#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/prctl.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/module.h>
#include <linux/pm.h>
#include <linux/tick.h>
#include <linux/random.h>
#include <linux/user-return-notifier.h>
#include <linux/dmi.h>
#include <linux/utsname.h>
#include <linux/stackprotector.h>
#include <linux/tick.h>
#include <linux/cpuidle.h>
#include <trace/events/power.h>
#include <linux/hw_breakpoint.h>
#include <asm/cpu.h>
#include <asm/apic.h>
#include <asm/syscalls.h>
#include <asm/idle.h>
#include <asm/uaccess.h>
#include <asm/mwait.h>
#include <asm/fpu/internal.h>
#include <asm/debugreg.h>
#include <asm/nmi.h>
#include <asm/tlbflush.h>
#include <asm/mce.h>
#include <asm/vm86.h>

/*
 * per-CPU TSS segments. Threads are completely 'soft' on Linux,
 * no more per-task TSS's. The TSS size is kept cacheline-aligned
 * so they are allowed to end up in the .data..cacheline_aligned
 * section. Since TSS's are completely CPU-local, we want them
 * on exact cacheline boundaries, to eliminate cacheline ping-pong.
 */
__visible DEFINE_PER_CPU_SHARED_ALIGNED(struct tss_struct, cpu_tss) = {
        .x86_tss = {
                .sp0 = TOP_OF_INIT_STACK,
#ifdef CONFIG_X86_32
                .ss0 = __KERNEL_DS,
                .ss1 = __KERNEL_CS,
                .io_bitmap_base = INVALID_IO_BITMAP_OFFSET,
#endif
         },
#ifdef CONFIG_X86_32
         /*
          * Note that the .io_bitmap member must be extra-big. This is because
          * the CPU will access an additional byte beyond the end of the IO
          * permission bitmap. The extra byte must be all 1 bits, and must
          * be within the limit.
          */
        .io_bitmap              = { [0 ... IO_BITMAP_LONGS] = ~0 },
#endif
};
EXPORT_PER_CPU_SYMBOL(cpu_tss);

#ifdef CONFIG_X86_64
static DEFINE_PER_CPU(unsigned char, is_idle);
static ATOMIC_NOTIFIER_HEAD(idle_notifier);

void idle_notifier_register(struct notifier_block *n)
{
        atomic_notifier_chain_register(&idle_notifier, n);
}
EXPORT_SYMBOL_GPL(idle_notifier_register);

void idle_notifier_unregister(struct notifier_block *n)
{
        atomic_notifier_chain_unregister(&idle_notifier, n);
}
EXPORT_SYMBOL_GPL(idle_notifier_unregister);
#endif

/*
 * this gets called so that we can store lazy state into memory and copy the
 * current task into the new thread.
 */
int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
{
        memcpy(dst, src, arch_task_struct_size);
#ifdef CONFIG_VM86
        dst->thread.vm86 = NULL;
#endif

        return fpu__copy(&dst->thread.fpu, &src->thread.fpu);
}

/*
 * Free current thread data structures etc..
 */
void exit_thread(void)
{
        struct task_struct *me = current;
        struct thread_struct *t = &me->thread;
        unsigned long *bp = t->io_bitmap_ptr;
        struct fpu *fpu = &t->fpu;

        if (bp) {
                struct tss_struct *tss = &per_cpu(cpu_tss, get_cpu());

                t->io_bitmap_ptr = NULL;
                clear_thread_flag(TIF_IO_BITMAP);
                /*
                 * Careful, clear this in the TSS too:
                 */
                memset(tss->io_bitmap, 0xff, t->io_bitmap_max);
                t->io_bitmap_max = 0;
                put_cpu();
                kfree(bp);
        }

        free_vm86(t);

        fpu__drop(fpu);
}

void flush_thread(void)
{
        struct task_struct *tsk = current;

        flush_ptrace_hw_breakpoint(tsk);
        memset(tsk->thread.tls_array, 0, sizeof(tsk->thread.tls_array));

        fpu__clear(&tsk->thread.fpu);
}

static void hard_disable_TSC(void)
{
        cr4_set_bits(X86_CR4_TSD);
}

void disable_TSC(void)
{
        preempt_disable();
        if (!test_and_set_thread_flag(TIF_NOTSC))
                /*
                 * Must flip the CPU state synchronously with
                 * TIF_NOTSC in the current running context.
                 */
                hard_disable_TSC();
        preempt_enable();
}

