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Linux/arch/mips/kernel/kgdb.c

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  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 #include <asm/irq_regs.h>
 37 
 38 static struct hard_trap_info {
 39         unsigned char tt;       /* Trap type code for MIPS R3xxx and R4xxx */
 40         unsigned char signo;    /* Signal that we map this trap into */
 41 } hard_trap_info[] = {
 42         { 6, SIGBUS },          /* instruction bus error */
 43         { 7, SIGBUS },          /* data bus error */
 44         { 9, SIGTRAP },         /* break */
 45 /*      { 11, SIGILL }, */      /* CPU unusable */
 46         { 12, SIGFPE },         /* overflow */
 47         { 13, SIGTRAP },        /* trap */
 48         { 14, SIGSEGV },        /* virtual instruction cache coherency */
 49         { 15, SIGFPE },         /* floating point exception */
 50         { 23, SIGSEGV },        /* watch */
 51         { 31, SIGSEGV },        /* virtual data cache coherency */
 52         { 0, 0}                 /* Must be last */
 53 };
 54 
 55 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
 56 {
 57         { "zero", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0]) },
 58         { "at", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1]) },
 59         { "v0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2]) },
 60         { "v1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3]) },
 61         { "a0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4]) },
 62         { "a1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5]) },
 63         { "a2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6]) },
 64         { "a3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7]) },
 65         { "t0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8]) },
 66         { "t1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9]) },
 67         { "t2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10]) },
 68         { "t3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11]) },
 69         { "t4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12]) },
 70         { "t5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13]) },
 71         { "t6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14]) },
 72         { "t7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15]) },
 73         { "s0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[16]) },
 74         { "s1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[17]) },
 75         { "s2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[18]) },
 76         { "s3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[19]) },
 77         { "s4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[20]) },
 78         { "s5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[21]) },
 79         { "s6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[22]) },
 80         { "s7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[23]) },
 81         { "t8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[24]) },
 82         { "t9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[25]) },
 83         { "k0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[26]) },
 84         { "k1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[27]) },
 85         { "gp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[28]) },
 86         { "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[29]) },
 87         { "s8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[30]) },
 88         { "ra", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[31]) },
 89         { "sr", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_status) },
 90         { "lo", GDB_SIZEOF_REG, offsetof(struct pt_regs, lo) },
 91         { "hi", GDB_SIZEOF_REG, offsetof(struct pt_regs, hi) },
 92         { "bad", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_badvaddr) },
 93         { "cause", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_cause) },
 94         { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, cp0_epc) },
 95         { "f0", GDB_SIZEOF_REG, 0 },
 96         { "f1", GDB_SIZEOF_REG, 1 },
 97         { "f2", GDB_SIZEOF_REG, 2 },
 98         { "f3", GDB_SIZEOF_REG, 3 },
 99         { "f4", GDB_SIZEOF_REG, 4 },
100         { "f5", GDB_SIZEOF_REG, 5 },
101         { "f6", GDB_SIZEOF_REG, 6 },
102         { "f7", GDB_SIZEOF_REG, 7 },
103         { "f8", GDB_SIZEOF_REG, 8 },
104         { "f9", GDB_SIZEOF_REG, 9 },
105         { "f10", GDB_SIZEOF_REG, 10 },
106         { "f11", GDB_SIZEOF_REG, 11 },
107         { "f12", GDB_SIZEOF_REG, 12 },
108         { "f13", GDB_SIZEOF_REG, 13 },
109         { "f14", GDB_SIZEOF_REG, 14 },
110         { "f15", GDB_SIZEOF_REG, 15 },
111         { "f16", GDB_SIZEOF_REG, 16 },
112         { "f17", GDB_SIZEOF_REG, 17 },
113         { "f18", GDB_SIZEOF_REG, 18 },
114         { "f19", GDB_SIZEOF_REG, 19 },
115         { "f20", GDB_SIZEOF_REG, 20 },
116         { "f21", GDB_SIZEOF_REG, 21 },
117         { "f22", GDB_SIZEOF_REG, 22 },
118         { "f23", GDB_SIZEOF_REG, 23 },
119         { "f24", GDB_SIZEOF_REG, 24 },
120         { "f25", GDB_SIZEOF_REG, 25 },
121         { "f26", GDB_SIZEOF_REG, 26 },
122         { "f27", GDB_SIZEOF_REG, 27 },
123         { "f28", GDB_SIZEOF_REG, 28 },
