/*
 * Based on arch/arm/kernel/process.c
 *
 * Original Copyright (C) 1995  Linus Torvalds
 * Copyright (C) 1996-2000 Russell King - Converted to ARM.
 * Copyright (C) 2012 ARM Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdarg.h>

#include <linux/export.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/stddef.h>
#include <linux/unistd.h>
#include <linux/user.h>
#include <linux/delay.h>
#include <linux/reboot.h>
#include <linux/interrupt.h>
#include <linux/kallsyms.h>
#include <linux/init.h>
#include <linux/cpu.h>
#include <linux/elfcore.h>
#include <linux/pm.h>
#include <linux/tick.h>
#include <linux/utsname.h>
#include <linux/uaccess.h>
#include <linux/random.h>
#include <linux/hw_breakpoint.h>
#include <linux/personality.h>
#include <linux/notifier.h>

#include <asm/compat.h>
#include <asm/cacheflush.h>
#include <asm/fpsimd.h>
#include <asm/mmu_context.h>
#include <asm/processor.h>
#include <asm/stacktrace.h>

static void setup_restart(void)
{
        /*
         * Tell the mm system that we are going to reboot -
         * we may need it to insert some 1:1 mappings so that
         * soft boot works.
         */
        setup_mm_for_reboot();

        /* Clean and invalidate caches */
        flush_cache_all();

        /* Turn D-cache off */
        cpu_cache_off();

        /* Push out any further dirty data, and ensure cache is empty */
        flush_cache_all();
}

void soft_restart(unsigned long addr)
{
        setup_restart();
        cpu_reset(addr);
}

/*
 * Function pointers to optional machine specific functions
 */
void (*pm_power_off)(void);
EXPORT_SYMBOL_GPL(pm_power_off);

void (*arm_pm_restart)(enum reboot_mode reboot_mode, const char *cmd);
EXPORT_SYMBOL_GPL(arm_pm_restart);

void arch_cpu_idle_prepare(void)
{
        local_fiq_enable();
}

/*
 * This is our default idle handler.
 */
void arch_cpu_idle(void)
{
        /*
         * This should do all the clock switching and wait for interrupt
         * tricks
         */
        cpu_do_idle();
        local_irq_enable();
}

void machine_shutdown(void)
{
#ifdef CONFIG_SMP
        smp_send_stop();
#endif
}

void machine_halt(void)
{
        machine_shutdown();
        while (1);
}

void machine_power_off(void)
{
        machine_shutdown();
        if (pm_power_off)
                pm_power_off();
}

void machine_restart(char *cmd)
{
        machine_shutdown();

        /* Disable interrupts first */
        local_irq_disable();
        local_fiq_disable();

        /* Now call the architecture specific reboot code. */
        if (arm_pm_restart)
                arm_pm_restart(reboot_mode, cmd);

        /*
         * Whoops - the architecture was unable to reboot.
         */
        printk("Reboot failed -- System halted\n");
        while (1);
}

void __show_regs(struct pt_regs *regs)
{
        int i;

        show_regs_print_info(KERN_DEFAULT);
        print_symbol("PC is at %s\n", instruction_pointer(regs));
        print_symbol("LR is at %s\n", regs->regs[30]);
        printk("pc : [<%016llx>] lr : [<%016llx>] pstate: %08llx\n",
               regs->pc, regs->regs[30], regs->pstate);
        printk("sp : %016llx\n", regs->sp);
        for (i = 29; i >= 0; i--) {
                printk("x%-2d: %016llx ", i, regs->regs[i]);
                if (i % 2 == 0)
                        printk("\n");
        }
        printk("\n");
}

void show_regs(struct pt_regs * regs)
{
        printk("\n");
        __show_regs(regs);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
}

void flush_thread(void)
{
        fpsimd_flush_thread();
        flush_ptrace_hw_breakpoint(current);
}

void release_thread(struct task_struct *dead_task)
{
}

int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
        fpsimd_save_state(&current->thread.fpsimd_state);
        *dst = *src;
        return 0;
}

