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/patching.h> 21 #include <asm/traps.h> 22 23 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { 24 { "x0", 8, offsetof(struct pt_regs, regs[0])}, 25 { "x1", 8, offsetof(struct pt_regs, regs[1])}, 26 { "x2", 8, offsetof(struct pt_regs, regs[2])}, 27 { "x3", 8, offsetof(struct pt_regs, regs[3])}, 28 { "x4", 8, offsetof(struct pt_regs, regs[4])}, 29 { "x5", 8, offsetof(struct pt_regs, regs[5])}, 30 { "x6", 8, offsetof(struct pt_regs, regs[6])}, 31 { "x7", 8, offsetof(struct pt_regs, regs[7])}, 32 { "x8", 8, offsetof(struct pt_regs, regs[8])}, 33 { "x9", 8, offsetof(struct pt_regs, regs[9])}, 34 { "x10", 8, offsetof(struct pt_regs, regs[10])}, 35 { "x11", 8, offsetof(struct pt_regs, regs[11])}, 36 { "x12", 8, offsetof(struct pt_regs, regs[12])}, 37 { "x13", 8, offsetof(struct pt_regs, regs[13])}, 38 { "x14", 8, offsetof(struct pt_regs, regs[14])}, 39 { "x15", 8, offsetof(struct pt_regs, regs[15])}, 40 { "x16", 8, offsetof(struct pt_regs, regs[16])}, 41 { "x17", 8, offsetof(struct pt_regs, regs[17])}, 42 { "x18", 8, offsetof(struct pt_regs, regs[18])}, 43 { "x19", 8, offsetof(struct pt_regs, regs[19])}, 44 { "x20", 8, offsetof(struct pt_regs, regs[20])}, 45 { "x21", 8, offsetof(struct pt_regs, regs[21])}, 46 { "x22", 8, offsetof(struct pt_regs, regs[22])}, 47 { "x23", 8, offsetof(struct pt_regs, regs[23])}, 48 { "x24", 8, offsetof(struct pt_regs, regs[24])}, 49 { "x25", 8, offsetof(struct pt_regs, regs[25])}, 50 { "x26", 8, offsetof(struct pt_regs, regs[26])}, 51 { "x27", 8, offsetof(struct pt_regs, regs[27])}, 52 { "x28", 8, offsetof(struct pt_regs, regs[28])}, 53 { "x29", 8, offsetof(struct pt_regs, regs[29])}, 54 { "x30", 8, offsetof(struct pt_regs, regs[30])}, 55 { "sp", 8, offsetof(struct pt_regs, sp)}, 56 { "pc", 8, offsetof(struct pt_regs, pc)}, 57 /* 58 * struct pt_regs thinks PSTATE is 64-bits wide but gdb remote 59 * protocol disagrees. Therefore we must extract only the lower 60 * 32-bits. Look for the big comment in asm/kgdb.h for more 61 * detail. 62 */ 63 { "pstate", 4, offsetof(struct pt_regs, pstate) 64 #ifdef CONFIG_CPU_BIG_ENDIAN 65 + 4 66 #endif 67 }, 68 { "v0", 16, -1 }, 69 { "v1", 16, -1 }, 70 { "v2", 16, -1 }, 71 { "v3", 16, -1 }, 72 { "v4", 16, -1 }, 73 { "v5", 16, -1 }, 74 { "v6", 16, -1 }, 75 { "v7", 16, -1 }, 76 { "v8", 16, -1 }, 77 { "v9", 16, -1 }, 78 { "v10", 16, -1 }, 79 { "v11", 16, -1 }, 80 { "v12", 16, -1 }, 81 { "v13", 16, -1 }, 82 { "v14", 16, -1 }, 83 { "v15", 16, -1 }, 84 { "v16", 16, -1 }, 85 { "v17", 16, -1 }, 86 { "v18", 16, -1 }, 87 { "v19", 16, -1 }, 88 { "v20", 16, -1 }, 89 { "v21", 16, -1 }, 90 { "v22", 16, -1 }, 91 { "v23", 16, -1 }, 92 { "v24", 16, -1 }, 93 { "v25", 16, -1 }, 94 { "v26", 16, -1 }, 95 { "v27", 16, -1 }, 96 { "v28", 16, -1 }, 97 { "v29", 16, -1 }, 98 { "v30", 16, -1 }, 99 { "v31", 16, -1 }, 100 { "fpsr", 4, -1 }, 101 { "fpcr", 4, -1 }, 102 }; 103 104 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) 105 { 106 if (regno >= DBG_MAX_REG_NUM || regno < 0) 107 return NULL; 108 109 if (dbg_reg_def[regno].offset != -1) 110 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, 111 dbg_reg_def[regno].size); 112 else 113 