arch/tile/kernel/kgdb.c

   1 /*
   2  * Copyright 2013 Tilera Corporation. All Rights Reserved.
   3  *
   4  *   This program is free software; you can redistribute it and/or
   5  *   modify it under the terms of the GNU General Public License
   6  *   as published by the Free Software Foundation, version 2.
   7  *
   8  *   This program is distributed in the hope that it will be useful, but
   9  *   WITHOUT ANY WARRANTY; without even the implied warranty of
  10  *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
  11  *   NON INFRINGEMENT.  See the GNU General Public License for
  12  *   more details.
  13  *
  14  * TILE-Gx KGDB support.
  15  */
  16
  17 #include <linux/ptrace.h>
  18 #include <linux/kgdb.h>
  19 #include <linux/kdebug.h>
  20 #include <linux/uaccess.h>
  21 #include <linux/module.h>
  22 #include <asm/cacheflush.h>
  23
  24 static tile_bundle_bits singlestep_insn = TILEGX_BPT_BUNDLE | DIE_SSTEPBP;
  25 static unsigned long stepped_addr;
  26 static tile_bundle_bits stepped_instr;
  27
  28 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
  29         { "r0", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[0])},
  30         { "r1", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[1])},
  31         { "r2", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[2])},
  32         { "r3", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[3])},
  33         { "r4", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[4])},
  34         { "r5", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[5])},
  35         { "r6", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[6])},
  36         { "r7", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[7])},
  37         { "r8", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[8])},
  38         { "r9", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[9])},
  39         { "r10", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[10])},
  40         { "r11", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[11])},
  41         { "r12", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[12])},
  42         { "r13", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[13])},
  43         { "r14", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[14])},
  44         { "r15", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[15])},
  45         { "r16", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[16])},
  46         { "r17", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[17])},
  47         { "r18", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[18])},
  48         { "r19", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[19])},
  49         { "r20", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[20])},
  50         { "r21", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[21])},
  51         { "r22", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[22])},
  52         { "r23", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[23])},
  53         { "r24", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[24])},
  54         { "r25", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[25])},
  55         { "r26", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[26])},
  56         { "r27", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[27])},
  57         { "r28", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[28])},
  58         { "r29", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[29])},
  59         { "r30", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[30])},
  60         { "r31", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[31])},
  61         { "r32", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[32])},
  62         { "r33", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[33])},
  63         { "r34", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[34])},
  64         { "r35", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[35])},
  65         { "r36", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[36])},
  66         { "r37", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[37])},
  67         { "r38", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[38])},
  68         { "r39", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[39])},
  69         { "r40", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[40])},
  70         { "r41", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[41])},
  71         { "r42", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[42])},
  72         { "r43", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[43])},
  73         { "r44", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[44])},
  74         { "r45", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[45])},
  75         { "r46", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[46])},
  76         { "r47", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[47])},
  77         { "r48", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[48])},
  78         { "r49", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[49])},
  79         { "r50", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[50])},
  80         { "r51", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[51])},
  81         { "r52", GDB_SIZEOF_REG, offsetof(struct pt_regs, regs[52])},
  82         { "tp", GDB_SIZEOF_REG, offsetof(struct pt_regs, tp)},
  83         { "sp", GDB_SIZEOF_REG, offsetof(struct pt_regs, sp)},
  84         { "lr", GDB_SIZEOF_REG, offsetof(struct pt_regs, lr)},
  85         { "sn", GDB_SIZEOF_REG, -1},
  86         { "idn0", GDB_SIZEOF_REG, -1},
  87         { "idn1", GDB_SIZEOF_REG, -1},
  88         { "udn0", GDB_SIZEOF_REG, -1},
  89         { "udn1", GDB_SIZEOF_REG, -1},
  90         { "udn2", GDB_SIZEOF_REG, -1},
  91         { "udn3", GDB_SIZEOF_REG, -1},
  92         { "zero", GDB_SIZEOF_REG, -1},
  93         { "pc", GDB_SIZEOF_REG, offsetof(struct pt_regs, pc)},
  94         { "faultnum", GDB_SIZEOF_REG, offsetof(struct pt_regs, faultnum)},
  95 };
  96
  97 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
  98 {
  99         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 100                 return NULL;
 101
 102         if (dbg_reg_def[regno].offset != -1)
 103                 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
 104                        dbg_reg_def[regno].size);
 105         else
 106                 memset(mem, 0, dbg_reg_def[regno].size);
 107         return dbg_reg_def[regno].name;
 108 }
 109
 110 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
 111 {
 112         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 113                 return -EINVAL;
 114
 115         if (dbg_reg_def[regno].offset != -1)
 116                 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
 117                        dbg_reg_def[regno].size);
 118         return 0;
 119 }
 120
 121 /*
 122  * Similar to pt_regs_to_gdb_regs() except that process is sleeping and so
 123  * we may not be able to get all the info.
