arch/arm/kernel/kgdb.c

   1 /*
   2  * arch/arm/kernel/kgdb.c
   3  *
   4  * ARM KGDB support
   5  *
   6  * Copyright (c) 2002-2004 MontaVista Software, Inc
   7  * Copyright (c) 2008 Wind River Systems, Inc.
   8  *
   9  * Authors:  George Davis <davis_g@mvista.com>
  10  *           Deepak Saxena <dsaxena@plexity.net>
  11  */
  12 #include <linux/irq.h>
  13 #include <linux/kdebug.h>
  14 #include <linux/kgdb.h>
  15 #include <linux/uaccess.h>
  16
  17 #include <asm/patch.h>
  18 #include <asm/traps.h>
  19
  20 struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
  21 {
  22         { "r0", 4, offsetof(struct pt_regs, ARM_r0)},
  23         { "r1", 4, offsetof(struct pt_regs, ARM_r1)},
  24         { "r2", 4, offsetof(struct pt_regs, ARM_r2)},
  25         { "r3", 4, offsetof(struct pt_regs, ARM_r3)},
  26         { "r4", 4, offsetof(struct pt_regs, ARM_r4)},
  27         { "r5", 4, offsetof(struct pt_regs, ARM_r5)},
  28         { "r6", 4, offsetof(struct pt_regs, ARM_r6)},
  29         { "r7", 4, offsetof(struct pt_regs, ARM_r7)},
  30         { "r8", 4, offsetof(struct pt_regs, ARM_r8)},
  31         { "r9", 4, offsetof(struct pt_regs, ARM_r9)},
  32         { "r10", 4, offsetof(struct pt_regs, ARM_r10)},
  33         { "fp", 4, offsetof(struct pt_regs, ARM_fp)},
  34         { "ip", 4, offsetof(struct pt_regs, ARM_ip)},
  35         { "sp", 4, offsetof(struct pt_regs, ARM_sp)},
  36         { "lr", 4, offsetof(struct pt_regs, ARM_lr)},
  37         { "pc", 4, offsetof(struct pt_regs, ARM_pc)},
  38         { "f0", 12, -1 },
  39         { "f1", 12, -1 },
  40         { "f2", 12, -1 },
  41         { "f3", 12, -1 },
  42         { "f4", 12, -1 },
  43         { "f5", 12, -1 },
  44         { "f6", 12, -1 },
  45         { "f7", 12, -1 },
  46         { "fps", 4, -1 },
  47         { "cpsr", 4, offsetof(struct pt_regs, ARM_cpsr)},
  48 };
  49
  50 char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
  51 {
  52         if (regno >= DBG_MAX_REG_NUM || regno < 0)
  53                 return NULL;
  54
  55         if (dbg_reg_def[regno].offset != -1)
  56                 memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
  57                        dbg_reg_def[regno].size);
  58         else
  59                 memset(mem, 0, dbg_reg_def[regno].size);
  60         return dbg_reg_def[regno].name;
  61 }
  62
  63 int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
  64 {
  65         if (regno >= DBG_MAX_REG_NUM || regno < 0)
  66                 return -EINVAL;
  67
  68         if (dbg_reg_def[regno].offset != -1)
  69                 memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
  70                        dbg_reg_def[regno].size);
  71         return 0;
  72 }
  73
  74 void
  75 sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
  76 {
  77         struct pt_regs *thread_regs;
  78         int regno;
  79
  80         /* Just making sure... */
  81         if (task == NULL)
  82                 return;
  83
  84         /* Initialize to zero */
  85         for (regno = 0; regno < GDB_MAX_REGS; regno++)
  86                 gdb_regs[regno] = 0;
  87
  88         /* Otherwise, we have only some registers from switch_to() */
  89         thread_regs             = task_pt_regs(task);
  90         gdb_regs[_R0]           = thread_regs->ARM_r0;
  91         gdb_regs[_R1]           = thread_regs->ARM_r1;
  92         gdb_regs[_R2]           = thread_regs->ARM_r2;
  93         gdb_regs[_R3]           = thread_regs->ARM_r3;
  94         gdb_regs[_R4]           = thread_regs->ARM_r4;
  95         gdb_regs[_R5]           = thread_regs->ARM_r5;
  96         gdb_regs[_R6]           = thread_regs->ARM_r6;
  97         gdb_regs[_R7]           = thread_regs->ARM_r7;
  98         gdb_regs[_R8]           = thread_regs->ARM_r8;
  99         gdb_regs[_R9]           = thread_regs->ARM_r9;
 100         gdb_regs[_R10]          = thread_regs->ARM_r10;
 101         gdb_regs[_FP]           = thread_regs->ARM_fp;
 102         gdb_regs[_IP]           = thread_regs->ARM_ip;
 103         gdb_regs[_SPT]          = thread_regs->ARM_sp;
 104         gdb_regs[_LR]           = thread_regs->ARM_lr;
 105         gdb_regs[_PC]           = thread_regs->ARM_pc;
 106         gdb_regs[_CPSR]         = thread_regs->ARM_cpsr;
 107 }
 108
 109 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 110 {
 111         regs->ARM_pc = pc;
 112 }
 113
 114 static int compiled_break;
 115
 116 int kgdb_arch_handle_exception(int exception_vector, int signo,
 117                                int err_code, char *remcom_in_buffer,
 118                                char *remcom_out_buffer,
 119                                struct pt_regs *linux_regs)
 120 {
 121         unsigned long addr;
 122         char *ptr;
 123
 124         switch (remcom_in_buffer[0]) {
 125         case 'D':
 126         case 'k':
 127         case 'c':
 128                 /*
 129                  * Try to read optional parameter, pc unchanged if no parm.
