1 /* kgdb support for MN10300
2 *
3 * Copyright (C) 2010 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public Licence
8 * as published by the Free Software Foundation; either version
9 * 2 of the Licence, or (at your option) any later version.
10 */
11
12 #include <linux/slab.h>
13 #include <linux/ptrace.h>
14 #include <linux/kgdb.h>
15 #include <linux/uaccess.h>
16 #include <unit/leds.h>
17 #include <unit/serial.h>
18 #include <asm/debugger.h>
19 #include <asm/serial-regs.h>
20 #include "internal.h"
21
22 /*
23 * Software single-stepping breakpoint save (used by __switch_to())
24 */
25 static struct thread_info *kgdb_sstep_thread;
26 u8 *kgdb_sstep_bp_addr[2];
27 u8 kgdb_sstep_bp[2];
28
29 /*
30 * Copy kernel exception frame registers to the GDB register file
31 */
pt_regs_to_gdb_regs(unsigned long * gdb_regs,struct pt_regs * regs)32 void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
33 {
34 unsigned long ssp = (unsigned long) (regs + 1);
35
36 gdb_regs[GDB_FR_D0] = regs->d0;
37 gdb_regs[GDB_FR_D1] = regs->d1;
38 gdb_regs[GDB_FR_D2] = regs->d2;
39 gdb_regs[GDB_FR_D3] = regs->d3;
40 gdb_regs[GDB_FR_A0] = regs->a0;
41 gdb_regs[GDB_FR_A1] = regs->a1;
42 gdb_regs[GDB_FR_A2] = regs->a2;
43 gdb_regs[GDB_FR_A3] = regs->a3;
44 gdb_regs[GDB_FR_SP] = (regs->epsw & EPSW_nSL) ? regs->sp : ssp;
45 gdb_regs[GDB_FR_PC] = regs->pc;
46 gdb_regs[GDB_FR_MDR] = regs->mdr;
47 gdb_regs[GDB_FR_EPSW] = regs->epsw;
48 gdb_regs[GDB_FR_LIR] = regs->lir;
49 gdb_regs[GDB_FR_LAR] = regs->lar;
50 gdb_regs[GDB_FR_MDRQ] = regs->mdrq;
51 gdb_regs[GDB_FR_E0] = regs->e0;
52 gdb_regs[GDB_FR_E1] = regs->e1;
53 gdb_regs[GDB_FR_E2] = regs->e2;
54 gdb_regs[GDB_FR_E3] = regs->e3;
55 gdb_regs[GDB_FR_E4] = regs->e4;
56 gdb_regs[GDB_FR_E5] = regs->e5;
57 gdb_regs[GDB_FR_E6] = regs->e6;
58 gdb_regs[GDB_FR_E7] = regs->e7;
59 gdb_regs[GDB_FR_SSP] = ssp;
60 gdb_regs[GDB_FR_MSP] = 0;
61 gdb_regs[GDB_FR_USP] = regs->sp;
62 gdb_regs[GDB_FR_MCRH] = regs->mcrh;
63 gdb_regs[GDB_FR_MCRL] = regs->mcrl;
64 gdb_regs[GDB_FR_MCVF] = regs->mcvf;
65 gdb_regs[GDB_FR_DUMMY0] = 0;
66 gdb_regs[GDB_FR_DUMMY1] = 0;
67 gdb_regs[GDB_FR_FS0] = 0;
68 }
69
70 /*
71 * Extracts kernel SP/PC values understandable by gdb from the values
72 * saved by switch_to().
