// SPDX-License-Identifier: GPL-2.0
/*  linux/arch/sparc/kernel/process.c
 *
 *  Copyright (C) 1995, 2008 David S. Miller (davem@davemloft.net)
 *  Copyright (C) 1996 Eddie C. Dost   (ecd@skynet.be)
 */

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

#include <stdarg.h>

#include <linux/elfcore.h>
#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/stddef.h>
#include <linux/ptrace.h>
#include <linux/user.h>
#include <linux/smp.h>
#include <linux/reboot.h>
#include <linux/delay.h>
#include <linux/pm.h>
#include <linux/slab.h>
#include <linux/cpu.h>

#include <asm/auxio.h>
#include <asm/oplib.h>
#include <linux/uaccess.h>
#include <asm/page.h>
#include <asm/delay.h>
#include <asm/processor.h>
#include <asm/psr.h>
#include <asm/elf.h>
#include <asm/prom.h>
#include <asm/unistd.h>
#include <asm/setup.h>

#include "kernel.h"

/* 
 * Power management idle function 
 * Set in pm platform drivers (apc.c and pmc.c)
 */
void (*sparc_idle)(void);

/* 
 * Power-off handler instantiation for pm.h compliance
 * This is done via auxio, but could be used as a fallback
 * handler when auxio is not present-- unused for now...
 */
void (*pm_power_off)(void) = machine_power_off;
EXPORT_SYMBOL(pm_power_off);

/*
 * sysctl - toggle power-off restriction for serial console 
 * systems in machine_power_off()
 */
int scons_pwroff = 1;

extern void fpsave(unsigned long *, unsigned long *, void *, unsigned long *);

struct task_struct *last_task_used_math = NULL;
struct thread_info *current_set[NR_CPUS];

/* Idle loop support. */
void arch_cpu_idle(void)
{
        if (sparc_idle)
                (*sparc_idle)();
        raw_local_irq_enable();
}

/* XXX cli/sti -> local_irq_xxx here, check this works once SMP is fixed. */
void machine_halt(void)
{
        local_irq_enable();
        mdelay(8);
        local_irq_disable();
        prom_halt();
        panic("Halt failed!");
}

void machine_restart(char * cmd)
{
        char *p;
        
        local_irq_enable();
        mdelay(8);
        local_irq_disable();

        p = strchr (reboot_command, '\n');
        if (p) *p = 0;
        if (cmd)
                prom_reboot(cmd);
        if (*reboot_command)
                prom_reboot(reboot_command);
        prom_feval ("reset");
        panic("Reboot failed!");
}

void machine_power_off(void)
{
        if (auxio_power_register &&
            (!of_node_is_type(of_console_device, "serial") || scons_pwroff)) {
                u8 power_register = sbus_readb(auxio_power_register);
                power_register |= AUXIO_POWER_OFF;
                sbus_writeb(power_register, auxio_power_register);
        }

        machine_halt();
}

void show_regs(struct pt_regs *r)
{
        struct reg_window32 *rw = (struct reg_window32 *) r->u_regs[14];

        show_regs_print_info(KERN_DEFAULT);

        printk("PSR: %08lx PC: %08lx NPC: %08lx Y: %08lx    %s\n",
               r->psr, r->pc, r->npc, r->y, print_tainted());
        printk("PC: <%pS>\n", (void *) r->pc);
        printk("%%G: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
               r->u_regs[0], r->u_regs[1], r->u_regs[2], r->u_regs[3],
               r->u_regs[4], r->u_regs[5], r->u_regs[6], r->u_regs[7]);
        printk("%%O: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
               r->u_regs[8], r->u_regs[9], r->u_regs[10], r->u_regs[11],
               r->u_regs[12], r->u_regs[13], r->u_regs[14], r->u_regs[15]);
        printk("RPC: <%pS>\n", (void *) r->u_regs[15]);

        printk("%%L: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
               rw->locals[0], rw->locals[1], rw->locals[2], rw->locals[3],
               rw->locals[4], rw->locals[5], rw->locals[6], rw->locals[7]);
        printk("%%I: %08lx %08lx  %08lx %08lx  %08lx %08lx  %08lx %08lx\n",
               rw->ins[0], rw->ins[1], rw->ins[2], rw->ins[3],
               rw->ins[4], rw->ins[5], rw->ins[6], rw->ins[7]);
}

