1// SPDX-License-Identifier: GPL-2.0
2/*
3 * arch/arm/kernel/kgdb.c
4 *
5 * ARM KGDB support
6 *
7 * Copyright (c) 2002-2004 MontaVista Software, Inc
8 * Copyright (c) 2008 Wind River Systems, Inc.
9 *
10 * Authors:  George Davis <davis_g@mvista.com>
11 *           Deepak Saxena <dsaxena@plexity.net>
12 */
13#include <linux/irq.h>
14#include <linux/kdebug.h>
15#include <linux/kgdb.h>
16#include <linux/uaccess.h>
17
18#include <asm/patch.h>
19#include <asm/traps.h>
20
21struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
22{
23	{ "r0", 4, offsetof(struct pt_regs, ARM_r0)},
24	{ "r1", 4, offsetof(struct pt_regs, ARM_r1)},
25	{ "r2", 4, offsetof(struct pt_regs, ARM_r2)},
26	{ "r3", 4, offsetof(struct pt_regs, ARM_r3)},
27	{ "r4", 4, offsetof(struct pt_regs, ARM_r4)},
28	{ "r5", 4, offsetof(struct pt_regs, ARM_r5)},
29	{ "r6", 4, offsetof(struct pt_regs, ARM_r6)},
30	{ "r7", 4, offsetof(struct pt_regs, ARM_r7)},
31	{ "r8", 4, offsetof(struct pt_regs, ARM_r8)},
32	{ "r9", 4, offsetof(struct pt_regs, ARM_r9)},
33	{ "r10", 4, offsetof(struct pt_regs, ARM_r10)},
34	{ "fp", 4, offsetof(struct pt_regs, ARM_fp)},
35	{ "ip", 4, offsetof(struct pt_regs, ARM_ip)},
36	{ "sp", 4, offsetof(struct pt_regs, ARM_sp)},
37	{ "lr", 4, offsetof(struct pt_regs, ARM_lr)},
38	{ "pc", 4, offsetof(struct pt_regs, ARM_pc)},
39	{ "f0", 12, -1 },
40	{ "f1", 12, -1 },
41	{ "f2", 12, -1 },
42	{ "f3", 12, -1 },
43	{ "f4", 12, -1 },
44	{ "f5", 12, -1 },
45	{ "f6", 12, -1 },
46	{ "f7", 12, -1 },
47	{ "fps", 4, -1 },
48	{ "cpsr", 4, offsetof(struct pt_regs, ARM_cpsr)},
49};
50
51char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
52{
53	if (regno >= DBG_MAX_REG_NUM || regno < 0)
54		return NULL;
55
56	if (dbg_reg_def[regno].offset != -1)
57		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
58		       dbg_reg_def[regno].size);
59	else
60		memset(mem, 0, dbg_reg_def[regno].size);
61	return dbg_reg_def[regno].name;
62}
63
64int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
65{
66	if (regno >= DBG_MAX_REG_NUM || regno < 0)
67		return -EINVAL;
68
69	if (dbg_reg_def[regno].offset != -1)
70		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
71		       dbg_reg_def[regno].size);
72	return 0;
73}
74
75void
76sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
77{
78	struct thread_info *ti;
79	int regno;
80
81	/* Just making sure... */
82	if (task == NULL)
83		return;
84
85	/* Initialize to zero */
86	for (regno = 0; regno < GDB_MAX_REGS; regno++)
87		gdb_regs[regno] = 0;
88
89	/* Otherwise, we have only some registers from switch_to() */
90	ti			= task_thread_info(task);
91	gdb_regs[_R4]		= ti->cpu_context.r4;
92	gdb_regs[_R5]		= ti->cpu_context.r5;
93	gdb_regs[_R6]		= ti->cpu_context.r6;
94	gdb_regs[_R7]		= ti->cpu_context.r7;
95	gdb_regs[_R8]		= ti->cpu_context.r8;
96	gdb_regs[_R9]		= ti->cpu_context.r9;
97	gdb_regs[_R10]		= ti->cpu_context.sl;
98	gdb_regs[_FP]		= ti->cpu_context.fp;
99	gdb_regs[_SPT]		= ti->cpu_context.sp;
100	gdb_regs[_PC]		= ti->cpu_context.pc;
101}
102
103void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
104{
105	regs->ARM_pc = pc;
106}
107
108static int compiled_break;
109
110int kgdb_arch_handle_exception(int exception_vector, int signo,
111			       int err_code, char *remcom_in_buffer,
112			       char *remcom_out_buffer,
113			       struct pt_regs *linux_regs)
114{
115	unsigned long addr;
116	char *ptr;
117
118	switch (remcom_in_buffer[0]) {
119	case 'D':
120	case 'k':
121	case 'c':
122		/*
123		 * Try to read optional parameter, pc unchanged if no parm.
124		 * If this was a compiled breakpoint, we need to move
125		 * to the next instruction or we will just breakpoint
126		 * over and over again.
