linux/arch/arm/kernel/kgdb.c
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   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
  21struct 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
  51char *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
  64int 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
  75void
  76sleeping_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
 103void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
 104{
 105        regs->ARM_pc = pc;
 106}
 107
 108static int compiled_break;
 109
 110int 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
 142static 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
 149static 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
 157static 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
 165static 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
 173static 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}
 181static int
 182kgdb_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
 194static 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 */
 206int 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 */
 225void 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
 232int 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
 251int 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 */
 265const 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};
 272