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