1/*
2 * arch/arm/kernel/kgdb.c
3 *
4 * ARM KGDB support
5 *
6 * Copyright (c) 2002-2004 MontaVista Software, Inc
7 * Copyright (c) 2008 Wind River Systems, Inc.
8 *
9 * Authors:  George Davis <davis_g@mvista.com>
10 *           Deepak Saxena <dsaxena@plexity.net>
11 */
12#include <linux/irq.h>
13#include <linux/kdebug.h>
14#include <linux/kgdb.h>
15#include <linux/uaccess.h>
16
17#include <asm/patch.h>
18#include <asm/traps.h>
19
20struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
21{
22	{ "r0", 4, offsetof(struct pt_regs, ARM_r0)},
23	{ "r1", 4, offsetof(struct pt_regs, ARM_r1)},
24	{ "r2", 4, offsetof(struct pt_regs, ARM_r2)},
25	{ "r3", 4, offsetof(struct pt_regs, ARM_r3)},
26	{ "r4", 4, offsetof(struct pt_regs, ARM_r4)},
27	{ "r5", 4, offsetof(struct pt_regs, ARM_r5)},
28	{ "r6", 4, offsetof(struct pt_regs, ARM_r6)},
29	{ "r7", 4, offsetof(struct pt_regs, ARM_r7)},
30	{ "r8", 4, offsetof(struct pt_regs, ARM_r8)},
31	{ "r9", 4, offsetof(struct pt_regs, ARM_r9)},
32	{ "r10", 4, offsetof(struct pt_regs, ARM_r10)},
33	{ "fp", 4, offsetof(struct pt_regs, ARM_fp)},
34	{ "ip", 4, offsetof(struct pt_regs, ARM_ip)},
35	{ "sp", 4, offsetof(struct pt_regs, ARM_sp)},
36	{ "lr", 4, offsetof(struct pt_regs, ARM_lr)},
37	{ "pc", 4, offsetof(struct pt_regs, ARM_pc)},
38	{ "f0", 12, -1 },
39	{ "f1", 12, -1 },
40	{ "f2", 12, -1 },
41	{ "f3", 12, -1 },
42	{ "f4", 12, -1 },
43	{ "f5", 12, -1 },
44	{ "f6", 12, -1 },
45	{ "f7", 12, -1 },
46	{ "fps", 4, -1 },
47	{ "cpsr", 4, offsetof(struct pt_regs, ARM_cpsr)},
48};
49
50char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
51{
52	if (regno >= DBG_MAX_REG_NUM || regno < 0)
53		return NULL;
54
55	if (dbg_reg_def[regno].offset != -1)
56		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
57		       dbg_reg_def[regno].size);
58	else
59		memset(mem, 0, dbg_reg_def[regno].size);
60	return dbg_reg_def[regno].name;
61}
62
63int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
64{
65	if (regno >= DBG_MAX_REG_NUM || regno < 0)
66		return -EINVAL;
67
68	if (dbg_reg_def[regno].offset != -1)
69		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
70		       dbg_reg_def[regno].size);
71	return 0;
72}
73
74void
75sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
76{
77	struct pt_regs *thread_regs;
78	int regno;
79
80	/* Just making sure... */
81	if (task == NULL)
82		return;
83
84	/* Initialize to zero */
85	for (regno = 0; regno < GDB_MAX_REGS; regno++)
86		gdb_regs[regno] = 0;
87
88	/* Otherwise, we have only some registers from switch_to() */
89	thread_regs		= task_pt_regs(task);
90	gdb_regs[_R0]		= thread_regs->ARM_r0;
91	gdb_regs[_R1]		= thread_regs->ARM_r1;
92	gdb_regs[_R2]		= thread_regs->ARM_r2;
93	gdb_regs[_R3]		= thread_regs->ARM_r3;
94	gdb_regs[_R4]		= thread_regs->ARM_r4;
95	gdb_regs[_R5]		= thread_regs->ARM_r5;
96	gdb_regs[_R6]		= thread_regs->ARM_r6;
97	gdb_regs[_R7]		= thread_regs->ARM_r7;
98	gdb_regs[_R8]		= thread_regs->ARM_r8;
99	gdb_regs[_R9]		= thread_regs->ARM_r9;
100	gdb_regs[_R10]		= thread_regs->ARM_r10;
101	gdb_regs[_FP]		= thread_regs->ARM_fp;
102	gdb_regs[_IP]		= thread_regs->ARM_ip;
103	gdb_regs[_SPT]		= thread_regs->ARM_sp;
104	gdb_regs[_LR]		= thread_regs->ARM_lr;
105	gdb_regs[_PC]		= thread_regs->ARM_pc;
106	gdb_regs[_CPSR]		= thread_regs->ARM_cpsr;
107}
108
109void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
110{
111	regs->ARM_pc = pc;
112}
113
114static int compiled_break;
115
116int kgdb_arch_handle_exception(int exception_vector, int signo,
117			       int err_code, char *remcom_in_buffer,
118			       char *remcom_out_buffer,
119			       struct pt_regs *linux_regs)
120{
121	unsigned long addr;
122	char *ptr;
123
124	switch (remcom_in_buffer[0]) {
125	case 'D':
126	case 'k':
127	case 'c':
128		/*
129		 * Try to read optional parameter, pc unchanged if no parm.
