summaryrefslogtreecommitdiff
path: root/arch/arm64/kernel/kgdb.c
blob: da880247c7342974550760f78f6b74308321435d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
/*
 * AArch64 KGDB support
 *
 * Based on arch/arm/kernel/kgdb.c
 *
 * Copyright (C) 2013 Cavium Inc.
 * Author: Vijaya Kumar K <vijaya.kumar@caviumnetworks.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <linux/bug.h>
#include <linux/irq.h>
#include <linux/kdebug.h>
#include <linux/kgdb.h>
#include <linux/kprobes.h>
#include <linux/sched/task_stack.h>

#include <asm/debug-monitors.h>
#include <asm/insn.h>
#include <asm/traps.h>

struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
	{ "x0", 8, offsetof(struct pt_regs, regs[0])},
	{ "x1", 8, offsetof(struct pt_regs, regs[1])},
	{ "x2", 8, offsetof(struct pt_regs, regs[2])},
	{ "x3", 8, offsetof(struct pt_regs, regs[3])},
	{ "x4", 8, offsetof(struct pt_regs, regs[4])},
	{ "x5", 8, offsetof(struct pt_regs, regs[5])},
	{ "x6", 8, offsetof(struct pt_regs, regs[6])},
	{ "x7", 8, offsetof(struct pt_regs, regs[7])},
	{ "x8", 8, offsetof(struct pt_regs, regs[8])},
	{ "x9", 8, offsetof(struct pt_regs, regs[9])},
	{ "x10", 8, offsetof(struct pt_regs, regs[10])},
	{ "x11", 8, offsetof(struct pt_regs, regs[11])},
	{ "x12", 8, offsetof(struct pt_regs, regs[12])},
	{ "x13", 8, offsetof(struct pt_regs, regs[13])},
	{ "x14", 8, offsetof(struct pt_regs, regs[14])},
	{ "x15", 8, offsetof(struct pt_regs, regs[15])},
	{ "x16", 8, offsetof(struct pt_regs, regs[16])},
	{ "x17", 8, offsetof(struct pt_regs, regs[17])},
	{ "x18", 8, offsetof(struct pt_regs, regs[18])},
	{ "x19", 8, offsetof(struct pt_regs, regs[19])},
	{ "x20", 8, offsetof(struct pt_regs, regs[20])},
	{ "x21", 8, offsetof(struct pt_regs, regs[21])},
	{ "x22", 8, offsetof(struct pt_regs, regs[22])},
	{ "x23", 8, offsetof(struct pt_regs, regs[23])},
	{ "x24", 8, offsetof(struct pt_regs, regs[24])},
	{ "x25", 8, offsetof(struct pt_regs, regs[25])},
	{ "x26", 8, offsetof(struct pt_regs, regs[26])},
	{ "x27", 8, offsetof(struct pt_regs, regs[27])},
	{ "x28", 8, offsetof(struct pt_regs, regs[28])},
	{ "x29", 8, offsetof(struct pt_regs, regs[29])},
	{ "x30", 8, offsetof(struct pt_regs, regs[30])},
	{ "sp", 8, offsetof(struct pt_regs, sp)},
	{ "pc", 8, offsetof(struct pt_regs, pc)},
	/*
	 * struct pt_regs thinks PSTATE is 64-bits wide but gdb remote
	 * protocol disagrees. Therefore we must extract only the lower
	 * 32-bits. Look for the big comment in asm/kgdb.h for more
	 * detail.
	 */
	{ "pstate", 4, offsetof(struct pt_regs, pstate)
#ifdef CONFIG_CPU_BIG_ENDIAN
							+ 4
#endif
	},
	{ "v0", 16, -1 },
	{ "v1", 16, -1 },
	{ "v2", 16, -1 },
	{ "v3", 16, -1 },
	{ "v4", 16, -1 },
	{ "v5", 16, -1 },
	{ "v6", 16, -1 },
	{ "v7", 16, -1 },
	{ "v8", 16, -1 },
	{ "v9", 16, -1 },
	{ "v10", 16, -1 },
	{ "v11", 16, -1 },
	{ "v12", 16, -1 },
	{ "v13", 16, -1 },
	{ "v14", 16, -1 },
	{ "v15", 16, -1 },
	{ "v16", 16, -1 },
	{ "v17", 16, -1 },
	{ "v18", 16, -1 },
	{ "v19", 16, -1 },
	{ "v20", 16, -1 },
	{ "v21", 16, -1 },
	{ "v22", 16, -1 },
	{ "v23", 16, -1 },
	{ "v24", 16, -1 },
	{ "v25", 16, -1 },
	{ "v26", 16, -1 },
	{ "v27", 16, -1 },
	{ "v28", 16, -1 },
	{ "v29", 16, -1 },
	{ "v30", 16, -1 },
	{ "v31", 16, -1 },
	{ "fpsr", 4, -1 },
	{ "fpcr", 4, -1 },
};

char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
{
	if (regno >= DBG_MAX_REG_NUM || regno < 0)
		return NULL;

	if (dbg_reg_def[regno].offset != -1)
		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
		       dbg_reg_def[regno].size);
	else
		memset(mem, 0, dbg_reg_def[regno].size);
	return dbg_reg_def[regno].name;
}

int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
{
	if (regno >= DBG_MAX_REG_NUM || regno < 0)
		return -EINVAL;

	if (dbg_reg_def[regno].offset != -1)
		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
		       dbg_reg_def[regno].size);
	return 0;
}

void
sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
{
	struct cpu_context *cpu_context = &task->thread.cpu_context;

