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         struct pt_regs *thread_regs;
 129
 130         if (task == NULL)
 131                 return;
 132
 133         /* Initialize to zero. */
 134         memset(gdb_regs, 0, NUMREGBYTES);
 135
 136         thread_regs = task_pt_regs(task);
 137         memcpy(gdb_regs, thread_regs, TREG_LAST_GPR * sizeof(unsigned long));
 138         gdb_regs[TILEGX_PC_REGNUM] = thread_regs->pc;
 139         gdb_regs[TILEGX_FAULTNUM_REGNUM] = thread_regs->faultnum;
 140 }
 141
 142 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 143 {
 144         regs->pc = pc;
 145 }
 146
 147 static void kgdb_call_nmi_hook(void *ignored)
 148 {
 149         kgdb_nmicallback(raw_smp_processor_id(), NULL);
 150 }
 151
 152 void kgdb_roundup_cpus(unsigned long flags)
 153 {
 154         local_irq_enable();
 155         smp_call_function(kgdb_call_nmi_hook, NULL, 0);
 156         local_irq_disable();
 157 }
 158
 159 /*
 160  * Convert a kernel address to the writable kernel text mapping.
 161  */
 162 static unsigned long writable_address(unsigned long addr)
 163 {
 164         unsigned long ret = 0;
 165
 166         if (core_kernel_text(addr))
 167                 ret = ktext_writable_addr(addr);
 168         else if (is_module_text_address(addr))
 169                 ret = addr;
 170         else
 171                 pr_err("Unknown virtual address 0x%lx\n", addr);
 172
 173         return ret;
 174 }
 175
 176 /*
 177  * Calculate the new address for after a step.
 178  */
 179 static unsigned long get_step_address(struct pt_regs *regs)
 180 {
 181         int src_reg;
 182         int jump_off;
 183         int br_off;
 184         unsigned long addr;
 185         unsigned int opcode;
 186         tile_bundle_bits bundle;
 187
 188         /* Move to the next instruction by default. */
 189         addr = regs->pc + TILEGX_BUNDLE_SIZE_IN_BYTES;
 190         bundle = *(unsigned long *)instruction_pointer(regs);
 191
 192         /* 0: X mode, Otherwise: Y mode. */
 193         if (bundle & TILEGX_BUNDLE_MODE_MASK) {
 194                 if (get_Opcode_Y1(bundle) == RRR_1_OPCODE_Y1 &&
 195                     get_RRROpcodeExtension_Y1(bundle) ==
 196                     UNARY_RRR_1_OPCODE_Y1) {
 197                         opcode = get_UnaryOpcodeExtension_Y1(bundle);
 198
 199                         switch (opcode) {
 200                         case JALR_UNARY_OPCODE_Y1:
 201                         case JALRP_UNARY_OPCODE_Y1:
 202                         case JR_UNARY_OPCODE_Y1:
 203                         case JRP_UNARY_OPCODE_Y1:
 204                                 src_reg = get_SrcA_Y1(bundle);
 205                                 dbg_get_reg(src_reg, &addr, regs);
 206                                 break;
 207                         }
 208                 }
 209         } else if (get_Opcode_X1(bundle) == RRR_0_OPCODE_X1) {
 210                 if (get_RRROpcodeExtension_X1(bundle) ==
 211                     UNARY_RRR_0_OPCODE_X1) {
 212                         opcode = get_UnaryOpcodeExtension_X1(bundle);
 213
 214                         switch (opcode) {
 215                         case JALR_UNARY_OPCODE_X1:
 216                         case JALRP_UNARY_OPCODE_X1:
 217                         case JR_UNARY_OPCODE_X1:
 218                         case JRP_UNARY_OPCODE_X1:
 219                                 src_reg = get_SrcA_X1(bundle);
 220                                 dbg_get_reg(src_reg, &addr, regs);
 221                                 break;
 222                         }
 223                 }
 224         } else if (get_Opcode_X1(bundle) == JUMP_OPCODE_X1) {
 225                 opcode = get_JumpOpcodeExtension_X1(bundle);
 226
 227                 switch (opcode) {
 228                 case JAL_JUMP_OPCODE_X1:
 229                 case J_JUMP_OPCODE_X1:
 230                         jump_off = sign_extend(get_JumpOff_X1(bundle), 27);
 231                         addr = regs->pc +
 232                                 (jump_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
 233                         break;
 234                 }
 235         } else if (get_Opcode_X1(bundle) == BRANCH_OPCODE_X1) {
 236                 br_off = 0;
 237                 opcode = get_BrType_X1(bundle);
 238
 239                 switch (opcode) {
 240                 case BEQZT_BRANCH_OPCODE_X1:
 241                 case BEQZ_BRANCH_OPCODE_X1:
 242                         if (get_SrcA_X1(bundle) == 0)
 243                                 br_off = get_BrOff_X1(bundle);
 244                         break;
 245                 case BGEZT_BRANCH_OPCODE_X1:
 246                 case BGEZ_BRANCH_OPCODE_X1:
 247                         if (get_SrcA_X1(bundle) >= 0)
 248                                 br_off = get_BrOff_X1(bundle);
