1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * arch/arm/kernel/kgdb.c 4 * 5 * ARM KGDB support 6 * 7 * Copyright (c) 2002-2004 MontaVista Software, Inc 8 * Copyright (c) 2008 Wind River Systems, Inc. 9 * 10 * Authors: George Davis <davis_g@mvista.com> 11 * Deepak Saxena <dsaxena@plexity.net> 12 */ 13 #include <linux/irq.h> 14 #include <linux/kdebug.h> 15 #include <linux/kgdb.h> 16 #include <linux/uaccess.h> 17 18 #include <asm/patch.h> 19 #include <asm/traps.h> 20 21 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] = 22 { 23 { "r0", 4, offsetof(struct pt_regs, ARM_r0)}, 24 { "r1", 4, offsetof(struct pt_regs, ARM_r1)}, 25 { "r2", 4, offsetof(struct pt_regs, ARM_r2)}, 26 { "r3", 4, offsetof(struct pt_regs, ARM_r3)}, 27 { "r4", 4, offsetof(struct pt_regs, ARM_r4)}, 28 { "r5", 4, offsetof(struct pt_regs, ARM_r5)}, 29 { "r6", 4, offsetof(struct pt_regs, ARM_r6)}, 30 { "r7", 4, offsetof(struct pt_regs, ARM_r7)}, 31 { "r8", 4, offsetof(struct pt_regs, ARM_r8)}, 32 { "r9", 4, offsetof(struct pt_regs, ARM_r9)}, 33 { "r10", 4, offsetof(struct pt_regs, ARM_r10)}, 34 { "fp", 4, offsetof(struct pt_regs, ARM_fp)}, 35 { "ip", 4, offsetof(struct pt_regs, ARM_ip)}, 36 { "sp", 4, offsetof(struct pt_regs, ARM_sp)}, 37 { "lr", 4, offsetof(struct pt_regs, ARM_lr)}, 38 { "pc", 4, offsetof(struct pt_regs, ARM_pc)}, 39 { "f0", 12, -1 }, 40 { "f1", 12, -1 }, 41 { "f2", 12, -1 }, 42 { "f3", 12, -1 }, 43 { "f4", 12, -1 }, 44 { "f5", 12, -1 }, 45 { "f6", 12, -1 }, 46 { "f7", 12, -1 }, 47 { "fps", 4, -1 }, 48 { "cpsr", 4, offsetof(struct pt_regs, ARM_cpsr)}, 49 }; 50 51 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs) 52 { 53 if (regno >= DBG_MAX_REG_NUM || regno < 0) 54 return NULL; 55 56 if (dbg_reg_def[regno].offset != -1) 57 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset, 58 dbg_reg_def[regno].size); 59 else 60 memset(mem, 0, dbg_reg_def[regno].size); 61 return dbg_reg_def[regno].name; 62 } 63 64 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs) 65 { 66 if (regno >= DBG_MAX_REG_NUM || regno < 0) 67 return -EINVAL; 68 69 if (dbg_reg_def[regno].offset != -1) 70 memcpy((void *)regs + dbg_reg_def[regno].offset, mem, 71 dbg_reg_def[regno].size); 72 return 0; 73 } 74 75 void 76 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task) 77 { 78 struct thread_info *ti; 79 int regno; 80 81 /* Just making sure... */ 82 if (task == NULL) 83 return; 84 85 /* Initialize to zero */ 86 for (regno = 0; regno < GDB_MAX_REGS; regno++) 87 gdb_regs[regno] = 0; 88 89 /* Otherwise, we have only some registers from switch_to() */ 90 ti = task_thread_info(task); 91 gdb_regs[_R4] = ti->cpu_context.r4; 92 gdb_regs[_R5] = ti->cpu_context.r5; 93 gdb_regs[_R6] = ti->cpu_context.r6; 94 gdb_regs[_R7] = ti->cpu_context.r7; 95 gdb_regs[_R8] = ti->cpu_context.r8; 96 gdb_regs[_R9] = ti->cpu_context.r9; 97 gdb_regs[_R10] = ti->cpu_context.sl; 98 gdb_regs[_FP] = ti->cpu_context.fp; 99 gdb_regs[_SPT] = ti->cpu_context.sp; 100 gdb_regs[_PC] = ti->cpu_context.pc; 101 } 102 103 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc) 104 { 105 regs->ARM_pc = pc; 106 } 107 108 static int compiled_break; 109 110 int kgdb_arch_handle_exception(int exception_vector, int signo, 111 int err_code, char *remcom_in_buffer, 112 char *remcom_out_buffer, 113 struct pt_regs *linux_regs) 114 { 115 unsigned long addr; 116 char *ptr; 117 118 switch (remcom_in_buffer[0]) { 119 case 'D': 120 case 'k': 121 case 'c': 122 /* 123 * Try to read optional parameter, pc unchanged if no parm. 124 * If this was a compiled breakpoint, we need to move 125 * to the next instruction or we will just breakpoint 126 * over and over again. 