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 struct pt_regs *thread_regs;
129 const int NGPRS = TREG_LAST_GPR + 1;
130
131 if (task == NULL)
132 return;
133
134 thread_regs = task_pt_regs(task);
135 memcpy(gdb_regs, thread_regs, NGPRS * sizeof(unsigned long));
136 memset(&gdb_regs[NGPRS], 0,
137 (TILEGX_PC_REGNUM - NGPRS) * sizeof(unsigned long));
138 gdb_regs[TILEGX_PC_REGNUM] = thread_regs->pc;
139 gdb_regs[TILEGX_FAULTNUM_REGNUM] = thread_regs->faultnum;
140 }
141
kgdb_arch_set_pc(struct pt_regs * regs,unsigned long pc)142 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
143 {
144 regs->pc = pc;
145 }
146
kgdb_call_nmi_hook(void * ignored)147 static void kgdb_call_nmi_hook(void *ignored)
148 {
149 kgdb_nmicallback(raw_smp_processor_id(), NULL);
150 }
151
kgdb_roundup_cpus(unsigned long flags)152 void kgdb_roundup_cpus(unsigned long flags)
153 {
154 local_irq_enable();
155 smp_call_function(kgdb_call_nmi_hook, NULL, 0);
156 local_irq_disable();
157 }
158
159 /*
160 * Convert a kernel address to the writable kernel text mapping.
161 */
writable_address(unsigned long addr)162 static unsigned long writable_address(unsigned long addr)
163 {
164 unsigned long ret = 0;
165
166 if (core_kernel_text(addr))
167 ret = ktext_writable_addr(addr);
168 else if (is_module_text_address(addr))
169 ret = addr;
170 else
171 pr_err("Unknown virtual address 0x%lx\n", addr);
172
173 return ret;
174 }
175
176 /*
177 * Calculate the new address for after a step.
178 */
get_step_address(struct pt_regs * regs)179 static unsigned long get_step_address(struct pt_regs *regs)
180 {
181 int src_reg;
182 int jump_off;
183 int br_off;
184 unsigned long addr;
185 unsigned int opcode;
186 tile_bundle_bits bundle;
187
188 /* Move to the next instruction by default. */
189 addr = regs->pc + TILEGX_BUNDLE_SIZE_IN_BYTES;
190 bundle = *(unsigned long *)instruction_pointer(regs);
191
192 /* 0: X mode, Otherwise: Y mode. */
193 if (bundle & TILEGX_BUNDLE_MODE_MASK) {
194 if (get_Opcode_Y1(bundle) == RRR_1_OPCODE_Y1 &&
195 get_RRROpcodeExtension_Y1(bundle) ==
196 UNARY_RRR_1_OPCODE_Y1) {
197 opcode = get_UnaryOpcodeExtension_Y1(bundle);
198
199 switch (opcode) {
200 case JALR_UNARY_OPCODE_Y1:
201 case JALRP_UNARY_OPCODE_Y1:
202 case JR_UNARY_OPCODE_Y1:
203 case JRP_UNARY_OPCODE_Y1:
204 src_reg = get_SrcA_Y1(bundle);
205 dbg_get_reg(src_reg, &addr, regs);
206 break;
207 }
208 }
209 } else if (get_Opcode_X1(bundle) == RRR_0_OPCODE_X1) {
210 if (get_RRROpcodeExtension_X1(bundle) ==
211 UNARY_RRR_0_OPCODE_X1) {
212 opcode = get_UnaryOpcodeExtension_X1(bundle);
213
214 switch (opcode) {
215 case JALR_UNARY_OPCODE_X1:
216 case JALRP_UNARY_OPCODE_X1:
217 case JR_UNARY_OPCODE_X1:
218 case JRP_UNARY_OPCODE_X1:
219 src_reg = get_SrcA_X1(bundle);
220 dbg_get_reg(src_reg, &addr, regs);
221 break;
222 }
223 }
224 } else if (get_Opcode_X1(bundle) == JUMP_OPCODE_X1) {
225 opcode = get_JumpOpcodeExtension_X1(bundle);
226
227 switch (opcode) {
228 case JAL_JUMP_OPCODE_X1:
229 case J_JUMP_OPCODE_X1:
230 jump_off = sign_extend(get_JumpOff_X1(bundle), 27);
231 addr = regs->pc +
232 (jump_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
233 break;
234 }
235 } else if (get_Opcode_X1(bundle) == BRANCH_OPCODE_X1) {
236 br_off = 0;
237 opcode = get_BrType_X1(bundle);
238
239 switch (opcode) {
240 case BEQZT_BRANCH_OPCODE_X1:
241 case BEQZ_BRANCH_OPCODE_X1:
242 if (get_SrcA_X1(bundle) == 0)
243 br_off = get_BrOff_X1(bundle);
244 break;
245 case BGEZT_BRANCH_OPCODE_X1:
246 case BGEZ_BRANCH_OPCODE_X1:
247 if (get_SrcA_X1(bundle) >= 0)
