visor/include/x86/gdt.h

#ifndef _VISOR_GDT_H_
#define _VISOR_GDT_H_

#include <stdint.h>
#include <stdbool.h>

__attribute__ ((packed))
struct segdescr {
	uint16_t limit0;
	uint16_t base0;
	uint8_t  base1;
	uint8_t  access;
	uint8_t  flags;
	uint8_t  base2;
};

__attribute__ ((packed))
struct GDTR {
	uint16_t limit;
	struct segdescr *base;
};

__attribute__ ((packed))
struct TSS {
	uint32_t reserved0;
	uint64_t rsp0;
	uint64_t rsp1;
	uint64_t rsp2;
	uint64_t reserved1;
	uint64_t ist1;
	uint64_t ist2;
	uint64_t ist3;
	uint64_t ist4;
	uint64_t ist5;
	uint64_t ist6;
	uint64_t ist7;
	uint64_t reserved2;
	uint16_t reserved3;
	uint16_t iopb;
};

static inline struct GDTR
storegdt(void)
{
	struct GDTR gdtr;
	__asm__ ("sgdt %0\n\t" : "=m"(gdtr));
	return gdtr;
}

static inline void
setsegdescr(struct segdescr *descr, uint32_t base, uint32_t limit, uint8_t access, uint8_t flags)
{
	descr->limit0   = limit;
	descr->base0    = base;
	descr->base1    = base >> 16;
	descr->access   = access;
	descr->flags    = flags | (limit >> 16);
	descr->base2    = base >> 24;
}

static inline uint32_t
getsegbase(struct segdescr *descr)
{
	return descr->base0 | ((uint32_t)descr->base1 << 16) | ((uint32_t)descr->base2 << 24);
}

static inline uint32_t
getsegbaseext(struct segdescr *descr)
{
	uint32_t *words = (void *)descr;
	return words[0];
}

static inline uint32_t
getseglimit(struct segdescr *descr)
{
	return descr->limit0 | ((uint32_t)(descr->flags & 0xf) << 16);
}

static inline uint32_t
getsegaccess(struct segdescr *descr, bool unusable)
{
	uint32_t *words = (void *)descr;
	return (words[1] & 0x00ffffff) | (unusable ? 0x10000 : 0);
}

#endif