memset(mem, 0, dbg_reg_def[regno].size); 114 return dbg_reg_def[regno].name; 115 } 116 117 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) 118 { 119 if (regno >= DBG_MAX_REG_NUM || regno < 0) 120 return -EINVAL; 121 122 if (dbg_reg_def[regno].offset != -1) 123 memcpy((void *)regs + dbg_reg_def[regno].offset, mem, 124 dbg_reg_def[regno].size); 125 return 0; 126 } 127 128 void 129 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task) 130 { 131 struct cpu_context *cpu_context = &task->thread.cpu_context; 132 133 /* Initialize to zero */ 134 memset((char *)gdb_regs, 0, NUMREGBYTES); 135 136 gdb_regs[19] = cpu_context->x19; 137 gdb_regs[20] = cpu_context->x20; 138 gdb_regs[21] = cpu_context->x21; 139 gdb_regs[22] = cpu_context->x22; 140 gdb_regs[23] = cpu_context->x23; 141 gdb_regs[24] = cpu_context->x24; 142 gdb_regs[25] = cpu_context->x25; 143 gdb_regs[26] = cpu_context->x26; 144 gdb_regs[27] = cpu_context->x27; 145 gdb_regs[28] = cpu_context->x28; 146 gdb_regs[29] = cpu_context->fp; 147 148 gdb_regs[31] = cpu_context->sp; 149 gdb_regs[32] = cpu_context->pc; 150 } 151 152 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) 153 { 154 regs->pc = pc; 155 } 156 157 static int compiled_break; 158 159 static void kgdb_arch_update_addr(struct pt_regs *regs, 160 char *remcom_in_buffer) 161 { 162 unsigned long addr; 163 char *ptr; 164 165 ptr = &remcom_in_buffer[1]; 166 if (kgdb_hex2long(&ptr, &addr)) 167 kgdb_arch_set_pc(regs, addr); 168 else if (compiled_break == 1) 169 kgdb_arch_set_pc(regs, regs->pc + 4); 170 171 compiled_break = 0; 172 } 173 174 int kgdb_arch_handle_exception(int exception_vector, int signo, 175 int err_code, char *remcom_in_buffer, 176 char *remcom_out_buffer, 177 struct pt_regs *linux_regs) 178 { 179 int err; 180 181 switch (remcom_in_buffer[0]) { 182 case 'D': 183 case 'k': 184 /* 185 * Packet D (Detach), k (kill). No special handling 186 * is required here. Handle same as c packet. 187 */ 188 case 'c': 189 /* 190 * Packet c (Continue) to continue executing. 191 * Set pc to required address. 192 * Try to read optional parameter and set pc. 193 * If this was a compiled breakpoint, we need to move 194 * to the next instruction else we will just breakpoint 195 * over and over again. 196 */ 197 kgdb_arch_update_addr(linux_regs, remcom_in_buffer); 198 atomic_set(&kgdb_cpu_doing_single_step, -1); 199 kgdb_single_step = 0; 200 201 /* 202 * Received continue command, disable single step 203 */ 204 if (kernel_active_single_step()) 205 kernel_disable_single_step(); 206 207 err = 0; 208 break; 209 case 's': 210 /* 211 * Update step address value with address passed 212 * with step packet. 213 * On debug exception return PC is copied to ELR 214 * So just update PC. 215 * If no step address is passed, resume from the address 216 * pointed by PC. Do not update PC 217 */ 218 kgdb_arch_update_addr(linux_regs, remcom_in_buffer); 219 atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id()); 220 kgdb_single_step = 1; 221 222 /* 223 * Enable single step handling 224 */ 225 if (!kernel_active_single_step()) 226 kernel_enable_single_step(linux_regs); 227 err = 0; 228 break; 229 default: 230 err = -1; 231 } 232 return err; 233 } 234 235 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr) 236 { 237 kgdb_handle_exception(1, SIGTRAP, 0, regs); 238 return DBG_HOOK_HANDLED; 239 } 240 NOKPROBE_SYMBOL(kgdb_brk_fn) 241 242 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr) 243 { 244 compiled_break = 1; 245 kgdb_handle_exception(1, SIGTRAP, 0, regs); 246 247 return DBG_HOOK_HANDLED; 248 } 249 NOKPROBE_SYMBOL(kgdb_compiled_brk_fn); 250 251 static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) 252 { 253 if (!kgdb_single_step) 254 return DBG_HOOK_ERROR; 255 256 kgdb_handle_exception(0, SIGTRAP, 0, regs); 257 return DBG_HOOK_HANDLED; 258 } 259 NOKPROBE_SYMBOL(kgdb_step_brk_fn); 260 261 static struct break_hook kgdb_brkpt_hook = { 262 .fn = kgdb_brk_fn, 263 .imm = KGDB_DYN_DBG_BRK_IMM, 264 }; 265 266 static struct break_hook kgdb_compiled_brkpt_hook = { 267 .fn = kgdb_compiled_brk_fn, 268 .imm = KGDB_COMPILED_DBG_BRK_IMM, 269 }; 270 271 static struct step_hook kgdb_step_hook = { 272 .fn = kgdb_step_brk_fn 273 }; 274 275 static int __kgdb_notify(struct die_args *args, unsigned long cmd) 276 { 277 struct pt_regs *regs = args->regs; 278 279 if (kgdb_handle_exception(1, args->signr, cmd, regs)) 280 return NOTIFY_DONE; 281 return NOTIFY_STOP; 282 } 283 284 static int 285 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) 286 { 287 unsigned long flags; 288 int ret; 289 290 local_irq_save(flags); 291 ret = __kgdb_notify(ptr, cmd); 292 local_irq_restore(flags); 293 294 return ret; 295 } 296 297 static struct notifier_block kgdb_notifier = { 298 .notifier_call = kgdb_notify, 299 /* 300 * Want to be lowest priority 301 */ 302 .priority = -INT_MAX, 303 }; 304 305 /* 306 * kgdb_arch_init - Perform any architecture specific initialization. 307 * This function will handle the initialization of any architecture 308 * specific callbacks. 309 */ 310 int kgdb_arch_init(void) 311 { 312 int ret = register_die_notifier(&kgdb_notifier); 313 314 if (ret != 0) 315 return ret; 316 317 register_kernel_break_hook(&kgdb_brkpt_hook); 318 register_kernel_break_hook(&kgdb_compiled_brkpt_hook); 319 register_kernel_step_hook(&kgdb_step_hook); 320 return 0; 321 } 322 323 /* 324 * kgdb_arch_exit - Perform any architecture specific uninitalization. 325 * This function will handle the uninitalization of any architecture 326 * specific callbacks, for dynamic registration and unregistration. 327 */ 328 void kgdb_arch_exit(void) 329 { 330 unregister_kernel_break_hook(&kgdb_brkpt_hook); 331 unregister_kernel_break_hook(&kgdb_compiled_brkpt_hook); 332 unregister_kernel_step_hook(&kgdb_step_hook); 333 unregister_die_notifier(&kgdb_notifier); 334 } 335 336 const struct kgdb_arch arch_kgdb_ops; 337 338 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 339 { 340 int err; 341 342 BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE); 343 344 err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr); 345 if (err) 346 return err; 347 348 return aarch64_insn_write((void *)bpt->bpt_addr, 349 (u32)AARCH64_BREAK_KGDB_DYN_DBG); 350 } 351 352 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 353 { 354 return aarch64_insn_write((void *)bpt->bpt_addr, 355 *(u32 *)bpt->saved_instr); 356 } 357