/*  Paravirtualization interfaces
    Copyright (C) 2006 Rusty Russell IBM Corporation

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    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, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA

    2007 - x86_64 support added by Glauber de Oliveira Costa, Red Hat Inc
*/

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/export.h>
#include <linux/efi.h>
#include <linux/bcd.h>
#include <linux/highmem.h>
#include <linux/kprobes.h>

#include <asm/bug.h>
#include <asm/paravirt.h>
#include <asm/debugreg.h>
#include <asm/desc.h>
#include <asm/setup.h>
#include <asm/pgtable.h>
#include <asm/time.h>
#include <asm/pgalloc.h>
#include <asm/irq.h>
#include <asm/delay.h>
#include <asm/fixmap.h>
#include <asm/apic.h>
#include <asm/tlbflush.h>
#include <asm/timer.h>
#include <asm/special_insns.h>

/*
 * nop stub, which must not clobber anything *including the stack* to
 * avoid confusing the entry prologues.
 */
extern void _paravirt_nop(void);
asm (".pushsection .entry.text, \"ax\"\n"
     ".global _paravirt_nop\n"
     "_paravirt_nop:\n\t"
     "ret\n\t"
     ".size _paravirt_nop, . - _paravirt_nop\n\t"
     ".type _paravirt_nop, @function\n\t"
     ".popsection");

/* identity function, which can be inlined */
u32 notrace _paravirt_ident_32(u32 x)
{
        return x;
}

u64 notrace _paravirt_ident_64(u64 x)
{
        return x;
}

void __init default_banner(void)
{
        printk(KERN_INFO "Booting paravirtualized kernel on %s\n",
               pv_info.name);
}

/* Undefined instruction for dealing with missing ops pointers. */
static const unsigned char ud2a[] = { 0x0f, 0x0b };

struct branch {
        unsigned char opcode;
        u32 delta;
} __attribute__((packed));

unsigned paravirt_patch_call(void *insnbuf,
                             const void *target, u16 tgt_clobbers,
                             unsigned long addr, u16 site_clobbers,
                             unsigned len)
{
        struct branch *b = insnbuf;
        unsigned long delta = (unsigned long)target - (addr+5);

        if (tgt_clobbers & ~site_clobbers)
                return len;     /* target would clobber too much for this site */
        if (len < 5)
                return len;     /* call too long for patch site */

        b->opcode = 0xe8; /* call */
        b->delta = delta;
        BUILD_BUG_ON(sizeof(*b) != 5);

        return 5;
}

unsigned paravirt_patch_jmp(void *insnbuf, const void *target,
                            unsigned long addr, unsigned len)
{
        struct branch *b = insnbuf;
        unsigned long delta = (unsigned long)target - (addr+5);

        if (len < 5)
                return len;     /* call too long for patch site */

        b->opcode = 0xe9;       /* jmp */
        b->delta = delta;

        return 5;
}

/* Neat trick to map patch type back to the call within the
 * corresponding structure. */
static void *get_call_destination(u8 type)
{
        struct paravirt_patch_template tmpl = {
                .pv_init_ops = pv_init_ops,
                .pv_time_ops = pv_time_ops,
                .pv_cpu_ops = pv_cpu_ops,
                .pv_irq_ops = pv_irq_ops,
                .pv_mmu_ops = pv_mmu_ops,
#ifdef CONFIG_PARAVIRT_SPINLOCKS
                .pv_lock_ops = pv_lock_ops,
#endif
        };
        return *((void **)&tmpl + type);
}

unsigned paravirt_patch_default(u8 type, u16 clobbers, void *insnbuf,
                                unsigned long addr, unsigned len)
{
        void *opfunc = get_call_destination(type);
        unsigned ret;

        if (opfunc == NULL)
                /* If there's no function, patch it with a ud2a (BUG) */
                ret = paravirt_patch_insns(insnbuf, len, ud2a, ud2a+sizeof(ud2a));
        else if (opfunc == _paravirt_nop)
                ret = 0;

        /* identity functions just return their single argument */
        else if (opfunc == _paravirt_ident_32)
                ret = paravirt_patch_ident_32(insnbuf, len);
        else if (opfunc == _paravirt_ident_64)
                ret = paravirt_patch_ident_64(insnbuf, len);

        else if (type == PARAVIRT_PATCH(pv_cpu_ops.iret) ||
                 type == PARAVIRT_PATCH(pv_cpu_ops.usergs_sysret64))
                /* If operation requires a jmp, then jmp */
                ret = paravirt_patch_jmp(insnbuf, opfunc, addr, len);
        else
                /* Otherwise call the function; assume target could
                   clobber any caller-save reg */
                ret = paravirt_patch_call(insnbuf, opfunc, CLBR_ANY,
                                          addr, clobbers, len);

        return ret;
}

unsigned paravirt_patch_insns(void *insnbuf, unsigned len,
                              const char *start, const char *end)
{
        unsigned insn_len = end - start;

        if (insn_len > len || start == NULL)
                insn_len = len;
        else
                memcpy(insnbuf, start, insn_len);

