
100 2 * 4, /* %d0 */
101 3 * 4, /* %d1 */
102 -1, /* %d2 */
103 -1, /* %d3 */
104 -1, /* %d4 */
105 -1, /* %d5 */
106 -1, /* %d6 */
107 -1, /* %d7 */
108 4 * 4, /* %a0 */
109 5 * 4, /* %a1 */
110 -1, /* %a2 */
111 -1, /* %a3 */
112 -1, /* %a4 */
113 -1, /* %a5 */
114 -1, /* %fp */
115 1 * 4, /* %sp */
116 6 * 4, /* %sr */
117 6 * 4 + 2, /* %pc */
118 8 * 4, /* %fp0 */
119 11 * 4, /* %fp1 */
120 -1, /* %fp2 */
121 -1, /* %fp3 */
122 -1, /* %fp4 */
123 -1, /* %fp5 */
124 -1, /* %fp6 */
125 -1, /* %fp7 */
126 14 * 4, /* %fpcr */
127 15 * 4, /* %fpsr */
128 16 * 4 /* %fpiaddr */
129 };
130
131 static int m68k_uclinux_sigcontext_reg_offset[M68K_NUM_REGS] =
132 {
133 2 * 4, /* %d0 */
134 3 * 4, /* %d1 */
135 -1, /* %d2 */
136 -1, /* %d3 */
137 -1, /* %d4 */
138 -1, /* %d5 */
139 -1, /* %d6 */
140 -1, /* %d7 */
141 4 * 4, /* %a0 */
142 5 * 4, /* %a1 */
143 -1, /* %a2 */
144 -1, /* %a3 */
145 -1, /* %a4 */
146 6 * 4, /* %a5 */
147 -1, /* %fp */
148 1 * 4, /* %sp */
149 7 * 4, /* %sr */
150 7 * 4 + 2, /* %pc */
151 -1, /* %fp0 */
152 -1, /* %fp1 */
153 -1, /* %fp2 */
154 -1, /* %fp3 */
155 -1, /* %fp4 */
156 -1, /* %fp5 */
157 -1, /* %fp6 */
158 -1, /* %fp7 */
159 -1, /* %fpcr */
160 -1, /* %fpsr */
161 -1 /* %fpiaddr */
162 };
163
164 /* From <asm/ucontext.h>. */
165 static int m68k_linux_ucontext_reg_offset[M68K_NUM_REGS] =
166 {
167 6 * 4, /* %d0 */
168 7 * 4, /* %d1 */
169 8 * 4, /* %d2 */
170 9 * 4, /* %d3 */
171 10 * 4, /* %d4 */
172 11 * 4, /* %d5 */
173 12 * 4, /* %d6 */
174 13 * 4, /* %d7 */
175 14 * 4, /* %a0 */
176 15 * 4, /* %a1 */
177 16 * 4, /* %a2 */
178 17 * 4, /* %a3 */
179 18 * 4, /* %a4 */
180 19 * 4, /* %a5 */
181 20 * 4, /* %fp */
182 21 * 4, /* %sp */
183 23 * 4, /* %sr */
184 22 * 4, /* %pc */
185 27 * 4, /* %fp0 */
186 30 * 4, /* %fp1 */
187 33 * 4, /* %fp2 */
188 36 * 4, /* %fp3 */
189 39 * 4, /* %fp4 */
190 42 * 4, /* %fp5 */
191 45 * 4, /* %fp6 */
192 48 * 4, /* %fp7 */
193 24 * 4, /* %fpcr */
194 25 * 4, /* %fpsr */
195 26 * 4 /* %fpiaddr */
196 };
197
198
199 /* Get info about saved registers in sigtramp. */
200
201 struct m68k_linux_sigtramp_info
202 {
203 /* Address of sigcontext. */
204 CORE_ADDR sigcontext_addr;
205
206 /* Offset of registers in `struct sigcontext'. */
207 int *sc_reg_offset;
208 };
209
210 /* Nonzero if running on uClinux. */
211 static int target_is_uclinux;
212
213 static void
m68k_linux_inferior_created(inferior * inf)214 m68k_linux_inferior_created (inferior *inf)
215 {
216 /* Record that we will need to re-evaluate whether we are running on a
217 uClinux or normal GNU/Linux target (see m68k_linux_get_sigtramp_info). */
218 target_is_uclinux = -1;
219 }
220
221 static struct m68k_linux_sigtramp_info
m68k_linux_get_sigtramp_info(struct frame_info * this_frame)222 m68k_linux_get_sigtramp_info (struct frame_info *this_frame)
223 {
224 struct gdbarch *gdbarch = get_frame_arch (this_frame);
225 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
226 CORE_ADDR sp;
227 struct m68k_linux_sigtramp_info info;
228
229 /* Determine whether we are running on a uClinux or normal GNU/Linux
230 target so we can use the correct sigcontext layouts. */
231 if (target_is_uclinux == -1)
232 target_is_uclinux = linux_is_uclinux ();
233
234 sp = get_frame_register_unsigned (this_frame, M68K_SP_REGNUM);
235
236 /* Get sigcontext address, it is the third parameter on the stack. */
237 info.sigcontext_addr = read_memory_unsigned_integer (sp + 8, 4, byte_order);
238