124         { "f29", GDB_SIZEOF_REG, 29 },
125         { "f30", GDB_SIZEOF_REG, 30 },
126         { "f31", GDB_SIZEOF_REG, 31 },
127         { "fsr", GDB_SIZEOF_REG, 0 },
128         { "fir", GDB_SIZEOF_REG, 0 },
129 };
130 
131 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
132 {
133         int fp_reg;
134 
135         if (regno < 0 || regno >= DBG_MAX_REG_NUM)
136                 return -EINVAL;
137 
138         if (dbg_reg_def[regno].offset != -1 && regno < 38) {
139                 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
140                        dbg_reg_def[regno].size);
141         } else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
142                 /* FP registers 38 -> 69 */
143                 if (!(regs->cp0_status & ST0_CU1))
144                         return 0;
145                 if (regno == 70) {
146                         /* Process the fcr31/fsr (register 70) */
147                         memcpy((void *)&current->thread.fpu.fcr31, mem,
148                                dbg_reg_def[regno].size);
149                         goto out_save;
150                 } else if (regno == 71) {
151                         /* Ignore the fir (register 71) */
152                         goto out_save;
153                 }
154                 fp_reg = dbg_reg_def[regno].offset;
155                 memcpy((void *)&current->thread.fpu.fpr[fp_reg], mem,
156                        dbg_reg_def[regno].size);
157 out_save:
158                 restore_fp(current);
159         }
160 
161         return 0;
162 }
163 
164 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
165 {
166         int fp_reg;
167 
168         if (regno >= DBG_MAX_REG_NUM || regno < 0)
169                 return NULL;
170 
171         if (dbg_reg_def[regno].offset != -1 && regno < 38) {
172                 /* First 38 registers */
173                 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
174                        dbg_reg_def[regno].size);
175         } else if (current && dbg_reg_def[regno].offset != -1 && regno < 72) {
176                 /* FP registers 38 -> 69 */
177                 if (!(regs->cp0_status & ST0_CU1))
178                         goto out;
179                 save_fp(current);
180                 if (regno == 70) {
181                         /* Process the fcr31/fsr (register 70) */
182                         memcpy(mem, (void *)&current->thread.fpu.fcr31,
183                                dbg_reg_def[regno].size);
184                         goto out;
185                 } else if (regno == 71) {
186                         /* Ignore the fir (register 71) */
187                         memset(mem, 0, dbg_reg_def[regno].size);
188                         goto out;
189                 }
190                 fp_reg = dbg_reg_def[regno].offset;
191                 memcpy(mem, (void *)&current->thread.fpu.fpr[fp_reg],
192                        dbg_reg_def[regno].size);
193         }
194 
195 out:
196         return dbg_reg_def[regno].name;
197 
198 }
199 
200 void arch_kgdb_breakpoint(void)
201 {
202         __asm__ __volatile__(
203                 ".globl breakinst\n\t"
204                 ".set\tnoreorder\n\t"
205                 "nop\n"
206                 "breakinst:\tbreak\n\t"
207                 "nop\n\t"
208                 ".set\treorder");
209 }
210 
211 void kgdb_call_nmi_hook(void *ignored)
212 {
213         mm_segment_t old_fs;
214 
215         old_fs = get_fs();
216         set_fs(KERNEL_DS);
217 
218         kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
219 
220         set_fs(old_fs);
221 }
222 
223 static int compute_signal(int tt)
224 {
225         struct hard_trap_info *ht;
226 
227         for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
228                 if (ht->tt == tt)
229                         return ht->signo;
230 
231         return SIGHUP;          /* default for things we don't know about */
232 }
233 
234 /*
235  * Similar to regs_to_gdb_regs() except that process is sleeping and so
236  * we may not be able to get all the info.
237  */
238 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
239 {
240         int reg;
241 #if (KGDB_GDB_REG_SIZE == 32)
242         u32 *ptr = (u32 *)gdb_regs;
243 #else
244         u64 *ptr = (u64 *)gdb_regs;
245 #endif
246 
247         for (reg = 0; reg < 16; reg++)
248                 *(ptr++) = 0;
249 
250         /* S0 - S7 */
251         *(ptr++) = p->thread.reg16;
252         *(ptr++) = p->thread.reg17;
253         *(ptr++) = p->thread.reg18;
254         *(ptr++) = p->thread.reg19;
255         *(ptr++) = p->thread.reg20;
256         *(ptr++) = p->thread.reg21;
257         *(ptr++) = p->thread.reg22;
258         *(ptr++) = p->thread.reg23;
259 
260         for (reg = 24; reg < 28; reg++)
261                 *(ptr++) = 0;
262 
263         /* GP, SP, FP, RA */
264         *(ptr++) = (long)p;
265         *(ptr++) = p->thread.reg29;
266         *(ptr++) = p->thread.reg30;
267         *(ptr++) = p->thread.reg31;
268 
269         *(ptr++) = p->thread.cp0_status;
270 
271         /* lo, hi */
272         *(ptr++) = 0;
273         *(ptr++) = 0;
274 
275         /*
276          * BadVAddr, Cause
277          * Ideally these would come from the last exception frame up the stack
278          * but that requires unwinding, otherwise we can't know much for sure.