 124  */
 125 void
 126 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
 127 {
 128         int reg;
 129         struct pt_regs *thread_regs;
 130         unsigned long *ptr = gdb_regs;
 131
 132         if (task == NULL)
 133                 return;
 134
 135         /* Initialize to zero. */
 136         memset(gdb_regs, 0, NUMREGBYTES);
 137
 138         thread_regs = task_pt_regs(task);
 139         for (reg = 0; reg <= TREG_LAST_GPR; reg++)
 140                 *(ptr++) = thread_regs->regs[reg];
 141
 142         gdb_regs[TILEGX_PC_REGNUM] = thread_regs->pc;
 143         gdb_regs[TILEGX_FAULTNUM_REGNUM] = thread_regs->faultnum;
 144 }
 145
 146 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 147 {
 148         regs->pc = pc;
 149 }
 150
 151 static void kgdb_call_nmi_hook(void *ignored)
 152 {
 153         kgdb_nmicallback(raw_smp_processor_id(), NULL);
 154 }
 155
 156 void kgdb_roundup_cpus(unsigned long flags)
 157 {
 158         local_irq_enable();
 159         smp_call_function(kgdb_call_nmi_hook, NULL, 0);
 160         local_irq_disable();
 161 }
 162
 163 /*
 164  * Convert a kernel address to the writable kernel text mapping.
 165  */
 166 static unsigned long writable_address(unsigned long addr)
 167 {
 168         unsigned long ret = 0;
 169
 170         if (core_kernel_text(addr))
 171                 ret = addr - MEM_SV_START + PAGE_OFFSET;
 172         else if (is_module_text_address(addr))
 173                 ret = addr;
 174         else
 175                 pr_err("Unknown virtual address 0x%lx\n", addr);
 176
 177         return ret;
 178 }
 179
 180 /*
 181  * Calculate the new address for after a step.
 182  */
 183 static unsigned long get_step_address(struct pt_regs *regs)
 184 {
 185         int src_reg;
 186         int jump_off;
 187         int br_off;
 188         unsigned long addr;
 189         unsigned int opcode;
 190         tile_bundle_bits bundle;
 191
 192         /* Move to the next instruction by default. */
 193         addr = regs->pc + TILEGX_BUNDLE_SIZE_IN_BYTES;
 194         bundle = *(unsigned long *)instruction_pointer(regs);
 195
 196         /* 0: X mode, Otherwise: Y mode. */
 197         if (bundle & TILEGX_BUNDLE_MODE_MASK) {
 198                 if (get_Opcode_Y1(bundle) == RRR_1_OPCODE_Y1 &&
 199                     get_RRROpcodeExtension_Y1(bundle) ==
 200                     UNARY_RRR_1_OPCODE_Y1) {
 201                         opcode = get_UnaryOpcodeExtension_Y1(bundle);
 202
 203                         switch (opcode) {
 204                         case JALR_UNARY_OPCODE_Y1:
 205                         case JALRP_UNARY_OPCODE_Y1:
 206                         case JR_UNARY_OPCODE_Y1:
 207                         case JRP_UNARY_OPCODE_Y1:
 208                                 src_reg = get_SrcA_Y1(bundle);
 209                                 dbg_get_reg(src_reg, &addr, regs);
 210                                 break;
 211                         }
 212                 }
 213         } else if (get_Opcode_X1(bundle) == RRR_0_OPCODE_X1) {
 214                 if (get_RRROpcodeExtension_X1(bundle) ==
 215                     UNARY_RRR_0_OPCODE_X1) {
 216                         opcode = get_UnaryOpcodeExtension_X1(bundle);
 217
 218                         switch (opcode) {
 219                         case JALR_UNARY_OPCODE_X1:
 220                         case JALRP_UNARY_OPCODE_X1:
 221                         case JR_UNARY_OPCODE_X1:
 222                         case JRP_UNARY_OPCODE_X1:
 223                                 src_reg = get_SrcA_X1(bundle);
 224                                 dbg_get_reg(src_reg, &addr, regs);
 225                                 break;
 226                         }
 227                 }
 228         } else if (get_Opcode_X1(bundle) == JUMP_OPCODE_X1) {
 229                 opcode = get_JumpOpcodeExtension_X1(bundle);
 230
 231                 switch (opcode) {
 232                 case JAL_JUMP_OPCODE_X1:
 233                 case J_JUMP_OPCODE_X1:
 234                         jump_off = sign_extend(get_JumpOff_X1(bundle), 27);
 235                         addr = regs->pc +
 236                                 (jump_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
 237                         break;
 238                 }
 239         } else if (get_Opcode_X1(bundle) == BRANCH_OPCODE_X1) {
 240                 br_off = 0;
 241                 opcode = get_BrType_X1(bundle);
 242
 243                 switch (opcode) {
 244                 case BEQZT_BRANCH_OPCODE_X1:
 245                 case BEQZ_BRANCH_OPCODE_X1:
 246                         if (get_SrcA_X1(bundle) == 0)
 247                                 br_off = get_BrOff_X1(bundle);
 248                         break;
 249                 case BGEZT_BRANCH_OPCODE_X1:
 250                 case BGEZ_BRANCH_OPCODE_X1:
 251                         if (get_SrcA_X1(bundle) >= 0)
