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 pt_regs *thread_regs;
 142
 143         /* Initialize to zero */
 144         memset((char *)gdb_regs, 0, NUMREGBYTES);
 145         thread_regs = task_pt_regs(task);
 146         memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES);
 147         /* Special case for PSTATE (check comments in asm/kgdb.h for details) */
 148         dbg_get_reg(33, gdb_regs + GP_REG_BYTES, thread_regs);
 149 }
 150
 151 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 152 {
 153         regs->pc = pc;
 154 }
 155
 156 static int compiled_break;
 157
 158 static void kgdb_arch_update_addr(struct pt_regs *regs,
 159                                 char *remcom_in_buffer)
 160 {
 161         unsigned long addr;
 162         char *ptr;
 163
 164         ptr = &remcom_in_buffer[1];
 165         if (kgdb_hex2long(&ptr, &addr))
 166                 kgdb_arch_set_pc(regs, addr);
 167         else if (compiled_break == 1)
 168                 kgdb_arch_set_pc(regs, regs->pc + 4);
 169
 170         compiled_break = 0;
 171 }
 172
 173 int kgdb_arch_handle_exception(int exception_vector, int signo,
 174                                int err_code, char *remcom_in_buffer,
 175                                char *remcom_out_buffer,
 176                                struct pt_regs *linux_regs)
 177 {
 178         int err;
 179
 180         switch (remcom_in_buffer[0]) {
 181         case 'D':
 182         case 'k':
 183                 /*
 184                  * Packet D (Detach), k (kill). No special handling
 185                  * is required here. Handle same as c packet.
 186                  */
 187         case 'c':
 188                 /*
 189                  * Packet c (Continue) to continue executing.
 190                  * Set pc to required address.
 191                  * Try to read optional parameter and set pc.
 192                  * If this was a compiled breakpoint, we need to move
 193                  * to the next instruction else we will just breakpoint
 194                  * over and over again.
 195                  */
 196                 kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
 197                 atomic_set(&kgdb_cpu_doing_single_step, -1);
 198                 kgdb_single_step =  0;
 199
 200                 /*
 201                  * Received continue command, disable single step
 202                  */
 203                 if (kernel_active_single_step())
 204                         kernel_disable_single_step();
 205
 206                 err = 0;
 207                 break;
 208         case 's':
 209                 /*
 210                  * Update step address value with address passed
 211                  * with step packet.
 212                  * On debug exception return PC is copied to ELR
 213                  * So just update PC.
 214                  * If no step address is passed, resume from the address
 215                  * pointed by PC. Do not update PC
 216                  */
 217                 kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
 218                 atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id());
 219                 kgdb_single_step =  1;
 220
 221                 /*
 222                  * Enable single step handling
 223                  */
 224                 if (!kernel_active_single_step())
 225                         kernel_enable_single_step(linux_regs);
 226                 err = 0;
 227                 break;
 228         default:
 229                 err = -1;
 230         }
 231         return err;
 232 }
 233
 234 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
 235 {
 236         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 237         return 0;
 238 }
 239 NOKPROBE_SYMBOL(kgdb_brk_fn)
 240
 241 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
 242 {
 243         compiled_break = 1;
 244         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 245
 246         return 0;
 247 }
 248 NOKPROBE_SYMBOL(kgdb_compiled_brk_fn);
 249
 250 static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
 251 {
 252         if (!kgdb_single_step)
 253                 return DBG_HOOK_ERROR;
 254
 255         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 256         return 0;
 257 }
 258 NOKPROBE_SYMBOL(kgdb_step_brk_fn);
 259
 260 static struct break_hook kgdb_brkpt_hook = {
 261         .esr_mask       = 0xffffffff,
 262         .esr_val        = (u32)ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM),
 263         .fn             = kgdb_brk_fn
 264 };
 265
 266 static struct break_hook kgdb_compiled_brkpt_hook = {
 267         .esr_mask       = 0xffffffff,
 268         .esr_val        = (u32)ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM),
 269         .fn             = kgdb_compiled_brk_fn
 270 };
 271
 272 static struct step_hook kgdb_step_hook = {
 273         .fn             = kgdb_step_brk_fn
 274 };
 275
 276 static void kgdb_call_nmi_hook(void *ignored)
 277 {
 278         kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 279 }
 280
 281 void kgdb_roundup_cpus(unsigned long flags)
 282 {
 283         local_irq_enable();
 284         smp_call_function(kgdb_call_nmi_hook, NULL, 0);
 285         local_irq_disable();
 286 }
 287
 288 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 289 {
 290         struct pt_regs *regs = args->regs;
 291
 292         if (kgdb_handle_exception(1, args->signr, cmd, regs))
 293                 return NOTIFY_DONE;
 294         return NOTIFY_STOP;
 295 }
 296
 297 static int
 298 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 299 {
 300         unsigned long flags;
 301         int ret;
 302
 303         local_irq_save(flags);
 304         ret = __kgdb_notify(ptr, cmd);
 305         local_irq_restore(flags);
 306
 307         return ret;
 308 }
 309
 310 static struct notifier_block kgdb_notifier = {
 311         .notifier_call  = kgdb_notify,
 312         /*
 313          * Want to be lowest priority
 314          */
 315         .priority       = -INT_MAX,
 316 };
 317
 318 /*
 319  * kgdb_arch_init - Perform any architecture specific initialization.
 320  * This function will handle the initialization of any architecture
 321  * specific callbacks.
 322  */
 323 int kgdb_arch_init(void)
 324 {
 325         int ret = register_die_notifier(&kgdb_notifier);
 326
 327         if (ret != 0)
 328                 return ret;
 329
 330         register_break_hook(&kgdb_brkpt_hook);
 331         register_break_hook(&kgdb_compiled_brkpt_hook);
 332         register_step_hook(&kgdb_step_hook);
 333         return 0;
 334 }
 335
 336 /*
 337  * kgdb_arch_exit - Perform any architecture specific uninitalization.
 338  * This function will handle the uninitalization of any architecture
 339  * specific callbacks, for dynamic registration and unregistration.
 340  */
 341 void kgdb_arch_exit(void)
 342 {
 343         unregister_break_hook(&kgdb_brkpt_hook);
 344         unregister_break_hook(&kgdb_compiled_brkpt_hook);
 345         unregister_step_hook(&kgdb_step_hook);
 346         unregister_die_notifier(&kgdb_notifier);
 347 }
 348
 349 struct kgdb_arch arch_kgdb_ops;
 350
 351 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 352 {
 353         int err;
 354
 355         BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE);
 356
 357         err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr);
 358         if (err)
 359                 return err;
 360
 361         return aarch64_insn_write((void *)bpt->bpt_addr,
 362                         (u32)AARCH64_BREAK_KGDB_DYN_DBG);
 363 }
 364
 365 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 366 {
 367         return aarch64_insn_write((void *)bpt->bpt_addr,
 368                         *(u32 *)bpt->saved_instr);
 369 }