239 if (m68k_linux_pc_in_sigtramp (this_frame) == 2)
240 info.sc_reg_offset = m68k_linux_ucontext_reg_offset;
241 else
242 info.sc_reg_offset = (target_is_uclinux
243 ? m68k_uclinux_sigcontext_reg_offset
244 : m68k_linux_sigcontext_reg_offset);
245 return info;
246 }
247
248 /* Signal trampolines. */
249
250 static struct trad_frame_cache *
m68k_linux_sigtramp_frame_cache(struct frame_info * this_frame,void ** this_cache)251 m68k_linux_sigtramp_frame_cache (struct frame_info *this_frame,
252 void **this_cache)
253 {
254 struct frame_id this_id;
255 struct trad_frame_cache *cache;
256 struct gdbarch *gdbarch = get_frame_arch (this_frame);
257 enum bfd_endian byte_order = gdbarch_byte_order (gdbarch);
258 struct m68k_linux_sigtramp_info info;
259 gdb_byte buf[4];
260 int i;
261
262 if (*this_cache)
263 return (struct trad_frame_cache *) *this_cache;
264
265 cache = trad_frame_cache_zalloc (this_frame);
266
267 /* FIXME: cagney/2004-05-01: This is is long standing broken code.
268 The frame ID's code address should be the start-address of the
269 signal trampoline and not the current PC within that
270 trampoline. */
271 get_frame_register (this_frame, M68K_SP_REGNUM, buf);
272 /* See the end of m68k_push_dummy_call. */
273 this_id = frame_id_build (extract_unsigned_integer (buf, 4, byte_order)
274 - 4 + 8, get_frame_pc (this_frame));
275 trad_frame_set_id (cache, this_id);
276
277 info = m68k_linux_get_sigtramp_info (this_frame);
278
279 for (i = 0; i < M68K_NUM_REGS; i++)
280 if (info.sc_reg_offset[i] != -1)
281 trad_frame_set_reg_addr (cache, i,
282 info.sigcontext_addr + info.sc_reg_offset[i]);
283
284 *this_cache = cache;
285 return cache;
286 }
287
288 static void
m68k_linux_sigtramp_frame_this_id(struct frame_info * this_frame,void ** this_cache,struct frame_id * this_id)289 m68k_linux_sigtramp_frame_this_id (struct frame_info *this_frame,
290 void **this_cache,
291 struct frame_id *this_id)
292 {
293 struct trad_frame_cache *cache =
294 m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
295 trad_frame_get_id (cache, this_id);
296 }
297
298 static struct value *
m68k_linux_sigtramp_frame_prev_register(struct frame_info * this_frame,void ** this_cache,int regnum)299 m68k_linux_sigtramp_frame_prev_register (struct frame_info *this_frame,
300 void **this_cache,
301 int regnum)
302 {
303 /* Make sure we've initialized the cache. */
304 struct trad_frame_cache *cache =
305 m68k_linux_sigtramp_frame_cache (this_frame, this_cache);
306 return trad_frame_get_register (cache, this_frame, regnum);
307 }
308
309 static int
m68k_linux_sigtramp_frame_sniffer(const struct frame_unwind * self,struct frame_info * this_frame,void ** this_prologue_cache)310 m68k_linux_sigtramp_frame_sniffer (const struct frame_unwind *self,
311 struct frame_info *this_frame,
312 void **this_prologue_cache)
313 {
314 return m68k_linux_pc_in_sigtramp (this_frame);
315 }
316
317 static const struct frame_unwind m68k_linux_sigtramp_frame_unwind =
318 {
319 "m68k linux sigtramp",
320 SIGTRAMP_FRAME,
321 default_frame_unwind_stop_reason,
322 m68k_linux_sigtramp_frame_this_id,
323 m68k_linux_sigtramp_frame_prev_register,
324 NULL,
325 m68k_linux_sigtramp_frame_sniffer
326 };
327
328 /* Register maps for supply/collect regset functions. */
329
330 static const struct regcache_map_entry m68k_linux_gregmap[] =
331 {
332 { 7, M68K_D1_REGNUM, 4 }, /* d1 ... d7 */
333 { 7, M68K_A0_REGNUM, 4 }, /* a0 ... a6 */
334 { 1, M68K_D0_REGNUM, 4 },