 249                         break;
 250                 case BGTZT_BRANCH_OPCODE_X1:
 251                 case BGTZ_BRANCH_OPCODE_X1:
 252                         if (get_SrcA_X1(bundle) > 0)
 253                                 br_off = get_BrOff_X1(bundle);
 254                         break;
 255                 case BLBCT_BRANCH_OPCODE_X1:
 256                 case BLBC_BRANCH_OPCODE_X1:
 257                         if (!(get_SrcA_X1(bundle) & 1))
 258                                 br_off = get_BrOff_X1(bundle);
 259                         break;
 260                 case BLBST_BRANCH_OPCODE_X1:
 261                 case BLBS_BRANCH_OPCODE_X1:
 262                         if (get_SrcA_X1(bundle) & 1)
 263                                 br_off = get_BrOff_X1(bundle);
 264                         break;
 265                 case BLEZT_BRANCH_OPCODE_X1:
 266                 case BLEZ_BRANCH_OPCODE_X1:
 267                         if (get_SrcA_X1(bundle) <= 0)
 268                                 br_off = get_BrOff_X1(bundle);
 269                         break;
 270                 case BLTZT_BRANCH_OPCODE_X1:
 271                 case BLTZ_BRANCH_OPCODE_X1:
 272                         if (get_SrcA_X1(bundle) < 0)
 273                                 br_off = get_BrOff_X1(bundle);
 274                         break;
 275                 case BNEZT_BRANCH_OPCODE_X1:
 276                 case BNEZ_BRANCH_OPCODE_X1:
 277                         if (get_SrcA_X1(bundle) != 0)
 278                                 br_off = get_BrOff_X1(bundle);
 279                         break;
 280                 }
 281
 282                 if (br_off != 0) {
 283                         br_off = sign_extend(br_off, 17);
 284                         addr = regs->pc +
 285                                 (br_off << TILEGX_LOG2_BUNDLE_SIZE_IN_BYTES);
 286                 }
 287         }
 288
 289         return addr;
 290 }
 291
 292 /*
 293  * Replace the next instruction after the current instruction with a
 294  * breakpoint instruction.
 295  */
 296 static void do_single_step(struct pt_regs *regs)
 297 {
 298         unsigned long addr_wr;
 299
 300         /* Determine where the target instruction will send us to. */
 301         stepped_addr = get_step_address(regs);
 302         probe_kernel_read((char *)&stepped_instr, (char *)stepped_addr,
 303                           BREAK_INSTR_SIZE);
 304
 305         addr_wr = writable_address(stepped_addr);
 306         probe_kernel_write((char *)addr_wr, (char *)&singlestep_insn,
 307                            BREAK_INSTR_SIZE);
 308         smp_wmb();
 309         flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
 310 }
 311
 312 static void undo_single_step(struct pt_regs *regs)
 313 {
 314         unsigned long addr_wr;
 315
 316         if (stepped_instr == 0)
 317                 return;
 318
 319         addr_wr = writable_address(stepped_addr);
 320         probe_kernel_write((char *)addr_wr, (char *)&stepped_instr,
 321                            BREAK_INSTR_SIZE);
 322         stepped_instr = 0;
 323         smp_wmb();
 324         flush_icache_range(stepped_addr, stepped_addr + BREAK_INSTR_SIZE);
 325 }
 326
 327 /*
 328  * Calls linux_debug_hook before the kernel dies. If KGDB is enabled,
 329  * then try to fall into the debugger.
 330  */
 331 static int
 332 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 333 {
 334         int ret;
 335         unsigned long flags;
 336         struct die_args *args = (struct die_args *)ptr;
 337         struct pt_regs *regs = args->regs;
 338
 339 #ifdef CONFIG_KPROBES
 340         /*
 341          * Return immediately if the kprobes fault notifier has set
 342          * DIE_PAGE_FAULT.
 343          */
 344         if (cmd == DIE_PAGE_FAULT)
 345                 return NOTIFY_DONE;
 346 #endif /* CONFIG_KPROBES */
 347
 348         switch (cmd) {
 349         case DIE_BREAK:
 350         case DIE_COMPILED_BPT:
 351                 break;
 352         case DIE_SSTEPBP:
 353                 local_irq_save(flags);
 354                 kgdb_handle_exception(0, SIGTRAP, 0, regs);
 355                 local_irq_restore(flags);
 356                 return NOTIFY_STOP;
 357         default:
 358                 /* Userspace events, ignore. */
 359                 if (user_mode(regs))
 360                         return NOTIFY_DONE;
 361         }
 362
 363         local_irq_save(flags);
 364         ret = kgdb_handle_exception(args->trapnr, args->signr, args->err, regs);
 365         local_irq_restore(flags);
 366         if (ret)
 367                 return NOTIFY_DONE;
 368
 369         return NOTIFY_STOP;
 370 }
 371
 372 static struct notifier_block kgdb_notifier = {
 373         .notifier_call = kgdb_notify,
 374 };
 375
 376 /*
 377  * kgdb_arch_handle_exception - Handle architecture specific GDB packets.
