1/*
2 * AArch64 KGDB support
3 *
4 * Based on arch/arm/kernel/kgdb.c
5 *
6 * Copyright (C) 2013 Cavium Inc.
7 * Author: Vijaya Kumar K <vijaya.kumar@caviumnetworks.com>
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License version 2 as
11 * published by the Free Software Foundation.
12 *
13 * This program is distributed in the hope that it will be useful,
14 * but WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16 * GNU General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
20 */
21
22#include <linux/irq.h>
23#include <linux/kdebug.h>
24#include <linux/kgdb.h>
25#include <asm/traps.h>
26
27struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
28	{ "x0", 8, offsetof(struct pt_regs, regs[0])},
29	{ "x1", 8, offsetof(struct pt_regs, regs[1])},
30	{ "x2", 8, offsetof(struct pt_regs, regs[2])},
31	{ "x3", 8, offsetof(struct pt_regs, regs[3])},
32	{ "x4", 8, offsetof(struct pt_regs, regs[4])},
33	{ "x5", 8, offsetof(struct pt_regs, regs[5])},
34	{ "x6", 8, offsetof(struct pt_regs, regs[6])},
35	{ "x7", 8, offsetof(struct pt_regs, regs[7])},
36	{ "x8", 8, offsetof(struct pt_regs, regs[8])},
37	{ "x9", 8, offsetof(struct pt_regs, regs[9])},
38	{ "x10", 8, offsetof(struct pt_regs, regs[10])},
39	{ "x11", 8, offsetof(struct pt_regs, regs[11])},
40	{ "x12", 8, offsetof(struct pt_regs, regs[12])},
41	{ "x13", 8, offsetof(struct pt_regs, regs[13])},
42	{ "x14", 8, offsetof(struct pt_regs, regs[14])},
43	{ "x15", 8, offsetof(struct pt_regs, regs[15])},
44	{ "x16", 8, offsetof(struct pt_regs, regs[16])},
45	{ "x17", 8, offsetof(struct pt_regs, regs[17])},
46	{ "x18", 8, offsetof(struct pt_regs, regs[18])},
47	{ "x19", 8, offsetof(struct pt_regs, regs[19])},
48	{ "x20", 8, offsetof(struct pt_regs, regs[20])},
49	{ "x21", 8, offsetof(struct pt_regs, regs[21])},
50	{ "x22", 8, offsetof(struct pt_regs, regs[22])},
51	{ "x23", 8, offsetof(struct pt_regs, regs[23])},
52	{ "x24", 8, offsetof(struct pt_regs, regs[24])},
53	{ "x25", 8, offsetof(struct pt_regs, regs[25])},
54	{ "x26", 8, offsetof(struct pt_regs, regs[26])},
55	{ "x27", 8, offsetof(struct pt_regs, regs[27])},
56	{ "x28", 8, offsetof(struct pt_regs, regs[28])},
57	{ "x29", 8, offsetof(struct pt_regs, regs[29])},
58	{ "x30", 8, offsetof(struct pt_regs, regs[30])},
59	{ "sp", 8, offsetof(struct pt_regs, sp)},
60	{ "pc", 8, offsetof(struct pt_regs, pc)},
61	{ "pstate", 8, offsetof(struct pt_regs, pstate)},
62	{ "v0", 16, -1 },
63	{ "v1", 16, -1 },
64	{ "v2", 16, -1 },
65	{ "v3", 16, -1 },
66	{ "v4", 16, -1 },
67	{ "v5", 16, -1 },
68	{ "v6", 16, -1 },
69	{ "v7", 16, -1 },
70	{ "v8", 16, -1 },
71	{ "v9", 16, -1 },
72	{ "v10", 16, -1 },
73	{ "v11", 16, -1 },
74	{ "v12", 16, -1 },
75	{ "v13", 16, -1 },
76	{ "v14", 16, -1 },
77	{ "v15", 16, -1 },
78	{ "v16", 16, -1 },
79	{ "v17", 16, -1 },
80	{ "v18", 16, -1 },
81	{ "v19", 16, -1 },
82	{ "v20", 16, -1 },
83	{ "v21", 16, -1 },
84	{ "v22", 16, -1 },
85	{ "v23", 16, -1 },
86	{ "v24", 16, -1 },
87	{ "v25", 16, -1 },
88	{ "v26", 16, -1 },
89	{ "v27", 16, -1 },
90	{ "v28", 16, -1 },
91	{ "v29", 16, -1 },
92	{ "v30", 16, -1 },
93	{ "v31", 16, -1 },
94	{ "fpsr", 4, -1 },
95	{ "fpcr", 4, -1 },
96};
97
98char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
99{
100	if (regno >= DBG_MAX_REG_NUM || regno < 0)
101		return NULL;
102
103	if (dbg_reg_def[regno].offset != -1)
104		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
105		       dbg_reg_def[regno].size);
106	else
107		memset(mem, 0, dbg_reg_def[regno].size);
108	return dbg_reg_def[regno].name;
109}
110
111int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
112{
113	if (regno >= DBG_MAX_REG_NUM || regno < 0)
114		return -EINVAL;
115
116	if (dbg_reg_def[regno].offset != -1)
117		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
118		       dbg_reg_def[regno].size);
119	return 0;
120}
121
122void
123sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
124{
125	struct pt_regs *thread_regs;
126
127	/* Initialize to zero */
128	memset((char *)gdb_regs, 0, NUMREGBYTES);
129	thread_regs = task_pt_regs(task);
130	memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES);
131}
132
133void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
134{
135	regs->pc = pc;
136}
137
138static int compiled_break;
139
140static void kgdb_arch_update_addr(struct pt_regs *regs,
141				char *remcom_in_buffer)
142{
143	unsigned long addr;
144	char *ptr;
145
146	ptr = &remcom_in_buffer[1];
147	if (kgdb_hex2long(&ptr, &addr))
148		kgdb_arch_set_pc(regs, addr);
149	else if (compiled_break == 1)
150		kgdb_arch_set_pc(regs, regs->pc + 4);
151
152	compiled_break = 0;
153}
154
155int kgdb_arch_handle_exception(int exception_vector, int signo,
156			       int err_code, char *remcom_in_buffer,
157			       char *remcom_out_buffer,
158			       struct pt_regs *linux_regs)
159{
160	int err;
161
162	switch (remcom_in_buffer[0]) {
163	case 'D':
164	case 'k':
165		/*
166		 * Packet D (Detach), k (kill). No special handling
167		 * is required here. Handle same as c packet.
