/*
 * Suspend support specific for i386/x86-64.
 *
 * Distribute under GPLv2
 *
 * Copyright (c) 2007 Rafael J. Wysocki <rjw@sisk.pl>
 * Copyright (c) 2002 Pavel Machek <pavel@ucw.cz>
 * Copyright (c) 2001 Patrick Mochel <mochel@osdl.org>
 */

#include <linux/suspend.h>
#include <linux/export.h>
#include <linux/smp.h>
#include <linux/perf_event.h>
#include <linux/tboot.h>

#include <asm/pgtable.h>
#include <asm/proto.h>
#include <asm/mtrr.h>
#include <asm/page.h>
#include <asm/mce.h>
#include <asm/suspend.h>
#include <asm/fpu/internal.h>
#include <asm/debugreg.h>
#include <asm/cpu.h>
#include <asm/mmu_context.h>
#include <linux/dmi.h>

#ifdef CONFIG_X86_32
__visible unsigned long saved_context_ebx;
__visible unsigned long saved_context_esp, saved_context_ebp;
__visible unsigned long saved_context_esi, saved_context_edi;
__visible unsigned long saved_context_eflags;
#endif
struct saved_context saved_context;

static void msr_save_context(struct saved_context *ctxt)
{
        struct saved_msr *msr = ctxt->saved_msrs.array;
        struct saved_msr *end = msr + ctxt->saved_msrs.num;

        while (msr < end) {
                msr->valid = !rdmsrl_safe(msr->info.msr_no, &msr->info.reg.q);
                msr++;
        }
}

static void msr_restore_context(struct saved_context *ctxt)
{
        struct saved_msr *msr = ctxt->saved_msrs.array;
        struct saved_msr *end = msr + ctxt->saved_msrs.num;

        while (msr < end) {
                if (msr->valid)
                        wrmsrl(msr->info.msr_no, msr->info.reg.q);
                msr++;
        }
}

/**
 *      __save_processor_state - save CPU registers before creating a
 *              hibernation image and before restoring the memory state from it
 *      @ctxt - structure to store the registers contents in
 *
 *      NOTE: If there is a CPU register the modification of which by the
 *      boot kernel (ie. the kernel used for loading the hibernation image)
 *      might affect the operations of the restored target kernel (ie. the one
 *      saved in the hibernation image), then its contents must be saved by this
 *      function.  In other words, if kernel A is hibernated and different
 *      kernel B is used for loading the hibernation image into memory, the
 *      kernel A's __save_processor_state() function must save all registers
 *      needed by kernel A, so that it can operate correctly after the resume
 *      regardless of what kernel B does in the meantime.
 */
static void __save_processor_state(struct saved_context *ctxt)
{
#ifdef CONFIG_X86_32
        mtrr_save_fixed_ranges(NULL);
#endif
        kernel_fpu_begin();

        /*
         * descriptor tables
         */
        store_idt(&ctxt->idt);

        /*
         * We save it here, but restore it only in the hibernate case.
         * For ACPI S3 resume, this is loaded via 'early_gdt_desc' in 64-bit
         * mode in "secondary_startup_64". In 32-bit mode it is done via
         * 'pmode_gdt' in wakeup_start.
         */
        ctxt->gdt_desc.size = GDT_SIZE - 1;
        ctxt->gdt_desc.address = (unsigned long)get_cpu_gdt_rw(smp_processor_id());

        store_tr(ctxt->tr);

