1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * AArch64 KGDB support 4 * 5 * Based on arch/arm/kernel/kgdb.c 6 * 7 * Copyright (C) 2013 Cavium Inc. 8 * Author: Vijaya Kumar K <vijaya.kumar@caviumnetworks.com> 9 */ 10 11 #include <linux/bug.h> 12 #include <linux/irq.h> 13 #include <linux/kdebug.h> 14 #include <linux/kgdb.h> 15 #include <linux/kprobes.h> 16 #include <linux/sched/task_stack.h> 17 18 #include <asm/debug-monitors.h> 19 #include <asm/insn.h> 20 #include <asm/traps.h> 21 22 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { 23 { "x0", 8, offsetof(struct pt_regs, regs[0])}, 24 { "x1", 8, offsetof(struct pt_regs, regs[1])}, 25 { "x2", 8, offsetof(struct pt_regs, regs[2])}, 26 { "x3", 8, offsetof(struct pt_regs, regs[3])}, 27 { "x4", 8, offsetof(struct pt_regs, regs[4])}, 28 { "x5", 8, offsetof(struct pt_regs, regs[5])}, 29 { "x6", 8, offsetof(struct pt_regs, regs[6])}, 30 { "x7", 8, offsetof(struct pt_regs, regs[7])}, 31 { "x8", 8, offsetof(struct pt_regs, regs[8])}, 32 { "x9", 8, offsetof(struct pt_regs, regs[9])}, 33 { "x10", 8, offsetof(struct pt_regs, regs[10])}, 34 { "x11", 8, offsetof(struct pt_regs, regs[11])}, 35 { "x12", 8, offsetof(struct pt_regs, regs[12])}, 36 { "x13", 8, offsetof(struct pt_regs, regs[13])}, 37 { "x14", 8, offsetof(struct pt_regs, regs[14])}, 38 { "x15", 8, offsetof(struct pt_regs, regs[15])}, 39 { "x16", 8, offsetof(struct pt_regs, regs[16])}, 40 { "x17", 8, offsetof(struct pt_regs, regs[17])}, 41 { "x18", 8, offsetof(struct pt_regs, regs[18])}, 42 { "x19", 8, offsetof(struct pt_regs, regs[19])}, 43 { "x20", 8, offsetof(struct pt_regs, regs[20])}, 44 { "x21", 8, offsetof(struct pt_regs, regs[21])}, 45 { "x22", 8, offsetof(struct pt_regs, regs[22])}, 46 { "x23", 8, offsetof(struct pt_regs, regs[23])}, 47 { "x24", 8, offsetof(struct pt_regs, regs[24])}, 48 { "x25", 8, offsetof(struct pt_regs, regs[25])}, 49 { "x26", 8, offsetof(struct pt_regs, regs[26])}, 50 { "x27", 8, offsetof(struct pt_regs, regs[27])}, 51 { "x28", 8, offsetof(struct pt_regs, regs[28])}, 52 { "x29", 8, offsetof(struct pt_regs, regs[29])}, 53 { "x30", 8, offsetof(struct pt_regs, regs[30])}, 54 { "sp", 8, offsetof(struct pt_regs, sp)}, 55 { "pc", 8, offsetof(struct pt_regs, pc)}, 56 /* 57 * struct pt_regs thinks PSTATE is 64-bits wide but gdb remote 58 * protocol disagrees. Therefore we must extract only the lower 59 * 32-bits. Look for the big comment in asm/kgdb.h for more 60 * detail. 61 */ 62 { "pstate", 4, offsetof(struct pt_regs, pstate) 63 #ifdef CONFIG_CPU_BIG_ENDIAN 64 + 4 65 #endif 66 }, 67 { "v0", 16, -1 }, 68 { "v1", 16, -1 }, 69 { "v2", 16, -1 }, 70 { "v3", 16, -1 }, 71 { "v4", 16, -1 }, 72 { "v5", 16, -1 }, 73 { "v6", 16, -1 }, 74 { "v7", 16, -1 }, 75 { "v8", 16, -1 }, 76 { "v9", 16, -1 }, 77 { "v10", 16, -1 }, 78 { "v11", 16, -1 }, 79 { "v12", 16, -1 }, 80 { "v13", 16, -1 }, 81 { "v14", 16, -1 }, 82 { "v15", 16, -1 }, 83 { "v16", 16, -1 }, 84 { "v17", 16, -1 }, 85 { "v18", 16, -1 }, 86 { "v19", 16, -1 }, 87 { "v20", 16, -1 }, 88 { "v21", 16, -1 }, 89 { "v22", 16, -1 }, 90 { "v23", 16, -1 }, 91 { "v24", 16, -1 }, 92 { "v25", 16, -1 }, 93 { "v26", 16, -1 }, 94 { "v27", 16, -1 }, 95 { "v28", 16, -1 }, 96 { "v29", 16, -1 }, 97 { "v30", 16, -1 }, 98 { "v31", 16, -1 }, 99 { "fpsr", 4, -1 }, 100 { "fpcr", 4, -1 }, 101 }; 102 103 