127		 */
128		ptr = &remcom_in_buffer[1];
129		if (kgdb_hex2long(&ptr, &addr))
130			linux_regs->ARM_pc = addr;
131		else if (compiled_break == 1)
132			linux_regs->ARM_pc += 4;
133
134		compiled_break = 0;
135
136		return 0;
137	}
138
139	return -1;
140}
141
142static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
143{
144	kgdb_handle_exception(1, SIGTRAP, 0, regs);
145
146	return 0;
147}
148
149static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
150{
151	compiled_break = 1;
152	kgdb_handle_exception(1, SIGTRAP, 0, regs);
153
154	return 0;
155}
156
157static struct undef_hook kgdb_brkpt_arm_hook = {
158	.instr_mask		= 0xffffffff,
159	.instr_val		= KGDB_BREAKINST,
160	.cpsr_mask		= PSR_T_BIT | MODE_MASK,
161	.cpsr_val		= SVC_MODE,
162	.fn			= kgdb_brk_fn
163};
164
165static struct undef_hook kgdb_brkpt_thumb_hook = {
166	.instr_mask		= 0xffff,
167	.instr_val		= KGDB_BREAKINST & 0xffff,
168	.cpsr_mask		= PSR_T_BIT | MODE_MASK,
169	.cpsr_val		= PSR_T_BIT | SVC_MODE,
170	.fn			= kgdb_brk_fn
171};
172
173static struct undef_hook kgdb_compiled_brkpt_arm_hook = {
174	.instr_mask		= 0xffffffff,
175	.instr_val		= KGDB_COMPILED_BREAK,
176	.cpsr_mask		= PSR_T_BIT | MODE_MASK,
177	.cpsr_val		= SVC_MODE,
178	.fn			= kgdb_compiled_brk_fn
179};
180
181static struct undef_hook kgdb_compiled_brkpt_thumb_hook = {
182	.instr_mask		= 0xffff,
183	.instr_val		= KGDB_COMPILED_BREAK & 0xffff,
184	.cpsr_mask		= PSR_T_BIT | MODE_MASK,
185	.cpsr_val		= PSR_T_BIT | SVC_MODE,
186	.fn			= kgdb_compiled_brk_fn
187};
188
189static int __kgdb_notify(struct die_args *args, unsigned long cmd)
190{
191	struct pt_regs *regs = args->regs;
192
193	if (kgdb_handle_exception(1, args->signr, cmd, regs))
194		return NOTIFY_DONE;
195	return NOTIFY_STOP;
196}
197static int
198kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
199{
200	unsigned long flags;
201	int ret;
202
203	local_irq_save(flags);
204	ret = __kgdb_notify(ptr, cmd);
205	local_irq_restore(flags);
206
207	return ret;
208}
209
210static struct notifier_block kgdb_notifier = {
211	.notifier_call	= kgdb_notify,
212	.priority	= -INT_MAX,
213};
214
215
216/**
217 *	kgdb_arch_init - Perform any architecture specific initalization.
218 *
219 *	This function will handle the initalization of any architecture
220 *	specific callbacks.
221 */
222int kgdb_arch_init(void)
223{
224	int ret = register_die_notifier(&kgdb_notifier);
225
226	if (ret != 0)
227		return ret;
228
229	register_undef_hook(&kgdb_brkpt_arm_hook);
230	register_undef_hook(&kgdb_brkpt_thumb_hook);
231	register_undef_hook(&kgdb_compiled_brkpt_arm_hook);
232	register_undef_hook(&kgdb_compiled_brkpt_thumb_hook);
233
234	return 0;
235}
236
237/**
238 *	kgdb_arch_exit - Perform any architecture specific uninitalization.
239 *
240 *	This function will handle the uninitalization of any architecture
241 *	specific callbacks, for dynamic registration and unregistration.
242 */
243void kgdb_arch_exit(void)
244{
245	unregister_undef_hook(&kgdb_brkpt_arm_hook);
246	unregister_undef_hook(&kgdb_brkpt_thumb_hook);
247	unregister_undef_hook(&kgdb_compiled_brkpt_arm_hook);
248	unregister_undef_hook(&kgdb_compiled_brkpt_thumb_hook);
249	unregister_die_notifier(&kgdb_notifier);
250}
251
252int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
253{
254	int err;
255
256	/* patch_text() only supports int-sized breakpoints */
257	BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);
258
259	err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr,
260				BREAK_INSTR_SIZE);
261	if (err)
262		return err;
263
264	/* Machine is already stopped, so we can use __patch_text() directly */
265	__patch_text((void *)bpt->bpt_addr,
266		     *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
267
268	return err;
269}
270
271int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
272{
273	/* Machine is already stopped, so we can use __patch_text() directly */
274	__patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
275
276	return 0;
277}
278
279/*
280 * Register our undef instruction hooks with ARM undef core.
281 * We register a hook specifically looking for the KGB break inst
282 * and we handle the normal undef case within the do_undefinstr
283 * handler.
284 */
285const struct kgdb_arch arch_kgdb_ops = {
286#ifndef __ARMEB__
287	.gdb_bpt_instr		= {0xfe, 0xde, 0xff, 0xe7}
288#else /* ! __ARMEB__ */
289	.gdb_bpt_instr		= {0xe7, 0xff, 0xde, 0xfe}
290#endif
291};
292