335 { 1, M68K_SP_REGNUM, 4 },
336 { 1, REGCACHE_MAP_SKIP, 4 }, /* orig_d0 (skip) */
337 { 1, M68K_PS_REGNUM, 4 },
338 { 1, M68K_PC_REGNUM, 4 },
339 /* Ignore 16-bit fields 'fmtvec' and '__fill'. */
340 { 0 }
341 };
342
343 #define M68K_LINUX_GREGS_SIZE (20 * 4)
344
345 static const struct regcache_map_entry m68k_linux_fpregmap[] =
346 {
347 { 8, M68K_FP0_REGNUM, 12 }, /* fp0 ... fp7 */
348 { 1, M68K_FPC_REGNUM, 4 },
349 { 1, M68K_FPS_REGNUM, 4 },
350 { 1, M68K_FPI_REGNUM, 4 },
351 { 0 }
352 };
353
354 #define M68K_LINUX_FPREGS_SIZE (27 * 4)
355
356 /* Register sets. */
357
358 static const struct regset m68k_linux_gregset =
359 {
360 m68k_linux_gregmap,
361 regcache_supply_regset, regcache_collect_regset
362 };
363
364 static const struct regset m68k_linux_fpregset =
365 {
366 m68k_linux_fpregmap,
367 regcache_supply_regset, regcache_collect_regset
368 };
369
370 /* Iterate over core file register note sections. */
371
372 static void
m68k_linux_iterate_over_regset_sections(struct gdbarch * gdbarch,iterate_over_regset_sections_cb * cb,void * cb_data,const struct regcache * regcache)373 m68k_linux_iterate_over_regset_sections (struct gdbarch *gdbarch,
374 iterate_over_regset_sections_cb *cb,
375 void *cb_data,
376 const struct regcache *regcache)
377 {
378 cb (".reg", M68K_LINUX_GREGS_SIZE, M68K_LINUX_GREGS_SIZE, &m68k_linux_gregset,
379 NULL, cb_data);
380 cb (".reg2", M68K_LINUX_FPREGS_SIZE, M68K_LINUX_FPREGS_SIZE,
381 &m68k_linux_fpregset, NULL, cb_data);
382 }
383
384 static void
m68k_linux_init_abi(struct gdbarch_info info,struct gdbarch * gdbarch)385 m68k_linux_init_abi (struct gdbarch_info info, struct gdbarch *gdbarch)
386 {
387 struct gdbarch_tdep *tdep = gdbarch_tdep (gdbarch);
388
389 linux_init_abi (info, gdbarch, 0);
390
391 tdep->jb_pc = M68K_LINUX_JB_PC;
392 tdep->jb_elt_size = M68K_LINUX_JB_ELEMENT_SIZE;
393
394 /* GNU/Linux uses a calling convention that's similar to SVR4. It
395 returns integer values in %d0/%d1, pointer values in %a0 and
396 floating values in %fp0, just like SVR4, but uses %a1 to pass the
397 address to store a structure value. It also returns small
398 structures in registers instead of memory. */
399 m68k_svr4_init_abi (info, gdbarch);
400 tdep->struct_value_regnum = M68K_A1_REGNUM;
401 tdep->struct_return = reg_struct_return;
402
403 set_gdbarch_decr_pc_after_break (gdbarch, 2);
404
405 frame_unwind_append_unwinder (gdbarch, &m68k_linux_sigtramp_frame_unwind);
406
407 /* Shared library handling. */
408
409 /* GNU/Linux uses SVR4-style shared libraries. */
410 set_solib_svr4_fetch_link_map_offsets (gdbarch,
411 svr4_ilp32_fetch_link_map_offsets);
412
413 /* GNU/Linux uses the dynamic linker included in the GNU C Library. */
414 set_gdbarch_skip_solib_resolver (gdbarch, glibc_skip_solib_resolver);
415
416 set_gdbarch_skip_trampoline_code (gdbarch, find_solib_trampoline_target);
417
418 /* Core file support. */
419 set_gdbarch_iterate_over_regset_sections
420 (gdbarch, m68k_linux_iterate_over_regset_sections);
421
422 /* Enable TLS support. */
423 set_gdbarch_fetch_tls_load_module_address (gdbarch,
424 svr4_fetch_objfile_link_map);
425 }
426
427 void _initialize_m68k_linux_tdep ();
428 void
_initialize_m68k_linux_tdep()429 _initialize_m68k_linux_tdep ()
430 {
431 gdbarch_register_osabi (bfd_arch_m68k, 0, GDB_OSABI_LINUX,
432 m68k_linux_init_abi);
433 gdb::observers::inferior_created.attach (m68k_linux_inferior_created,
434 "m68k-linux-tdep");
435 }
436