130		 * If this was a compiled breakpoint, we need to move
131		 * to the next instruction or we will just breakpoint
132		 * over and over again.
133		 */
134		ptr = &remcom_in_buffer[1];
135		if (kgdb_hex2long(&ptr, &addr))
136			linux_regs->ARM_pc = addr;
137		else if (compiled_break == 1)
138			linux_regs->ARM_pc += 4;
139
140		compiled_break = 0;
141
142		return 0;
143	}
144
145	return -1;
146}
147
148static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
149{
150	kgdb_handle_exception(1, SIGTRAP, 0, regs);
151
152	return 0;
153}
154
155static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
156{
157	compiled_break = 1;
158	kgdb_handle_exception(1, SIGTRAP, 0, regs);
159
160	return 0;
161}
162
163static struct undef_hook kgdb_brkpt_hook = {
164	.instr_mask		= 0xffffffff,
165	.instr_val		= KGDB_BREAKINST,
166	.cpsr_mask		= MODE_MASK,
167	.cpsr_val		= SVC_MODE,
168	.fn			= kgdb_brk_fn
169};
170
171static struct undef_hook kgdb_compiled_brkpt_hook = {
172	.instr_mask		= 0xffffffff,
173	.instr_val		= KGDB_COMPILED_BREAK,
174	.cpsr_mask		= MODE_MASK,
175	.cpsr_val		= SVC_MODE,
176	.fn			= kgdb_compiled_brk_fn
177};
178
179static void kgdb_call_nmi_hook(void *ignored)
180{
181       kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
182}
183
184void kgdb_roundup_cpus(unsigned long flags)
185{
186       local_irq_enable();
187       smp_call_function(kgdb_call_nmi_hook, NULL, 0);
188       local_irq_disable();
189}
190
191static int __kgdb_notify(struct die_args *args, unsigned long cmd)
192{
193	struct pt_regs *regs = args->regs;
194
195	if (kgdb_handle_exception(1, args->signr, cmd, regs))
196		return NOTIFY_DONE;
197	return NOTIFY_STOP;
198}
199static int
200kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
201{
202	unsigned long flags;
203	int ret;
204
205	local_irq_save(flags);
206	ret = __kgdb_notify(ptr, cmd);
207	local_irq_restore(flags);
208
209	return ret;
210}
211
212static struct notifier_block kgdb_notifier = {
213	.notifier_call	= kgdb_notify,
214	.priority	= -INT_MAX,
215};
216
217
218/**
219 *	kgdb_arch_init - Perform any architecture specific initalization.
220 *
221 *	This function will handle the initalization of any architecture
222 *	specific callbacks.
223 */
224int kgdb_arch_init(void)
225{
226	int ret = register_die_notifier(&kgdb_notifier);
227
228	if (ret != 0)
229		return ret;
230
231	register_undef_hook(&kgdb_brkpt_hook);
232	register_undef_hook(&kgdb_compiled_brkpt_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_hook);
246	unregister_undef_hook(&kgdb_compiled_brkpt_hook);
247	unregister_die_notifier(&kgdb_notifier);
248}
249
250int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
251{
252	int err;
253
254	/* patch_text() only supports int-sized breakpoints */
255	BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);
256
257	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
258				BREAK_INSTR_SIZE);
259	if (err)
260		return err;
261
262	/* Machine is already stopped, so we can use __patch_text() directly */
263	__patch_text((void *)bpt->bpt_addr,
264		     *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
265
266	return err;
267}
268
269int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
270{
271	/* Machine is already stopped, so we can use __patch_text() directly */
272	__patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
273
274	return 0;
275}
276
277/*
278 * Register our undef instruction hooks with ARM undef core.
279 * We regsiter a hook specifically looking for the KGB break inst
280 * and we handle the normal undef case within the do_undefinstr
281 * handler.
282 */
283struct kgdb_arch arch_kgdb_ops = {
284#ifndef __ARMEB__
285	.gdb_bpt_instr		= {0xfe, 0xde, 0xff, 0xe7}
286#else /* ! __ARMEB__ */
287	.gdb_bpt_instr		= {0xe7, 0xff, 0xde, 0xfe}
288#endif
289};
290