73 */
sleeping_thread_to_gdb_regs(unsigned long * gdb_regs,struct task_struct * p)74 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
75 {
76 gdb_regs[GDB_FR_SSP] = p->thread.sp;
77 gdb_regs[GDB_FR_PC] = p->thread.pc;
78 gdb_regs[GDB_FR_A3] = p->thread.a3;
79 gdb_regs[GDB_FR_USP] = p->thread.usp;
80 gdb_regs[GDB_FR_FPCR] = p->thread.fpu_state.fpcr;
81 }
82
83 /*
84 * Fill kernel exception frame registers from the GDB register file
85 */
gdb_regs_to_pt_regs(unsigned long * gdb_regs,struct pt_regs * regs)86 void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
87 {
88 regs->d0 = gdb_regs[GDB_FR_D0];
89 regs->d1 = gdb_regs[GDB_FR_D1];
90 regs->d2 = gdb_regs[GDB_FR_D2];
91 regs->d3 = gdb_regs[GDB_FR_D3];
92 regs->a0 = gdb_regs[GDB_FR_A0];
93 regs->a1 = gdb_regs[GDB_FR_A1];
94 regs->a2 = gdb_regs[GDB_FR_A2];
95 regs->a3 = gdb_regs[GDB_FR_A3];
96 regs->sp = gdb_regs[GDB_FR_SP];
97 regs->pc = gdb_regs[GDB_FR_PC];
98 regs->mdr = gdb_regs[GDB_FR_MDR];
99 regs->epsw = gdb_regs[GDB_FR_EPSW];
100 regs->lir = gdb_regs[GDB_FR_LIR];
101 regs->lar = gdb_regs[GDB_FR_LAR];
102 regs->mdrq = gdb_regs[GDB_FR_MDRQ];
103 regs->e0 = gdb_regs[GDB_FR_E0];
104 regs->e1 = gdb_regs[GDB_FR_E1];
105 regs->e2 = gdb_regs[GDB_FR_E2];
106 regs->e3 = gdb_regs[GDB_FR_E3];
107 regs->e4 = gdb_regs[GDB_FR_E4];
108 regs->e5 = gdb_regs[GDB_FR_E5];
109 regs->e6 = gdb_regs[GDB_FR_E6];
110 regs->e7 = gdb_regs[GDB_FR_E7];
111 regs->sp = gdb_regs[GDB_FR_SSP];
112 /* gdb_regs[GDB_FR_MSP]; */
113 // regs->usp = gdb_regs[GDB_FR_USP];
114 regs->mcrh = gdb_regs[GDB_FR_MCRH];
115 regs->mcrl = gdb_regs[GDB_FR_MCRL];
116 regs->mcvf = gdb_regs[GDB_FR_MCVF];
117 /* gdb_regs[GDB_FR_DUMMY0]; */
118 /* gdb_regs[GDB_FR_DUMMY1]; */
119
120 // regs->fpcr = gdb_regs[GDB_FR_FPCR];
121 // regs->fs0 = gdb_regs[GDB_FR_FS0];
122 }
123
124 struct kgdb_arch arch_kgdb_ops = {
125 .gdb_bpt_instr = { 0xff },
126 .flags = KGDB_HW_BREAKPOINT,
127 };
128
129 static const unsigned char mn10300_kgdb_insn_sizes[256] =
130 {
131 /* 1 2 3 4 5 6 7 8 9 a b c d e f */
132 1, 3, 3, 3, 1, 3, 3, 3, 1, 3, 3, 3, 1, 3, 3, 3, /* 0 */
133 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 1 */
134 2, 2, 2, 2, 3, 3, 3, 3, 2, 2, 2, 2, 3, 3, 3, 3, /* 2 */
135 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 1, 1, 1, 1, /* 3 */
136 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, /* 4 */
137 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, /* 5 */
138 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 6 */
139 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* 7 */
140 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* 8 */
141 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* 9 */
142 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* a */
143 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, 1, 1, 1, 1, 2, /* b */
144 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 2, 2, /* c */
145 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, /* d */
146 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, /* e */
147 0, 2, 2, 2, 2, 2, 2, 4, 0, 3, 0, 4, 0, 6, 7, 1 /* f */
148 };
149
150 /*
151 * Attempt to emulate single stepping by means of breakpoint instructions.
152 * Although there is a single-step trace flag in EPSW, its use is not
153 * sufficiently documented and is only intended for use with the JTAG debugger.
