1 /*
2  *  Originally written by Glenn Engel, Lake Stevens Instrument Division
3  *
4  *  Contributed by HP Systems
5  *
6  *  Modified for Linux/MIPS (and MIPS in general) by Andreas Busse
7  *  Send complaints, suggestions etc. to <andy@waldorf-gmbh.de>
8  *
9  *  Copyright (C) 1995 Andreas Busse
10  *
11  *  Copyright (C) 2003 MontaVista Software Inc.
12  *  Author: Jun Sun, jsun@mvista.com or jsun@junsun.net
13  *
14  *  Copyright (C) 2004-2005 MontaVista Software Inc.
15  *  Author: Manish Lachwani, mlachwani@mvista.com or manish@koffee-break.com
16  *
17  *  Copyright (C) 2007-2008 Wind River Systems, Inc.
18  *  Author/Maintainer: Jason Wessel, jason.wessel@windriver.com
19  *
20  *  This file is licensed under the terms of the GNU General Public License
21  *  version 2. This program is licensed "as is" without any warranty of any
22  *  kind, whether express or implied.
23  */
24 
25 #include <linux/ptrace.h>		/* for linux pt_regs struct */
26 #include <linux/kgdb.h>
27 #include <linux/kdebug.h>
28 #include <linux/sched.h>
29 #include <linux/smp.h>
30 #include <asm/inst.h>
31 #include <asm/fpu.h>
32 #include <asm/cacheflush.h>
33 #include <asm/processor.h>
34 #include <asm/sigcontext.h>
35 #include <linux/uaccess.h>
36 
37 static struct hard_trap_info {
38 	unsigned char tt;	/* Trap type code for MIPS R3xxx and R4xxx */
39 	unsigned char signo;	/* Signal that we map this trap into */
40 } hard_trap_info[] = {
41 	{ 6, SIGBUS },		/* instruction bus error */
42 	{ 7, SIGBUS },		/* data bus error */
43 	{ 9, SIGTRAP },		/* break */
44 /*	{ 11, SIGILL }, */	/* CPU unusable */
45 	{ 12, SIGFPE },		/* overflow */
46 	{ 13, SIGTRAP },	/* trap */
47 	{ 14, SIGSEGV },	/* virtual instruction cache coherency */
48 	{ 15, SIGFPE },		/* floating point exception */
49 	{ 23, SIGSEGV },	/* watch */
50 	{ 31, SIGSEGV },	/* virtual data cache coherency */
51 	{ 0, 0}			/* Must be last */
52 };
53 
54 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
55 {
56 	{ "zero", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0]) },
57 	{ "at", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1]) },
58 	{ "v0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2]) },
59 	{ "v1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3]) },
60 	{ "a0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4]) },
61 	{ "a1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5]) },
62 	{ "a2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6]) },
63 	{ "a3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7]) },
64 	{ "t0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8]) },
65 	{ "t1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9]) },
66 	{ "t2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10]) },
67 	{ "t3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11]) },
68 	{ "t4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12]) },
69 	{ "t5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13]) },
70 	{ "t6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14]) },
71 	{ "t7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15]) },
72 	{ "s0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[16]) },
73 	{ "s1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[17]) },
74 	{ "s2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[18]) },
75 	{ "s3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[19]) },
76 	{ "s4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[20]) },