 252                                 br_off = get_BrOff_X1(bundle);
 253                         break;
 254                 case BGTZT_BRANCH_OPCODE_X1:
 255                 case BGTZ_BRANCH_OPCODE_X1:
 256                         if (get_SrcA_X1(bundle) > 0)
 257                                 br_off = get_BrOff_X1(bundle);
 258                         break;
 259                 case BLBCT_BRANCH_OPCODE_X1:
 260                 case BLBC_BRANCH_OPCODE_X1:
 261                         if (!(get_SrcA_X1(bundle) & 1))
 262                                 br_off = get_BrOff_X1(bundle);
 263                         break;
 264                 case BLBST_BRANCH_OPCODE_X1:
 265                 case BLBS_BRANCH_OPCODE_X1:
 266                         if (get_SrcA_X1(bundle) & 1)
 267                                 br_off = get_BrOff_X1(bundle);
 268                         break;
 269                 case BLEZT_BRANCH_OPCODE_X1:
 270                 case BLEZ_BRANCH_OPCODE_X1:
 271                         if (get_SrcA_X1(bundle) <= 0)
 272                                 br_off = get_BrOff_X1(bundle);
 273                         break;
 274                 case BLTZT_BRANCH_OPCODE_X1:
 275                 case BLTZ_BRANCH_OPCODE_X1:
 276                         if (get_SrcA_X1(bundle) < 0)
 277                                 br_off = get_BrOff_X1(bundle);
 278                         break;
 279                 case BNEZT_BRANCH_OPCODE_X1:
 280                 case BNEZ_BRANCH_OPCODE_X1:
 281                         if (get_SrcA_X1(bundle) != 0)
 282                                 br_off = get_BrOff_X1(bundle);
 283                         break;
 284                 }
 285
 286                 if (br_off != 0) {
 287                         br_off = sign_extend(br_off, 17);
 288                         addr = regs->pc +
 289                                 (br_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
 290                 }
 291         }
 292
 293         return addr;
 294 }
 295
 296 /*
 297  * Replace the next instruction after the current instruction with a
 298  * breakpoint instruction.
 299  */
 300 static void do_single_step(struct pt_regs *regs)
 301 {
 302         unsigned long addr_wr;
 303
 304         /* Determine where the target instruction will send us to. */
 305         stepped_addr = get_step_address(regs);
 306         probe_kernel_read((char *)&stepped_instr, (char *)stepped_addr,
 307                           BREAK_INSTR_SIZE);
 308
 309         addr_wr = writable_address(stepped_addr);
 310         probe_kernel_write((char *)addr_wr, (char *)&singlestep_insn,
 311                            BREAK_INSTR_SIZE);
 312         smp_wmb();
 313         flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
 314 }
 315
 316 static void undo_single_step(struct pt_regs *regs)
 317 {
 318         unsigned long addr_wr;
 319
 320         if (stepped_instr == 0)
 321                 return;
 322
 323         addr_wr = writable_address(stepped_addr);
 324         probe_kernel_write((char *)addr_wr, (char *)&stepped_instr,
 325                            BREAK_INSTR_SIZE);
 326         stepped_instr = 0;
 327         smp_wmb();
 328         flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
 329 }
 330
 331 /*
 332  * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
 333  * then try to fall into the debugger.
 334  */
 335 static int
 336 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 337 {
 338         int ret;
 339         unsigned long flags;
 340         struct die_args *args = (struct die_args *)ptr;
 341         struct pt_regs *regs = args->regs;
 342
 343 #ifdef CONFIG_KPROBES
 344         /*
 345          * Return immediately if the kprobes fault notifier has set
 346          * DIE_PAGE_FAULT.
 347          */
 348         if (cmd == DIE_PAGE_FAULT)
 349                 return NOTIFY_DONE;
 350 #endif /* CONFIG_KPROBES */
 351
 352         switch (cmd) {
 353         case DIE_BREAK:
 354         case DIE_COMPILED_BPT:
 355                 break;
 356         case DIE_SSTEPBP:
 357                 local_irq_save(flags);
 358                 kgdb_handle_exception(0, SIGTRAP, 0, regs);
 359                 local_irq_restore(flags);
 360                 return NOTIFY_STOP;
 361         default:
 362                 /* Userspace events, ignore. */
 363                 if (user_mode(regs))
 364                         return NOTIFY_DONE;
 365         }
 366
 367         local_irq_save(flags);
 368         ret = kgdb_handle_exception(args->trapnr, args->signr, args->err, regs);
 369         local_irq_restore(flags);
 370         if (ret)
 371                 return NOTIFY_DONE;
 372
 373         return NOTIFY_STOP;
 374 }
 375
 376 static struct notifier_block kgdb_notifier = {
 377         .notifier_call = kgdb_notify,
 378 };
 379
 380 /*
 381  * kgdb_arch_handle_exception - Handle architecture specific GDB packets.
