1 /*
2 * Copyright 2013 Tilera Corporation. All Rights Reserved.
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation, version 2.
7 *
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
11 * NON INFRINGEMENT. See the GNU General Public License for
12 * more details.
13 *
14 * TILE-Gx KGDB support.
15 */
16
17 #include <linux/ptrace.h>
18 #include <linux/kgdb.h>
19 #include <linux/kdebug.h>
20 #include <linux/uaccess.h>
21 #include <linux/module.h>
22 #include <asm/cacheflush.h>
23
24 static tile_bundle_bits singlestep_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
25 static unsigned long stepped_addr;
26 static tile_bundle_bits stepped_instr;
27
28 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
29 { "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0])},
30 { "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1])},
31 { "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2])},
32 { "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3])},
33 { "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4])},
34 { "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5])},
35 { "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6])},
36 { "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7])},
37 { "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8])},
38 { "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9])},
39 { "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10])},
40 { "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11])},
41 { "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12])},
42 { "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13])},
43 { "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14])},
44 { "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15])},
45 { "r16", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[16])},
46 { "r17", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[17])},
47 { "r18", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[18])},
48 { "r19", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[19])},
49 { "r20", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[20])},
50 { "r21", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[21])},
51 { "r22", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[22])},
52 { "r23", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[23])},
53 { "r24", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[24])},
54 { "r25", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[25])},
55 { "r26", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[26])},
56 { "r27", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[27])},
57 { "r28", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[28])},
58 { "r29", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[29])},
59 { "r30", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[30])},
60 { "r31", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[31])},
61 { "r32", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[32])},
62 { "r33", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[33])},
63 { "r34", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[34])},
64 { "r35", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[35])},
65 { "r36", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[36])},
66 { "r37", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[37])},
67 { "r38", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[38])},
68 { "r39", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[39])},
69 { "r40", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[40])},
70 { "r41", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[41])},
71 { "r42", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[42])},
72 { "r43", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[43])},
73 { "r44", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[44])},
74 { "r45", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[45])},
75 { "r46", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[46])},
76 { "r47", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[47])},
77 { "r48", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[48])},
78 { "r49", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[49])},
79 { "r50", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[50])},
80 { "r51", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[51])},
81 { "r52", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[52])},
82 { "tp", GDB_SIZEOF_REG, offsetof(struct pt_regs, tp)},
83 { "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, sp)},
84 { "lr", GDB_SIZEOF_REG, offsetof(struct pt_regs, lr)},
85 { "sn", GDB_SIZEOF_REG, -1},
86 { "idn0", GDB_SIZEOF_REG, -1},
87 { "idn1", GDB_SIZEOF_REG, -1},
88 { "udn0", GDB_SIZEOF_REG, -1},
89 { "udn1", GDB_SIZEOF_REG, -1},
90 { "udn2", GDB_SIZEOF_REG, -1},
91 { "udn3", GDB_SIZEOF_REG, -1},
92 { "zero", GDB_SIZEOF_REG, -1},
93 { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, pc)},
94 { "faultnum", GDB_SIZEOF_REG, offsetof(struct pt_regs, faultnum)},
95 };
96
dbg_get_reg(int regno,void * mem,struct pt_regs * regs)97 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
98 {
99 if (regno >= DBG_MAX_REG_NUM || regno < 0)
100 return NULL;
101
102 if (dbg_reg_def[regno].offset != -1)
103 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
104 dbg_reg_def[regno].size);
105 else
106 memset(mem, 0, dbg_reg_def[regno].size);
107 return dbg_reg_def[regno].name;
108 }
109
dbg_set_reg(int regno,void * mem,struct pt_regs * regs)110 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
111 {
112 if (regno >= DBG_MAX_REG_NUM || regno < 0)
113 return -EINVAL;
114
115 if (dbg_reg_def[regno].offset != -1)
116 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
117 dbg_reg_def[regno].size);
118 return 0;
119 }
120
121 /*
122 * Similar to pt_regs_to_gdb_regs() except that process is sleeping and so
123 * we may not be able to get all the info.
