// SPDX-License-Identifier: GPL-2.0
/*
 *  linux/arch/m68k/kernel/process.c
 *
 *  Copyright (C) 1995  Hamish Macdonald
 *
 *  68060 fixes by Jesper Skov
 */

/*
 * This file handles the architecture-dependent parts of process handling..
 */

#include <linux/errno.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/sched/debug.h>
#include <linux/sched/task.h>
#include <linux/sched/task_stack.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/smp.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/reboot.h>
#include <linux/init_task.h>
#include <linux/mqueue.h>
#include <linux/rcupdate.h>
#include <linux/syscalls.h>
#include <linux/uaccess.h>

#include <asm/traps.h>
#include <asm/machdep.h>
#include <asm/setup.h>


asmlinkage void ret_from_fork(void);
asmlinkage void ret_from_kernel_thread(void);

void arch_cpu_idle(void)
{
#if defined(MACH_ATARI_ONLY)
        /* block out HSYNC on the atari (falcon) */
        __asm__("stop #0x2200" : : : "cc");
#else
        __asm__("stop #0x2000" : : : "cc");
#endif
}

void machine_restart(char * __unused)
{
        if (mach_reset)
                mach_reset();
        for (;;);
}

void machine_halt(void)
{
        if (mach_halt)
                mach_halt();
        for (;;);
}

void machine_power_off(void)
{
        if (mach_power_off)
                mach_power_off();
        for (;;);
}

void (*pm_power_off)(void) = machine_power_off;
EXPORT_SYMBOL(pm_power_off);

void show_regs(struct pt_regs * regs)
{
        pr_info("Format %02x  Vector: %04x  PC: %08lx  Status: %04x    %s\n",
                regs->format, regs->vector, regs->pc, regs->sr,
                print_tainted());
        pr_info("ORIG_D0: %08lx  D0: %08lx  A2: %08lx  A1: %08lx\n",
                regs->orig_d0, regs->d0, regs->a2, regs->a1);
        pr_info("A0: %08lx  D5: %08lx  D4: %08lx\n", regs->a0, regs->d5,
                regs->d4);
        pr_info("D3: %08lx  D2: %08lx  D1: %08lx\n", regs->d3, regs->d2,
                regs->d1);
        if (!(regs->sr & PS_S))
                pr_info("USP: %08lx\n", rdusp());
}

void flush_thread(void)
{
        current->thread.fs = __USER_DS;
#ifdef CONFIG_FPU
        if (!FPU_IS_EMU) {
                unsigned long zero = 0;
                asm volatile("frestore %0": :"m" (zero));
        }
#endif
}

/*
 * Why not generic sys_clone, you ask?  m68k passes all arguments on stack.
 * And we need all registers saved, which means a bunch of stuff pushed
 * on top of pt_regs, which means that sys_clone() arguments would be
 * buried.  We could, of course, copy them, but it's too costly for no
 * good reason - generic clone() would have to copy them *again* for
 * kernel_clone() anyway.  So in this case it's actually better to pass pt_regs *
 * and extract arguments for kernel_clone() from there.  Eventually we might
 * go for calling kernel_clone() directly from the wrapper, but only after we
 * are finished with kernel_clone() prototype conversion.
 */
asmlinkage int m68k_clone(struct pt_regs *regs)
{
        /* regs will be equal to current_pt_regs() */
        struct kernel_clone_args args = {
                .flags          = regs->d1 & ~CSIGNAL,
                .pidfd          = (int __user *)regs->d3,
                .child_tid      = (int __user *)regs->d4,
                .parent_tid     = (int __user *)regs->d3,
                .exit_signal    = regs->d1 & CSIGNAL,
                .stack          = regs->d2,
                .tls            = regs->d5,
        };

        return kernel_clone(&args);
}

/*
 * Because extra registers are saved on the stack after the sys_clone3()
 * arguments, this C wrapper extracts them from pt_regs * and then calls the
 * generic sys_clone3() implementation.
 */
asmlinkage int m68k_clone3(struct pt_regs *regs)
{
        return sys_clone3((struct clone_args __user *)regs->d1, regs->d2);
}

int copy_thread(unsigned long clone_flags, unsigned long usp, unsigned long arg,
                struct task_struct *p, unsigned long tls)
{
        struct fork_frame {
                struct switch_stack sw;
                struct pt_regs regs;
        } *frame;

        frame = (struct fork_frame *) (task_stack_page(p) + THREAD_SIZE) - 1;

        p->thread.ksp = (unsigned long)frame;
        p->thread.esp0 = (unsigned long)&frame->regs;