127 */ 128 ptr = &remcom_in_buffer[1]; 129 if (kgdb_hex2long(&ptr, &addr)) 130 linux_regs->ARM_pc = addr; 131 else if (compiled_break == 1) 132 linux_regs->ARM_pc += 4; 133 134 compiled_break = 0; 135 136 return 0; 137 } 138 139 return -1; 140 } 141 142 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr) 143 { 144 kgdb_handle_exception(1, SIGTRAP, 0, regs); 145 146 return 0; 147 } 148 149 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr) 150 { 151 compiled_break = 1; 152 kgdb_handle_exception(1, SIGTRAP, 0, regs); 153 154 return 0; 155 } 156 157 static struct undef_hook kgdb_brkpt_arm_hook = { 158 .instr_mask = 0xffffffff, 159 .instr_val = KGDB_BREAKINST, 160 .cpsr_mask = PSR_T_BIT | MODE_MASK, 161 .cpsr_val = SVC_MODE, 162 .fn = kgdb_brk_fn 163 }; 164 165 static struct undef_hook kgdb_brkpt_thumb_hook = { 166 .instr_mask = 0xffff, 167 .instr_val = KGDB_BREAKINST & 0xffff, 168 .cpsr_mask = PSR_T_BIT | MODE_MASK, 169 .cpsr_val = PSR_T_BIT | SVC_MODE, 170 .fn = kgdb_brk_fn 171 }; 172 173 static struct undef_hook kgdb_compiled_brkpt_arm_hook = { 174 .instr_mask = 0xffffffff, 175 .instr_val = KGDB_COMPILED_BREAK, 176 .cpsr_mask = PSR_T_BIT | MODE_MASK, 177 .cpsr_val = SVC_MODE, 178 .fn = kgdb_compiled_brk_fn 179 }; 180 181 static struct undef_hook kgdb_compiled_brkpt_thumb_hook = { 182 .instr_mask = 0xffff, 183 .instr_val = KGDB_COMPILED_BREAK & 0xffff, 184 .cpsr_mask = PSR_T_BIT | MODE_MASK, 185 .cpsr_val = PSR_T_BIT | SVC_MODE, 186 .fn = kgdb_compiled_brk_fn 187 }; 188 189 static int __kgdb_notify(struct die_args *args, unsigned long cmd) 190 { 191 struct pt_regs *regs = args->regs; 192 193 if (kgdb_handle_exception(1, args->signr, cmd, regs)) 194 return NOTIFY_DONE; 195 return NOTIFY_STOP; 196 } 197 static int 198 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr) 199 { 200 unsigned long flags; 201 int ret; 202 203 local_irq_save(flags); 204 ret = __kgdb_notify(ptr, cmd); 205 local_irq_restore(flags); 206 207 return ret; 208 } 209 210 static struct notifier_block kgdb_notifier = { 211 .notifier_call = kgdb_notify, 212 .priority = -INT_MAX, 213 }; 214 215 216 /** 217 * kgdb_arch_init - Perform any architecture specific initalization. 218 * 219 * This function will handle the initalization of any architecture 220 * specific callbacks. 221 */ 222 int kgdb_arch_init(void) 223 { 224 int ret = register_die_notifier(&kgdb_notifier); 225 226 if (ret != 0) 227 return ret; 228 229 register_undef_hook(&kgdb_brkpt_arm_hook); 230 register_undef_hook(&kgdb_brkpt_thumb_hook); 231 register_undef_hook(&kgdb_compiled_brkpt_arm_hook); 232 register_undef_hook(&kgdb_compiled_brkpt_thumb_hook); 233 234 return 0; 235 } 236 237 /** 238 * kgdb_arch_exit - Perform any architecture specific uninitalization. 239 * 240 * This function will handle the uninitalization of any architecture 241 * specific callbacks, for dynamic registration and unregistration. 242 */ 243 void kgdb_arch_exit(void) 244 { 245 unregister_undef_hook(&kgdb_brkpt_arm_hook); 246 unregister_undef_hook(&kgdb_brkpt_thumb_hook); 247 unregister_undef_hook(&kgdb_compiled_brkpt_arm_hook); 248 unregister_undef_hook(&kgdb_compiled_brkpt_thumb_hook); 249 unregister_die_notifier(&kgdb_notifier); 250 } 251 252 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt) 253 { 254 int err; 255 256 /* patch_text() only supports int-sized breakpoints */ 257 BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE); 258 259 err = copy_from_kernel_nofault(bpt->saved_instr, (char *)bpt->bpt_addr, 260 BREAK_INSTR_SIZE); 261 if (err) 262 return err; 263 264 /* Machine is already stopped, so we can use __patch_text() directly */ 265 __patch_text((void *)bpt->bpt_addr, 266 *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr); 267 268 return err; 269 } 270 271 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt) 272 { 273 /* Machine is already stopped, so we can use __patch_text() directly */ 274 __patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr); 275 276 return 0; 277 } 278 279 /* 280 * Register our undef instruction hooks with ARM undef core. 281 * We register a hook specifically looking for the KGB break inst 282 * and we handle the normal undef case within the do_undefinstr 283 * handler. 284 */ 285 const struct kgdb_arch arch_kgdb_ops = { 286 #ifndef __ARMEB__ 287 .gdb_bpt_instr = {0xfe, 0xde, 0xff, 0xe7} 288 #else /* ! __ARMEB__ */ 289 .gdb_bpt_instr = {0xe7, 0xff, 0xde, 0xfe} 290 #endif 291 }; 292