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 thread_info *ti;
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	ti			= task_thread_info(task);
90	gdb_regs[_R4]		= ti->cpu_context.r4;
91	gdb_regs[_R5]		= ti->cpu_context.r5;
92	gdb_regs[_R6]		= ti->cpu_context.r6;
93	gdb_regs[_R7]		= ti->cpu_context.r7;
94	gdb_regs[_R8]		= ti->cpu_context.r8;
95	gdb_regs[_R9]		= ti->cpu_context.r9;
96	gdb_regs[_R10]		= ti->cpu_context.sl;
97	gdb_regs[_FP]		= ti->cpu_context.fp;
98	gdb_regs[_SPT]		= ti->cpu_context.sp;
99	gdb_regs[_PC]		= ti->cpu_context.pc;
100}
101
102void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
103{
104	regs->ARM_pc = pc;
105}
106
107static int compiled_break;
108
109int kgdb_arch_handle_exception(int exception_vector, int signo,
110			       int err_code, char *remcom_in_buffer,
111			       char *remcom_out_buffer,
112			       struct pt_regs *linux_regs)
113{
114	unsigned long addr;
115	char *ptr;
116
117	switch (remcom_in_buffer[0]) {
118	case 'D':
119	case 'k':
120	case 'c':
121		/*
122		 * Try to read optional parameter, pc unchanged if no parm.
123		 * If this was a compiled breakpoint, we need to move
124		 * to the next instruction or we will just breakpoint
125		 * over and over again.
126		 */
127		ptr = &remcom_in_buffer[1];
128		if (kgdb_hex2long(&ptr, &addr))
129			linux_regs->ARM_pc = addr;
130		else if (compiled_break == 1)
131			linux_regs->ARM_pc += 4;
132
133		compiled_break = 0;
134
135		return 0;
136	}
137
138	return -1;
139}
140
141static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
142{
143	kgdb_handle_exception(1, SIGTRAP, 0, regs);
144
145	return 0;
146}
147
148static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
149{
150	compiled_break = 1;
151	kgdb_handle_exception(1, SIGTRAP, 0, regs);
152
153	return 0;
154}
155
156static struct undef_hook kgdb_brkpt_hook = {
157	.instr_mask		= 0xffffffff,
158	.instr_val		= KGDB_BREAKINST,
159	.cpsr_mask		= MODE_MASK,
160	.cpsr_val		= SVC_MODE,
161	.fn			= kgdb_brk_fn
162};
163
164static struct undef_hook kgdb_compiled_brkpt_hook = {
165	.instr_mask		= 0xffffffff,
166	.instr_val		= KGDB_COMPILED_BREAK,
167	.cpsr_mask		= MODE_MASK,
168	.cpsr_val		= SVC_MODE,
169	.fn			= kgdb_compiled_brk_fn
170};
171
172static void kgdb_call_nmi_hook(void *ignored)
173{
174       kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
175}
176
177void kgdb_roundup_cpus(unsigned long flags)
178{
179       local_irq_enable();
180       smp_call_function(kgdb_call_nmi_hook, NULL, 0);
181       local_irq_disable();
182}
183
184static int __kgdb_notify(struct die_args *args, unsigned long cmd)
185{
186	struct pt_regs *regs = args->regs;
187
188	if (kgdb_handle_exception(1, args->signr, cmd, regs))
189		return NOTIFY_DONE;
190	return NOTIFY_STOP;
191}
192static int
193kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
194{
195	unsigned long flags;
196	int ret;
197
198	local_irq_save(flags);
199	ret = __kgdb_notify(ptr, cmd);
200	local_irq_restore(flags);
201
202	return ret;
203}
204
205static struct notifier_block kgdb_notifier = {
206	.notifier_call	= kgdb_notify,
207	.priority	= -INT_MAX,
208};
209
210
211/**
212 *	kgdb_arch_init - Perform any architecture specific initalization.
213 *
214 *	This function will handle the initalization of any architecture
215 *	specific callbacks.
216 */
217int kgdb_arch_init(void)
218{
219	int ret = register_die_notifier(&kgdb_notifier);
220
221	if (ret != 0)
222		return ret;
223
224	register_undef_hook(&kgdb_brkpt_hook);
225	register_undef_hook(&kgdb_compiled_brkpt_hook);
226
227	return 0;
228}
229
230/**
231 *	kgdb_arch_exit - Perform any architecture specific uninitalization.
232 *
233 *	This function will handle the uninitalization of any architecture
234 *	specific callbacks, for dynamic registration and unregistration.
235 */
236void kgdb_arch_exit(void)
237{
238	unregister_undef_hook(&kgdb_brkpt_hook);
239	unregister_undef_hook(&kgdb_compiled_brkpt_hook);
240	unregister_die_notifier(&kgdb_notifier);
241}
242
243int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
244{
245	int err;
246
247	/* patch_text() only supports int-sized breakpoints */
248	BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);
249
250	err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
251				BREAK_INSTR_SIZE);
252	if (err)
253		return err;
254
255	/* Machine is already stopped, so we can use __patch_text() directly */
256	__patch_text((void *)bpt->bpt_addr,
257		     *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
258
259	return err;
260}
261
262int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
263{
264	/* Machine is already stopped, so we can use __patch_text() directly */
265	__patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
266
267	return 0;
268}
269
270/*
271 * Register our undef instruction hooks with ARM undef core.
272 * We regsiter a hook specifically looking for the KGB break inst
273 * and we handle the normal undef case within the do_undefinstr
274 * handler.
275 */
276struct kgdb_arch arch_kgdb_ops = {
277#ifndef __ARMEB__
278	.gdb_bpt_instr		= {0xfe, 0xde, 0xff, 0xe7}
279#else /* ! __ARMEB__ */
280	.gdb_bpt_instr		= {0xe7, 0xff, 0xde, 0xfe}
281#endif
282};
283