asmlinkage void ret_from_fork(void) asm("ret_from_fork");

int copy_thread(unsigned long clone_flags, unsigned long stack_start,
                unsigned long stk_sz, struct task_struct *p)
{
        struct pt_regs *childregs = task_pt_regs(p);
        unsigned long tls = p->thread.tp_value;

        memset(&p->thread.cpu_context, 0, sizeof(struct cpu_context));

        if (likely(!(p->flags & PF_KTHREAD))) {
                *childregs = *current_pt_regs();
                childregs->regs[0] = 0;
                if (is_compat_thread(task_thread_info(p))) {
                        if (stack_start)
                                childregs->compat_sp = stack_start;
                } else {
                        /*
                         * Read the current TLS pointer from tpidr_el0 as it may be
                         * out-of-sync with the saved value.
                         */
                        asm("mrs %0, tpidr_el0" : "=r" (tls));
                        if (stack_start) {
                                /* 16-byte aligned stack mandatory on AArch64 */
                                if (stack_start & 15)
                                        return -EINVAL;
                                childregs->sp = stack_start;
                        }
                }
                /*
                 * If a TLS pointer was passed to clone (4th argument), use it
                 * for the new thread.
                 */
                if (clone_flags & CLONE_SETTLS)
                        tls = childregs->regs[3];
        } else {
                memset(childregs, 0, sizeof(struct pt_regs));
                childregs->pstate = PSR_MODE_EL1h;
                p->thread.cpu_context.x19 = stack_start;
                p->thread.cpu_context.x20 = stk_sz;
        }
        p->thread.cpu_context.pc = (unsigned long)ret_from_fork;
        p->thread.cpu_context.sp = (unsigned long)childregs;
        p->thread.tp_value = tls;

        ptrace_hw_copy_thread(p);

        return 0;
}

static void tls_thread_switch(struct task_struct *next)
{
        unsigned long tpidr, tpidrro;

        if (!is_compat_task()) {
                asm("mrs %0, tpidr_el0" : "=r" (tpidr));
                current->thread.tp_value = tpidr;
        }

        if (is_compat_thread(task_thread_info(next))) {
                tpidr = 0;
                tpidrro = next->thread.tp_value;
        } else {
                tpidr = next->thread.tp_value;
                tpidrro = 0;
        }

        asm(
        "       msr     tpidr_el0, %0\n"
        "       msr     tpidrro_el0, %1"
        : : "r" (tpidr), "r" (tpidrro));
}

/*
 * Thread switching.
 */
struct task_struct *__switch_to(struct task_struct *prev,
                                struct task_struct *next)
{
        struct task_struct *last;

        fpsimd_thread_switch(next);
        tls_thread_switch(next);
        hw_breakpoint_thread_switch(next);
        contextidr_thread_switch(next);

        /*
         * Complete any pending TLB or cache maintenance on this CPU in case
         * the thread migrates to a different CPU.
         */
        dsb();

        /* the actual thread switch */
        last = cpu_switch_to(prev, next);

        return last;
}

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

        frame.fp = thread_saved_fp(p);
        frame.sp = thread_saved_sp(p);
        frame.pc = thread_saved_pc(p);
        do {
                int ret = unwind_frame(&frame);
                if (ret < 0)
                        return 0;
                if (!in_sched_functions(frame.pc))
                        return frame.pc;
        } while (count ++ < 16);
        return 0;
}

unsigned long arch_align_stack(unsigned long sp)
{
        if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
                sp -= get_random_int() & ~PAGE_MASK;
        return sp & ~0xf;
}

static unsigned long randomize_base(unsigned long base)
{
        unsigned long range_end = base + (STACK_RND_MASK << PAGE_SHIFT) + 1;
        return randomize_range(base, range_end, 0) ? : base;
}

unsigned long arch_randomize_brk(struct mm_struct *mm)
{
        return randomize_base(mm->brk);
}

unsigned long randomize_et_dyn(unsigned long base)
{
        return randomize_base(base);
}