279          */
280         *(ptr++) = 0;
281         *(ptr++) = 0;
282 
283         /*
284          * PC
285          * use return address (RA), i.e. the moment after return from resume()
286          */
287         *(ptr++) = p->thread.reg31;
288 }
289 
290 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
291 {
292         regs->cp0_epc = pc;
293 }
294 
295 /*
296  * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
297  * then try to fall into the debugger
298  */
299 static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd,
300                             void *ptr)
301 {
302         struct die_args *args = (struct die_args *)ptr;
303         struct pt_regs *regs = args->regs;
304         int trap = (regs->cp0_cause & 0x7c) >> 2;
305         mm_segment_t old_fs;
306 
307 #ifdef CONFIG_KPROBES
308         /*
309          * Return immediately if the kprobes fault notifier has set
310          * DIE_PAGE_FAULT.
311          */
312         if (cmd == DIE_PAGE_FAULT)
313                 return NOTIFY_DONE;
314 #endif /* CONFIG_KPROBES */
315 
316         /* Userspace events, ignore. */
317         if (user_mode(regs))
318                 return NOTIFY_DONE;
319 
320         /* Kernel mode. Set correct address limit */
321         old_fs = get_fs();
322         set_fs(KERNEL_DS);
323 
324         if (atomic_read(&kgdb_active) != -1)
325                 kgdb_nmicallback(smp_processor_id(), regs);
326 
327         if (kgdb_handle_exception(trap, compute_signal(trap), cmd, regs)) {
328                 set_fs(old_fs);
329                 return NOTIFY_DONE;
330         }
331 
332         if (atomic_read(&kgdb_setting_breakpoint))
333                 if ((trap == 9) && (regs->cp0_epc == (unsigned long)breakinst))
334                         regs->cp0_epc += 4;
335 
336         /* In SMP mode, __flush_cache_all does IPI */
337         local_irq_enable();
338         __flush_cache_all();
339 
340         set_fs(old_fs);
341         return NOTIFY_STOP;
342 }
343 
344 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
345 int kgdb_ll_trap(int cmd, const char *str,
346                  struct pt_regs *regs, long err, int trap, int sig)
347 {
348         struct die_args args = {
349                 .regs   = regs,
350                 .str    = str,
351                 .err    = err,
352                 .trapnr = trap,
353                 .signr  = sig,
354 
355         };
356 
357         if (!kgdb_io_module_registered)
358                 return NOTIFY_DONE;
359 
360         return kgdb_mips_notify(NULL, cmd, &args);
361 }
362 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
363 
364 static struct notifier_block kgdb_notifier = {
365         .notifier_call = kgdb_mips_notify,
366 };
367 
368 /*
369  * Handle the 'c' command
370  */
371 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
372                                char *remcom_in_buffer, char *remcom_out_buffer,
373                                struct pt_regs *regs)
374 {
375         char *ptr;
376         unsigned long address;
377 
378         switch (remcom_in_buffer[0]) {
379         case 'c':
380                 /* handle the optional parameter */
381                 ptr = &remcom_in_buffer[1];
382                 if (kgdb_hex2long(&ptr, &address))
383                         regs->cp0_epc = address;
384 
385                 return 0;
386         }
387 
388         return -1;
389 }
390 
391 const struct kgdb_arch arch_kgdb_ops = {
392 #ifdef CONFIG_CPU_BIG_ENDIAN
393         .gdb_bpt_instr = { spec_op << 2, 0x00, 0x00, break_op },
394 #else
395         .gdb_bpt_instr = { break_op, 0x00, 0x00, spec_op << 2 },
396 #endif
397 };
398 
399 int kgdb_arch_init(void)
400 {
401         register_die_notifier(&kgdb_notifier);
402 
403         return 0;
404 }
405 
406 /*
407  *      kgdb_arch_exit - Perform any architecture specific uninitalization.
408  *
409  *      This function will handle the uninitalization of any architecture
410  *      specific callbacks, for dynamic registration and unregistration.
411  */
412 void kgdb_arch_exit(void)
413 {
414         unregister_die_notifier(&kgdb_notifier);
415 }
416 

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