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) 104 { 105 if (regno >= DBG_MAX_REG_NUM || regno < 0) 106 return NULL; 107 108 if (dbg_reg_def[regno].offset != -1) 109 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, 110 dbg_reg_def[regno].size); 111 else 112 memset(mem, 0, dbg_reg_def[regno].size); 113 return dbg_reg_def[regno].name; 114 } 115 116 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) 117 { 118 if (regno >= DBG_MAX_REG_NUM || regno < 0) 119 return -EINVAL; 120 121 if (dbg_reg_def[regno].offset != -1) 122 memcpy((void *)regs + dbg_reg_def[regno].offset, mem, 123 dbg_reg_def[regno].size); 124 return 0; 125 } 126 127 void 128 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task) 129 { 130 struct cpu_context *cpu_context = &task->thread.cpu_context; 131 132 /* Initialize to zero */ 133 memset((char *)gdb_regs, 0, NUMREGBYTES); 134 135 gdb_regs[19] = cpu_context->x19; 136 gdb_regs[20] = cpu_context->x20; 137 gdb_regs[21] = cpu_context->x21; 138 gdb_regs[22] = cpu_context->x22; 139 gdb_regs[23] = cpu_context->x23; 140 gdb_regs[24] = cpu_context->x24; 141 gdb_regs[25] = cpu_context->x25; 142 gdb_regs[26] = cpu_context->x26; 143 gdb_regs[27] = cpu_context->x27; 144 gdb_regs[28] = cpu_context->x28; 145 gdb_regs[29] = cpu_context->fp; 146 147 gdb_regs[31] = cpu_context->sp; 148 gdb_regs[32] = cpu_context->pc; 149 } 150 151 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) 152 { 153 regs->pc = pc; 154 } 155 156 static int compiled_break; 157 158 static void kgdb_arch_update_addr(struct pt_regs *regs, 159 char *remcom_in_buffer) 160 { 161 unsigned long addr; 162 char *ptr; 163 164 ptr = &remcom_in_buffer[1]; 165 if (kgdb_hex2long(&ptr, &addr)) 166 kgdb_arch_set_pc(regs, addr); 167 else if (compiled_break == 1) 168 kgdb_arch_set_pc(regs, regs->pc + 4); 169 170 compiled_break = 0; 171 } 172 173 int kgdb_arch_handle_exception(int exception_vector, int signo, 174 int err_code, char *remcom_in_buffer, 175 char *remcom_out_buffer, 176 struct pt_regs *linux_regs) 177 { 178 int err; 179 180 switch (remcom_in_buffer[0]) { 181 case 'D': 182 case 'k': 183 /* 184 * Packet D (Detach), k (kill). No special handling 185 * is required here. Handle same as c packet. 186 */ 187 case 'c': 188 /* 189 * Packet c (Continue) to continue executing. 190 * Set pc to required address. 191 * Try to read optional parameter and set pc. 192 * If this was a compiled breakpoint, we need to move 193 * to the next instruction else we will just breakpoint 194 * over and over again. 195 */ 196 kgdb_arch_update_addr(linux_regs, remcom_in_buffer); 197 atomic_set(&kgdb_cpu_doing_single_step, -1); 198 kgdb_single_step = 0; 199 200 /* 201 * Received continue command, disable single step 202 */ 203 if (kernel_active_single_step()) 204 kernel_disable_single_step(); 205 206 err = 0; 207 break; 208 case 's': 209 /* 210 * Update step address value with address passed 211 * with step packet. 