arch/arm64/kernel/kgdb.c

   1 /*
   2  * AArch64 KGDB support
   3  *
   4  * Based on arch/arm/kernel/kgdb.c
   5  *
   6  * Copyright (C) 2013 Cavium Inc.
   7  * Author: Vijaya Kumar K <vijaya.kumar@caviumnetworks.com>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20  */
  21
  22 #include <linux/bug.h>
  23 #include <linux/irq.h>
  24 #include <linux/kdebug.h>
  25 #include <linux/kgdb.h>
  26 #include <linux/kprobes.h>
  27 #include <linux/sched/task_stack.h>
  28
  29 #include <asm/debug-monitors.h>
  30 #include <asm/insn.h>
  31 #include <asm/traps.h>
  32
  33 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
  34         { "x0", 8, offsetof(struct pt_regs, regs[0])},
  35         { "x1", 8, offsetof(struct pt_regs, regs[1])},
  36         { "x2", 8, offsetof(struct pt_regs, regs[2])},
  37         { "x3", 8, offsetof(struct pt_regs, regs[3])},
  38         { "x4", 8, offsetof(struct pt_regs, regs[4])},
  39         { "x5", 8, offsetof(struct pt_regs, regs[5])},
  40         { "x6", 8, offsetof(struct pt_regs, regs[6])},
  41         { "x7", 8, offsetof(struct pt_regs, regs[7])},
  42         { "x8", 8, offsetof(struct pt_regs, regs[8])},
  43         { "x9", 8, offsetof(struct pt_regs, regs[9])},
  44         { "x10", 8, offsetof(struct pt_regs, regs[10])},
  45         { "x11", 8, offsetof(struct pt_regs, regs[11])},
  46         { "x12", 8, offsetof(struct pt_regs, regs[12])},
  47         { "x13", 8, offsetof(struct pt_regs, regs[13])},
  48         { "x14", 8, offsetof(struct pt_regs, regs[14])},
  49         { "x15", 8, offsetof(struct pt_regs, regs[15])},
  50         { "x16", 8, offsetof(struct pt_regs, regs[16])},
  51         { "x17", 8, offsetof(struct pt_regs, regs[17])},
  52         { "x18", 8, offsetof(struct pt_regs, regs[18])},
  53         { "x19", 8, offsetof(struct pt_regs, regs[19])},
  54         { "x20", 8, offsetof(struct pt_regs, regs[20])},
  55         { "x21", 8, offsetof(struct pt_regs, regs[21])},
  56         { "x22", 8, offsetof(struct pt_regs, regs[22])},
  57         { "x23", 8, offsetof(struct pt_regs, regs[23])},
  58         { "x24", 8, offsetof(struct pt_regs, regs[24])},
  59         { "x25", 8, offsetof(struct pt_regs, regs[25])},
  60         { "x26", 8, offsetof(struct pt_regs, regs[26])},
  61         { "x27", 8, offsetof(struct pt_regs, regs[27])},
  62         { "x28", 8, offsetof(struct pt_regs, regs[28])},
  63         { "x29", 8, offsetof(struct pt_regs, regs[29])},
  64         { "x30", 8, offsetof(struct pt_regs, regs[30])},
  65         { "sp", 8, offsetof(struct pt_regs, sp)},
  66         { "pc", 8, offsetof(struct pt_regs, pc)},
  67         /*
  68          * struct pt_regs thinks PSTATE is 64-bits wide but gdb remote
  69          * protocol disagrees. Therefore we must extract only the lower
  70          * 32-bits. Look for the big comment in asm/kgdb.h for more
  71          * detail.
