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Linux/arch/mips/kernel/kgdb.c

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Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  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 <asm/irq_regs.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 
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 
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 
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 
210 static int compute_signal(int tt)
211 {
212         struct hard_trap_info *ht;
213 
214         for (ht = hard_trap_info; ht->tt && ht->signo; ht++)
215                 if (ht->tt == tt)
216                         return ht->signo;
217 
218         return SIGHUP;          /* default for things we don't know about */
219 }
220 
221 /*
222  * Similar to regs_to_gdb_regs() except that process is sleeping and so
223  * we may not be able to get all the info.
224  */
225 void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *p)
226 {
227         int reg;
228 #if (KGDB_GDB_REG_SIZE == 32)
229         u32 *ptr = (u32 *)gdb_regs;
230 #else
231         u64 *ptr = (u64 *)gdb_regs;
232 #endif
233 
234         for (reg = 0; reg < 16; reg++)
235                 *(ptr++) = 0;
236 
237         /* S0 - S7 */
238         *(ptr++) = p->thread.reg16;
239         *(ptr++) = p->thread.reg17;
240         *(ptr++) = p->thread.reg18;
241         *(ptr++) = p->thread.reg19;
242         *(ptr++) = p->thread.reg20;
243         *(ptr++) = p->thread.reg21;
244         *(ptr++) = p->thread.reg22;
245         *(ptr++) = p->thread.reg23;
246 
247         for (reg = 24; reg < 28; reg++)
248                 *(ptr++) = 0;
249 
250         /* GP, SP, FP, RA */
251         *(ptr++) = (long)p;
252         *(ptr++) = p->thread.reg29;
253         *(ptr++) = p->thread.reg30;
254         *(ptr++) = p->thread.reg31;
255 
256         *(ptr++) = p->thread.cp0_status;
257 
258         /* lo, hi */
259         *(ptr++) = 0;
260         *(ptr++) = 0;
261 
262         /*
263          * BadVAddr, Cause
264          * Ideally these would come from the last exception frame up the stack
265          * but that requires unwinding, otherwise we can't know much for sure.
266          */
267         *(ptr++) = 0;
268         *(ptr++) = 0;
269 
270         /*
271          * PC
272          * use return address (RA), i.e. the moment after return from resume()
273          */
274         *(ptr++) = p->thread.reg31;
275 }
276 
277 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
278 {
279         regs->cp0_epc = pc;
280 }
281 
282 /*
283  * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
284  * then try to fall into the debugger
285  */
286 static int kgdb_mips_notify(struct notifier_block *self, unsigned long cmd,
287                             void *ptr)
288 {
289         struct die_args *args = (struct die_args *)ptr;
290         struct pt_regs *regs = args->regs;
291         int trap = (regs->cp0_cause & 0x7c) >> 2;
292 
293 #ifdef CONFIG_KPROBES
294         /*
295          * Return immediately if the kprobes fault notifier has set
296          * DIE_PAGE_FAULT.
297          */
298         if (cmd == DIE_PAGE_FAULT)
299                 return NOTIFY_DONE;
300 #endif /* CONFIG_KPROBES */
301 
302         /* Userspace events, ignore. */
303         if (user_mode(regs))
304                 return NOTIFY_DONE;
305 
306         if (atomic_read(&kgdb_active) != -1)
307                 kgdb_nmicallback(smp_processor_id(), regs);
308 
309         if (kgdb_handle_exception(trap, compute_signal(trap), cmd, regs))
310                 return NOTIFY_DONE;
311 
312         if (atomic_read(&kgdb_setting_breakpoint))
313                 if ((trap == 9) && (regs->cp0_epc == (unsigned long)breakinst))
314                         regs->cp0_epc += 4;
315 
316         /* In SMP mode, __flush_cache_all does IPI */
317         local_irq_enable();
318         __flush_cache_all();
319 
320         return NOTIFY_STOP;
321 }
322 
323 #ifdef CONFIG_KGDB_LOW_LEVEL_TRAP
324 int kgdb_ll_trap(int cmd, const char *str,
325                  struct pt_regs *regs, long err, int trap, int sig)
326 {
327         struct die_args args = {
328                 .regs   = regs,
329                 .str    = str,
330                 .err    = err,
331                 .trapnr = trap,
332                 .signr  = sig,
333 
334         };
335 
336         if (!kgdb_io_module_registered)
337                 return NOTIFY_DONE;
338 
339         return kgdb_mips_notify(NULL, cmd, &args);
340 }
341 #endif /* CONFIG_KGDB_LOW_LEVEL_TRAP */
342 
343 static struct notifier_block kgdb_notifier = {
344         .notifier_call = kgdb_mips_notify,
345 };
346 
347 /*
348  * Handle the 'c' command
349  */
350 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
351                                char *remcom_in_buffer, char *remcom_out_buffer,
352                                struct pt_regs *regs)
353 {
354         char *ptr;
355         unsigned long address;
356 
357         switch (remcom_in_buffer[0]) {
358         case 'c':
359                 /* handle the optional parameter */
360                 ptr = &remcom_in_buffer[1];
361                 if (kgdb_hex2long(&ptr, &address))
362                         regs->cp0_epc = address;
363 
364                 return 0;
365         }
366 
367         return -1;
368 }
369 
370 const struct kgdb_arch arch_kgdb_ops = {
371 #ifdef CONFIG_CPU_BIG_ENDIAN
372         .gdb_bpt_instr = { spec_op << 2, 0x00, 0x00, break_op },
373 #else
374         .gdb_bpt_instr = { break_op, 0x00, 0x00, spec_op << 2 },
375 #endif
376 };
377 
378 int kgdb_arch_init(void)
379 {
380         register_die_notifier(&kgdb_notifier);
381 
382         return 0;
383 }
384 
385 /*
386  *      kgdb_arch_exit - Perform any architecture specific uninitalization.
387  *
388  *      This function will handle the uninitalization of any architecture
389  *      specific callbacks, for dynamic registration and unregistration.
390  */
391 void kgdb_arch_exit(void)
392 {
393         unregister_die_notifier(&kgdb_notifier);
394 }
395 

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