// SPDX-License-Identifier: GPL-2.0
/*
 * arch/arm/kernel/kgdb.c
 *
 * ARM KGDB support
 *
 * Copyright (c) 2002-2004 MontaVista Software, Inc
 * Copyright (c) 2008 Wind River Systems, Inc.
 *
 * Authors:  George Davis <davis_g@mvista.com>
 *           Deepak Saxena <dsaxena@plexity.net>
 */
#include <linux/irq.h>
#include <linux/kdebug.h>
#include <linux/kgdb.h>
#include <linux/uaccess.h>

#include <asm/patch.h>
#include <asm/traps.h>

struct dbg_reg_def_t dbg_reg_def[DBG_MAX_REG_NUM] =
{
        { "r0", 4, offsetof(struct pt_regs, ARM_r0)},
        { "r1", 4, offsetof(struct pt_regs, ARM_r1)},
        { "r2", 4, offsetof(struct pt_regs, ARM_r2)},
        { "r3", 4, offsetof(struct pt_regs, ARM_r3)},
        { "r4", 4, offsetof(struct pt_regs, ARM_r4)},
        { "r5", 4, offsetof(struct pt_regs, ARM_r5)},
        { "r6", 4, offsetof(struct pt_regs, ARM_r6)},
        { "r7", 4, offsetof(struct pt_regs, ARM_r7)},
        { "r8", 4, offsetof(struct pt_regs, ARM_r8)},
        { "r9", 4, offsetof(struct pt_regs, ARM_r9)},
        { "r10", 4, offsetof(struct pt_regs, ARM_r10)},
        { "fp", 4, offsetof(struct pt_regs, ARM_fp)},
        { "ip", 4, offsetof(struct pt_regs, ARM_ip)},
        { "sp", 4, offsetof(struct pt_regs, ARM_sp)},
        { "lr", 4, offsetof(struct pt_regs, ARM_lr)},
        { "pc", 4, offsetof(struct pt_regs, ARM_pc)},
        { "f0", 12, -1 },
        { "f1", 12, -1 },
        { "f2", 12, -1 },
        { "f3", 12, -1 },
        { "f4", 12, -1 },
        { "f5", 12, -1 },
        { "f6", 12, -1 },
        { "f7", 12, -1 },
        { "fps", 4, -1 },
        { "cpsr", 4, offsetof(struct pt_regs, ARM_cpsr)},
};

char *dbg_get_reg(int regno, void *mem, struct pt_regs *regs)
{
        if (regno >= DBG_MAX_REG_NUM || regno < 0)
                return NULL;

        if (dbg_reg_def[regno].offset != -1)
                memcpy(mem, (void *)regs + dbg_reg_def[regno].offset,
                       dbg_reg_def[regno].size);
        else
                memset(mem, 0, dbg_reg_def[regno].size);
        return dbg_reg_def[regno].name;
}

int dbg_set_reg(int regno, void *mem, struct pt_regs *regs)
{
        if (regno >= DBG_MAX_REG_NUM || regno < 0)
                return -EINVAL;

        if (dbg_reg_def[regno].offset != -1)
                memcpy((void *)regs + dbg_reg_def[regno].offset, mem,
                       dbg_reg_def[regno].size);
        return 0;
}

void
sleeping_thread_to_gdb_regs(unsigned long *gdb_regs, struct task_struct *task)
{
        struct thread_info *ti;
        int regno;

        /* Just making sure... */
        if (task == NULL)
                return;

        /* Initialize to zero */
        for (regno = 0; regno < GDB_MAX_REGS; regno++)
                gdb_regs[regno] = 0;

        /* Otherwise, we have only some registers from switch_to() */
        ti                      = task_thread_info(task);
        gdb_regs[_R4]           = ti->cpu_context.r4;
        gdb_regs[_R5]           = ti->cpu_context.r5;
        gdb_regs[_R6]           = ti->cpu_context.r6;
        gdb_regs[_R7]           = ti->cpu_context.r7;
        gdb_regs[_R8]           = ti->cpu_context.r8;
        gdb_regs[_R9]           = ti->cpu_context.r9;
        gdb_regs[_R10]          = ti->cpu_context.sl;
        gdb_regs[_FP]           = ti->cpu_context.fp;
        gdb_regs[_SPT]          = ti->cpu_context.sp;
        gdb_regs[_PC]           = ti->cpu_context.pc;
}

void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long pc)
{
        regs->ARM_pc = pc;
}

static int compiled_break;

int kgdb_arch_handle_exception(int exception_vector, int signo,
                               int err_code, char *remcom_in_buffer,
                               char *remcom_out_buffer,
                               struct pt_regs *linux_regs)
{
        unsigned long addr;
        char *ptr;