  72          */
  73         { "pstate", 4, offsetof(struct pt_regs, pstate)
  74 #ifdef CONFIG_CPU_BIG_ENDIAN
  75                                                         + 4
  76 #endif
  77         },
  78         { "v0", 16, -1 },
  79         { "v1", 16, -1 },
  80         { "v2", 16, -1 },
  81         { "v3", 16, -1 },
  82         { "v4", 16, -1 },
  83         { "v5", 16, -1 },
  84         { "v6", 16, -1 },
  85         { "v7", 16, -1 },
  86         { "v8", 16, -1 },
  87         { "v9", 16, -1 },
  88         { "v10", 16, -1 },
  89         { "v11", 16, -1 },
  90         { "v12", 16, -1 },
  91         { "v13", 16, -1 },
  92         { "v14", 16, -1 },
  93         { "v15", 16, -1 },
  94         { "v16", 16, -1 },
  95         { "v17", 16, -1 },
  96         { "v18", 16, -1 },
  97         { "v19", 16, -1 },
  98         { "v20", 16, -1 },
  99         { "v21", 16, -1 },
 100         { "v22", 16, -1 },
 101         { "v23", 16, -1 },
 102         { "v24", 16, -1 },
 103         { "v25", 16, -1 },
 104         { "v26", 16, -1 },
 105         { "v27", 16, -1 },
 106         { "v28", 16, -1 },
 107         { "v29", 16, -1 },
 108         { "v30", 16, -1 },
 109         { "v31", 16, -1 },
 110         { "fpsr", 4, -1 },
 111         { "fpcr", 4, -1 },
 112 };
 113
 114 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
 115 {
 116         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 117                 return NULL;
 118
 119         if (dbg_reg_def[regno].offset != -1)
 120                 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
 121                        dbg_reg_def[regno].size);
 122         else
 123                 memset(mem, 0, dbg_reg_def[regno].size);
 124         return dbg_reg_def[regno].name;
 125 }
 126
 127 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
 128 {
 129         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 130                 return -EINVAL;
 131
 132         if (dbg_reg_def[regno].offset != -1)
 133                 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
 134                        dbg_reg_def[regno].size);
 135         return 0;
 136 }
 137
 138 void
 139 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
 140 {
 141         struct cpu_context *cpu_context = &task->thread.cpu_context;
 142
 143         /* Initialize to zero */
 144         memset((char *)gdb_regs, 0, NUMREGBYTES);
 145
 146         gdb_regs[19] = cpu_context->x19;
 147         gdb_regs[20] = cpu_context->x20;
 148         gdb_regs[21] = cpu_context->x21;
 149         gdb_regs[22] = cpu_context->x22;
 150         gdb_regs[23] = cpu_context->x23;
 151         gdb_regs[24] = cpu_context->x24;
 152         gdb_regs[25] = cpu_context->x25;
 153         gdb_regs[26] = cpu_context->x26;
 154         gdb_regs[27] = cpu_context->x27;
 155         gdb_regs[28] = cpu_context->x28;
 156         gdb_regs[29] = cpu_context->fp;
 157
 158         gdb_regs[31] = cpu_context->sp;
 159         gdb_regs[32] = cpu_context->pc;
 160 }
 161
 162 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 163 {
 164         regs->pc = pc;
 165 }
 166
 167 static int compiled_break;
 168
 169 static void kgdb_arch_update_addr(struct pt_regs *regs,
 170                                 char *remcom_in_buffer)
 171 {
 172         unsigned long addr;
 173         char *ptr;
 174
 175         ptr = &remcom_in_buffer[1];
 176         if (kgdb_hex2long(&ptr, &addr))
 177                 kgdb_arch_set_pc(regs, addr);
 178         else if (compiled_break == 1)
 179                 kgdb_arch_set_pc(regs, regs->pc + 4);
 180
 181         compiled_break = 0;
 182 }
 183
 184 int kgdb_arch_handle_exception(int exception_vector, int signo,
 185                                int err_code, char *remcom_in_buffer,
 186                                char *remcom_out_buffer,
 187                                struct pt_regs *linux_regs)
 188 {
 189         int err;
 190
 191         switch (remcom_in_buffer[0]) {
 192         case 'D':
 193         case 'k':
 194                 /*
 195                  * Packet D (Detach), k (kill). No special handling
 196                  * is required here. Handle same as c packet.
 197                  */
 198         case 'c':
 199                 /*
 200                  * Packet c (Continue) to continue executing.
 201                  * Set pc to required address.
 202                  * Try to read optional parameter and set pc.
 203                  * If this was a compiled breakpoint, we need to move
 204                  * to the next instruction else we will just breakpoint
 205                  * over and over again.
 206                  */
 207                 kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
 208                 atomic_set(&kgdb_cpu_doing_single_step, -1);
 209                 kgdb_single_step =  0;
 210
 211                 /*
 212                  * Received continue command, disable single step
 213                  */
 214                 if (kernel_active_single_step())
 215                         kernel_disable_single_step();
 216
 217                 err = 0;
 218                 break;
 219         case 's':
 220                 /*
 221                  * Update step address value with address passed
 222                  * with step packet.