154 */
kgdb_arch_do_singlestep(struct pt_regs * regs)155 static int kgdb_arch_do_singlestep(struct pt_regs *regs)
156 {
157 unsigned long arg;
158 unsigned size;
159 u8 *pc = (u8 *)regs->pc, *sp = (u8 *)(regs + 1), cur;
160 u8 *x = NULL, *y = NULL;
161 int ret;
162
163 ret = probe_kernel_read(&cur, pc, 1);
164 if (ret < 0)
165 return ret;
166
167 size = mn10300_kgdb_insn_sizes[cur];
168 if (size > 0) {
169 x = pc + size;
170 goto set_x;
171 }
172
173 switch (cur) {
174 /* Bxx (d8,PC) */
175 case 0xc0 ... 0xca:
176 ret = probe_kernel_read(&arg, pc + 1, 1);
177 if (ret < 0)
178 return ret;
179 x = pc + 2;
180 if (arg >= 0 && arg <= 2)
181 goto set_x;
182 y = pc + (s8)arg;
183 goto set_x_and_y;
184
185 /* LXX (d8,PC) */
186 case 0xd0 ... 0xda:
187 x = pc + 1;
188 if (regs->pc == regs->lar)
189 goto set_x;
190 y = (u8 *)regs->lar;
191 goto set_x_and_y;
192
193 /* SETLB - loads the next four bytes into the LIR register
194 * (which mustn't include a breakpoint instruction) */
195 case 0xdb:
196 x = pc + 5;
197 goto set_x;
198
199 /* JMP (d16,PC) or CALL (d16,PC) */
200 case 0xcc:
201 case 0xcd:
202 ret = probe_kernel_read(&arg, pc + 1, 2);
203 if (ret < 0)
204 return ret;
205 x = pc + (s16)arg;
206 goto set_x;
207
208 /* JMP (d32,PC) or CALL (d32,PC) */
209 case 0xdc:
210 case 0xdd:
211 ret = probe_kernel_read(&arg, pc + 1, 4);
212 if (ret < 0)
213 return ret;
214 x = pc + (s32)arg;
215 goto set_x;
216
217 /* RETF */
218 case 0xde:
219 x = (u8 *)regs->mdr;
220 goto set_x;
221
222 /* RET */
223 case 0xdf:
224 ret = probe_kernel_read(&arg, pc + 2, 1);
225 if (ret < 0)
226 return ret;
227 ret = probe_kernel_read(&x, sp + (s8)arg, 4);
228 if (ret < 0)
229 return ret;
230 goto set_x;
231
232 case 0xf0:
233 ret = probe_kernel_read(&cur, pc + 1, 1);
234 if (ret < 0)
235 return ret;
236
237 if (cur >= 0xf0 && cur <= 0xf7) {
238 /* JMP (An) / CALLS (An) */
239 switch (cur & 3) {
240 case 0: x = (u8 *)regs->a0; break;
241 case 1: x = (u8 *)regs->a1; break;
242 case 2: x = (u8 *)regs->a2; break;
243 case 3: x = (u8 *)regs->a3; break;
244 }
245 goto set_x;
246 } else if (cur == 0xfc) {
247 /* RETS */
248 ret = probe_kernel_read(&x, sp, 4);
249 if (ret < 0)
250 return ret;
251 goto set_x;
252 } else if (cur == 0xfd) {
253 /* RTI */
254 ret = probe_kernel_read(&x, sp + 4, 4);
255 if (ret < 0)
256 return ret;
257 goto set_x;
258 } else {
259 x = pc + 2;
260 goto set_x;
261 }
262 break;
263
264 /* potential 3-byte conditional branches */
265 case 0xf8:
266 ret = probe_kernel_read(&cur, pc + 1, 1);
267 if (ret < 0)
268 return ret;
269 x = pc + 3;
270
271 if (cur >= 0xe8 && cur <= 0xeb) {
272 ret = probe_kernel_read(&arg, pc + 2, 1);
273 if (ret < 0)
274 return ret;
275 if (arg >= 0 && arg <= 3)
276 goto set_x;
277 y = pc + (s8)arg;
278 goto set_x_and_y;
279 }
280 goto set_x;
281
282 case 0xfa:
283 ret = probe_kernel_read(&cur, pc + 1, 1);