77 	{ "s5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[21]) },
78 	{ "s6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[22]) },
79 	{ "s7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[23]) },
80 	{ "t8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[24]) },
81 	{ "t9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[25]) },
82 	{ "k0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[26]) },
83 	{ "k1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[27]) },
84 	{ "gp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[28]) },
85 	{ "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[29]) },
86 	{ "s8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[30]) },
87 	{ "ra", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[31]) },
88 	{ "sr", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_status) },
89 	{ "lo", GDB_SIZEOF_REG, offsetof(struct pt_regs, lo) },
90 	{ "hi", GDB_SIZEOF_REG, offsetof(struct pt_regs, hi) },
91 	{ "bad", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_badvaddr) },
92 	{ "cause", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_cause) },
93 	{ "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_epc) },
94 	{ "f0", GDB_SIZEOF_REG, 0 },
95 	{ "f1", GDB_SIZEOF_REG, 1 },
96 	{ "f2", GDB_SIZEOF_REG, 2 },
97 	{ "f3", GDB_SIZEOF_REG, 3 },
98 	{ "f4", GDB_SIZEOF_REG, 4 },
99 	{ "f5", GDB_SIZEOF_REG, 5 },
100 	{ "f6", GDB_SIZEOF_REG, 6 },
101 	{ "f7", GDB_SIZEOF_REG, 7 },
102 	{ "f8", GDB_SIZEOF_REG, 8 },
103 	{ "f9", GDB_SIZEOF_REG, 9 },
104 	{ "f10", GDB_SIZEOF_REG, 10 },
105 	{ "f11", GDB_SIZEOF_REG, 11 },
106 	{ "f12", GDB_SIZEOF_REG, 12 },
107 	{ "f13", GDB_SIZEOF_REG, 13 },
108 	{ "f14", GDB_SIZEOF_REG, 14 },
109 	{ "f15", GDB_SIZEOF_REG, 15 },
110 	{ "f16", GDB_SIZEOF_REG, 16 },
111 	{ "f17", GDB_SIZEOF_REG, 17 },
112 	{ "f18", GDB_SIZEOF_REG, 18 },
113 	{ "f19", GDB_SIZEOF_REG, 19 },
114 	{ "f20", GDB_SIZEOF_REG, 20 },
115 	{ "f21", GDB_SIZEOF_REG, 21 },
116 	{ "f22", GDB_SIZEOF_REG, 22 },
117 	{ "f23", GDB_SIZEOF_REG, 23 },
118 	{ "f24", GDB_SIZEOF_REG, 24 },
119 	{ "f25", GDB_SIZEOF_REG, 25 },
120 	{ "f26", GDB_SIZEOF_REG, 26 },
121 	{ "f27", GDB_SIZEOF_REG, 27 },
122 	{ "f28", GDB_SIZEOF_REG, 28 },
123 	{ "f29", GDB_SIZEOF_REG, 29 },
124 	{ "f30", GDB_SIZEOF_REG, 30 },
125 	{ "f31", GDB_SIZEOF_REG, 31 },
126 	{ "fsr", GDB_SIZEOF_REG, 0 },
127 	{ "fir", GDB_SIZEOF_REG, 0 },
128 };
129 
dbg_set_reg(int regno,void * mem,struct pt_regs * regs)130 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
131 {
132 	int fp_reg;
133 
134 	if (regno < 0 || regno >= DBG_MAX_REG_NUM)
135 		return -EINVAL;
136 
137 	if (dbg_reg_def[regno].offset != -1 && regno < 38) {
138 		memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
139 		       dbg_reg_def[regno].size);
140 	} else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
141 		/* FP registers 38 -> 69 */
142 		if (!(regs->cp0_status & ST0_CU1))
143 			return 0;
144 		if (regno == 70) {
145 			/* Process the fcr31/fsr (register 70) */
146 			memcpy((void *)&current->thread.fpu.fcr31, mem,
147 			       dbg_reg_def[regno].size);
148 			goto out_save;
149 		} else if (regno == 71) {
150 			/* Ignore the fir (register 71) */
151 			goto out_save;
152 		}
153 		fp_reg = dbg_reg_def[regno].offset;
154 		memcpy((void *)&current->thread.fpu.fpr[fp_reg], mem,
155 		       dbg_reg_def[regno].size);
156 out_save:
157 		restore_fp(current);
158 	}
159 
