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