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 <asm/debug-monitors.h> 28 #include <asm/insn.h> 29 #include <asm/traps.h> 30 31 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = { 32 { "x0", 8, offsetof(struct pt_regs, regs[0])}, 33 { "x1", 8, offsetof(struct pt_regs, regs[1])}, 34 { "x2", 8, offsetof(struct pt_regs, regs[2])}, 35 { "x3", 8, offsetof(struct pt_regs, regs[3])}, 36 { "x4", 8, offsetof(struct pt_regs, regs[4])}, 37 { "x5", 8, offsetof(struct pt_regs, regs[5])}, 38 { "x6", 8, offsetof(struct pt_regs, regs[6])}, 39 { "x7", 8, offsetof(struct pt_regs, regs[7])}, 40 { "x8", 8, offsetof(struct pt_regs, regs[8])}, 41 { "x9", 8, offsetof(struct pt_regs, regs[9])}, 42 { "x10", 8, offsetof(struct pt_regs, regs[10])}, 43 { "x11", 8, offsetof(struct pt_regs, regs[11])}, 44 { "x12", 8, offsetof(struct pt_regs, regs[12])}, 45 { "x13", 8, offsetof(struct pt_regs, regs[13])}, 46 { "x14", 8, offsetof(struct pt_regs, regs[14])}, 47 { "x15", 8, offsetof(struct pt_regs, regs[15])}, 48 { "x16", 8, offsetof(struct pt_regs, regs[16])}, 49 { "x17", 8, offsetof(struct pt_regs, regs[17])}, 50 { "x18", 8, offsetof(struct pt_regs, regs[18])}, 51 { "x19", 8, offsetof(struct pt_regs, regs[19])}, 52 { "x20", 8, offsetof(struct pt_regs, regs[20])}, 53 { "x21", 8, offsetof(struct pt_regs, regs[21])}, 54 { "x22", 8, offsetof(struct pt_regs, regs[22])}, 55 { "x23", 8, offsetof(struct pt_regs, regs[23])}, 56 { "x24", 8, offsetof(struct pt_regs, regs[24])}, 57 { "x25", 8, offsetof(struct pt_regs, regs[25])}, 58 { "x26", 8, offsetof(struct pt_regs, regs[26])}, 59 { "x27", 8, offsetof(struct pt_regs, regs[27])}, 60 { "x28", 8, offsetof(struct pt_regs, regs[28])}, 61 { "x29", 8, offsetof(struct pt_regs, regs[29])}, 62 { "x30", 8, offsetof(struct pt_regs, regs[30])}, 63 { "sp", 8, offsetof(struct pt_regs, sp)}, 64 { "pc", 8, offsetof(struct pt_regs, pc)}, 65 /* 66 * struct pt_regs thinks PSTATE is 64-bits wide but gdb remote 67 * protocol disagrees. Therefore we must extract only the lower 68 * 32-bits. Look for the big comment in asm/kgdb.h for more 69 * detail. 70 */ 71 { "pstate", 4, offsetof(struct pt_regs, pstate) 72 #ifdef CONFIG_CPU_BIG_ENDIAN 73 + 4 74 #endif 75 }, 76 { "v0", 16, -1 }, 77 { "v1", 16, -1 }, 78 { "v2", 16, -1 }, 79 { "v3", 16, -1 }, 80 { "v4", 16, -1 }, 81 { "v5", 16, -1 }, 82 { "v6", 16, -1 }, 83 { "v7", 16, -1 }, 84 { "v8", 16, -1 }, 85 { "v9", 16, -1 }, 86 { "v10", 16, -1 }, 87 { "v11", 16, -1 }, 88 { "v12", 16, -1 }, 89 { "v13", 16, -1 }, 90 { "v14", 16, -1 }, 91 { "v15", 16, -1 }, 92 { "v16", 16, -1 }, 93 { "v17", 16, -1 }, 94 { "v18", 16, -1 }, 95 { "v19", 16, -1 }, 96 { "v20", 16, -1 }, 97 { "v21", 16, -1 }, 98 { "v22", 16, -1 }, 99 { "v23", 16, -1 }, 100 { "v24", 16, -1 }, 101 { "v25", 16, -1 }, 102 { "v26", 16, -1 }, 103 { "v27", 16, -1 }, 104 { "v28", 16, -1 }, 105 { "v29", 16, -1 }, 106 { "v30", 16, -1 }, 107 { "v31", 16, -1 }, 108 { "fpsr", 4, -1 }, 109 { "fpcr", 4, -1 }, 110 }; 111 112 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) 113 { 114 if (regno >= DBG_MAX_REG_NUM || regno < 0) 115 return NULL; 116 117 if (dbg_reg_def[regno].offset != -1) 118 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, 119 dbg_reg_def[regno].size); 120 else 