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