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