121 memset(mem, 0, dbg_reg_def[regno].size); 122 return dbg_reg_def[regno].name; 123 } 124 125 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) 126 { 127 if (regno >= DBG_MAX_REG_NUM || regno < 0) 128 return -EINVAL; 129 130 if (dbg_reg_def[regno].offset != -1) 131 memcpy((void *)regs + dbg_reg_def[regno].offset, mem, 132 dbg_reg_def[regno].size); 133 return 0; 134 } 135 136 void 137 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task) 138 { 139 struct pt_regs *thread_regs; 140 141 /* Initialize to zero */ 142 memset((char *)gdb_regs, 0, NUMREGBYTES); 143 thread_regs = task_pt_regs(task); 144 memcpy((void *)gdb_regs, (void *)thread_regs->regs, GP_REG_BYTES); 145 /* Special case for PSTATE (check comments in asm/kgdb.h for details) */ 146 dbg_get_reg(33, gdb_regs + GP_REG_BYTES, thread_regs); 147 } 148 149 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) 150 { 151 regs->pc = pc; 152 } 153 154 static int compiled_break; 155 156 static void kgdb_arch_update_addr(struct pt_regs *regs, 157 char *remcom_in_buffer) 158 { 159 unsigned long addr; 160 char *ptr; 161 162 ptr = &remcom_in_buffer[1]; 163 if (kgdb_hex2long(&ptr, &addr)) 164 kgdb_arch_set_pc(regs, addr); 165 else if (compiled_break == 1) 166 kgdb_arch_set_pc(regs, regs->pc + 4); 167 168 compiled_break = 0; 169 } 170 171 int kgdb_arch_handle_exception(int exception_vector, int signo, 172 int err_code, char *remcom_in_buffer, 173 char *remcom_out_buffer, 174 struct pt_regs *linux_regs) 175 { 176 int err; 177 178 switch (remcom_in_buffer[0]) { 179 case 'D': 180 case 'k': 181 /* 182 * Packet D (Detach), k (kill). No special handling 183 * is required here. Handle same as c packet. 184 */ 185 case 'c': 186 /* 187 * Packet c (Continue) to continue executing. 188 * Set pc to required address. 189 * Try to read optional parameter and set pc. 190 * If this was a compiled breakpoint, we need to move 191 * to the next instruction else we will just breakpoint 192 * over and over again. 193 */ 194 kgdb_arch_update_addr(linux_regs, remcom_in_buffer); 195 atomic_set(&kgdb_cpu_doing_single_step, -1); 196 kgdb_single_step = 0; 197 198 /* 199 * Received continue command, disable single step 200 */ 201 if (kernel_active_single_step()) 202 kernel_disable_single_step(); 203 204 err = 0; 205 break; 206 case 's': 207 /* 208 * Update step address value with address passed 209 * with step packet. 210 * On debug exception return PC is copied to ELR 211 * So just update PC. 212 * If no step address is passed, resume from the address 213 * pointed by PC. Do not update PC 214 */ 215 kgdb_arch_update_addr(linux_regs, remcom_in_buffer); 216 atomic_set(&kgdb_cpu_doing_single_step, raw_smp_processor_id()); 217 kgdb_single_step = 1; 218 219 /* 220 * Enable single step handling 221 */ 222 if (!kernel_active_single_step()) 223 kernel_enable_single_step(linux_regs); 224 err = 0; 225 break; 226 default: 227 err = -1; 228 } 229 return err; 230 } 231 232 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int esr) 233 { 234 kgdb_handle_exception(1, SIGTRAP, 0, regs); 235 return 0; 236 } 237 NOKPROBE_SYMBOL(kgdb_brk_fn) 238 239 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int esr) 240 { 241 compiled_break = 1; 242 