124 */
125 void
sleeping_thread_to_gdb_regs(unsigned long * gdb_regs,struct task_struct * task)126 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
127 {
128 int reg;
129 struct pt_regs *thread_regs;
130 unsigned long *ptr = gdb_regs;
131
132 if (task == NULL)
133 return;
134
135 /* Initialize to zero. */
136 memset(gdb_regs, 0, NUMREGBYTES);
137
138 thread_regs = task_pt_regs(task);
139 for (reg = 0; reg <= TREG_LAST_GPR; reg++)
140 *(ptr++) = thread_regs->regs[reg];
141
142 gdb_regs[TILEGX_PC_REGNUM] = thread_regs->pc;
143 gdb_regs[TILEGX_FAULTNUM_REGNUM] = thread_regs->faultnum;
144 }
145
kgdb_arch_set_pc(struct pt_regs * regs,unsigned long pc)146 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
147 {
148 regs->pc = pc;
149 }
150
kgdb_call_nmi_hook(void * ignored)151 static void kgdb_call_nmi_hook(void *ignored)
152 {
153 kgdb_nmicallback(raw_smp_processor_id(), NULL);
154 }
155
kgdb_roundup_cpus(unsigned long flags)156 void kgdb_roundup_cpus(unsigned long flags)
157 {
158 local_irq_enable();
159 smp_call_function(kgdb_call_nmi_hook, NULL, 0);
160 local_irq_disable();
161 }
162
163 /*
164 * Convert a kernel address to the writable kernel text mapping.
165 */
writable_address(unsigned long addr)166 static unsigned long writable_address(unsigned long addr)
167 {
168 unsigned long ret = 0;
169
170 if (core_kernel_text(addr))
171 ret = addr - MEM_SV_START + PAGE_OFFSET;
172 else if (is_module_text_address(addr))
173 ret = addr;
174 else
175 pr_err("Unknown virtual address 0x%lx\n", addr);
176
177 return ret;
178 }
179
180 /*
181 * Calculate the new address for after a step.
182 */
get_step_address(struct pt_regs * regs)183 static unsigned long get_step_address(struct pt_regs *regs)
184 {
185 int src_reg;
186 int jump_off;
187 int br_off;
188 unsigned long addr;
189 unsigned int opcode;
190 tile_bundle_bits bundle;
191
192 /* Move to the next instruction by default. */
193 addr = regs->pc + TILEGX_BUNDLE_SIZE_IN_BYTES;
194 bundle = *(unsigned long *)instruction_pointer(regs);
195
196 /* 0: X mode, Otherwise: Y mode. */
197 if (bundle & TILEGX_BUNDLE_MODE_MASK) {
198 if (get_Opcode_Y1(bundle) == RRR_1_OPCODE_Y1 &&
199 get_RRROpcodeExtension_Y1(bundle) ==
200 UNARY_RRR_1_OPCODE_Y1) {
201 opcode = get_UnaryOpcodeExtension_Y1(bundle);
202
203 switch (opcode) {
204 case JALR_UNARY_OPCODE_Y1:
205 case JALRP_UNARY_OPCODE_Y1:
206 case JR_UNARY_OPCODE_Y1:
207 case JRP_UNARY_OPCODE_Y1:
208 src_reg = get_SrcA_Y1(bundle);
209 dbg_get_reg(src_reg, &addr, regs);
210 break;
211 }
212 }
213 } else if (get_Opcode_X1(bundle) == RRR_0_OPCODE_X1) {
214 if (get_RRROpcodeExtension_X1(bundle) ==
215 UNARY_RRR_0_OPCODE_X1) {
216 opcode = get_UnaryOpcodeExtension_X1(bundle);
217
218 switch (opcode) {
219 case JALR_UNARY_OPCODE_X1:
220 case JALRP_UNARY_OPCODE_X1:
221 case JR_UNARY_OPCODE_X1:
222 case JRP_UNARY_OPCODE_X1:
223 src_reg = get_SrcA_X1(bundle);
224 dbg_get_reg(src_reg, &addr, regs);
225 break;
226 }
227 }
228 } else if (get_Opcode_X1(bundle) == JUMP_OPCODE_X1) {
229 opcode = get_JumpOpcodeExtension_X1(bundle);
230
231 switch (opcode) {
232 case JAL_JUMP_OPCODE_X1:
233 case J_JUMP_OPCODE_X1:
234 jump_off = sign_extend(get_JumpOff_X1(bundle), 27);
235 addr = regs->pc +
236 (jump_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
237 break;
238 }
239 } else if (get_Opcode_X1(bundle) == BRANCH_OPCODE_X1) {
240 br_off = 0;
241 opcode = get_BrType_X1(bundle);
242
243 switch (opcode) {
244 case BEQZT_BRANCH_OPCODE_X1:
245 case BEQZ_BRANCH_OPCODE_X1:
246 if (get_SrcA_X1(bundle) == 0)
247 br_off = get_BrOff_X1(bundle);
248 break;
249 case BGEZT_BRANCH_OPCODE_X1:
250 case BGEZ_BRANCH_OPCODE_X1:
251 if (get_SrcA_X1(bundle) >= 0)
252 br_off = get_BrOff_X1(bundle);
253 break;
254 case BGTZT_BRANCH_OPCODE_X1:
255 case BGTZ_BRANCH_OPCODE_X1:
256 if (get_SrcA_X1(bundle) > 0)
257 br_off = get_BrOff_X1(bundle);
258 break;
259 case BLBCT_BRANCH_OPCODE_X1:
260 case BLBC_BRANCH_OPCODE_X1:
261 if (!(get_SrcA_X1(bundle) & 1))
262 br_off = get_BrOff_X1(bundle);
263 break;
264 case BLBST_BRANCH_OPCODE_X1:
265 case BLBS_BRANCH_OPCODE_X1:
266 if (get_SrcA_X1(bundle) & 1)
267 br_off = get_BrOff_X1(bundle);
268 break;
269 case BLEZT_BRANCH_OPCODE_X1:
270 case BLEZ_BRANCH_OPCODE_X1:
271 if (get_SrcA_X1(bundle) <= 0)
272 br_off = get_BrOff_X1(bundle);
273 break;
274 case BLTZT_BRANCH_OPCODE_X1:
275 case BLTZ_BRANCH_OPCODE_X1:
276 if (get_SrcA_X1(bundle) < 0)
277 br_off = get_BrOff_X1(bundle);
278 break;
279 case BNEZT_BRANCH_OPCODE_X1:
280 case BNEZ_BRANCH_OPCODE_X1:
281 if (get_SrcA_X1(bundle) != 0)
282 br_off = get_BrOff_X1(bundle);
283 break;
284 }
285
286 if (br_off != 0) {
287 br_off = sign_extend(br_off, 17);
288 addr = regs->pc +
289 (br_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
290 }
291 }
292
293 return addr;
294 }
295
296 /*
297 * Replace the next instruction after the current instruction with a
298 * breakpoint instruction.
299 */
do_single_step(struct pt_regs * regs)300 static void do_single_step(struct pt_regs *regs)
301 {
302 unsigned long addr_wr;
303
304 /* Determine where the target instruction will send us to. */
305 stepped_addr = get_step_address(regs);
306 probe_kernel_read((char *)&stepped_instr, (char *)stepped_addr,
307 BREAK_INSTR_SIZE);
308
309 addr_wr = writable_address(stepped_addr);
310 probe_kernel_write((char *)addr_wr, (char *)&singlestep_insn,
311 BREAK_INSTR_SIZE);
312 smp_wmb();
313 flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
314 }
315
undo_single_step(struct pt_regs * regs)316 static void undo_single_step(struct pt_regs *regs)
317 {
318 unsigned long addr_wr;
319
320 if (stepped_instr == 0)
321 return;
322
323 addr_wr = writable_address(stepped_addr);
324 probe_kernel_write((char *)addr_wr, (char *)&stepped_instr,
325 BREAK_INSTR_SIZE);
326 stepped_instr = 0;
327 smp_wmb();
328 flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
329 }
330
331 /*
332 * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
333 * then try to fall into the debugger.
334 */
335 static int
kgdb_notify(struct notifier_block * self,unsigned long cmd,void * ptr)336 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
337 {
338 int ret;
339 unsigned long flags;
340 struct die_args *args = (struct die_args *)ptr;
341 struct pt_regs *regs = args->regs;
342
343 #ifdef CONFIG_KPROBES
344 /*
345 * Return immediately if the kprobes fault notifier has set
346 * DIE_PAGE_FAULT.
347 */
348 if (cmd == DIE_PAGE_FAULT)
349 return NOTIFY_DONE;
350 #endif /* CONFIG_KPROBES */
351
352 switch (cmd) {
353 case DIE_BREAK:
354 case DIE_COMPILED_BPT:
355 break;
356 case DIE_SSTEPBP:
357 local_irq_save(flags);
358 kgdb_handle_exception(0, SIGTRAP, 0, regs);
359 local_irq_restore(flags);
360 return NOTIFY_STOP;
361 default:
362 /* Userspace events, ignore. */
363 if (user_mode(regs))
364 return NOTIFY_DONE;
365 }
366
367 local_irq_save(flags);
368 ret = kgdb_handle_exception(args->trapnr, args->signr, args->err, regs);
369 local_irq_restore(flags);
370 if (ret)
371 return NOTIFY_DONE;
372
373 return NOTIFY_STOP;
374 }
375
376 static struct notifier_block kgdb_notifier = {
377 .notifier_call = kgdb_notify,
378 };
379
380 /*
381 * kgdb_arch_handle_exception - Handle architecture specific GDB packets.