static void hard_enable_TSC(void)
{
        cr4_clear_bits(X86_CR4_TSD);
}

static void enable_TSC(void)
{
        preempt_disable();
        if (test_and_clear_thread_flag(TIF_NOTSC))
                /*
                 * Must flip the CPU state synchronously with
                 * TIF_NOTSC in the current running context.
                 */
                hard_enable_TSC();
        preempt_enable();
}

int get_tsc_mode(unsigned long adr)
{
        unsigned int val;

        if (test_thread_flag(TIF_NOTSC))
                val = PR_TSC_SIGSEGV;
        else
                val = PR_TSC_ENABLE;

        return put_user(val, (unsigned int __user *)adr);
}

int set_tsc_mode(unsigned int val)
{
        if (val == PR_TSC_SIGSEGV)
                disable_TSC();
        else if (val == PR_TSC_ENABLE)
                enable_TSC();
        else
                return -EINVAL;

        return 0;
}

void __switch_to_xtra(struct task_struct *prev_p, struct task_struct *next_p,
                      struct tss_struct *tss)
{
        struct thread_struct *prev, *next;

        prev = &prev_p->thread;
        next = &next_p->thread;

        if (test_tsk_thread_flag(prev_p, TIF_BLOCKSTEP) ^
            test_tsk_thread_flag(next_p, TIF_BLOCKSTEP)) {
                unsigned long debugctl = get_debugctlmsr();

                debugctl &= ~DEBUGCTLMSR_BTF;
                if (test_tsk_thread_flag(next_p, TIF_BLOCKSTEP))
                        debugctl |= DEBUGCTLMSR_BTF;

                update_debugctlmsr(debugctl);
        }

        if (test_tsk_thread_flag(prev_p, TIF_NOTSC) ^
            test_tsk_thread_flag(next_p, TIF_NOTSC)) {
                /* prev and next are different */
                if (test_tsk_thread_flag(next_p, TIF_NOTSC))
                        hard_disable_TSC();
                else
                        hard_enable_TSC();
        }

        if (test_tsk_thread_flag(next_p, TIF_IO_BITMAP)) {
                /*
                 * Copy the relevant range of the IO bitmap.
                 * Normally this is 128 bytes or less:
                 */
                memcpy(tss->io_bitmap, next->io_bitmap_ptr,
                       max(prev->io_bitmap_max, next->io_bitmap_max));
        } else if (test_tsk_thread_flag(prev_p, TIF_IO_BITMAP)) {
                /*
                 * Clear any possible leftover bits:
                 */
                memset(tss->io_bitmap, 0xff, prev->io_bitmap_max);
        }
        propagate_user_return_notify(prev_p, next_p);
}

/*
 * Idle related variables and functions
 */
unsigned long boot_option_idle_override = IDLE_NO_OVERRIDE;
EXPORT_SYMBOL(boot_option_idle_override);

static void (*x86_idle)(void);

#ifndef CONFIG_SMP
static inline void play_dead(void)
{
        BUG();
}
#endif

#ifdef CONFIG_X86_64
void enter_idle(void)
{
        this_cpu_write(is_idle, 1);
        atomic_notifier_call_chain(&idle_notifier, IDLE_START, NULL);
}

static void __exit_idle(void)
{
        if (x86_test_and_clear_bit_percpu(0, is_idle) == 0)
                return;
        atomic_notifier_call_chain(&idle_notifier, IDLE_END, NULL);
}

/* Called from interrupts to signify idle end */
void exit_idle(void)
{
        /* idle loop has pid 0 */
        if (current->pid)
                return;
        __exit_idle();
}
#endif

void arch_cpu_idle_enter(void)
{
        local_touch_nmi();
        enter_idle();
}

void arch_cpu_idle_exit(void)
{
        __exit_idle();
}

void arch_cpu_idle_dead(void)
{
        play_dead();
}

/*
 * Called from the generic idle code.
 */
void arch_cpu_idle(void)
{
        x86_idle();
}