160 	return 0;
161 }
162 
dbg_get_reg(int regno,void * mem,struct pt_regs * regs)163 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
164 {
165 	int fp_reg;
166 
167 	if (regno >= DBG_MAX_REG_NUM || regno < 0)
168 		return NULL;
169 
170 	if (dbg_reg_def[regno].offset != -1 && regno < 38) {
171 		/* First 38 registers */
172 		memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
173 		       dbg_reg_def[regno].size);
174 	} else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
175 		/* FP registers 38 -> 69 */
176 		if (!(regs->cp0_status & ST0_CU1))
177 			goto out;
178 		save_fp(current);
179 		if (regno == 70) {
180 			/* Process the fcr31/fsr (register 70) */
181 			memcpy(mem, (void *)&current->thread.fpu.fcr31,
182 			       dbg_reg_def[regno].size);
183 			goto out;
184 		} else if (regno == 71) {
185 			/* Ignore the fir (register 71) */
186 			memset(mem, 0, dbg_reg_def[regno].size);
187 			goto out;
188 		}
189 		fp_reg = dbg_reg_def[regno].offset;
190 		memcpy(mem, (void *)&current->thread.fpu.fpr[fp_reg],
191 		       dbg_reg_def[regno].size);
192 	}
193 
194 out:
195 	return dbg_reg_def[regno].name;
196 
197 }
198 
arch_kgdb_breakpoint(void)199 void arch_kgdb_breakpoint(void)
200 {
201 	__asm__ __volatile__(
202 		".globl breakinst\n\t"
203 		".set\tnoreorder\n\t"
204 		"nop\n"
205 		"breakinst:\tbreak\n\t"
206 		"nop\n\t"
207 		".set\treorder");
208 }
209 
kgdb_call_nmi_hook(void * ignored)210 static void kgdb_call_nmi_hook(void *ignored)
211 {
212 	mm_segment_t old_fs;
213 
214 	old_fs = get_fs();
215 	set_fs(get_ds());
216 
217 	kgdb_nmicallback(raw_smp_processor_id(), NULL);
218 
219 	set_fs(old_fs);
220 }
221 
kgdb_roundup_cpus(unsigned long flags)222 void kgdb_roundup_cpus(unsigned long flags)
223 {
224 	local_irq_enable();
225 	smp_call_function(kgdb_call_nmi_hook, NULL, 0);
226 	local_irq_disable();
227 }
228 
compute_signal(int tt)229 static int compute_signal(int tt)
230 {
231 	struct hard_trap_info *ht;
232 
233 	for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
234 		if (ht->tt == tt)
235 			return ht->signo;
236 
237 	return SIGHUP;		/* default for things we don't know about */
238 }
239 
240 /*
241  * Similar to regs_to_gdb_regs() except that process is sleeping and so
242  * we may not be able to get all the info.
243  */
sleeping_thread_to_gdb_regs(unsigned long * gdb_regs,struct task_struct * p)244 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
245 {
246 	int reg;
247 #if (KGDB_GDB_REG_SIZE == 32)
248 	u32 *ptr = (u32 *)gdb_regs;
249 #else
250 	u64 *ptr = (u64 *)gdb_regs;
251 #endif
252 
253 	for (reg = 0; reg < 16; reg++)
254 		*(ptr++) = 0;
255 
256 	/* S0 - S7 */
257 	*(ptr++) = p->thread.reg16;
258 	*(ptr++) = p->thread.reg17;
259 	*(ptr++) = p->thread.reg18;
260 	*(ptr++) = p->thread.reg19;
261 	*(ptr++) = p->thread.reg20;
262 	*(ptr++) = p->thread.reg21;
263 	*(ptr++) = p->thread.reg22;
264 	*(ptr++) = p->thread.reg23;
265 
266 	for (reg = 24; reg < 28; reg++)
267 		*(ptr++) = 0;
268 
269 	/* GP, SP, FP, RA */
270 	*(ptr++) = (long)p;
271 	*(ptr++) = p->thread.reg29;
272 	*(ptr++) = p->thread.reg30;
273 	*(ptr++) = p->thread.reg31;
274 
275 	*(ptr++) = p->thread.cp0_status;
276 
277 	/* lo, hi */
278 	*(ptr++) = 0;
279 	*(ptr++) = 0;
280 
281 	/*
282 	 * BadVAddr, Cause
283 	 * Ideally these would come from the last exception frame up the stack
284 	 * but that requires unwinding, otherwise we can't know much for sure.
