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 <asm/debug-monitors.h>
  28 #include <asm/insn.h>
  29 #include <asm/traps.h>
  30
  31 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = {
  32         { "x0", 8, offsetof(struct pt_regs, regs[0])},
  33         { "x1", 8, offsetof(struct pt_regs, regs[1])},
  34         { "x2", 8, offsetof(struct pt_regs, regs[2])},
  35         { "x3", 8, offsetof(struct pt_regs, regs[3])},
  36         { "x4", 8, offsetof(struct pt_regs, regs[4])},
  37         { "x5", 8, offsetof(struct pt_regs, regs[5])},
  38         { "x6", 8, offsetof(struct pt_regs, regs[6])},
  39         { "x7", 8, offsetof(struct pt_regs, regs[7])},
  40         { "x8", 8, offsetof(struct pt_regs, regs[8])},
  41         { "x9", 8, offsetof(struct pt_regs, regs[9])},
  42         { "x10", 8, offsetof(struct pt_regs, regs[10])},
  43         { "x11", 8, offsetof(struct pt_regs, regs[11])},
  44         { "x12", 8, offsetof(struct pt_regs, regs[12])},
  45         { "x13", 8, offsetof(struct pt_regs, regs[13])},
  46         { "x14", 8, offsetof(struct pt_regs, regs[14])},
  47         { "x15", 8, offsetof(struct pt_regs, regs[15])},
  48         { "x16", 8, offsetof(struct pt_regs, regs[16])},
  49         { "x17", 8, offsetof(struct pt_regs, regs[17])},
  50         { "x18", 8, offsetof(struct pt_regs, regs[18])},
  51         { "x19", 8, offsetof(struct pt_regs, regs[19])},
  52         { "x20", 8, offsetof(struct pt_regs, regs[20])},
  53         { "x21", 8, offsetof(struct pt_regs, regs[21])},
  54         { "x22", 8, offsetof(struct pt_regs, regs[22])},
  55         { "x23", 8, offsetof(struct pt_regs, regs[23])},
  56         { "x24", 8, offsetof(struct pt_regs, regs[24])},
  57         { "x25", 8, offsetof(struct pt_regs, regs[25])},
  58         { "x26", 8, offsetof(struct pt_regs, regs[26])},
  59         { "x27", 8, offsetof(struct pt_regs, regs[27])},
  60         { "x28", 8, offsetof(struct pt_regs, regs[28])},
  61         { "x29", 8, offsetof(struct pt_regs, regs[29])},
  62         { "x30", 8, offsetof(struct pt_regs, regs[30])},
  63         { "sp", 8, offsetof(struct pt_regs, sp)},
  64         { "pc", 8, offsetof(struct pt_regs, pc)},
  65         /*
  66          * struct pt_regs thinks PSTATE is 64-bits wide but gdb remote
  67          * protocol disagrees. Therefore we must extract only the lower
  68          * 32-bits. Look for the big comment in asm/kgdb.h for more
  69          * detail.