	/* Initialize to zero */
	memset((char *)gdb_regs, 0, NUMREGBYTES);

	gdb_regs[19] = cpu_context->x19;
	gdb_regs[20] = cpu_context->x20;
	gdb_regs[21] = cpu_context->x21;
	gdb_regs[22] = cpu_context->x22;
	gdb_regs[23] = cpu_context->x23;
	gdb_regs[24] = cpu_context->x24;
	gdb_regs[25] = cpu_context->x25;
	gdb_regs[26] = cpu_context->x26;
	gdb_regs[27] = cpu_context->x27;
	gdb_regs[28] = cpu_context->x28;
	gdb_regs[29] = cpu_context->fp;

	gdb_regs[31] = cpu_context->sp;
	gdb_regs[32] = cpu_context->pc;
}

void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
{
	regs->pc = pc;
}

static int compiled_break;

static void kgdb_arch_update_addr(struct pt_regs *regs,
				char *remcom_in_buffer)
{
	unsigned long addr;
	char *ptr;

	ptr = &remcom_in_buffer[1];
	if (kgdb_hex2long(&ptr, &addr))
		kgdb_arch_set_pc(regs, addr);
	else if (compiled_break == 1)
		kgdb_arch_set_pc(regs, regs->pc + 4);

	compiled_break = 0;
}

int kgdb_arch_handle_exception(int exception_vector, int signo,
			       int err_code, char *remcom_in_buffer,
			       char *remcom_out_buffer,
			       struct pt_regs *linux_regs)
{
	int err;

	switch (remcom_in_buffer[0]) {
	case 'D':
	case 'k':
		/*
		 * Packet D (Detach), k (kill). No special handling
		 * is required here. Handle same as c packet.
		 */
	case 'c':
		/*
		 * Packet c (Continue) to continue executing.
		 * Set pc to required address.
		 * Try to read optional parameter and set pc.
		 * If this was a compiled breakpoint, we need to move
		 * to the next instruction else we will just breakpoint
		 * over and over again.
		 */
		kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
		atomic_set(&kgdb_cpu_doing_single_step, -1);
		kgdb_single_step =  0;

		/*
		 * Received continue command, disable single step
		 */
		if (kernel_active_single_step())
			kernel_disable_single_step();

		err = 0;
		break;
	case 's':
		/*
		 * Update step address value with address passed
		 * with step packet.
		 * On debug exception return PC is copied to ELR
		 * So just update PC.
		 * If no step address is passed, resume from the address
		 * pointed by PC. Do not update PC
		 */
		kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
		atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id());
		kgdb_single_step =  1;

		/*
		 * Enable single step handling
		 */
		if (!kernel_active_single_step())
			kernel_enable_single_step(linux_regs);
		err = 0;
		break;
	default:
		err = -1;
	}
	return err;
}

static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
{
	kgdb_handle_exception(1, SIGTRAP, 0, regs);
	return 0;
}
NOKPROBE_SYMBOL(kgdb_brk_fn)

static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
{
	compiled_break = 1;
	kgdb_handle_exception(1, SIGTRAP, 0, regs);

	return 0;
}
NOKPROBE_SYMBOL(kgdb_compiled_brk_fn);

static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
{
	if (!kgdb_single_step)
		return DBG_HOOK_ERROR;

	kgdb_handle_exception(1, SIGTRAP, 0, regs);
	return 0;
}
NOKPROBE_SYMBOL(kgdb_step_brk_fn);

static struct break_hook kgdb_brkpt_hook = {
	.esr_mask	= 0xffffffff,
	.esr_val	= (u32)ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM),
	.fn		= kgdb_brk_fn
};

static struct break_hook kgdb_compiled_brkpt_hook = {
	.esr_mask	= 0xffffffff,
	.esr_val	= (u32)ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM),
	.fn		= kgdb_compiled_brk_fn
};

static struct step_hook kgdb_step_hook = {
	.fn		= kgdb_step_brk_fn
};

static int __kgdb_notify(struct die_args *args, unsigned long cmd)
{
	struct pt_regs *regs = args->regs;

	if (kgdb_handle_exception(1, args->signr, cmd, regs))
		return NOTIFY_DONE;
	return NOTIFY_STOP;
}

static int
kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
{
	unsigned long flags;
	int ret;

	local_irq_save(flags);
	ret = __kgdb_notify(ptr, cmd);
	local_irq_restore(flags);

	return ret;
}

static struct notifier_block kgdb_notifier = {
	.notifier_call	= kgdb_notify,
	/*
	 * Want to be lowest priority
	 */
	.priority	= -INT_MAX,
};

/*
 * kgdb_arch_init - Perform any architecture specific initialization.
 * This function will handle the initialization of any architecture
 * specific callbacks.
 */
int kgdb_arch_init(void)
{
	int ret = register_die_notifier(&kgdb_notifier);

	if (ret != 0)
		return ret;

	register_break_hook(&kgdb_brkpt_hook);
	register_break_hook(&kgdb_compiled_brkpt_hook);
	register_step_hook(&kgdb_step_hook);
	return 0;
}

/*
 * kgdb_arch_exit - Perform any architecture specific uninitalization.
 * This function will handle the uninitalization of any architecture
 * specific callbacks, for dynamic registration and unregistration.
 */
void kgdb_arch_exit(void)
{
	unregister_break_hook(&kgdb_brkpt_hook);
	unregister_break_hook(&kgdb_compiled_brkpt_hook);
	unregister_step_hook(&kgdb_step_hook);
	unregister_die_notifier(&kgdb_notifier);
}

struct kgdb_arch arch_kgdb_ops;

int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
{
	int err;

	BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE);

	err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr);
	if (err)
		return err;

	return aarch64_insn_write((void *)bpt->bpt_addr,
			(u32)AARCH64_BREAK_KGDB_DYN_DBG);
}

int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
{
	return aarch64_insn_write((void *)bpt->bpt_addr,
			*(u32 *)bpt->saved_instr);
}