        return insn_len;
}

static void native_flush_tlb(void)
{
        __native_flush_tlb();
}

/*
 * Global pages have to be flushed a bit differently. Not a real
 * performance problem because this does not happen often.
 */
static void native_flush_tlb_global(void)
{
        __native_flush_tlb_global();
}

static void native_flush_tlb_single(unsigned long addr)
{
        __native_flush_tlb_single(addr);
}

struct static_key paravirt_steal_enabled;
struct static_key paravirt_steal_rq_enabled;

static u64 native_steal_clock(int cpu)
{
        return 0;
}

/* These are in entry.S */
extern void native_iret(void);
extern void native_usergs_sysret64(void);

static struct resource reserve_ioports = {
        .start = 0,
        .end = IO_SPACE_LIMIT,
        .name = "paravirt-ioport",
        .flags = IORESOURCE_IO | IORESOURCE_BUSY,
};

/*
 * Reserve the whole legacy IO space to prevent any legacy drivers
 * from wasting time probing for their hardware.  This is a fairly
 * brute-force approach to disabling all non-virtual drivers.
 *
 * Note that this must be called very early to have any effect.
 */
int paravirt_disable_iospace(void)
{
        return request_resource(&ioport_resource, &reserve_ioports);
}

static DEFINE_PER_CPU(enum paravirt_lazy_mode, paravirt_lazy_mode) = PARAVIRT_LAZY_NONE;

static inline void enter_lazy(enum paravirt_lazy_mode mode)
{
        BUG_ON(this_cpu_read(paravirt_lazy_mode) != PARAVIRT_LAZY_NONE);

        this_cpu_write(paravirt_lazy_mode, mode);
}

static void leave_lazy(enum paravirt_lazy_mode mode)
{
        BUG_ON(this_cpu_read(paravirt_lazy_mode) != mode);

        this_cpu_write(paravirt_lazy_mode, PARAVIRT_LAZY_NONE);
}

void paravirt_enter_lazy_mmu(void)
{
        enter_lazy(PARAVIRT_LAZY_MMU);
}

void paravirt_leave_lazy_mmu(void)
{
        leave_lazy(PARAVIRT_LAZY_MMU);
}

void paravirt_flush_lazy_mmu(void)
{
        preempt_disable();

        if (paravirt_get_lazy_mode() == PARAVIRT_LAZY_MMU) {
                arch_leave_lazy_mmu_mode();
                arch_enter_lazy_mmu_mode();
        }

        preempt_enable();
}

void paravirt_start_context_switch(struct task_struct *prev)
{
        BUG_ON(preemptible());

        if (this_cpu_read(paravirt_lazy_mode) == PARAVIRT_LAZY_MMU) {
                arch_leave_lazy_mmu_mode();
                set_ti_thread_flag(task_thread_info(prev), TIF_LAZY_MMU_UPDATES);
        }
        enter_lazy(PARAVIRT_LAZY_CPU);
}

void paravirt_end_context_switch(struct task_struct *next)
{
        BUG_ON(preemptible());

        leave_lazy(PARAVIRT_LAZY_CPU);

        if (test_and_clear_ti_thread_flag(task_thread_info(next), TIF_LAZY_MMU_UPDATES))
                arch_enter_lazy_mmu_mode();
}

enum paravirt_lazy_mode paravirt_get_lazy_mode(void)
{
        if (in_interrupt())
                return PARAVIRT_LAZY_NONE;

        return this_cpu_read(paravirt_lazy_mode);
}

struct pv_info pv_info = {
        .name = "bare hardware",
        .kernel_rpl = 0,
        .shared_kernel_pmd = 1, /* Only used when CONFIG_X86_PAE is set */

#ifdef CONFIG_X86_64
        .extra_user_64bit_cs = __USER_CS,
#endif
};

struct pv_init_ops pv_init_ops = {
        .patch = native_patch,
};

struct pv_time_ops pv_time_ops = {
        .sched_clock = native_sched_clock,
        .steal_clock = native_steal_clock,
};

__visible struct pv_irq_ops pv_irq_ops = {
        .save_fl = __PV_IS_CALLEE_SAVE(native_save_fl),
        .restore_fl = __PV_IS_CALLEE_SAVE(native_restore_fl),
        .irq_disable = __PV_IS_CALLEE_SAVE(native_irq_disable),
        .irq_enable = __PV_IS_CALLEE_SAVE(native_irq_enable),
        .safe_halt = native_safe_halt,
        .halt = native_halt,
#ifdef CONFIG_X86_64
        .adjust_exception_frame = paravirt_nop,
#endif
};