212 * On debug exception return PC is copied to ELR 213 * So just update PC. 214 * If no step address is passed, resume from the address 215 * pointed by PC. Do not update PC 216 */ 217 kgdb_arch_update_addr(linux_regs, remcom_in_buffer); 218 atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id()); 219 kgdb_single_step = 1; 220 221 /* 222 * Enable single step handling 223 */ 224 if (!kernel_active_single_step()) 225 kernel_enable_single_step(linux_regs); 226 err = 0; 227 break; 228 default: 229 err = -1; 230 } 231 return err; 232 } 233 234 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr) 235 { 236 kgdb_handle_exception(1, SIGTRAP, 0, regs); 237 return DBG_HOOK_HANDLED; 238 } 239 NOKPROBE_SYMBOL(kgdb_brk_fn) 240 241 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr) 242 { 243 compiled_break = 1; 244 kgdb_handle_exception(1, SIGTRAP, 0, regs); 245 246 return DBG_HOOK_HANDLED; 247 } 248 NOKPROBE_SYMBOL(kgdb_compiled_brk_fn); 249 250 static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) 251 { 252 if (!kgdb_single_step) 253 return DBG_HOOK_ERROR; 254 255 kgdb_handle_exception(0, SIGTRAP, 0, regs); 256 return DBG_HOOK_HANDLED; 257 } 258 NOKPROBE_SYMBOL(kgdb_step_brk_fn); 259 260 static struct break_hook kgdb_brkpt_hook = { 261 .fn = kgdb_brk_fn, 262 .imm = KGDB_DYN_DBG_BRK_IMM, 263 }; 264 265 static struct break_hook kgdb_compiled_brkpt_hook = { 266 .fn = kgdb_compiled_brk_fn, 267 .imm = KGDB_COMPILED_DBG_BRK_IMM, 268 }; 269 270 static struct step_hook kgdb_step_hook = { 271 .fn = kgdb_step_brk_fn 272 }; 273 274 static int __kgdb_notify(struct die_args *args, unsigned long cmd) 275 { 276 struct pt_regs *regs = args->regs; 277 278 if (kgdb_handle_exception(1, args->signr, cmd, regs)) 279 return NOTIFY_DONE; 280 return NOTIFY_STOP; 281 } 282 283 static int 284 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) 285 { 286 unsigned long flags; 287 int ret; 288 289 local_irq_save(flags); 290 ret = __kgdb_notify(ptr, cmd); 291 local_irq_restore(flags); 292 293 return ret; 294 } 295 296 static struct notifier_block kgdb_notifier = { 297 .notifier_call = kgdb_notify, 298 /* 299 * Want to be lowest priority 300 */ 301 .priority = -INT_MAX, 302 }; 303 304 /* 305 * kgdb_arch_init - Perform any architecture specific initialization. 306 * This function will handle the initialization of any architecture 307 * specific callbacks. 308 */ 309 int kgdb_arch_init(void) 310 { 311 int ret = register_die_notifier(&kgdb_notifier); 312 313 if (ret != 0) 314 return ret; 315 316 register_kernel_break_hook(&kgdb_brkpt_hook); 317 register_kernel_break_hook(&kgdb_compiled_brkpt_hook); 318 register_kernel_step_hook(&kgdb_step_hook); 319 return 0; 320 } 321 322 /* 323 * kgdb_arch_exit - Perform any architecture specific uninitalization. 324 * This function will handle the uninitalization of any architecture 325 * specific callbacks, for dynamic registration and unregistration. 326 */ 327 void kgdb_arch_exit(void) 328 { 329 unregister_kernel_break_hook(&kgdb_brkpt_hook); 330 unregister_kernel_break_hook(&kgdb_compiled_brkpt_hook); 331 unregister_kernel_step_hook(&kgdb_step_hook); 332 unregister_die_notifier(&kgdb_notifier); 333 } 334 335 const struct kgdb_arch arch_kgdb_ops; 336 337 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 338 { 339 int err; 340 341 BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE); 342 343 err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr); 344 if (err) 345 return err; 346 347 return aarch64_insn_write((void *)bpt->bpt_addr, 348 (u32)AARCH64_BREAK_KGDB_DYN_DBG); 349 } 350 351 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 352 { 353 return aarch64_insn_write((void *)bpt->bpt_addr, 354 *(u32 *)bpt->saved_instr); 355 } 356