/*
 * The show_stack() is external API which we do not use ourselves.
 * The oops is printed in die_if_kernel.
 */
void show_stack(struct task_struct *tsk, unsigned long *_ksp, const char *loglvl)
{
        unsigned long pc, fp;
        unsigned long task_base;
        struct reg_window32 *rw;
        int count = 0;

        if (!tsk)
                tsk = current;

        if (tsk == current && !_ksp)
                __asm__ __volatile__("mov       %%fp, %0" : "=r" (_ksp));

        task_base = (unsigned long) task_stack_page(tsk);
        fp = (unsigned long) _ksp;
        do {
                /* Bogus frame pointer? */
                if (fp < (task_base + sizeof(struct thread_info)) ||
                    fp >= (task_base + (PAGE_SIZE << 1)))
                        break;
                rw = (struct reg_window32 *) fp;
                pc = rw->ins[7];
                printk("%s[%08lx : ", loglvl, pc);
                printk("%s%pS ] ", loglvl, (void *) pc);
                fp = rw->ins[6];
        } while (++count < 16);
        printk("%s\n", loglvl);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(struct task_struct *tsk)
{
#ifndef CONFIG_SMP
        if (last_task_used_math == tsk) {
#else
        if (test_ti_thread_flag(task_thread_info(tsk), TIF_USEDFPU)) {
#endif
                /* Keep process from leaving FPU in a bogon state. */
                put_psr(get_psr() | PSR_EF);
                fpsave(&tsk->thread.float_regs[0], &tsk->thread.fsr,
                       &tsk->thread.fpqueue[0], &tsk->thread.fpqdepth);
#ifndef CONFIG_SMP
                last_task_used_math = NULL;
#else
                clear_ti_thread_flag(task_thread_info(tsk), TIF_USEDFPU);
#endif
        }
}

void flush_thread(void)
{
        current_thread_info()->w_saved = 0;

#ifndef CONFIG_SMP
        if(last_task_used_math == current) {
#else
        if (test_thread_flag(TIF_USEDFPU)) {
#endif
                /* Clean the fpu. */
                put_psr(get_psr() | PSR_EF);
                fpsave(&current->thread.float_regs[0], &current->thread.fsr,
                       &current->thread.fpqueue[0], &current->thread.fpqdepth);
#ifndef CONFIG_SMP
                last_task_used_math = NULL;
#else
                clear_thread_flag(TIF_USEDFPU);
#endif
        }

        /* This task is no longer a kernel thread. */
        if (current->thread.flags & SPARC_FLAG_KTHREAD) {
                current->thread.flags &= ~SPARC_FLAG_KTHREAD;

                /* We must fixup kregs as well. */
                /* XXX This was not fixed for ti for a while, worked. Unused? */
                current->thread.kregs = (struct pt_regs *)
                    (task_stack_page(current) + (THREAD_SIZE - TRACEREG_SZ));
        }
}

static inline struct sparc_stackf __user *
clone_stackframe(struct sparc_stackf __user *dst,
                 struct sparc_stackf __user *src)
{
        unsigned long size, fp;
        struct sparc_stackf *tmp;
        struct sparc_stackf __user *sp;

        if (get_user(tmp, &src->fp))
                return NULL;

        fp = (unsigned long) tmp;
        size = (fp - ((unsigned long) src));
        fp = (unsigned long) dst;
        sp = (struct sparc_stackf __user *)(fp - size); 

        /* do_fork() grabs the parent semaphore, we must release it
         * temporarily so we can build the child clone stack frame
         * without deadlocking.
         */
        if (__copy_user(sp, src, size))
                sp = NULL;
        else if (put_user(fp, &sp->fp))
                sp = NULL;

        return sp;
}

/* Copy a Sparc thread.  The fork() return value conventions
 * under SunOS are nothing short of bletcherous:
 * Parent -->  %o0 == childs  pid, %o1 == 0
 * Child  -->  %o0 == parents pid, %o1 == 1
 *
 * NOTE: We have a separate fork kpsr/kwim because
 *       the parent could change these values between
 *       sys_fork invocation and when we reach here
 *       if the parent should sleep while trying to
 *       allocate the task_struct and kernel stack in
 *       do_fork().
 * XXX See comment above sys_vfork in sparc64. todo.
 */
extern void ret_from_fork(void);
extern void ret_from_kernel_thread(void);

int copy_thread(unsigned long clone_flags, unsigned long sp, unsigned long arg,
                struct task_struct *p, unsigned long tls)
{
        struct thread_info *ti = task_thread_info(p);
        struct pt_regs *childregs, *regs = current_pt_regs();
        char *new_stack;