285 	 */
286 	*(ptr++) = 0;
287 	*(ptr++) = 0;
288 
289 	/*
290 	 * PC
291 	 * use return address (RA), i.e. the moment after return from resume()
292 	 */
293 	*(ptr++) = p->thread.reg31;
294 }
295 
kgdb_arch_set_pc(struct pt_regs * regs,unsigned long pc)296 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
297 {
298 	regs->cp0_epc = pc;
299 }
300 
301 /*
302  * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
303  * then try to fall into the debugger
304  */
kgdb_mips_notify(struct notifier_block * self,unsigned long cmd,void * ptr)305 static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd,
306 			    void *ptr)
307 {
308 	struct die_args *args = (struct die_args *)ptr;
309 	struct pt_regs *regs = args->regs;
310 	int trap = (regs->cp0_cause & 0x7c) >> 2;
311 	mm_segment_t old_fs;
312 
313 #ifdef CONFIG_KPROBES
314 	/*
315 	 * Return immediately if the kprobes fault notifier has set
316 	 * DIE_PAGE_FAULT.
317 	 */
318 	if (cmd == DIE_PAGE_FAULT)
319 		return NOTIFY_DONE;
320 #endif /* CONFIG_KPROBES */
321 
322 	/* Userspace events, ignore. */
323 	if (user_mode(regs))
324 		return NOTIFY_DONE;
325 
326 	/* Kernel mode. Set correct address limit */
327 	old_fs = get_fs();
328 	set_fs(get_ds());
329 
330 	if (atomic_read(&kgdb_active) != -1)
331 		kgdb_nmicallback(smp_processor_id(), regs);
332 
333 	if (kgdb_handle_exception(trap, compute_signal(trap), cmd, regs)) {
334 		set_fs(old_fs);
335 		return NOTIFY_DONE;
336 	}
337 
338 	if (atomic_read(&kgdb_setting_breakpoint))
339 		if ((trap == 9) && (regs->cp0_epc == (unsigned long)breakinst))
340 			regs->cp0_epc += 4;
341 
342 	/* In SMP mode, __flush_cache_all does IPI */
343 	local_irq_enable();
344 	__flush_cache_all();
345 
346 	set_fs(old_fs);
347 	return NOTIFY_STOP;
348 }
349 
350 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
kgdb_ll_trap(int cmd,const char * str,struct pt_regs * regs,long err,int trap,int sig)351 int kgdb_ll_trap(int cmd, const char *str,
352 		 struct pt_regs *regs, long err, int trap, int sig)
353 {
354 	struct die_args args = {
355 		.regs	= regs,
356 		.str	= str,
357 		.err	= err,
358 		.trapnr = trap,
359 		.signr	= sig,
360 
361 	};
362 
363 	if (!kgdb_io_module_registered)
364 		return NOTIFY_DONE;
365 
366 	return kgdb_mips_notify(NULL, cmd, &args);
367 }
368 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
369 
370 static struct notifier_block kgdb_notifier = {
371 	.notifier_call = kgdb_mips_notify,
372 };
373 
374 /*
375  * Handle the 'c' command
376  */
kgdb_arch_handle_exception(int vector,int signo,int err_code,char * remcom_in_buffer,char * remcom_out_buffer,struct pt_regs * regs)377 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
378 			       char *remcom_in_buffer, char *remcom_out_buffer,
379 			       struct pt_regs *regs)
380 {
381 	char *ptr;
382 	unsigned long address;
383 
384 	switch (remcom_in_buffer[0]) {
385 	case 'c':
386 		/* handle the optional parameter */
387 		ptr = &remcom_in_buffer[1];
388 		if (kgdb_hex2long(&ptr, &address))
389 			regs->cp0_epc = address;
390 
391 		return 0;
392 	}
393 
394 	return -1;
395 }
396 
397 struct kgdb_arch arch_kgdb_ops;
398 
kgdb_arch_init(void)399 int kgdb_arch_init(void)
400 {
401 	union mips_instruction insn = {
402 		.r_format = {
403 			.opcode = spec_op,
404 			.func	= break_op,
405 		}
406 	};
407 	memcpy(arch_kgdb_ops.gdb_bpt_instr, insn.byte, BREAK_INSTR_SIZE);
408 
409 	register_die_notifier(&kgdb_notifier);
410 
411 	return 0;
412 }
413 
414 /*
415  *	kgdb_arch_exit - Perform any architecture specific uninitalization.
416  *
417  *	This function will handle the uninitalization of any architecture
418  *	specific callbacks, for dynamic registration and unregistration.
419  */
kgdb_arch_exit(void)420 void kgdb_arch_exit(void)
421 {
422 	unregister_die_notifier(&kgdb_notifier);
423 }
424