382 * @vector: The error vector of the exception that happened.
383 * @signo: The signal number of the exception that happened.
384 * @err_code: The error code of the exception that happened.
385 * @remcom_in_buffer: The buffer of the packet we have read.
386 * @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
387 * @regs: The &struct pt_regs of the current process.
388 *
389 * This function MUST handle the 'c' and 's' command packets,
390 * as well packets to set / remove a hardware breakpoint, if used.
391 * If there are additional packets which the hardware needs to handle,
392 * they are handled here. The code should return -1 if it wants to
393 * process more packets, and a %0 or %1 if it wants to exit from the
394 * kgdb callback.
395 */
kgdb_arch_handle_exception(int vector,int signo,int err_code,char * remcom_in_buffer,char * remcom_out_buffer,struct pt_regs * regs)396 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
397 char *remcom_in_buffer, char *remcom_out_buffer,
398 struct pt_regs *regs)
399 {
400 char *ptr;
401 unsigned long address;
402
403 /* Undo any stepping we may have done. */
404 undo_single_step(regs);
405
406 switch (remcom_in_buffer[0]) {
407 case 'c':
408 case 's':
409 case 'D':
410 case 'k':
411 /*
412 * Try to read optional parameter, pc unchanged if no parm.
413 * If this was a compiled-in breakpoint, we need to move
414 * to the next instruction or we will just breakpoint
415 * over and over again.
416 */
417 ptr = &remcom_in_buffer[1];
418 if (kgdb_hex2long(&ptr, &address))
419 regs->pc = address;
420 else if (*(unsigned long *)regs->pc == compiled_bpt)
421 regs->pc += BREAK_INSTR_SIZE;
422
423 if (remcom_in_buffer[0] == 's') {
424 do_single_step(regs);
425 kgdb_single_step = 1;
426 atomic_set(&kgdb_cpu_doing_single_step,
427 raw_smp_processor_id());
428 } else
429 atomic_set(&kgdb_cpu_doing_single_step, -1);
430
431 return 0;
432 }
433
434 return -1; /* this means that we do not want to exit from the handler */
435 }
436
437 struct kgdb_arch arch_kgdb_ops;
438
439 /*
440 * kgdb_arch_init - Perform any architecture specific initalization.
441 *
442 * This function will handle the initalization of any architecture
443 * specific callbacks.
444 */
kgdb_arch_init(void)445 int kgdb_arch_init(void)
446 {
447 tile_bundle_bits bundle = TILEGX_BPT_BUNDLE;
448
449 memcpy(arch_kgdb_ops.gdb_bpt_instr, &bundle, BREAK_INSTR_SIZE);
450 return register_die_notifier(&kgdb_notifier);
451 }
452
453 /*
454 * kgdb_arch_exit - Perform any architecture specific uninitalization.
455 *
456 * This function will handle the uninitalization of any architecture
457 * specific callbacks, for dynamic registration and unregistration.
458 */
kgdb_arch_exit(void)459 void kgdb_arch_exit(void)
460 {
461 unregister_die_notifier(&kgdb_notifier);
462 }
463
kgdb_arch_set_breakpoint(struct kgdb_bkpt * bpt)464 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
465 {
466 int err;
467 unsigned long addr_wr = writable_address(bpt->bpt_addr);
468
469 if (addr_wr == 0)
470 return -1;
471
472 err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
473 BREAK_INSTR_SIZE);
474 if (err)
475 return err;
476
477 err = probe_kernel_write((char *)addr_wr, arch_kgdb_ops.gdb_bpt_instr,
478 BREAK_INSTR_SIZE);
479 smp_wmb();
480 flush_icache_range((unsigned long)bpt->bpt_addr,
481 (unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
482 return err;
483 }
484
kgdb_arch_remove_breakpoint(struct kgdb_bkpt * bpt)485 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
486 {
487 int err;
488 unsigned long addr_wr = writable_address(bpt->bpt_addr);
489
490 if (addr_wr == 0)
491 return -1;
492
493 err = probe_kernel_write((char *)addr_wr, (char *)bpt->saved_instr,
494 BREAK_INSTR_SIZE);
495 smp_wmb();
496 flush_icache_range((unsigned long)bpt->bpt_addr,
497 (unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
498 return err;
499 }
500