kgdb_handle_exception(1, SIGTRAP, 0, regs); 243 244 return 0; 245 } 246 NOKPROBE_SYMBOL(kgdb_compiled_brk_fn); 247 248 static int kgdb_step_brk_fn(struct pt_regs *regs, unsigned int esr) 249 { 250 if (!kgdb_single_step) 251 return DBG_HOOK_ERROR; 252 253 kgdb_handle_exception(1, SIGTRAP, 0, regs); 254 return 0; 255 } 256 NOKPROBE_SYMBOL(kgdb_step_brk_fn); 257 258 static struct break_hook kgdb_brkpt_hook = { 259 .esr_mask = 0xffffffff, 260 .esr_val = (u32)ESR_ELx_VAL_BRK64(KGDB_DYN_DBG_BRK_IMM), 261 .fn = kgdb_brk_fn 262 }; 263 264 static struct break_hook kgdb_compiled_brkpt_hook = { 265 .esr_mask = 0xffffffff, 266 .esr_val = (u32)ESR_ELx_VAL_BRK64(KGDB_COMPILED_DBG_BRK_IMM), 267 .fn = kgdb_compiled_brk_fn 268 }; 269 270 static struct step_hook kgdb_step_hook = { 271 .fn = kgdb_step_brk_fn 272 }; 273 274 static void kgdb_call_nmi_hook(void *ignored) 275 { 276 kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs()); 277 } 278 279 void kgdb_roundup_cpus(unsigned long flags) 280 { 281 local_irq_enable(); 282 smp_call_function(kgdb_call_nmi_hook, NULL, 0); 283 local_irq_disable(); 284 } 285 286 static int __kgdb_notify(struct die_args *args, unsigned long cmd) 287 { 288 struct pt_regs *regs = args->regs; 289 290 if (kgdb_handle_exception(1, args->signr, cmd, regs)) 291 return NOTIFY_DONE; 292 return NOTIFY_STOP; 293 } 294 295 static int 296 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) 297 { 298 unsigned long flags; 299 int ret; 300 301 local_irq_save(flags); 302 ret = __kgdb_notify(ptr, cmd); 303 local_irq_restore(flags); 304 305 return ret; 306 } 307 308 static struct notifier_block kgdb_notifier = { 309 .notifier_call = kgdb_notify, 310 /* 311 * Want to be lowest priority 312 */ 313 .priority = -INT_MAX, 314 }; 315 316 /* 317 * kgdb_arch_init - Perform any architecture specific initialization. 318 * This function will handle the initialization of any architecture 319 * specific callbacks. 320 */ 321 int kgdb_arch_init(void) 322 { 323 int ret = register_die_notifier(&kgdb_notifier); 324 325 if (ret != 0) 326 return ret; 327 328 register_break_hook(&kgdb_brkpt_hook); 329 register_break_hook(&kgdb_compiled_brkpt_hook); 330 register_step_hook(&kgdb_step_hook); 331 return 0; 332 } 333 334 /* 335 * kgdb_arch_exit - Perform any architecture specific uninitalization. 336 * This function will handle the uninitalization of any architecture 337 * specific callbacks, for dynamic registration and unregistration. 338 */ 339 void kgdb_arch_exit(void) 340 { 341 unregister_break_hook(&kgdb_brkpt_hook); 342 unregister_break_hook(&kgdb_compiled_brkpt_hook); 343 unregister_step_hook(&kgdb_step_hook); 344 unregister_die_notifier(&kgdb_notifier); 345 } 346 347 struct kgdb_arch arch_kgdb_ops; 348 349 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 350 { 351 int err; 352 353 BUILD_BUG_ON(AARCH64_INSN_SIZE != BREAK_INSTR_SIZE); 354 355 err = aarch64_insn_read((void *)bpt->bpt_addr, (u32 *)bpt->saved_instr); 356 if (err) 357 return err; 358 359 return aarch64_insn_write((void *)bpt->bpt_addr, 360 (u32)AARCH64_BREAK_KGDB_DYN_DBG); 361 } 362 363 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 364 { 365 return aarch64_insn_write((void *)bpt->bpt_addr, 366 *(u32 *)bpt->saved_instr); 367 } 368