248 br_off = get_BrOff_X1(bundle);
249 break;
250 case BGTZT_BRANCH_OPCODE_X1:
251 case BGTZ_BRANCH_OPCODE_X1:
252 if (get_SrcA_X1(bundle) > 0)
253 br_off = get_BrOff_X1(bundle);
254 break;
255 case BLBCT_BRANCH_OPCODE_X1:
256 case BLBC_BRANCH_OPCODE_X1:
257 if (!(get_SrcA_X1(bundle) & 1))
258 br_off = get_BrOff_X1(bundle);
259 break;
260 case BLBST_BRANCH_OPCODE_X1:
261 case BLBS_BRANCH_OPCODE_X1:
262 if (get_SrcA_X1(bundle) & 1)
263 br_off = get_BrOff_X1(bundle);
264 break;
265 case BLEZT_BRANCH_OPCODE_X1:
266 case BLEZ_BRANCH_OPCODE_X1:
267 if (get_SrcA_X1(bundle) <= 0)
268 br_off = get_BrOff_X1(bundle);
269 break;
270 case BLTZT_BRANCH_OPCODE_X1:
271 case BLTZ_BRANCH_OPCODE_X1:
272 if (get_SrcA_X1(bundle) < 0)
273 br_off = get_BrOff_X1(bundle);
274 break;
275 case BNEZT_BRANCH_OPCODE_X1:
276 case BNEZ_BRANCH_OPCODE_X1:
277 if (get_SrcA_X1(bundle) != 0)
278 br_off = get_BrOff_X1(bundle);
279 break;
280 }
281
282 if (br_off != 0) {
283 br_off = sign_extend(br_off, 17);
284 addr = regs->pc +
285 (br_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
286 }
287 }
288
289 return addr;
290 }
291
292 /*
293 * Replace the next instruction after the current instruction with a
294 * breakpoint instruction.
295 */
do_single_step(struct pt_regs * regs)296 static void do_single_step(struct pt_regs *regs)
297 {
298 unsigned long addr_wr;
299
300 /* Determine where the target instruction will send us to. */
301 stepped_addr = get_step_address(regs);
302 probe_kernel_read((char *)&stepped_instr, (char *)stepped_addr,
303 BREAK_INSTR_SIZE);
304
305 addr_wr = writable_address(stepped_addr);
306 probe_kernel_write((char *)addr_wr, (char *)&singlestep_insn,
307 BREAK_INSTR_SIZE);
308 smp_wmb();
309 flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
310 }
311
undo_single_step(struct pt_regs * regs)312 static void undo_single_step(struct pt_regs *regs)
313 {
314 unsigned long addr_wr;
315
316 if (stepped_instr == 0)
317 return;
318
319 addr_wr = writable_address(stepped_addr);
320 probe_kernel_write((char *)addr_wr, (char *)&stepped_instr,
321 BREAK_INSTR_SIZE);
322 stepped_instr = 0;
323 smp_wmb();
324 flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
325 }
326
327 /*
328 * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
329 * then try to fall into the debugger.
330 */
331 static int
kgdb_notify(struct notifier_block * self,unsigned long cmd,void * ptr)332 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
333 {
334 int ret;
335 unsigned long flags;
336 struct die_args *args = (struct die_args *)ptr;
337 struct pt_regs *regs = args->regs;
338
339 #ifdef CONFIG_KPROBES
340 /*
341 * Return immediately if the kprobes fault notifier has set
342 * DIE_PAGE_FAULT.
343 */
344 if (cmd == DIE_PAGE_FAULT)
345 return NOTIFY_DONE;
346 #endif /* CONFIG_KPROBES */
347
348 switch (cmd) {
349 case DIE_BREAK:
350 case DIE_COMPILED_BPT:
351 break;
352 case DIE_SSTEPBP:
353 local_irq_save(flags);
354 kgdb_handle_exception(0, SIGTRAP, 0, regs);
355 local_irq_restore(flags);
356 return NOTIFY_STOP;
357 default:
358 /* Userspace events, ignore. */
359 if (user_mode(regs))
360 return NOTIFY_DONE;
361 }
362
363 local_irq_save(flags);
364 ret = kgdb_handle_exception(args->trapnr, args->signr, args->err, regs);
365 local_irq_restore(flags);
366 if (ret)
367 return NOTIFY_DONE;
368
369 return NOTIFY_STOP;
370 }
371
372 static struct notifier_block kgdb_notifier = {
373 .notifier_call = kgdb_notify,
374 };
375
376 /*
377 * kgdb_arch_handle_exception - Handle architecture specific GDB packets.
