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 cpu_context *cpu_context = &task->thread.cpu_context; 142 143 /* Initialize to zero */ 144 memset((char *)gdb_regs, 0, NUMREGBYTES); 145 146 gdb_regs[19] = cpu_context->x19; 147 gdb_regs[20] = cpu_context->x20; 148 gdb_regs[21] = cpu_context->x21; 149 gdb_regs[22] = cpu_context->x22; 150 gdb_regs[23] = cpu_context->x23; 151 gdb_regs[24] = cpu_context->x24; 152 gdb_regs[25] = cpu_context->x25; 153 gdb_regs[26] = cpu_context->x26; 154 gdb_regs[27] = cpu_context->x27; 155 gdb_regs[28] = cpu_context->x28; 156 gdb_regs[29] = cpu_context->fp; 157 158 gdb_regs[31] = cpu_context->sp; 159 gdb_regs[32] = cpu_context->pc; 160 } 161 162 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) 163 { 164 regs->pc = pc; 165 } 166 167 static int compiled_break; 168 169 static void kgdb_arch_update_addr(struct pt_regs *regs, 170 char *remcom_in_buffer) 171 { 172 unsigned long addr; 173 char *ptr; 174 175 ptr = &remcom_in_buffer[1]; 176 if (kgdb_hex2long(&ptr, &addr)) 177 kgdb_arch_set_pc(regs, addr); 178 else if (compiled_break == 1) 179 kgdb_arch_set_pc(regs, regs->pc + 4); 180 181 compiled_break = 0; 182 } 183 184 int kgdb_arch_handle_exception(int exception_vector, int signo, 185 int err_code, char *remcom_in_buffer, 186 char *remcom_out_buffer, 187 struct pt_regs *linux_regs) 188 { 189 int err; 190 191 switch (remcom_in_buffer[0]) { 192 case 'D': 193 case 'k': 194 /* 195 * Packet D (Detach), k (kill). No special handling 196 * is required here. Handle same as c packet. 197 */ 198 case 'c': 199 /* 200 * Packet c (Continue) to continue executing. 201 * Set pc to required address. 202 * Try to read optional parameter and set pc. 203 * If this was a compiled breakpoint, we need to move 204 * to the next instruction else we will just breakpoint 205 * over and over again. 206 */ 207 kgdb_arch_update_addr(linux_regs, remcom_in_buffer); 208 atomic_set(&kgdb_cpu_doing_single_step, -1); 209 kgdb_single_step = 0; 210 211 /* 212 * Received continue command, disable single step 213 */ 214 if (kernel_active_single_step()) 215 kernel_disable_single_step(); 216 217 err = 0; 218 break; 219 case 's': 220 /* 221 * Update step address value with address passed 222 * with step packet. 223 * On debug exception return PC is copied to ELR 224 * So just update PC. 225 * If no step address is passed, resume from the address 226 * pointed by PC. Do not update PC 227 */ 228 kgdb_arch_update_addr(linux_regs, remcom_in_buffer); 229 atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id()); 230 kgdb_single_step = 1; 231 232 /* 233 * Enable single step handling 234 */ 235 if (!kernel_active_single_step()) 236 kernel_enable_single_step(linux_regs); 237 err = 0; 238 break; 239 default: 240 err = -1; 241 } 242 return err; 243 } 244 245 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr) 246 { 247 kgdb_handle_exception(1, SIGTRAP, 0, regs); 248 return DBG_HOOK_HANDLED; 249 } 250 NOKPROBE_SYMBOL(kgdb_brk_fn) 251 252 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr) 253 { 254 compiled_break = 1; 255 kgdb_handle_exception(1, SIGTRAP, 0, regs); 256 257 return DBG_HOOK_HANDLED; 258 } 259 NOKPROBE_SYMBOL(kgdb_compiled_brk_fn); 260 261 static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) 262 { 263 if (!kgdb_single_step) 264 return DBG_HOOK_ERROR; 265 266 kgdb_handle_exception(1, SIGTRAP, 0, regs); 267 return DBG_HOOK_HANDLED; 268 } 269 NOKPROBE_SYMBOL(kgdb_step_brk_fn); 270 271 static struct break_hook kgdb_brkpt_hook = { 272 .fn = kgdb_brk_fn, 273 .imm = KGDB_DYN_DBG_BRK_IMM, 274 }; 275 276 static struct break_hook kgdb_compiled_brkpt_hook = { 277 .fn = kgdb_compiled_brk_fn, 278 .imm = KGDB_COMPILED_DBG_BRK_IMM, 279 }; 280 281 static struct step_hook kgdb_step_hook = { 282 .fn = kgdb_step_brk_fn 283 }; 284 285 static int __kgdb_notify(struct die_args *args, unsigned long cmd) 286 { 287 struct pt_regs *regs = args->regs; 288 289 if (kgdb_handle_exception(1, args->signr, cmd, regs)) 290 return NOTIFY_DONE; 291 return NOTIFY_STOP; 292 } 293 294 static int 295 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) 296 { 297 unsigned long flags; 298 int ret; 299 300 local_irq_save(flags); 301 ret = __kgdb_notify(ptr, cmd); 302 local_irq_restore(flags); 303 304 return ret; 305 } 306 307 static struct notifier_block kgdb_notifier = { 308 .notifier_call = kgdb_notify, 309 /* 310 * Want to be lowest priority 311 */ 312 .priority = -INT_MAX, 313 }; 314 315 /* 316 * kgdb_arch_init - Perform any architecture specific initialization. 317 * This function will handle the initialization of any architecture 318 * specific callbacks. 319 */ 320 int kgdb_arch_init(void) 321 { 322 int ret = register_die_notifier(&kgdb_notifier); 323 324 if (ret != 0) 325 return ret; 326 327 register_kernel_break_hook(&kgdb_brkpt_hook); 328 register_kernel_break_hook(&kgdb_compiled_brkpt_hook); 329 register_kernel_step_hook(&kgdb_step_hook); 330 return 0; 331 } 332 333 /* 334 * kgdb_arch_exit - Perform any architecture specific uninitalization. 335 * This function will handle the uninitalization of any architecture 336 * specific callbacks, for dynamic registration and unregistration. 337 */ 338 void kgdb_arch_exit(void) 339 { 340 unregister_kernel_break_hook(&kgdb_brkpt_hook); 341 unregister_kernel_break_hook(&kgdb_compiled_brkpt_hook); 342 unregister_kernel_step_hook(&kgdb_step_hook); 343 unregister_die_notifier(&kgdb_notifier); 344 } 345 346 const struct kgdb_arch arch_kgdb_ops; 347 348 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 349 { 350 int err; 351 352 BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE); 353 354 err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr); 355 if (err) 356 return err; 357 358 return aarch64_insn_write((void *)bpt->bpt_addr, 359 (u32)AARCH64_BREAK_KGDB_DYN_DBG); 360 } 361 362 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 363 { 364 return aarch64_insn_write((void *)bpt->bpt_addr, 365 *(u32 *)bpt->saved_instr); 366 } 367