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 pt_regs *thread_regs; 142 143 /* Initialize to zero */ 144 memset((char *)gdb_regs, 0, NUMREGBYTES); 145 thread_regs = task_pt_regs(task); 146 memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES); 147 /* Special case for PSTATE (check comments in asm/kgdb.h for details) */ 148 dbg_get_reg(33, gdb_regs + GP_REG_BYTES, thread_regs); 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 0; 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 0; 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(1, SIGTRAP, 0, regs); 256 return 0; 257 } 258 NOKPROBE_SYMBOL(kgdb_step_brk_fn); 259 260 static struct break_hook kgdb_brkpt_hook = { 261 .esr_mask = 0xffffffff, 262 .esr_val = (u32)ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM), 263 .fn = kgdb_brk_fn 264 }; 265 266 static struct break_hook kgdb_compiled_brkpt_hook = { 267 .esr_mask = 0xffffffff, 268 .esr_val = (u32)ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM), 269 .fn = kgdb_compiled_brk_fn 270 }; 271 272 static struct step_hook kgdb_step_hook = { 273 .fn = kgdb_step_brk_fn 274 }; 275 276 static void kgdb_call_nmi_hook(void *ignored) 277 { 278 kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); 279 } 280 281 void kgdb_roundup_cpus(unsigned long flags) 282 { 283 local_irq_enable(); 284 smp_call_function(kgdb_call_nmi_hook, NULL, 0); 285 local_irq_disable(); 286 } 287 288 static int __kgdb_notify(struct die_args *args, unsigned long cmd) 289 { 290 struct pt_regs *regs = args->regs; 291 292 if (kgdb_handle_exception(1, args->signr, cmd, regs)) 293 return NOTIFY_DONE; 294 return NOTIFY_STOP; 295 } 296 297 static int 298 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) 299 { 300 unsigned long flags; 301 int ret; 302 303 local_irq_save(flags); 304 ret = __kgdb_notify(ptr, cmd); 305 local_irq_restore(flags); 306 307 return ret; 308 } 309 310 static struct notifier_block kgdb_notifier = { 311 .notifier_call = kgdb_notify, 312 /* 313 * Want to be lowest priority 314 */ 315 .priority = -INT_MAX, 316 }; 317 318 /* 319 * kgdb_arch_init - Perform any architecture specific initialization. 320 * This function will handle the initialization of any architecture 321 * specific callbacks. 322 */ 323 int kgdb_arch_init(void) 324 { 325 int ret = register_die_notifier(&kgdb_notifier); 326 327 if (ret != 0) 328 return ret; 329 330 register_break_hook(&kgdb_brkpt_hook); 331 register_break_hook(&kgdb_compiled_brkpt_hook); 332 register_step_hook(&kgdb_step_hook); 333 return 0; 334 } 335 336 /* 337 * kgdb_arch_exit - Perform any architecture specific uninitalization. 338 * This function will handle the uninitalization of any architecture 339 * specific callbacks, for dynamic registration and unregistration. 340 */ 341 void kgdb_arch_exit(void) 342 { 343 unregister_break_hook(&kgdb_brkpt_hook); 344 unregister_break_hook(&kgdb_compiled_brkpt_hook); 345 unregister_step_hook(&kgdb_step_hook); 346 unregister_die_notifier(&kgdb_notifier); 347 } 348 349 struct kgdb_arch arch_kgdb_ops; 350 351 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 352 { 353 int err; 354 355 BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE); 356 357 err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr); 358 if (err) 359 return err; 360 361 return aarch64_insn_write((void *)bpt->bpt_addr, 362 (u32)AARCH64_BREAK_KGDB_DYN_DBG); 363 } 364 365 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 366 { 367 return aarch64_insn_write((void *)bpt->bpt_addr, 368 *(u32 *)bpt->saved_instr); 369 } 370