#ifndef CONFIG_SMP
        if(last_task_used_math == current) {
#else
        if (test_thread_flag(TIF_USEDFPU)) {
#endif
                put_psr(get_psr() | PSR_EF);
                fpsave(&p->thread.float_regs[0], &p->thread.fsr,
                       &p->thread.fpqueue[0], &p->thread.fpqdepth);
        }

        /*
         *  p->thread_info         new_stack   childregs stack bottom
         *  !                      !           !             !
         *  V                      V (stk.fr.) V  (pt_regs)  V
         *  +----- - - - - - ------+===========+=============+
         */
        new_stack = task_stack_page(p) + THREAD_SIZE;
        new_stack -= STACKFRAME_SZ + TRACEREG_SZ;
        childregs = (struct pt_regs *) (new_stack + STACKFRAME_SZ);

        /*
         * A new process must start with interrupts disabled, see schedule_tail()
         * and finish_task_switch(). (If we do not do it and if a timer interrupt
         * hits before we unlock and attempts to take the rq->lock, we deadlock.)
         *
         * Thus, kpsr |= PSR_PIL.
         */
        ti->ksp = (unsigned long) new_stack;
        p->thread.kregs = childregs;

        if (unlikely(p->flags & PF_KTHREAD)) {
                extern int nwindows;
                unsigned long psr;
                memset(new_stack, 0, STACKFRAME_SZ + TRACEREG_SZ);
                p->thread.flags |= SPARC_FLAG_KTHREAD;
                p->thread.current_ds = KERNEL_DS;
                ti->kpc = (((unsigned long) ret_from_kernel_thread) - 0x8);
                childregs->u_regs[UREG_G1] = sp; /* function */
                childregs->u_regs[UREG_G2] = arg;
                psr = childregs->psr = get_psr();
                ti->kpsr = psr | PSR_PIL;
                ti->kwim = 1 << (((psr & PSR_CWP) + 1) % nwindows);
                return 0;
        }
        memcpy(new_stack, (char *)regs - STACKFRAME_SZ, STACKFRAME_SZ + TRACEREG_SZ);
        childregs->u_regs[UREG_FP] = sp;
        p->thread.flags &= ~SPARC_FLAG_KTHREAD;
        p->thread.current_ds = USER_DS;
        ti->kpc = (((unsigned long) ret_from_fork) - 0x8);
        ti->kpsr = current->thread.fork_kpsr | PSR_PIL;
        ti->kwim = current->thread.fork_kwim;

        if (sp != regs->u_regs[UREG_FP]) {
                struct sparc_stackf __user *childstack;
                struct sparc_stackf __user *parentstack;

                /*
                 * This is a clone() call with supplied user stack.
                 * Set some valid stack frames to give to the child.
                 */
                childstack = (struct sparc_stackf __user *)
                        (sp & ~0xfUL);
                parentstack = (struct sparc_stackf __user *)
                        regs->u_regs[UREG_FP];

#if 0
                printk("clone: parent stack:\n");
                show_stackframe(parentstack);
#endif

                childstack = clone_stackframe(childstack, parentstack);
                if (!childstack)
                        return -EFAULT;

#if 0
                printk("clone: child stack:\n");
                show_stackframe(childstack);
#endif

                childregs->u_regs[UREG_FP] = (unsigned long)childstack;
        }

#ifdef CONFIG_SMP
        /* FPU must be disabled on SMP. */
        childregs->psr &= ~PSR_EF;
        clear_tsk_thread_flag(p, TIF_USEDFPU);
#endif

        /* Set the return value for the child. */
        childregs->u_regs[UREG_I0] = current->pid;
        childregs->u_regs[UREG_I1] = 1;

        /* Set the return value for the parent. */
        regs->u_regs[UREG_I1] = 0;

        if (clone_flags & CLONE_SETTLS)
                childregs->u_regs[UREG_G7] = tls;

        return 0;
}

unsigned long get_wchan(struct task_struct *task)
{
        unsigned long pc, fp, bias = 0;
        unsigned long task_base = (unsigned long) task;
        unsigned long ret = 0;
        struct reg_window32 *rw;
        int count = 0;

        if (!task || task == current ||
            task->state == TASK_RUNNING)
                goto out;

        fp = task_thread_info(task)->ksp + bias;
        do {
                /* Bogus frame pointer? */
                if (fp < (task_base + sizeof(struct thread_info)) ||
                    fp >= (task_base + (2 * PAGE_SIZE)))
                        break;
                rw = (struct reg_window32 *) fp;
                pc = rw->ins[7];
                if (!in_sched_functions(pc)) {
                        ret = pc;
                        goto out;
                }
                fp = rw->ins[6] + bias;
        } while (++count < 16);

out:
        return ret;
}