 378  * @vector: The error vector of the exception that happened.
 379  * @signo: The signal number of the exception that happened.
 380  * @err_code: The error code of the exception that happened.
 381  * @remcom_in_buffer: The buffer of the packet we have read.
 382  * @remcom_out_buffer: The buffer of %BUFMAX bytes to write a packet into.
 383  * @regs: The &struct pt_regs of the current process.
 384  *
 385  * This function MUST handle the 'c' and 's' command packets,
 386  * as well packets to set / remove a hardware breakpoint, if used.
 387  * If there are additional packets which the hardware needs to handle,
 388  * they are handled here. The code should return -1 if it wants to
 389  * process more packets, and a %0 or %1 if it wants to exit from the
 390  * kgdb callback.
 391  */
 392 int kgdb_arch_handle_exception(int vector, int signo, int err_code,
 393                                char *remcom_in_buffer, char *remcom_out_buffer,
 394                                struct pt_regs *regs)
 395 {
 396         char *ptr;
 397         unsigned long address;
 398
 399         /* Undo any stepping we may have done. */
 400         undo_single_step(regs);
 401
 402         switch (remcom_in_buffer[0]) {
 403         case 'c':
 404         case 's':
 405         case 'D':
 406         case 'k':
 407                 /*
 408                  * Try to read optional parameter, pc unchanged if no parm.
 409                  * If this was a compiled-in breakpoint, we need to move
 410                  * to the next instruction or we will just breakpoint
 411                  * over and over again.
 412                  */
 413                 ptr = &remcom_in_buffer[1];
 414                 if (kgdb_hex2long(&ptr, &address))
 415                         regs->pc = address;
 416                 else if (*(unsigned long *)regs->pc == compiled_bpt)
 417                         regs->pc += BREAK_INSTR_SIZE;
 418
 419                 if (remcom_in_buffer[0] == 's') {
 420                         do_single_step(regs);
 421                         kgdb_single_step = 1;
 422                         atomic_set(&kgdb_cpu_doing_single_step,
 423                                    raw_smp_processor_id());
 424                 } else
 425                         atomic_set(&kgdb_cpu_doing_single_step, -1);
 426
 427                 return 0;
 428         }
 429
 430         return -1; /* this means that we do not want to exit from the handler */
 431 }
 432
 433 struct kgdb_arch arch_kgdb_ops;
 434
 435 /*
 436  * kgdb_arch_init - Perform any architecture specific initalization.
 437  *
 438  * This function will handle the initalization of any architecture
 439  * specific callbacks.
 440  */
 441 int kgdb_arch_init(void)
 442 {
 443         tile_bundle_bits bundle = TILEGX_BPT_BUNDLE;
 444
 445         memcpy(arch_kgdb_ops.gdb_bpt_instr, &bundle, BREAK_INSTR_SIZE);
 446         return register_die_notifier(&kgdb_notifier);
 447 }
 448
 449 /*
 450  * kgdb_arch_exit - Perform any architecture specific uninitalization.
 451  *
 452  * This function will handle the uninitalization of any architecture
 453  * specific callbacks, for dynamic registration and unregistration.
 454  */
 455 void kgdb_arch_exit(void)
 456 {
 457         unregister_die_notifier(&kgdb_notifier);
 458 }
 459
 460 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 461 {
 462         int err;
 463         unsigned long addr_wr = writable_address(bpt->bpt_addr);
 464
 465         if (addr_wr == 0)
 466                 return -1;
 467
 468         err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
 469                                 BREAK_INSTR_SIZE);
 470         if (err)
 471                 return err;
 472
 473         err = probe_kernel_write((char *)addr_wr, arch_kgdb_ops.gdb_bpt_instr,
 474                                  BREAK_INSTR_SIZE);
 475         smp_wmb();
 476         flush_icache_range((unsigned long)bpt->bpt_addr,
 477                            (unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
 478         return err;
 479 }
 480
 481 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 482 {
 483         int err;
 484         unsigned long addr_wr = writable_address(bpt->bpt_addr);
 485
 486         if (addr_wr == 0)
 487                 return -1;
 488
 489         err = probe_kernel_write((char *)addr_wr, (char *)bpt->saved_instr,
 490                                  BREAK_INSTR_SIZE);
 491         smp_wmb();
 492         flush_icache_range((unsigned long)bpt->bpt_addr,
 493                            (unsigned long)bpt->bpt_addr + BREAK_INSTR_SIZE);
 494         return err;
 495 }