        /* XMM0..XMM15 should be handled by kernel_fpu_begin(). */
        /*
         * segment registers
         */
#ifdef CONFIG_X86_32_LAZY_GS
        savesegment(gs, ctxt->gs);
#endif
#ifdef CONFIG_X86_64
        savesegment(gs, ctxt->gs);
        savesegment(fs, ctxt->fs);
        savesegment(ds, ctxt->ds);
        savesegment(es, ctxt->es);

        rdmsrl(MSR_FS_BASE, ctxt->fs_base);
        rdmsrl(MSR_GS_BASE, ctxt->kernelmode_gs_base);
        rdmsrl(MSR_KERNEL_GS_BASE, ctxt->usermode_gs_base);
        mtrr_save_fixed_ranges(NULL);

        rdmsrl(MSR_EFER, ctxt->efer);
#endif

        /*
         * control registers
         */
        ctxt->cr0 = read_cr0();
        ctxt->cr2 = read_cr2();
        ctxt->cr3 = __read_cr3();
        ctxt->cr4 = __read_cr4();
#ifdef CONFIG_X86_64
        ctxt->cr8 = read_cr8();
#endif
        ctxt->misc_enable_saved = !rdmsrl_safe(MSR_IA32_MISC_ENABLE,
                                               &ctxt->misc_enable);
        msr_save_context(ctxt);
}

/* Needed by apm.c */
void save_processor_state(void)
{
        __save_processor_state(&saved_context);
        x86_platform.save_sched_clock_state();
}
#ifdef CONFIG_X86_32
EXPORT_SYMBOL(save_processor_state);
#endif

static void do_fpu_end(void)
{
        /*
         * Restore FPU regs if necessary.
         */
        kernel_fpu_end();
}

static void fix_processor_context(void)
{
        int cpu = smp_processor_id();
#ifdef CONFIG_X86_64
        struct desc_struct *desc = get_cpu_gdt_rw(cpu);
        tss_desc tss;
#endif

        /*
         * We need to reload TR, which requires that we change the
         * GDT entry to indicate "available" first.
         *
         * XXX: This could probably all be replaced by a call to
         * force_reload_TR().
         */
        set_tss_desc(cpu, &get_cpu_entry_area(cpu)->tss.x86_tss);

#ifdef CONFIG_X86_64
        memcpy(&tss, &desc[GDT_ENTRY_TSS], sizeof(tss_desc));
        tss.type = 0x9; /* The available 64-bit TSS (see AMD vol 2, pg 91 */
        write_gdt_entry(desc, GDT_ENTRY_TSS, &tss, DESC_TSS);

        syscall_init();                         /* This sets MSR_*STAR and related */
#else
        if (boot_cpu_has(X86_FEATURE_SEP))
                enable_sep_cpu();
#endif
        load_TR_desc();                         /* This does ltr */
        load_mm_ldt(current->active_mm);        /* This does lldt */
        initialize_tlbstate_and_flush();

        fpu__resume_cpu();

        /* The processor is back on the direct GDT, load back the fixmap */
        load_fixmap_gdt(cpu);
}

/**
 * __restore_processor_state - restore the contents of CPU registers saved
 *                             by __save_processor_state()
 * @ctxt - structure to load the registers contents from
 *
 * The asm code that gets us here will have restored a usable GDT, although
 * it will be pointing to the wrong alias.
 */
static void notrace __restore_processor_state(struct saved_context *ctxt)
{
        if (ctxt->misc_enable_saved)
                wrmsrl(MSR_IA32_MISC_ENABLE, ctxt->misc_enable);
        /*
         * control registers
         */
        /* cr4 was introduced in the Pentium CPU */
#ifdef CONFIG_X86_32
        if (ctxt->cr4)
                __write_cr4(ctxt->cr4);
#else
/* CONFIG X86_64 */
        wrmsrl(MSR_EFER, ctxt->efer);
        write_cr8(ctxt->cr8);
        __write_cr4(ctxt->cr4);
#endif
        write_cr3(ctxt->cr3);
        write_cr2(ctxt->cr2);
        write_cr0(ctxt->cr0);

        /* Restore the IDT. */
        load_idt(&ctxt->idt);

        /*
         * Just in case the asm code got us here with the SS, DS, or ES
         * out of sync with the GDT, update them.
         */
        loadsegment(ss, __KERNEL_DS);
        loadsegment(ds, __USER_DS);
        loadsegment(es, __USER_DS);

