// SPDX-License-Identifier: GPL-2.0
/*
 * PA-RISC KGDB support
 *
 * Copyright (c) 2019 Sven Schnelle <svens@stackframe.org>
 * Copyright (c) 2022 Helge Deller <deller@gmx.de>
 *
 */

#include <linux/kgdb.h>
#include <linux/string.h>
#include <linux/sched.h>
#include <linux/notifier.h>
#include <linux/kdebug.h>
#include <linux/uaccess.h>
#include <asm/ptrace.h>
#include <asm/traps.h>
#include <asm/processor.h>
#include <asm/text-patching.h>
#include <asm/cacheflush.h>

const struct kgdb_arch arch_kgdb_ops = {
        .gdb_bpt_instr = { 0x03, 0xff, 0xa0, 0x1f }
};

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,
};

int kgdb_arch_init(void)
{
        return register_die_notifier(&kgdb_notifier);
}

void kgdb_arch_exit(void)
{
        unregister_die_notifier(&kgdb_notifier);
}

void pt_regs_to_gdb_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
        struct parisc_gdb_regs *gr = (struct parisc_gdb_regs *)gdb_regs;

        memset(gr, 0, sizeof(struct parisc_gdb_regs));

        memcpy(gr->gpr, regs->gr, sizeof(gr->gpr));
        memcpy(gr->fr, regs->fr, sizeof(gr->fr));

        gr->sr0 = regs->sr[0];
        gr->sr1 = regs->sr[1];
        gr->sr2 = regs->sr[2];
        gr->sr3 = regs->sr[3];
        gr->sr4 = regs->sr[4];
        gr->sr5 = regs->sr[5];
        gr->sr6 = regs->sr[6];
        gr->sr7 = regs->sr[7];

        gr->sar = regs->sar;
        gr->iir = regs->iir;
        gr->isr = regs->isr;
        gr->ior = regs->ior;
        gr->ipsw = regs->ipsw;
        gr->cr27 = regs->cr27;

        gr->iaoq_f = regs->iaoq[0];
        gr->iasq_f = regs->iasq[0];

        gr->iaoq_b = regs->iaoq[1];
        gr->iasq_b = regs->iasq[1];
}

void gdb_regs_to_pt_regs(unsigned long *gdb_regs, struct pt_regs *regs)
{
        struct parisc_gdb_regs *gr = (struct parisc_gdb_regs *)gdb_regs;


        memcpy(regs->gr, gr->gpr, sizeof(regs->gr));
        memcpy(regs->fr, gr->fr, sizeof(regs->fr));

        regs->sr[0] = gr->sr0;
        regs->sr[1] = gr->sr1;
        regs->sr[2] = gr->sr2;
        regs->sr[3] = gr->sr3;
        regs->sr[4] = gr->sr4;
        regs->sr[5] = gr->sr5;
        regs->sr[6] = gr->sr6;
        regs->sr[7] = gr->sr7;

        regs->sar = gr->sar;
        regs->iir = gr->iir;
        regs->isr = gr->isr;
        regs->ior = gr->ior;
        regs->ipsw = gr->ipsw;
        regs->cr27 = gr->cr27;

        regs->iaoq[0] = gr->iaoq_f;
        regs->iasq[0] = gr->iasq_f;

        regs->iaoq[1] = gr->iaoq_b;
        regs->iasq[1] = gr->iasq_b;
}

void sleeping_thread_to_gdb_regs(unsigned long *gdb_regs,
                                struct task_struct *task)
{
        struct pt_regs *regs = task_pt_regs(task);
        unsigned long gr30, iaoq;

        gr30 = regs->gr[30];
        iaoq = regs->iaoq[0];

        regs->gr[30] = regs->ksp;
        regs->iaoq[0] = regs->kpc;
        pt_regs_to_gdb_regs(gdb_regs, regs);

        regs->gr[30] = gr30;
        regs->iaoq[0] = iaoq;

}

static void step_instruction_queue(struct pt_regs *regs)
{
        regs->iaoq[0] = regs->iaoq[1];
        regs->iaoq[1] += 4;
}

void kgdb_arch_set_pc(struct pt_regs *regs, unsigned long ip)
{
        regs->iaoq[0] = ip;
        regs->iaoq[1] = ip + 4;
}

int kgdb_arch_set_breakpoint(struct kgdb_bkpt *bpt)
{
        int ret = copy_from_kernel_nofault(bpt->saved_instr,
                        (char *)bpt->bpt_addr, BREAK_INSTR_SIZE);
        if (ret)
                return ret;

        __patch_text((void *)bpt->bpt_addr,
                        *(unsigned int *)&arch_kgdb_ops.gdb_bpt_instr);
        return ret;
}

int kgdb_arch_remove_breakpoint(struct kgdb_bkpt *bpt)
{
        __patch_text((void *)bpt->bpt_addr, *(unsigned int *)&bpt->saved_instr);
        return 0;
}

int kgdb_arch_handle_exception(int trap, int signo,
                int err_code, char *inbuf, char *outbuf,
                struct pt_regs *regs)
{
        unsigned long addr;
        char *p = inbuf + 1;

        switch (inbuf[0]) {
        case 'D':
        case 'c':
        case 'k':
                kgdb_contthread = NULL;
                kgdb_single_step = 0;

                if (kgdb_hex2long(&p, &addr))
                        kgdb_arch_set_pc(regs, addr);
                else if (trap == 9 && regs->iir ==
                                PARISC_KGDB_COMPILED_BREAK_INSN)
                        step_instruction_queue(regs);
                return 0;
        case 's':
                kgdb_single_step = 1;
                if (kgdb_hex2long(&p, &addr)) {
                        kgdb_arch_set_pc(regs, addr);
                } else if (trap == 9 && regs->iir ==
                                PARISC_KGDB_COMPILED_BREAK_INSN) {
                        step_instruction_queue(regs);
                        mtctl(-1, 0);
                } else {
                        mtctl(0, 0);
                }
                regs->gr[0] |= PSW_R;
                return 0;

        }
        return -1;
}