378 * @vector: The error vector of the exception that happened.
379 * @signo: The signal number of the exception that happened.
380 * @err_code: The error code of the exception that happened.
381 * @remcom_in_buffer: The buffer of the packet we have read.
382 * @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
383 * @regs: The &struct pt_regs of the current process.
384 *
385 * This function MUST handle the 'c' and 's' command packets,
386 * as well packets to set / remove a hardware breakpoint, if used.
387 * If there are additional packets which the hardware needs to handle,
388 * they are handled here. The code should return -1 if it wants to
389 * process more packets, and a %0 or %1 if it wants to exit from the
390 * kgdb callback.
391 */
kgdb_arch_handle_exception(int vector,int signo,int err_code,char * remcom_in_buffer,char * remcom_out_buffer,struct pt_regs * regs)392 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
393 char *remcom_in_buffer, char *remcom_out_buffer,
394 struct pt_regs *regs)
395 {
396 char *ptr;
397 unsigned long address;
398
399 /* Undo any stepping we may have done. */
400 undo_single_step(regs);
401
402 switch (remcom_in_buffer[0]) {
403 case 'c':
404 case 's':
405 case 'D':
406 case 'k':
407 /*
408 * Try to read optional parameter, pc unchanged if no parm.
409 * If this was a compiled-in breakpoint, we need to move
410 * to the next instruction or we will just breakpoint
411 * over and over again.
412 */
413 ptr = &remcom_in_buffer[1];
414 if (kgdb_hex2long(&ptr, &address))
415 regs->pc = address;
416 else if (*(unsigned long *)regs->pc == compiled_bpt)
417 regs->pc += BREAK_INSTR_SIZE;
418
419 if (remcom_in_buffer[0] == 's') {
420 do_single_step(regs);
421 kgdb_single_step = 1;
422 atomic_set(&kgdb_cpu_doing_single_step,
423 raw_smp_processor_id());
424 } else
425 atomic_set(&kgdb_cpu_doing_single_step, -1);
426
427 return 0;
428 }
429
430 return -1; /* this means that we do not want to exit from the handler */
431 }
432
433 struct kgdb_arch arch_kgdb_ops;
434
435 /*
436 * kgdb_arch_init - Perform any architecture specific initialization.
437 *
438 * This function will handle the initialization of any architecture
439 * specific callbacks.
440 */
kgdb_arch_init(void)441 int kgdb_arch_init(void)
442 {
443 tile_bundle_bits bundle = TILEGX_BPT_BUNDLE;
444
445 memcpy(arch_kgdb_ops.gdb_bpt_instr, &bundle, BREAK_INSTR_SIZE);
446 return register_die_notifier(&kgdb_notifier);
447 }
448
449 /*
450 * kgdb_arch_exit - Perform any architecture specific uninitialization.
451 *
452 * This function will handle the uninitialization of any architecture
453 * specific callbacks, for dynamic registration and unregistration.
454 */
kgdb_arch_exit(void)455 void kgdb_arch_exit(void)
456 {
457 unregister_die_notifier(&kgdb_notifier);
458 }
459
kgdb_arch_set_breakpoint(struct kgdb_bkpt * bpt)460 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
461 {
462 int err;
463 unsigned long addr_wr = writable_address(bpt->bpt_addr);
464
465 if (addr_wr == 0)
466 return -1;
467
468 err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
469 BREAK_INSTR_SIZE);
470 if (err)
471 return err;
472
473 err = probe_kernel_write((char *)addr_wr, arch_kgdb_ops.gdb_bpt_instr,
474 BREAK_INSTR_SIZE);
475 smp_wmb();
476 flush_icache_range((unsigned long)bpt->bpt_addr,
477 (unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
478 return err;
479 }
480
kgdb_arch_remove_breakpoint(struct kgdb_bkpt * bpt)481 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
482 {
483 int err;
484 unsigned long addr_wr = writable_address(bpt->bpt_addr);
485
486 if (addr_wr == 0)
487 return -1;
488
489 err = probe_kernel_write((char *)addr_wr, (char *)bpt->saved_instr,
490 BREAK_INSTR_SIZE);
491 smp_wmb();
492 flush_icache_range((unsigned long)bpt->bpt_addr,
493 (unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
494 return err;
495 }
496