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