        /*
         * Must save the current SFC/DFC value, NOT the value when
         * the parent was last descheduled - RGH  10-08-96
         */
        p->thread.fs = get_fs().seg;

        if (unlikely(p->flags & PF_KTHREAD)) {
                /* kernel thread */
                memset(frame, 0, sizeof(struct fork_frame));
                frame->regs.sr = PS_S;
                frame->sw.a3 = usp; /* function */
                frame->sw.d7 = arg;
                frame->sw.retpc = (unsigned long)ret_from_kernel_thread;
                p->thread.usp = 0;
                return 0;
        }
        memcpy(frame, container_of(current_pt_regs(), struct fork_frame, regs),
                sizeof(struct fork_frame));
        frame->regs.d0 = 0;
        frame->sw.retpc = (unsigned long)ret_from_fork;
        p->thread.usp = usp ?: rdusp();

        if (clone_flags & CLONE_SETTLS)
                task_thread_info(p)->tp_value = tls;

#ifdef CONFIG_FPU
        if (!FPU_IS_EMU) {
                /* Copy the current fpu state */
                asm volatile ("fsave %0" : : "m" (p->thread.fpstate[0]) : "memory");

                if (!CPU_IS_060 ? p->thread.fpstate[0] : p->thread.fpstate[2]) {
                        if (CPU_IS_COLDFIRE) {
                                asm volatile ("fmovemd %/fp0-%/fp7,%0\n\t"
                                              "fmovel %/fpiar,%1\n\t"
                                              "fmovel %/fpcr,%2\n\t"
                                              "fmovel %/fpsr,%3"
                                              :
                                              : "m" (p->thread.fp[0]),
                                                "m" (p->thread.fpcntl[0]),
                                                "m" (p->thread.fpcntl[1]),
                                                "m" (p->thread.fpcntl[2])
                                              : "memory");
                        } else {
                                asm volatile ("fmovemx %/fp0-%/fp7,%0\n\t"
                                              "fmoveml %/fpiar/%/fpcr/%/fpsr,%1"
                                              :
                                              : "m" (p->thread.fp[0]),
                                                "m" (p->thread.fpcntl[0])
                                              : "memory");
                        }
                }

                /* Restore the state in case the fpu was busy */
                asm volatile ("frestore %0" : : "m" (p->thread.fpstate[0]));
        }
#endif /* CONFIG_FPU */

        return 0;
}

/* Fill in the fpu structure for a core dump.  */
int dump_fpu (struct pt_regs *regs, struct user_m68kfp_struct *fpu)
{
        if (FPU_IS_EMU) {
                int i;

                memcpy(fpu->fpcntl, current->thread.fpcntl, 12);
                memcpy(fpu->fpregs, current->thread.fp, 96);
                /* Convert internal fpu reg representation
                 * into long double format
                 */
                for (i = 0; i < 24; i += 3)
                        fpu->fpregs[i] = ((fpu->fpregs[i] & 0xffff0000) << 15) |
                                         ((fpu->fpregs[i] & 0x0000ffff) << 16);
                return 1;
        }

        if (IS_ENABLED(CONFIG_FPU)) {
                char fpustate[216];

                /* First dump the fpu context to avoid protocol violation.  */
                asm volatile ("fsave %0" :: "m" (fpustate[0]) : "memory");
                if (!CPU_IS_060 ? !fpustate[0] : !fpustate[2])
                        return 0;

                if (CPU_IS_COLDFIRE) {
                        asm volatile ("fmovel %/fpiar,%0\n\t"
                                      "fmovel %/fpcr,%1\n\t"
                                      "fmovel %/fpsr,%2\n\t"
                                      "fmovemd %/fp0-%/fp7,%3"
                                      :
                                      : "m" (fpu->fpcntl[0]),
                                        "m" (fpu->fpcntl[1]),
                                        "m" (fpu->fpcntl[2]),
                                        "m" (fpu->fpregs[0])
                                      : "memory");
                } else {
                        asm volatile ("fmovem %/fpiar/%/fpcr/%/fpsr,%0"
                                      :
                                      : "m" (fpu->fpcntl[0])
                                      : "memory");
                        asm volatile ("fmovemx %/fp0-%/fp7,%0"
                                      :
                                      : "m" (fpu->fpregs[0])
                                      : "memory");
                }
        }

        return 1;
}
EXPORT_SYMBOL(dump_fpu);

unsigned long get_wchan(struct task_struct *p)
{
        unsigned long fp, pc;
        unsigned long stack_page;
        int count = 0;
        if (!p || p == current || p->state == TASK_RUNNING)
                return 0;

        stack_page = (unsigned long)task_stack_page(p);
        fp = ((struct switch_stack *)p->thread.ksp)->a6;
        do {
                if (fp < stack_page+sizeof(struct thread_info) ||
                    fp >= 8184+stack_page)
                        return 0;
                pc = ((unsigned long *)fp)[1];
                if (!in_sched_functions(pc))
                        return pc;
                fp = *(unsigned long *) fp;
        } while (count++ < 16);
        return 0;
}