        switch (remcom_in_buffer[0]) {
        case 'D':
        case 'k':
        case 'c':
                /*
                 * Try to read optional parameter, pc unchanged if no parm.
                 * If this was a compiled breakpoint, we need to move
                 * to the next instruction or we will just breakpoint
                 * over and over again.
                 */
                ptr = &remcom_in_buffer[1];
                if (kgdb_hex2long(&ptr, &addr))
                        linux_regs->ARM_pc = addr;
                else if (compiled_break == 1)
                        linux_regs->ARM_pc += 4;

                compiled_break = 0;

                return 0;
        }

        return -1;
}

static int kgdb_brk_fn(struct pt_regs *regs, unsigned int instr)
{
        kgdb_handle_exception(1, SIGTRAP, 0, regs);

        return 0;
}

static int kgdb_compiled_brk_fn(struct pt_regs *regs, unsigned int instr)
{
        compiled_break = 1;
        kgdb_handle_exception(1, SIGTRAP, 0, regs);

        return 0;
}

static struct undef_hook kgdb_brkpt_hook = {
        .instr_mask             = 0xffffffff,
        .instr_val              = KGDB_BREAKINST,
        .cpsr_mask              = MODE_MASK,
        .cpsr_val               = SVC_MODE,
        .fn                     = kgdb_brk_fn
};

static struct undef_hook kgdb_compiled_brkpt_hook = {
        .instr_mask             = 0xffffffff,
        .instr_val              = KGDB_COMPILED_BREAK,
        .cpsr_mask              = MODE_MASK,
        .cpsr_val               = SVC_MODE,
        .fn                     = kgdb_compiled_brk_fn
};

static int __kgdb_notify(struct die_args *args, unsigned long cmd)
{
        struct pt_regs *regs = args->regs;

        if (kgdb_handle_exception(1, args->signr, cmd, regs))
                return NOTIFY_DONE;
        return NOTIFY_STOP;
}
static int
kgdb_notify(struct notifier_block *self, unsigned long cmd, void *ptr)
{
        unsigned long flags;
        int ret;

        local_irq_save(flags);
        ret = __kgdb_notify(ptr, cmd);
        local_irq_restore(flags);

        return ret;
}

static struct notifier_block kgdb_notifier = {
        .notifier_call  = kgdb_notify,
        .priority       = -INT_MAX,
};


/**
 *      kgdb_arch_init - Perform any architecture specific initalization.
 *
 *      This function will handle the initalization of any architecture
 *      specific callbacks.
 */
int kgdb_arch_init(void)
{
        int ret = register_die_notifier(&kgdb_notifier);

        if (ret != 0)
                return ret;

        register_undef_hook(&kgdb_brkpt_hook);
        register_undef_hook(&kgdb_compiled_brkpt_hook);

        return 0;
}

/**
 *      kgdb_arch_exit - Perform any architecture specific uninitalization.
 *
 *      This function will handle the uninitalization of any architecture
 *      specific callbacks, for dynamic registration and unregistration.
 */
void kgdb_arch_exit(void)
{
        unregister_undef_hook(&kgdb_brkpt_hook);
        unregister_undef_hook(&kgdb_compiled_brkpt_hook);
        unregister_die_notifier(&kgdb_notifier);
}

int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
{
        int err;

        /* patch_text() only supports int-sized breakpoints */
        BUILD_BUG_ON(sizeof(int) != BREAK_INSTR_SIZE);

        err = probe_kernel_read(bpt->saved_instr, (char *)bpt->bpt_addr,
                                BREAK_INSTR_SIZE);
        if (err)
                return err;

        /* Machine is already stopped, so we can use __patch_text() directly */
        __patch_text((void *)bpt->bpt_addr,
                     *(unsigned int *)arch_kgdb_ops.gdb_bpt_instr);

        return err;
}

int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
{
        /* Machine is already stopped, so we can use __patch_text() directly */
        __patch_text((void *)bpt->bpt_addr, *(unsigned int *)bpt->saved_instr);

        return 0;
}

/*
 * Register our undef instruction hooks with ARM undef core.
 * We register a hook specifically looking for the KGB break inst
 * and we handle the normal undef case within the do_undefinstr
 * handler.
 */
const struct kgdb_arch arch_kgdb_ops = {
#ifndef __ARMEB__
        .gdb_bpt_instr          = {0xfe, 0xde, 0xff, 0xe7}
#else /* ! __ARMEB__ */
        .gdb_bpt_instr          = {0xe7, 0xff, 0xde, 0xfe}
#endif
};