__visible struct pv_cpu_ops pv_cpu_ops = {
        .cpuid = native_cpuid,
        .get_debugreg = native_get_debugreg,
        .set_debugreg = native_set_debugreg,
        .read_cr0 = native_read_cr0,
        .write_cr0 = native_write_cr0,
        .read_cr4 = native_read_cr4,
        .write_cr4 = native_write_cr4,
#ifdef CONFIG_X86_64
        .read_cr8 = native_read_cr8,
        .write_cr8 = native_write_cr8,
#endif
        .wbinvd = native_wbinvd,
        .read_msr = native_read_msr,
        .write_msr = native_write_msr,
        .read_msr_safe = native_read_msr_safe,
        .write_msr_safe = native_write_msr_safe,
        .read_pmc = native_read_pmc,
        .load_tr_desc = native_load_tr_desc,
        .set_ldt = native_set_ldt,
        .load_gdt = native_load_gdt,
        .load_idt = native_load_idt,
        .store_idt = native_store_idt,
        .store_tr = native_store_tr,
        .load_tls = native_load_tls,
#ifdef CONFIG_X86_64
        .load_gs_index = native_load_gs_index,
#endif
        .write_ldt_entry = native_write_ldt_entry,
        .write_gdt_entry = native_write_gdt_entry,
        .write_idt_entry = native_write_idt_entry,

        .alloc_ldt = paravirt_nop,
        .free_ldt = paravirt_nop,

        .load_sp0 = native_load_sp0,

#ifdef CONFIG_X86_64
        .usergs_sysret64 = native_usergs_sysret64,
#endif
        .iret = native_iret,
        .swapgs = native_swapgs,

        .set_iopl_mask = native_set_iopl_mask,
        .io_delay = native_io_delay,

        .start_context_switch = paravirt_nop,
        .end_context_switch = paravirt_nop,
};

/* At this point, native_get/set_debugreg has real function entries */
NOKPROBE_SYMBOL(native_get_debugreg);
NOKPROBE_SYMBOL(native_set_debugreg);
NOKPROBE_SYMBOL(native_load_idt);

#if defined(CONFIG_X86_32) && !defined(CONFIG_X86_PAE)
/* 32-bit pagetable entries */
#define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_32)
#else
/* 64-bit pagetable entries */
#define PTE_IDENT       __PV_IS_CALLEE_SAVE(_paravirt_ident_64)
#endif

struct pv_mmu_ops pv_mmu_ops __ro_after_init = {

        .read_cr2 = native_read_cr2,
        .write_cr2 = native_write_cr2,
        .read_cr3 = __native_read_cr3,
        .write_cr3 = native_write_cr3,

        .flush_tlb_user = native_flush_tlb,
        .flush_tlb_kernel = native_flush_tlb_global,
        .flush_tlb_single = native_flush_tlb_single,
        .flush_tlb_others = native_flush_tlb_others,

        .pgd_alloc = __paravirt_pgd_alloc,
        .pgd_free = paravirt_nop,

        .alloc_pte = paravirt_nop,
        .alloc_pmd = paravirt_nop,
        .alloc_pud = paravirt_nop,
        .alloc_p4d = paravirt_nop,
        .release_pte = paravirt_nop,
        .release_pmd = paravirt_nop,
        .release_pud = paravirt_nop,
        .release_p4d = paravirt_nop,

        .set_pte = native_set_pte,
        .set_pte_at = native_set_pte_at,
        .set_pmd = native_set_pmd,
        .set_pmd_at = native_set_pmd_at,
        .pte_update = paravirt_nop,

        .ptep_modify_prot_start = __ptep_modify_prot_start,
        .ptep_modify_prot_commit = __ptep_modify_prot_commit,

#if CONFIG_PGTABLE_LEVELS >= 3
#ifdef CONFIG_X86_PAE
        .set_pte_atomic = native_set_pte_atomic,
        .pte_clear = native_pte_clear,
        .pmd_clear = native_pmd_clear,
#endif
        .set_pud = native_set_pud,
        .set_pud_at = native_set_pud_at,

        .pmd_val = PTE_IDENT,
        .make_pmd = PTE_IDENT,

#if CONFIG_PGTABLE_LEVELS >= 4
        .pud_val = PTE_IDENT,
        .make_pud = PTE_IDENT,

        .set_p4d = native_set_p4d,

#if CONFIG_PGTABLE_LEVELS >= 5
        .p4d_val = PTE_IDENT,
        .make_p4d = PTE_IDENT,

        .set_pgd = native_set_pgd,
#endif /* CONFIG_PGTABLE_LEVELS >= 5 */
#endif /* CONFIG_PGTABLE_LEVELS >= 4 */
#endif /* CONFIG_PGTABLE_LEVELS >= 3 */

        .pte_val = PTE_IDENT,
        .pgd_val = PTE_IDENT,

        .make_pte = PTE_IDENT,
        .make_pgd = PTE_IDENT,

        .dup_mmap = paravirt_nop,
        .exit_mmap = paravirt_nop,
        .activate_mm = paravirt_nop,

        .lazy_mode = {
                .enter = paravirt_nop,
                .leave = paravirt_nop,
                .flush = paravirt_nop,
        },

        .set_fixmap = native_set_fixmap,
};

EXPORT_SYMBOL_GPL(pv_time_ops);
EXPORT_SYMBOL    (pv_cpu_ops);
EXPORT_SYMBOL    (pv_mmu_ops);
EXPORT_SYMBOL_GPL(pv_info);
EXPORT_SYMBOL    (pv_irq_ops);