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 thread_info *ti;
  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         ti                      = task_thread_info(task);
  90         gdb_regs[_R4]           = ti->cpu_context.r4;
  91         gdb_regs[_R5]           = ti->cpu_context.r5;
  92         gdb_regs[_R6]           = ti->cpu_context.r6;
  93         gdb_regs[_R7]           = ti->cpu_context.r7;
  94         gdb_regs[_R8]           = ti->cpu_context.r8;
  95         gdb_regs[_R9]           = ti->cpu_context.r9;
  96         gdb_regs[_R10]          = ti->cpu_context.sl;
  97         gdb_regs[_FP]           = ti->cpu_context.fp;
  98         gdb_regs[_SPT]          = ti->cpu_context.sp;
  99         gdb_regs[_PC]           = ti->cpu_context.pc;
 100 }
 101
 102 void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 103 {
 104         regs->ARM_pc = pc;
 105 }
 106
 107 static int compiled_break;
 108
 109 int kgdb_arch_handle_exception(int exception_vector, int signo,
 110                                int err_code, char *remcom_in_buffer,
 111                                char *remcom_out_buffer,
 112                                struct pt_regs *linux_regs)
 113 {
 114         unsigned long addr;
 115         char *ptr;
 116
 117         switch (remcom_in_buffer[0]) {
 118         case 'D':
 119         case 'k':
 120         case 'c':
 121                 /*
 122                  * Try to read optional parameter, pc unchanged if no parm.
 123                  * If this was a compiled breakpoint, we need to move
 124                  * to the next instruction or we will just breakpoint
 125                  * over and over again.
 126                  */
 127                 ptr = &remcom_in_buffer[1];
 128                 if (kgdb_hex2long(&ptr, &addr))
 129                         linux_regs->ARM_pc = addr;
 130                 else if (compiled_break == 1)
 131                         linux_regs->ARM_pc += 4;
 132
 133                 compiled_break = 0;
 134
 135                 return 0;
 136         }
 137
 138         return -1;
 139 }
 140
 141 static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
 142 {
 143         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 144
 145         return 0;
 146 }
 147
 148 static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
 149 {
 150         compiled_break = 1;
 151         kgdb_handle_exception(1, SIGTRAP, 0, regs);
 152
 153         return 0;
 154 }
 155
 156 static struct undef_hook kgdb_brkpt_hook = {
 157         .instr_mask             = 0xffffffff,
 158         .instr_val              = KGDB_BREAKINST,
 159         .cpsr_mask              = MODE_MASK,
 160         .cpsr_val               = SVC_MODE,
 161         .fn                     = kgdb_brk_fn
 162 };
 163
 164 static struct undef_hook kgdb_compiled_brkpt_hook = {
 165         .instr_mask             = 0xffffffff,
 166         .instr_val              = KGDB_COMPILED_BREAK,
 167         .cpsr_mask              = MODE_MASK,
 168         .cpsr_val               = SVC_MODE,
 169         .fn                     = kgdb_compiled_brk_fn
 170 };
 171
 172 static void kgdb_call_nmi_hook(void *ignored)
 173 {
 174        kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 175 }
 176
 177 void kgdb_roundup_cpus(unsigned long flags)
 178 {
 179        local_irq_enable();
 180        smp_call_function(kgdb_call_nmi_hook, NULL, 0);
 181        local_irq_disable();
 182 }
 183
 184 static int __kgdb_notify(struct die_args *args, unsigned long cmd)
 185 {
 186         struct pt_regs *regs = args->regs;
 187
 188         if (kgdb_handle_exception(1, args->signr, cmd, regs))
 189                 return NOTIFY_DONE;
 190         return NOTIFY_STOP;
 191 }
 192 static int
 193 kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
 194 {
 195         unsigned long flags;
 196         int ret;
 197
 198         local_irq_save(flags);
 199         ret = __kgdb_notify(ptr, cmd);
 200         local_irq_restore(flags);
 201
 202         return ret;
 203 }
 204
 205 static struct notifier_block kgdb_notifier = {
 206         .notifier_call  = kgdb_notify,
 207         .priority       = -INT_MAX,
 208 };
 209
 210
 211 /**
 212  *      kgdb_arch_init - Perform any architecture specific initalization.
 213  *
 214  *      This function will handle the initalization of any architecture
 215  *      specific callbacks.
 216  */
 217 int kgdb_arch_init(void)
 218 {
 219         int ret = register_die_notifier(&kgdb_notifier);
 220
 221         if (ret != 0)
 222                 return ret;
 223
 224         register_undef_hook(&kgdb_brkpt_hook);
 225         register_undef_hook(&kgdb_compiled_brkpt_hook);
 226
 227         return 0;
 228 }
 229
 230 /**
 231  *      kgdb_arch_exit - Perform any architecture specific uninitalization.
 232  *
 233  *      This function will handle the uninitalization of any architecture
 234  *      specific callbacks, for dynamic registration and unregistration.
 235  */
 236 void kgdb_arch_exit(void)
 237 {
 238         unregister_undef_hook(&kgdb_brkpt_hook);
 239         unregister_undef_hook(&kgdb_compiled_brkpt_hook);
 240         unregister_die_notifier(&kgdb_notifier);
 241 }
 242
 243 int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
 244 {
 245         int err;
 246
 247         /* patch_text() only supports int-sized breakpoints */
 248         BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);
 249
 250         err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
 251                                 BREAK_INSTR_SIZE);
 252         if (err)
 253                 return err;
 254
 255         /* Machine is already stopped, so we can use __patch_text() directly */
 256         __patch_text((void *)bpt->bpt_addr,
 257                      *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);
 258
 259         return err;
 260 }
 261
 262 int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
 263 {
 264         /* Machine is already stopped, so we can use __patch_text() directly */
 265         __patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);
 266
 267         return 0;
 268 }
 269
 270 /*
 271  * Register our undef instruction hooks with ARM undef core.
 272  * We regsiter a hook specifically looking for the KGB break inst
 273  * and we handle the normal undef case within the do_undefinstr
 274  * handler.
 275  */
 276 struct kgdb_arch arch_kgdb_ops = {
 277 #ifndef __ARMEB__
 278         .gdb_bpt_instr          = {0xfe, 0xde, 0xff, 0xe7}
 279 #else /* ! __ARMEB__ */
 280         .gdb_bpt_instr          = {0xe7, 0xff, 0xde, 0xfe}
 281 #endif
 282 };