x86.h

/*
 * ps4-kexec - a kexec() implementation for Orbis OS / FreeBSD
 *
 * Copyright (C) 2015-2016 shuffle2 <godisgovernment@gmail.com>
 * Copyright (C) 2015-2016 Hector Martin "marcan" <marcan@marcan.st>
 *
 * This code is licensed to you under the 2-clause BSD license. See the LICENSE
 * file for more information.
 */

#ifndef X86_H
#define X86_H

#define	FLAGS_IF (1 << 9)

#define CR0_WP (1 << 16)
#define CR0_NW (1 << 29)
#define CR0_CD (1 << 30)

#define	PG_V  (1 << 0)
#define PG_RW (1 << 1)
#define PG_U  (1 << 2)
#define	PG_PS (1 << 7)

#define SEG_TYPE_DATA       (0 << 3)
#define SEG_TYPE_READ_WRITE (1 << 1)
#define SEG_TYPE_CODE       (1 << 3)
#define SEG_TYPE_EXEC_READ  (1 << 1)
#define SEG_TYPE_TSS        ((1 << 3) | (1 << 0))

static inline u64 cr0_read(void)
{
    u64 reg;
    asm volatile("mov %0, cr0;" : "=r" (reg));
    return reg;
}

static inline void cr0_write(u64 val)
{
    asm volatile("mov cr0, %0;" :: "r" (val));
}

static inline u64 write_protect_disable()
{
    u64 cr0 = cr0_read();
    cr0_write(cr0 & ~CR0_WP);
    return cr0;
}

static inline void write_protect_restore(u64 cr0)
{
    // Use only WP bit of input
    cr0_write(cr0_read() | (cr0 & CR0_WP));
}

static inline u64 cr3_read(void)
{
    u64 reg;
    asm volatile("mov %0, cr3;" : "=r" (reg));
    return reg;
}

static inline void cr3_write(u64 val)
{
    asm volatile("mov cr3, %0;" :: "r" (val));
}

static inline void cr4_pge_disable(void)
{
    u64 cr4_temp;
    asm volatile(
        "mov %0, cr4;"
        "and %0, ~0x80;"
        "mov cr4, %0;"
        : "=r" (cr4_temp)
    );
}

static inline void wbinvd(void)
{
    asm volatile("wbinvd");
}

static inline void cpu_stop(void)
{
    for (;;)
        asm volatile("cli; hlt;" : : : "memory");
}

static inline void outl(int port, unsigned int data)
{
    asm volatile("out %w1, %0" : : "a" (data), "d" (port));
}

static inline void wrmsr(u32 msr_id, u64 msr_value)
{
    asm volatile(
        "wrmsr"
        :
        : "c" (msr_id), "a" (msr_value & 0xffffffff), "d" (msr_value >> 32)
        );
}

static inline u64 rdtsc (void)
{
    unsigned int tickl, tickh;
    asm volatile(
        "rdtsc"
        :"=a"(tickl),"=d"(tickh)
        );
    return ((u64)tickh << 32) | tickl;
}

static inline void udelay(unsigned int usec) {
    u64 later = rdtsc() + usec * 1594ULL;
    while (((s64)(later - rdtsc())) > 0);
}

static inline void disable_interrupts(void)
{
    asm volatile("cli");
}

static inline void enable_interrupts(void)
{
    asm volatile("sti");
}

static inline u64 read_flags(void)
{
    u64 flags;
    asm volatile("pushf; pop %0;" : "=r" (flags));
    return flags;
}

static inline u64 intr_disable(void)
{
    u64 flags = read_flags();
    disable_interrupts();
    return flags;
}

static inline void intr_restore(u64 flags)
{
    // TODO should only IF be or'd in?
    asm volatile("push %0; popf;" : : "rm" (flags) : "memory");
}

#endif