 223                  * On debug exception return PC is copied to ELR
 224                  * So just update PC.
 225                  * If no step address is passed, resume from the address
 226                  * pointed by PC. Do not update PC
 227                  */
 228                 kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
 229                 atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id());
 230                 kgdb_single_step =  1;
 231
 232                 /*
 233                  * Enable single step handling
 234                  */
 235                 if (!kernel_active_single_step())
 236                         kernel_enable_single_step(linux_regs);
 237                 err = 0;
 238                 break;
 239         default:
 240                 err = -1;
 241         }
 242         return err;
 243 }
 244
 245 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
 246 {
 247         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 248         return DBG_HOOK_HANDLED;
 249 }
 250 NOKPROBE_SYMBOL(kgdb_brk_fn)
 251
 252 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
 253 {
 254         compiled_break = 1;
 255         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 256
 257         return DBG_HOOK_HANDLED;
 258 }
 259 NOKPROBE_SYMBOL(kgdb_compiled_brk_fn);
 260
 261 static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
 262 {
 263         if (!kgdb_single_step)
 264                 return DBG_HOOK_ERROR;
 265
 266         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 267         return DBG_HOOK_HANDLED;
 268 }
 269 NOKPROBE_SYMBOL(kgdb_step_brk_fn);
 270
 271 static struct break_hook kgdb_brkpt_hook = {
 272         .fn             = kgdb_brk_fn,
 273         .imm            = KGDB_DYN_DBG_BRK_IMM,
 274 };
 275
 276 static struct break_hook kgdb_compiled_brkpt_hook = {
 277         .fn             = kgdb_compiled_brk_fn,
 278         .imm            = KGDB_COMPILED_DBG_BRK_IMM,
 279 };
 280
 281 static struct step_hook kgdb_step_hook = {
 282         .fn             = kgdb_step_brk_fn
 283 };
 284
 285 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 286 {
 287         struct pt_regs *regs = args->regs;
 288
 289         if (kgdb_handle_exception(1, args->signr, cmd, regs))
 290                 return NOTIFY_DONE;
 291         return NOTIFY_STOP;
 292 }
 293
 294 static int
 295 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 296 {
 297         unsigned long flags;
 298         int ret;
 299
 300         local_irq_save(flags);
 301         ret = __kgdb_notify(ptr, cmd);
 302         local_irq_restore(flags);
 303
 304         return ret;
 305 }
 306
 307 static struct notifier_block kgdb_notifier = {
 308         .notifier_call  = kgdb_notify,
 309         /*
 310          * Want to be lowest priority
 311          */
 312         .priority       = -INT_MAX,
 313 };
 314
 315 /*
 316  * kgdb_arch_init - Perform any architecture specific initialization.
 317  * This function will handle the initialization of any architecture
 318  * specific callbacks.
 319  */
 320 int kgdb_arch_init(void)
 321 {
 322         int ret = register_die_notifier(&kgdb_notifier);
 323
 324         if (ret != 0)
 325                 return ret;
 326
 327         register_kernel_break_hook(&kgdb_brkpt_hook);
 328         register_kernel_break_hook(&kgdb_compiled_brkpt_hook);
 329         register_kernel_step_hook(&kgdb_step_hook);
 330         return 0;
 331 }
 332
 333 /*
 334  * kgdb_arch_exit - Perform any architecture specific uninitalization.
 335  * This function will handle the uninitalization of any architecture
 336  * specific callbacks, for dynamic registration and unregistration.
 337  */
 338 void kgdb_arch_exit(void)
 339 {
 340         unregister_kernel_break_hook(&kgdb_brkpt_hook);
 341         unregister_kernel_break_hook(&kgdb_compiled_brkpt_hook);
 342         unregister_kernel_step_hook(&kgdb_step_hook);
 343         unregister_die_notifier(&kgdb_notifier);
 344 }
 345
 346 const struct kgdb_arch arch_kgdb_ops;
 347
 348 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 349 {
 350         int err;
 351
 352         BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE);
 353
 354         err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr);
 355         if (err)
 356                 return err;
 357
 358         return aarch64_insn_write((void *)bpt->bpt_addr,
 359                         (u32)AARCH64_BREAK_KGDB_DYN_DBG);
 360 }
 361
 362 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 363 {
 364         return aarch64_insn_write((void *)bpt->bpt_addr,
 365                         *(u32 *)bpt->saved_instr);
 366 }