/*
 * We use this if we don't have any better idle routine..
 */
void default_idle(void)
{
        trace_cpu_idle_rcuidle(1, smp_processor_id());
        safe_halt();
        trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
}
#ifdef CONFIG_APM_MODULE
EXPORT_SYMBOL(default_idle);
#endif

#ifdef CONFIG_XEN
bool xen_set_default_idle(void)
{
        bool ret = !!x86_idle;

        x86_idle = default_idle;

        return ret;
}
#endif
void stop_this_cpu(void *dummy)
{
        local_irq_disable();
        /*
         * Remove this CPU:
         */
        set_cpu_online(smp_processor_id(), false);
        disable_local_APIC();
        mcheck_cpu_clear(this_cpu_ptr(&cpu_info));

        for (;;)
                halt();
}

bool amd_e400_c1e_detected;
EXPORT_SYMBOL(amd_e400_c1e_detected);

static cpumask_var_t amd_e400_c1e_mask;

void amd_e400_remove_cpu(int cpu)
{
        if (amd_e400_c1e_mask != NULL)
                cpumask_clear_cpu(cpu, amd_e400_c1e_mask);
}

/*
 * AMD Erratum 400 aware idle routine. We check for C1E active in the interrupt
 * pending message MSR. If we detect C1E, then we handle it the same
 * way as C3 power states (local apic timer and TSC stop)
 */
static void amd_e400_idle(void)
{
        if (!amd_e400_c1e_detected) {
                u32 lo, hi;

                rdmsr(MSR_K8_INT_PENDING_MSG, lo, hi);

                if (lo & K8_INTP_C1E_ACTIVE_MASK) {
                        amd_e400_c1e_detected = true;
                        if (!boot_cpu_has(X86_FEATURE_NONSTOP_TSC))
                                mark_tsc_unstable("TSC halt in AMD C1E");
                        pr_info("System has AMD C1E enabled\n");
                }
        }

        if (amd_e400_c1e_detected) {
                int cpu = smp_processor_id();

                if (!cpumask_test_cpu(cpu, amd_e400_c1e_mask)) {
                        cpumask_set_cpu(cpu, amd_e400_c1e_mask);
                        /* Force broadcast so ACPI can not interfere. */
                        tick_broadcast_force();
                        pr_info("Switch to broadcast mode on CPU%d\n", cpu);
                }
                tick_broadcast_enter();

                default_idle();

                /*
                 * The switch back from broadcast mode needs to be
                 * called with interrupts disabled.
                 */
                local_irq_disable();
                tick_broadcast_exit();
                local_irq_enable();
        } else
                default_idle();
}

/*
 * Intel Core2 and older machines prefer MWAIT over HALT for C1.
 * We can't rely on cpuidle installing MWAIT, because it will not load
 * on systems that support only C1 -- so the boot default must be MWAIT.
 *
 * Some AMD machines are the opposite, they depend on using HALT.
 *
 * So for default C1, which is used during boot until cpuidle loads,
 * use MWAIT-C1 on Intel HW that has it, else use HALT.
 */
static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
{
        if (c->x86_vendor != X86_VENDOR_INTEL)
                return 0;

        if (!cpu_has(c, X86_FEATURE_MWAIT))
                return 0;

        return 1;
}

/*
 * MONITOR/MWAIT with no hints, used for default C1 state. This invokes MWAIT
 * with interrupts enabled and no flags, which is backwards compatible with the
 * original MWAIT implementation.
 */
static void mwait_idle(void)
{
        if (!current_set_polling_and_test()) {
                trace_cpu_idle_rcuidle(1, smp_processor_id());
                if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) {
                        smp_mb(); /* quirk */
                        clflush((void *)&current_thread_info()->flags);
                        smp_mb(); /* quirk */
                }