284 if (ret < 0)
285 return ret;
286
287 if (cur == 0xff) {
288 /* CALLS (d16,PC) */
289 ret = probe_kernel_read(&arg, pc + 2, 2);
290 if (ret < 0)
291 return ret;
292 x = pc + (s16)arg;
293 goto set_x;
294 }
295
296 x = pc + 4;
297 goto set_x;
298
299 case 0xfc:
300 ret = probe_kernel_read(&cur, pc + 1, 1);
301 if (ret < 0)
302 return ret;
303
304 if (cur == 0xff) {
305 /* CALLS (d32,PC) */
306 ret = probe_kernel_read(&arg, pc + 2, 4);
307 if (ret < 0)
308 return ret;
309 x = pc + (s32)arg;
310 goto set_x;
311 }
312
313 x = pc + 6;
314 goto set_x;
315 }
316
317 return 0;
318
319 set_x:
320 kgdb_sstep_bp_addr[0] = x;
321 kgdb_sstep_bp_addr[1] = NULL;
322 ret = probe_kernel_read(&kgdb_sstep_bp[0], x, 1);
323 if (ret < 0)
324 return ret;
325 ret = probe_kernel_write(x, &arch_kgdb_ops.gdb_bpt_instr, 1);
326 if (ret < 0)
327 return ret;
328 kgdb_sstep_thread = current_thread_info();
329 debugger_local_cache_flushinv_one(x);
330 return ret;
331
332 set_x_and_y:
333 kgdb_sstep_bp_addr[0] = x;
334 kgdb_sstep_bp_addr[1] = y;
335 ret = probe_kernel_read(&kgdb_sstep_bp[0], x, 1);
336 if (ret < 0)
337 return ret;
338 ret = probe_kernel_read(&kgdb_sstep_bp[1], y, 1);
339 if (ret < 0)
340 return ret;
341 ret = probe_kernel_write(x, &arch_kgdb_ops.gdb_bpt_instr, 1);
342 if (ret < 0)
343 return ret;
344 ret = probe_kernel_write(y, &arch_kgdb_ops.gdb_bpt_instr, 1);
345 if (ret < 0) {
346 probe_kernel_write(kgdb_sstep_bp_addr[0],
347 &kgdb_sstep_bp[0], 1);
348 } else {
349 kgdb_sstep_thread = current_thread_info();
350 }
351 debugger_local_cache_flushinv_one(x);
352 debugger_local_cache_flushinv_one(y);
353 return ret;
354 }
355
356 /*
357 * Remove emplaced single-step breakpoints, returning true if we hit one of
358 * them.
359 */
kgdb_arch_undo_singlestep(struct pt_regs * regs)360 static bool kgdb_arch_undo_singlestep(struct pt_regs *regs)
361 {
362 bool hit = false;
363 u8 *x = kgdb_sstep_bp_addr[0], *y = kgdb_sstep_bp_addr[1];
364 u8 opcode;
365
366 if (kgdb_sstep_thread == current_thread_info()) {
367 if (x) {
368 if (x == (u8 *)regs->pc)
369 hit = true;
370 if (probe_kernel_read(&opcode, x,
371 1) < 0 ||
372 opcode != 0xff)
373 BUG();
374 probe_kernel_write(x, &kgdb_sstep_bp[0], 1);
375 debugger_local_cache_flushinv_one(x);
376 }
377 if (y) {
378 if (y == (u8 *)regs->pc)
379 hit = true;
380 if (probe_kernel_read(&opcode, y,
381 1) < 0 ||
382 opcode != 0xff)
383 BUG();
384 probe_kernel_write(y, &kgdb_sstep_bp[1], 1);
385 debugger_local_cache_flushinv_one(y);
386 }
387 }
388
389 kgdb_sstep_bp_addr[0] = NULL;
390 kgdb_sstep_bp_addr[1] = NULL;
391 kgdb_sstep_thread = NULL;
392 return hit;
393 }
394
395 /*
396 * Catch a single-step-pending thread being deleted and make sure the global
397 * single-step state is cleared. At this point the breakpoints should have
398 * been removed by __switch_to().
