arch/arm/kernel/kgdb.c

   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_hook = {
 158         .instr_mask             = 0xffffffff,
 159         .instr_val              = KGDB_BREAKINST,
 160         .cpsr_mask              = MODE_MASK,
 161         .cpsr_val               = SVC_MODE,
 162         .fn                     = kgdb_brk_fn
 163 };
 164
 165 static struct undef_hook kgdb_compiled_brkpt_hook = {
 166         .instr_mask             = 0xffffffff,
 167         .instr_val              = KGDB_COMPILED_BREAK,
 168         .cpsr_mask              = MODE_MASK,
 169         .cpsr_val               = SVC_MODE,
 170         .fn                     = kgdb_compiled_brk_fn
 171 };
 172
 173 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 174 {
 175         struct pt_regs *regs = args->regs;
 176
 177         if (kgdb_handle_exception(1, args->signr, cmd, regs))
 178                 return NOTIFY_DONE;
 179         return NOTIFY_STOP;
 180 }
 181 static int
 182 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 183 {
 184         unsigned long flags;
 185         int ret;
 186
 187         local_irq_save(flags);
 188         ret = __kgdb_notify(ptr, cmd);
 189         local_irq_restore(flags);
 190
 191         return ret;
 192 }
 193
 194 static struct notifier_block kgdb_notifier = {
 195         .notifier_call  = kgdb_notify,
 196         .priority       = -INT_MAX,
 197 };
 198
 199
 200 /**
 201  *      kgdb_arch_init - Perform any architecture specific initalization.
 202  *
 203  *      This function will handle the initalization of any architecture
 204  *      specific callbacks.
 205  */
 206 int kgdb_arch_init(void)
 207 {
 208         int ret = register_die_notifier(&kgdb_notifier);
 209
 210         if (ret != 0)
 211                 return ret;
 212
 213         register_undef_hook(&kgdb_brkpt_hook);
 214         register_undef_hook(&kgdb_compiled_brkpt_hook);
 215
 216         return 0;
 217 }
 218
 219 /**
 220  *      kgdb_arch_exit - Perform any architecture specific uninitalization.
 221  *
 222  *      This function will handle the uninitalization of any architecture
 223  *      specific callbacks, for dynamic registration and unregistration.
 224  */
 225 void kgdb_arch_exit(void)
 226 {
 227         unregister_undef_hook(&kgdb_brkpt_hook);
 228         unregister_undef_hook(&kgdb_compiled_brkpt_hook);
 229         unregister_die_notifier(&kgdb_notifier);
 230 }
 231
 232 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 233 {
 234         int err;
 235
 236         /* patch_text() only supports int-sized breakpoints */
 237         BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);
 238
 239         err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
 240                                 BREAK_INSTR_SIZE);
 241         if (err)
 242                 return err;
 243
 244         /* Machine is already stopped, so we can use __patch_text() directly */
 245         __patch_text((void *)bpt->bpt_addr,
 246                      *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
 247
 248         return err;
 249 }
 250
 251 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 252 {
 253         /* Machine is already stopped, so we can use __patch_text() directly */
 254         __patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
 255
 256         return 0;
 257 }
 258
 259 /*
 260  * Register our undef instruction hooks with ARM undef core.
 261  * We register a hook specifically looking for the KGB break inst
 262  * and we handle the normal undef case within the do_undefinstr
 263  * handler.
 264  */
 265 const struct kgdb_arch arch_kgdb_ops = {
 266 #ifndef __ARMEB__
 267         .gdb_bpt_instr          = {0xfe, 0xde, 0xff, 0xe7}
 268 #else /* ! __ARMEB__ */
 269         .gdb_bpt_instr          = {0xe7, 0xff, 0xde, 0xfe}
 270 #endif
 271 };