 382  * @vector: The error vector of the exception that happened.
 383  * @signo: The signal number of the exception that happened.
 384  * @err_code: The error code of the exception that happened.
 385  * @remcom_in_buffer: The buffer of the packet we have read.
 386  * @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
 387  * @regs: The &struct pt_regs of the current process.
 388  *
 389  * This function MUST handle the 'c' and 's' command packets,
 390  * as well packets to set / remove a hardware breakpoint, if used.
 391  * If there are additional packets which the hardware needs to handle,
 392  * they are handled here. The code should return -1 if it wants to
 393  * process more packets, and a %0 or %1 if it wants to exit from the
 394  * kgdb callback.
 395  */
 396 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 397                                char *remcom_in_buffer, char *remcom_out_buffer,
 398                                struct pt_regs *regs)
 399 {
 400         char *ptr;
 401         unsigned long address;
 402
 403         /* Undo any stepping we may have done. */
 404         undo_single_step(regs);
 405
 406         switch (remcom_in_buffer[0]) {
 407         case 'c':
 408         case 's':
 409         case 'D':
 410         case 'k':
 411                 /*
 412                  * Try to read optional parameter, pc unchanged if no parm.
 413                  * If this was a compiled-in breakpoint, we need to move
 414                  * to the next instruction or we will just breakpoint
 415                  * over and over again.
 416                  */
 417                 ptr = &remcom_in_buffer[1];
 418                 if (kgdb_hex2long(&ptr, &address))
 419                         regs->pc = address;
 420                 else if (*(unsigned long *)regs->pc == compiled_bpt)
 421                         regs->pc += BREAK_INSTR_SIZE;
 422
 423                 if (remcom_in_buffer[0] == 's') {
 424                         do_single_step(regs);
 425                         kgdb_single_step = 1;
 426                         atomic_set(&kgdb_cpu_doing_single_step,
 427                                    raw_smp_processor_id());
 428                 } else
 429                         atomic_set(&kgdb_cpu_doing_single_step, -1);
 430
 431                 return 0;
 432         }
 433
 434         return -1; /* this means that we do not want to exit from the handler */
 435 }
 436
 437 struct kgdb_arch arch_kgdb_ops;
 438
 439 /*
 440  * kgdb_arch_init - Perform any architecture specific initalization.
 441  *
 442  * This function will handle the initalization of any architecture
 443  * specific callbacks.
 444  */
 445 int kgdb_arch_init(void)
 446 {
 447         tile_bundle_bits bundle = TILEGX_BPT_BUNDLE;
 448
 449         memcpy(arch_kgdb_ops.gdb_bpt_instr, &bundle, BREAK_INSTR_SIZE);
 450         return register_die_notifier(&kgdb_notifier);
 451 }
 452
 453 /*
 454  * kgdb_arch_exit - Perform any architecture specific uninitalization.
 455  *
 456  * This function will handle the uninitalization of any architecture
 457  * specific callbacks, for dynamic registration and unregistration.
 458  */
 459 void kgdb_arch_exit(void)
 460 {
 461         unregister_die_notifier(&kgdb_notifier);
 462 }
 463
 464 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 465 {
 466         int err;
 467         unsigned long addr_wr = writable_address(bpt->bpt_addr);
 468
 469         if (addr_wr == 0)
 470                 return -1;
 471
 472         err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
 473                                 BREAK_INSTR_SIZE);
 474         if (err)
 475                 return err;
 476
 477         err = probe_kernel_write((char *)addr_wr, arch_kgdb_ops.gdb_bpt_instr,
 478                                  BREAK_INSTR_SIZE);
 479         smp_wmb();
 480         flush_icache_range((unsigned long)bpt->bpt_addr,
 481                            (unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
 482         return err;
 483 }
 484
 485 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 486 {
 487         int err;
 488         unsigned long addr_wr = writable_address(bpt->bpt_addr);
 489
 490         if (addr_wr == 0)
 491                 return -1;
 492
 493         err = probe_kernel_write((char *)addr_wr, (char *)bpt->saved_instr,
 494                                  BREAK_INSTR_SIZE);
 495         smp_wmb();
 496         flush_icache_range((unsigned long)bpt->bpt_addr,
 497                            (unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
 498         return err;
 499 }