399 */
free_thread_info(struct thread_info * ti)400 void free_thread_info(struct thread_info *ti)
401 {
402 if (kgdb_sstep_thread == ti) {
403 kgdb_sstep_thread = NULL;
404
405 /* However, we may now be running in degraded mode, with most
406 * of the CPUs disabled until such a time as KGDB is reentered,
407 * so force immediate reentry */
408 kgdb_breakpoint();
409 }
410 kfree(ti);
411 }
412
413 /*
414 * Handle unknown packets and [CcsDk] packets
415 * - at this point breakpoints have been installed
416 */
kgdb_arch_handle_exception(int vector,int signo,int err_code,char * remcom_in_buffer,char * remcom_out_buffer,struct pt_regs * regs)417 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
418 char *remcom_in_buffer, char *remcom_out_buffer,
419 struct pt_regs *regs)
420 {
421 long addr;
422 char *ptr;
423
424 switch (remcom_in_buffer[0]) {
425 case 'c':
426 case 's':
427 /* try to read optional parameter, pc unchanged if no parm */
428 ptr = &remcom_in_buffer[1];
429 if (kgdb_hex2long(&ptr, &addr))
430 regs->pc = addr;
431 case 'D':
432 case 'k':
433 atomic_set(&kgdb_cpu_doing_single_step, -1);
434
435 if (remcom_in_buffer[0] == 's') {
436 kgdb_arch_do_singlestep(regs);
437 kgdb_single_step = 1;
438 atomic_set(&kgdb_cpu_doing_single_step,
439 raw_smp_processor_id());
440 }
441 return 0;
442 }
443 return -1; /* this means that we do not want to exit from the handler */
444 }
445
446 /*
447 * Handle event interception
448 * - returns 0 if the exception should be skipped, -ERROR otherwise.
449 */
debugger_intercept(enum exception_code excep,int signo,int si_code,struct pt_regs * regs)450 int debugger_intercept(enum exception_code excep, int signo, int si_code,
451 struct pt_regs *regs)
452 {
453 int ret;
454
455 if (kgdb_arch_undo_singlestep(regs)) {
456 excep = EXCEP_TRAP;
457 signo = SIGTRAP;
458 si_code = TRAP_TRACE;
459 }
460
461 ret = kgdb_handle_exception(excep, signo, si_code, regs);
462
463 debugger_local_cache_flushinv();
464
465 return ret;
466 }
467
468 /*
469 * Determine if we've hit a debugger special breakpoint
470 */
at_debugger_breakpoint(struct pt_regs * regs)471 int at_debugger_breakpoint(struct pt_regs *regs)
472 {
473 return regs->pc == (unsigned long)&__arch_kgdb_breakpoint;
474 }
475
476 /*
477 * Initialise kgdb
478 */
kgdb_arch_init(void)479 int kgdb_arch_init(void)
480 {
481 return 0;
482 }
483
484 /*
485 * Do something, perhaps, but don't know what.
486 */
kgdb_arch_exit(void)487 void kgdb_arch_exit(void)
488 {
489 }
490
491 #ifdef CONFIG_SMP
debugger_nmi_interrupt(struct pt_regs * regs,enum exception_code code)492 void debugger_nmi_interrupt(struct pt_regs *regs, enum exception_code code)
493 {
494 kgdb_nmicallback(arch_smp_processor_id(), regs);
495 debugger_local_cache_flushinv();
496 }
497
kgdb_roundup_cpus(unsigned long flags)498 void kgdb_roundup_cpus(unsigned long flags)
499 {
500 smp_jump_to_debugger();
501 }
502 #endif
503