168		 */
169	case 'c':
170		/*
171		 * Packet c (Continue) to continue executing.
172		 * Set pc to required address.
173		 * Try to read optional parameter and set pc.
174		 * If this was a compiled breakpoint, we need to move
175		 * to the next instruction else we will just breakpoint
176		 * over and over again.
177		 */
178		kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
179		atomic_set(&kgdb_cpu_doing_single_step, -1);
180		kgdb_single_step =  0;
181
182		/*
183		 * Received continue command, disable single step
184		 */
185		if (kernel_active_single_step())
186			kernel_disable_single_step();
187
188		err = 0;
189		break;
190	case 's':
191		/*
192		 * Update step address value with address passed
193		 * with step packet.
194		 * On debug exception return PC is copied to ELR
195		 * So just update PC.
196		 * If no step address is passed, resume from the address
197		 * pointed by PC. Do not update PC
198		 */
199		kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
200		atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id());
201		kgdb_single_step =  1;
202
203		/*
204		 * Enable single step handling
205		 */
206		if (!kernel_active_single_step())
207			kernel_enable_single_step(linux_regs);
208		err = 0;
209		break;
210	default:
211		err = -1;
212	}
213	return err;
214}
215
216static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
217{
218	kgdb_handle_exception(1, SIGTRAP, 0, regs);
219	return 0;
220}
221
222static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
223{
224	compiled_break = 1;
225	kgdb_handle_exception(1, SIGTRAP, 0, regs);
226
227	return 0;
228}
229
230static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
231{
232	kgdb_handle_exception(1, SIGTRAP, 0, regs);
233	return 0;
234}
235
236static struct break_hook kgdb_brkpt_hook = {
237	.esr_mask	= 0xffffffff,
238	.esr_val	= (u32)ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM),
239	.fn		= kgdb_brk_fn
240};
241
242static struct break_hook kgdb_compiled_brkpt_hook = {
243	.esr_mask	= 0xffffffff,
244	.esr_val	= (u32)ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM),
245	.fn		= kgdb_compiled_brk_fn
246};
247
248static struct step_hook kgdb_step_hook = {
249	.fn		= kgdb_step_brk_fn
250};
251
252static void kgdb_call_nmi_hook(void *ignored)
253{
254	kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
255}
256
257void kgdb_roundup_cpus(unsigned long flags)
258{
259	local_irq_enable();
260	smp_call_function(kgdb_call_nmi_hook, NULL, 0);
261	local_irq_disable();
262}
263
264static int __kgdb_notify(struct die_args *args, unsigned long cmd)
265{
266	struct pt_regs *regs = args->regs;
267
268	if (kgdb_handle_exception(1, args->signr, cmd, regs))
269		return NOTIFY_DONE;
270	return NOTIFY_STOP;
271}
272
273static int
274kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
275{
276	unsigned long flags;
277	int ret;
278
279	local_irq_save(flags);
280	ret = __kgdb_notify(ptr, cmd);
281	local_irq_restore(flags);
282
283	return ret;
284}
285
286static struct notifier_block kgdb_notifier = {
287	.notifier_call	= kgdb_notify,
288	/*
289	 * Want to be lowest priority
290	 */
291	.priority	= -INT_MAX,
292};
293
294/*
295 * kgdb_arch_init - Perform any architecture specific initalization.
296 * This function will handle the initalization of any architecture
297 * specific callbacks.
298 */
299int kgdb_arch_init(void)
300{
301	int ret = register_die_notifier(&kgdb_notifier);
302
303	if (ret != 0)
304		return ret;
305
306	register_break_hook(&kgdb_brkpt_hook);
307	register_break_hook(&kgdb_compiled_brkpt_hook);
308	register_step_hook(&kgdb_step_hook);
309	return 0;
310}
311
312/*
313 * kgdb_arch_exit - Perform any architecture specific uninitalization.
314 * This function will handle the uninitalization of any architecture
315 * specific callbacks, for dynamic registration and unregistration.
316 */
317void kgdb_arch_exit(void)
318{
319	unregister_break_hook(&kgdb_brkpt_hook);
320	unregister_break_hook(&kgdb_compiled_brkpt_hook);
321	unregister_step_hook(&kgdb_step_hook);
322	unregister_die_notifier(&kgdb_notifier);
323}
324
325/*
326 * ARM instructions are always in LE.
327 * Break instruction is encoded in LE format
328 */
329struct kgdb_arch arch_kgdb_ops = {
330	.gdb_bpt_instr = {
331		KGDB_DYN_BRK_INS_BYTE(0),
332		KGDB_DYN_BRK_INS_BYTE(1),
333		KGDB_DYN_BRK_INS_BYTE(2),
334		KGDB_DYN_BRK_INS_BYTE(3),
335	}
336};
337