 130                  * If this was a compiled breakpoint, we need to move
 131                  * to the next instruction or we will just breakpoint
 132                  * over and over again.
 133                  */
 134                 ptr = &remcom_in_buffer[1];
 135                 if (kgdb_hex2long(&ptr, &addr))
 136                         linux_regs->ARM_pc = addr;
 137                 else if (compiled_break == 1)
 138                         linux_regs->ARM_pc += 4;
 139
 140                 compiled_break = 0;
 141
 142                 return 0;
 143         }
 144
 145         return -1;
 146 }
 147
 148 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
 149 {
 150         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 151
 152         return 0;
 153 }
 154
 155 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
 156 {
 157         compiled_break = 1;
 158         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 159
 160         return 0;
 161 }
 162
 163 static struct undef_hook kgdb_brkpt_hook = {
 164         .instr_mask             = 0xffffffff,
 165         .instr_val              = KGDB_BREAKINST,
 166         .cpsr_mask              = MODE_MASK,
 167         .cpsr_val               = SVC_MODE,
 168         .fn                     = kgdb_brk_fn
 169 };
 170
 171 static struct undef_hook kgdb_compiled_brkpt_hook = {
 172         .instr_mask             = 0xffffffff,
 173         .instr_val              = KGDB_COMPILED_BREAK,
 174         .cpsr_mask              = MODE_MASK,
 175         .cpsr_val               = SVC_MODE,
 176         .fn                     = kgdb_compiled_brk_fn
 177 };
 178
 179 static void kgdb_call_nmi_hook(void *ignored)
 180 {
 181        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 182 }
 183
 184 void kgdb_roundup_cpus(unsigned long flags)
 185 {
 186        local_irq_enable();
 187        smp_call_function(kgdb_call_nmi_hook, NULL, 0);
 188        local_irq_disable();
 189 }
 190
 191 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 192 {
 193         struct pt_regs *regs = args->regs;
 194
 195         if (kgdb_handle_exception(1, args->signr, cmd, regs))
 196                 return NOTIFY_DONE;
 197         return NOTIFY_STOP;
 198 }
 199 static int
 200 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 201 {
 202         unsigned long flags;
 203         int ret;
 204
 205         local_irq_save(flags);
 206         ret = __kgdb_notify(ptr, cmd);
 207         local_irq_restore(flags);
 208
 209         return ret;
 210 }
 211
 212 static struct notifier_block kgdb_notifier = {
 213         .notifier_call  = kgdb_notify,
 214         .priority       = -INT_MAX,
 215 };
 216
 217
 218 /**
 219  *      kgdb_arch_init - Perform any architecture specific initalization.
 220  *
 221  *      This function will handle the initalization of any architecture
 222  *      specific callbacks.
 223  */
 224 int kgdb_arch_init(void)
 225 {
 226         int ret = register_die_notifier(&kgdb_notifier);
 227
 228         if (ret != 0)
 229                 return ret;
 230
 231         register_undef_hook(&kgdb_brkpt_hook);
 232         register_undef_hook(&kgdb_compiled_brkpt_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_hook);
 246         unregister_undef_hook(&kgdb_compiled_brkpt_hook);
 247         unregister_die_notifier(&kgdb_notifier);
 248 }
 249
 250 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 251 {
 252         int err;
 253
 254         /* patch_text() only supports int-sized breakpoints */
 255         BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);
 256
 257         err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
 258                                 BREAK_INSTR_SIZE);
 259         if (err)
 260                 return err;
 261
 262         /* Machine is already stopped, so we can use __patch_text() directly */
 263         __patch_text((void *)bpt->bpt_addr,
 264                      *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
 265
 266         return err;
 267 }
 268
 269 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 270 {
 271         /* Machine is already stopped, so we can use __patch_text() directly */
 272         __patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
 273
 274         return 0;
 275 }
 276
 277 /*
 278  * Register our undef instruction hooks with ARM undef core.
 279  * We regsiter a hook specifically looking for the KGB break inst
 280  * and we handle the normal undef case within the do_undefinstr
 281  * handler.
 282  */
 283 struct kgdb_arch arch_kgdb_ops = {
 284 #ifndef __ARMEB__
 285         .gdb_bpt_instr          = {0xfe, 0xde, 0xff, 0xe7}
 286 #else /* ! __ARMEB__ */
 287         .gdb_bpt_instr          = {0xe7, 0xff, 0xde, 0xfe}
 288 #endif
 289 };