arch/mips/kernel/kgdb.c

   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 }