        /*
         * Restore percpu access.  Percpu access can happen in exception
         * handlers or in complicated helpers like load_gs_index().
         */
#ifdef CONFIG_X86_64
        wrmsrl(MSR_GS_BASE, ctxt->kernelmode_gs_base);
#else
        loadsegment(fs, __KERNEL_PERCPU);
        loadsegment(gs, __KERNEL_STACK_CANARY);
#endif

        /* Restore the TSS, RO GDT, LDT, and usermode-relevant MSRs. */
        fix_processor_context();

        /*
         * Now that we have descriptor tables fully restored and working
         * exception handling, restore the usermode segments.
         */
#ifdef CONFIG_X86_64
        loadsegment(ds, ctxt->es);
        loadsegment(es, ctxt->es);
        loadsegment(fs, ctxt->fs);
        load_gs_index(ctxt->gs);

        /*
         * Restore FSBASE and GSBASE after restoring the selectors, since
         * restoring the selectors clobbers the bases.  Keep in mind
         * that MSR_KERNEL_GS_BASE is horribly misnamed.
         */
        wrmsrl(MSR_FS_BASE, ctxt->fs_base);
        wrmsrl(MSR_KERNEL_GS_BASE, ctxt->usermode_gs_base);
#elif defined(CONFIG_X86_32_LAZY_GS)
        loadsegment(gs, ctxt->gs);
#endif

        do_fpu_end();
        tsc_verify_tsc_adjust(true);
        x86_platform.restore_sched_clock_state();
        mtrr_bp_restore();
        perf_restore_debug_store();
        msr_restore_context(ctxt);
}

/* Needed by apm.c */
void notrace restore_processor_state(void)
{
        __restore_processor_state(&saved_context);
}
#ifdef CONFIG_X86_32
EXPORT_SYMBOL(restore_processor_state);
#endif

#if defined(CONFIG_HIBERNATION) && defined(CONFIG_HOTPLUG_CPU)
static void resume_play_dead(void)
{
        play_dead_common();
        tboot_shutdown(TB_SHUTDOWN_WFS);
        hlt_play_dead();
}

int hibernate_resume_nonboot_cpu_disable(void)
{
        void (*play_dead)(void) = smp_ops.play_dead;
        int ret;

        /*
         * Ensure that MONITOR/MWAIT will not be used in the "play dead" loop
         * during hibernate image restoration, because it is likely that the
         * monitored address will be actually written to at that time and then
         * the "dead" CPU will attempt to execute instructions again, but the
         * address in its instruction pointer may not be possible to resolve
         * any more at that point (the page tables used by it previously may
         * have been overwritten by hibernate image data).
         */
        smp_ops.play_dead = resume_play_dead;
        ret = disable_nonboot_cpus();
        smp_ops.play_dead = play_dead;
        return ret;
}
#endif

/*
 * When bsp_check() is called in hibernate and suspend, cpu hotplug
 * is disabled already. So it's unnessary to handle race condition between
 * cpumask query and cpu hotplug.
 */
static int bsp_check(void)
{
        if (cpumask_first(cpu_online_mask) != 0) {
                pr_warn("CPU0 is offline.\n");
                return -ENODEV;
        }

        return 0;
}

static int bsp_pm_callback(struct notifier_block *nb, unsigned long action,
                           void *ptr)
{
        int ret = 0;