  70          */
  71         { "pstate", 4, offsetof(struct pt_regs, pstate)
  72 #ifdef CONFIG_CPU_BIG_ENDIAN
  73                                                         + 4
  74 #endif
  75         },
  76         { "v0", 16, -1 },
  77         { "v1", 16, -1 },
  78         { "v2", 16, -1 },
  79         { "v3", 16, -1 },
  80         { "v4", 16, -1 },
  81         { "v5", 16, -1 },
  82         { "v6", 16, -1 },
  83         { "v7", 16, -1 },
  84         { "v8", 16, -1 },
  85         { "v9", 16, -1 },
  86         { "v10", 16, -1 },
  87         { "v11", 16, -1 },
  88         { "v12", 16, -1 },
  89         { "v13", 16, -1 },
  90         { "v14", 16, -1 },
  91         { "v15", 16, -1 },
  92         { "v16", 16, -1 },
  93         { "v17", 16, -1 },
  94         { "v18", 16, -1 },
  95         { "v19", 16, -1 },
  96         { "v20", 16, -1 },
  97         { "v21", 16, -1 },
  98         { "v22", 16, -1 },
  99         { "v23", 16, -1 },
 100         { "v24", 16, -1 },
 101         { "v25", 16, -1 },
 102         { "v26", 16, -1 },
 103         { "v27", 16, -1 },
 104         { "v28", 16, -1 },
 105         { "v29", 16, -1 },
 106         { "v30", 16, -1 },
 107         { "v31", 16, -1 },
 108         { "fpsr", 4, -1 },
 109         { "fpcr", 4, -1 },
 110 };
 111
 112 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
 113 {
 114         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 115                 return NULL;
 116
 117         if (dbg_reg_def[regno].offset != -1)
 118                 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
 119                        dbg_reg_def[regno].size);
 120         else
 121                 memset(mem, 0, dbg_reg_def[regno].size);
 122         return dbg_reg_def[regno].name;
 123 }
 124
 125 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
 126 {
 127         if (regno >= DBG_MAX_REG_NUM || regno < 0)
 128                 return -EINVAL;
 129
 130         if (dbg_reg_def[regno].offset != -1)
 131                 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
 132                        dbg_reg_def[regno].size);
 133         return 0;
 134 }
 135
 136 void
 137 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
 138 {
 139         struct pt_regs *thread_regs;
 140
 141         /* Initialize to zero */
 142         memset((char *)gdb_regs, 0, NUMREGBYTES);
 143         thread_regs = task_pt_regs(task);
 144         memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES);
 145         /* Special case for PSTATE (check comments in asm/kgdb.h for details) */
 146         dbg_get_reg(33, gdb_regs + GP_REG_BYTES, thread_regs);
 147 }
 148
 149 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 150 {
 151         regs->pc = pc;
 152 }
 153
 154 static int compiled_break;
 155
 156 static void kgdb_arch_update_addr(struct pt_regs *regs,
 157                                 char *remcom_in_buffer)
 158 {
 159         unsigned long addr;
 160         char *ptr;
 161
 162         ptr = &remcom_in_buffer[1];
 163         if (kgdb_hex2long(&ptr, &addr))
 164                 kgdb_arch_set_pc(regs, addr);
 165         else if (compiled_break == 1)
 166                 kgdb_arch_set_pc(regs, regs->pc + 4);
 167
 168         compiled_break = 0;
 169 }
 170
 171 int kgdb_arch_handle_exception(int exception_vector, int signo,
 172                                int err_code, char *remcom_in_buffer,
 173                                char *remcom_out_buffer,
 174                                struct pt_regs *linux_regs)
 175 {
 176         int err;
 177
 178         switch (remcom_in_buffer[0]) {
 179         case 'D':
 180         case 'k':
 181                 /*
 182                  * Packet D (Detach), k (kill). No special handling
 183                  * is required here. Handle same as c packet.
 184                  */
 185         case 'c':
 186                 /*
 187                  * Packet c (Continue) to continue executing.
 188                  * Set pc to required address.
 189                  * Try to read optional parameter and set pc.
 190                  * If this was a compiled breakpoint, we need to move
 191                  * to the next instruction else we will just breakpoint
 192                  * over and over again.
 193                  */
 194                 kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
 195                 atomic_set(&kgdb_cpu_doing_single_step, -1);
 196                 kgdb_single_step =  0;
 197
 198                 /*
 199                  * Received continue command, disable single step
 200                  */
 201                 if (kernel_active_single_step())
 202                         kernel_disable_single_step();
 203
 204                 err = 0;
 205                 break;
 206         case 's':
 207                 /*
 208                  * Update step address value with address passed
 209                  * with step packet.
 210                  * On debug exception return PC is copied to ELR
 211                  * So just update PC.
