linux/arch/arm/kernel/kgdb.c
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   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
  20struct 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
  50char *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
  63int 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
  74void
  75sleeping_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
 102void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 103{
 104        regs->ARM_pc = pc;
 105}
 106
 107static int compiled_break;
 108
 109int 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
 141static 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
 148static 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
 156static 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
 164static 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
 172static void kgdb_call_nmi_hook(void *ignored)
 173{
 174       kgdb_nmicallback(raw_smp_processor_id(), get_irq_regs());
 175}
 176
 177void 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
 184static 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}
 192static int
 193kgdb_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
 205static 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 */
 217int 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 */
 236void 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
 243int 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
 262int 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 */
 276struct 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};
 283
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