        switch (action) {
        case PM_SUSPEND_PREPARE:
        case PM_HIBERNATION_PREPARE:
                ret = bsp_check();
                break;
#ifdef CONFIG_DEBUG_HOTPLUG_CPU0
        case PM_RESTORE_PREPARE:
                /*
                 * When system resumes from hibernation, online CPU0 because
                 * 1. it's required for resume and
                 * 2. the CPU was online before hibernation
                 */
                if (!cpu_online(0))
                        _debug_hotplug_cpu(0, 1);
                break;
        case PM_POST_RESTORE:
                /*
                 * When a resume really happens, this code won't be called.
                 *
                 * This code is called only when user space hibernation software
                 * prepares for snapshot device during boot time. So we just
                 * call _debug_hotplug_cpu() to restore to CPU0's state prior to
                 * preparing the snapshot device.
                 *
                 * This works for normal boot case in our CPU0 hotplug debug
                 * mode, i.e. CPU0 is offline and user mode hibernation
                 * software initializes during boot time.
                 *
                 * If CPU0 is online and user application accesses snapshot
                 * device after boot time, this will offline CPU0 and user may
                 * see different CPU0 state before and after accessing
                 * the snapshot device. But hopefully this is not a case when
                 * user debugging CPU0 hotplug. Even if users hit this case,
                 * they can easily online CPU0 back.
                 *
                 * To simplify this debug code, we only consider normal boot
                 * case. Otherwise we need to remember CPU0's state and restore
                 * to that state and resolve racy conditions etc.
                 */
                _debug_hotplug_cpu(0, 0);
                break;
#endif
        default:
                break;
        }
        return notifier_from_errno(ret);
}

static int __init bsp_pm_check_init(void)
{
        /*
         * Set this bsp_pm_callback as lower priority than
         * cpu_hotplug_pm_callback. So cpu_hotplug_pm_callback will be called
         * earlier to disable cpu hotplug before bsp online check.
         */
        pm_notifier(bsp_pm_callback, -INT_MAX);
        return 0;
}

core_initcall(bsp_pm_check_init);

static int msr_init_context(const u32 *msr_id, const int total_num)
{
        int i = 0;
        struct saved_msr *msr_array;

        if (saved_context.saved_msrs.array || saved_context.saved_msrs.num > 0) {
                pr_err("x86/pm: MSR quirk already applied, please check your DMI match table.\n");
                return -EINVAL;
        }

        msr_array = kmalloc_array(total_num, sizeof(struct saved_msr), GFP_KERNEL);
        if (!msr_array) {
                pr_err("x86/pm: Can not allocate memory to save/restore MSRs during suspend.\n");
                return -ENOMEM;
        }

        for (i = 0; i < total_num; i++) {
                msr_array[i].info.msr_no        = msr_id[i];
                msr_array[i].valid              = false;
                msr_array[i].info.reg.q         = 0;
        }
        saved_context.saved_msrs.num    = total_num;
        saved_context.saved_msrs.array  = msr_array;

        return 0;
}

/*
 * The following section is a quirk framework for problematic BIOSen:
 * Sometimes MSRs are modified by the BIOSen after suspended to
 * RAM, this might cause unexpected behavior after wakeup.
 * Thus we save/restore these specified MSRs across suspend/resume
 * in order to work around it.
 *
 * For any further problematic BIOSen/platforms,
 * please add your own function similar to msr_initialize_bdw.
 */
static int msr_initialize_bdw(const struct dmi_system_id *d)
{
        /* Add any extra MSR ids into this array. */
        u32 bdw_msr_id[] = { MSR_IA32_THERM_CONTROL };

        pr_info("x86/pm: %s detected, MSR saving is needed during suspending.\n", d->ident);
        return msr_init_context(bdw_msr_id, ARRAY_SIZE(bdw_msr_id));
}

static const struct dmi_system_id msr_save_dmi_table[] = {
        {
         .callback = msr_initialize_bdw,
         .ident = "BROADWELL BDX_EP",
         .matches = {
                DMI_MATCH(DMI_PRODUCT_NAME, "GRANTLEY"),
                DMI_MATCH(DMI_PRODUCT_VERSION, "E63448-400"),
                },
        },
        {}
};

static int pm_check_save_msr(void)
{
        dmi_check_system(msr_save_dmi_table);
        return 0;
}

device_initcall(pm_check_save_msr);