                __monitor((void *)&current_thread_info()->flags, 0, 0);
                if (!need_resched())
                        __sti_mwait(0, 0);
                else
                        local_irq_enable();
                trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
        } else {
                local_irq_enable();
        }
        __current_clr_polling();
}

void select_idle_routine(const struct cpuinfo_x86 *c)
{
#ifdef CONFIG_SMP
        if (boot_option_idle_override == IDLE_POLL && smp_num_siblings > 1)
                pr_warn_once("WARNING: polling idle and HT enabled, performance may degrade\n");
#endif
        if (x86_idle || boot_option_idle_override == IDLE_POLL)
                return;

        if (cpu_has_bug(c, X86_BUG_AMD_APIC_C1E)) {
                /* E400: APIC timer interrupt does not wake up CPU from C1e */
                pr_info("using AMD E400 aware idle routine\n");
                x86_idle = amd_e400_idle;
        } else if (prefer_mwait_c1_over_halt(c)) {
                pr_info("using mwait in idle threads\n");
                x86_idle = mwait_idle;
        } else
                x86_idle = default_idle;
}

void __init init_amd_e400_c1e_mask(void)
{
        /* If we're using amd_e400_idle, we need to allocate amd_e400_c1e_mask. */
        if (x86_idle == amd_e400_idle)
                zalloc_cpumask_var(&amd_e400_c1e_mask, GFP_KERNEL);
}

static int __init idle_setup(char *str)
{
        if (!str)
                return -EINVAL;

        if (!strcmp(str, "poll")) {
                pr_info("using polling idle threads\n");
                boot_option_idle_override = IDLE_POLL;
                cpu_idle_poll_ctrl(true);
        } else if (!strcmp(str, "halt")) {
                /*
                 * When the boot option of idle=halt is added, halt is
                 * forced to be used for CPU idle. In such case CPU C2/C3
                 * won't be used again.
                 * To continue to load the CPU idle driver, don't touch
                 * the boot_option_idle_override.
                 */
                x86_idle = default_idle;
                boot_option_idle_override = IDLE_HALT;
        } else if (!strcmp(str, "nomwait")) {
                /*
                 * If the boot option of "idle=nomwait" is added,
                 * it means that mwait will be disabled for CPU C2/C3
                 * states. In such case it won't touch the variable
                 * of boot_option_idle_override.
                 */
                boot_option_idle_override = IDLE_NOMWAIT;
        } else
                return -1;

        return 0;
}
early_param("idle", idle_setup);

unsigned long arch_align_stack(unsigned long sp)
{
        if (!(current->personality & ADDR_NO_RANDOMIZE) && randomize_va_space)
                sp -= get_random_int() % 8192;
        return sp & ~0xf;
}

unsigned long arch_randomize_brk(struct mm_struct *mm)
{
        unsigned long range_end = mm->brk + 0x02000000;
        return randomize_range(mm->brk, range_end, 0) ? : mm->brk;
}

/*
 * Called from fs/proc with a reference on @p to find the function
 * which called into schedule(). This needs to be done carefully
 * because the task might wake up and we might look at a stack
 * changing under us.
 */
unsigned long get_wchan(struct task_struct *p)
{
        unsigned long start, bottom, top, sp, fp, ip;
        int count = 0;

        if (!p || p == current || p->state == TASK_RUNNING)
                return 0;

        start = (unsigned long)task_stack_page(p);
        if (!start)
                return 0;

        /*
         * Layout of the stack page:
         *
         * ----------- topmax = start + THREAD_SIZE - sizeof(unsigned long)
         * PADDING
         * ----------- top = topmax - TOP_OF_KERNEL_STACK_PADDING
         * stack
         * ----------- bottom = start + sizeof(thread_info)
         * thread_info
         * ----------- start
         *
         * The tasks stack pointer points at the location where the
         * framepointer is stored. The data on the stack is:
         * ... IP FP ... IP FP
         *
         * We need to read FP and IP, so we need to adjust the upper
         * bound by another unsigned long.
         */
        top = start + THREAD_SIZE - TOP_OF_KERNEL_STACK_PADDING;
        top -= 2 * sizeof(unsigned long);
        bottom = start + sizeof(struct thread_info);

        sp = READ_ONCE(p->thread.sp);
        if (sp < bottom || sp > top)
                return 0;

        fp = READ_ONCE_NOCHECK(*(unsigned long *)sp);
        do {
                if (fp < bottom || fp > top)
                        return 0;
                ip = READ_ONCE_NOCHECK(*(unsigned long *)(fp + sizeof(unsigned long)));
                if (!in_sched_functions(ip))
                        return ip;
                fp = READ_ONCE_NOCHECK(*(unsigned long *)fp);
        } while (count++ < 16 && p->state != TASK_RUNNING);
        return 0;
}