 212                  * If no step address is passed, resume from the address
 213                  * pointed by PC. Do not update PC
 214                  */
 215                 kgdb_arch_update_addr(linux_regs, remcom_in_buffer);
 216                 atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id());
 217                 kgdb_single_step =  1;
 218
 219                 /*
 220                  * Enable single step handling
 221                  */
 222                 if (!kernel_active_single_step())
 223                         kernel_enable_single_step(linux_regs);
 224                 err = 0;
 225                 break;
 226         default:
 227                 err = -1;
 228         }
 229         return err;
 230 }
 231
 232 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr)
 233 {
 234         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 235         return 0;
 236 }
 237 NOKPROBE_SYMBOL(kgdb_brk_fn)
 238
 239 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr)
 240 {
 241         compiled_break = 1;
 242         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 243
 244         return 0;
 245 }
 246 NOKPROBE_SYMBOL(kgdb_compiled_brk_fn);
 247
 248 static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr)
 249 {
 250         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 251         return 0;
 252 }
 253 NOKPROBE_SYMBOL(kgdb_step_brk_fn);
 254
 255 static struct break_hook kgdb_brkpt_hook = {
 256         .esr_mask       = 0xffffffff,
 257         .esr_val        = (u32)ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM),
 258         .fn             = kgdb_brk_fn
 259 };
 260
 261 static struct break_hook kgdb_compiled_brkpt_hook = {
 262         .esr_mask       = 0xffffffff,
 263         .esr_val        = (u32)ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM),
 264         .fn             = kgdb_compiled_brk_fn
 265 };
 266
 267 static struct step_hook kgdb_step_hook = {
 268         .fn             = kgdb_step_brk_fn
 269 };
 270
 271 static void kgdb_call_nmi_hook(void *ignored)
 272 {
 273         kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 274 }
 275
 276 void kgdb_roundup_cpus(unsigned long flags)
 277 {
 278         local_irq_enable();
 279         smp_call_function(kgdb_call_nmi_hook, NULL, 0);
 280         local_irq_disable();
 281 }
 282
 283 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 284 {
 285         struct pt_regs *regs = args->regs;
 286
 287         if (kgdb_handle_exception(1, args->signr, cmd, regs))
 288                 return NOTIFY_DONE;
 289         return NOTIFY_STOP;
 290 }
 291
 292 static int
 293 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 294 {
 295         unsigned long flags;
 296         int ret;
 297
 298         local_irq_save(flags);
 299         ret = __kgdb_notify(ptr, cmd);
 300         local_irq_restore(flags);
 301
 302         return ret;
 303 }
 304
 305 static struct notifier_block kgdb_notifier = {
 306         .notifier_call  = kgdb_notify,
 307         /*
 308          * Want to be lowest priority
 309          */
 310         .priority       = -INT_MAX,
 311 };
 312
 313 /*
 314  * kgdb_arch_init - Perform any architecture specific initialization.
 315  * This function will handle the initialization of any architecture
 316  * specific callbacks.
 317  */
 318 int kgdb_arch_init(void)
 319 {
 320         int ret = register_die_notifier(&kgdb_notifier);
 321
 322         if (ret != 0)
 323                 return ret;
 324
 325         register_break_hook(&kgdb_brkpt_hook);
 326         register_break_hook(&kgdb_compiled_brkpt_hook);
 327         register_step_hook(&kgdb_step_hook);
 328         return 0;
 329 }
 330
 331 /*
 332  * kgdb_arch_exit - Perform any architecture specific uninitalization.
 333  * This function will handle the uninitalization of any architecture
 334  * specific callbacks, for dynamic registration and unregistration.
 335  */
 336 void kgdb_arch_exit(void)
 337 {
 338         unregister_break_hook(&kgdb_brkpt_hook);
 339         unregister_break_hook(&kgdb_compiled_brkpt_hook);
 340         unregister_step_hook(&kgdb_step_hook);
 341         unregister_die_notifier(&kgdb_notifier);
 342 }
 343
 344 struct kgdb_arch arch_kgdb_ops;
 345
 346 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 347 {
 348         int err;
 349
 350         BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE);
 351
 352         err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr);
 353         if (err)
 354                 return err;
 355
 356         return aarch64_insn_write((void *)bpt->bpt_addr,
 357                         (u32)AARCH64_BREAK_KGDB_DYN_DBG);
 358 }
 359
 360 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 361 {
 362         return aarch64_insn_write((void *)bpt->bpt_addr,
 363                         *(u32 *)bpt->saved_instr);
 364 }