nes-proj/cpu/x86/mm/segmentation.h

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/*
* Copyright (C) 2015, Intel Corporation. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the copyright holder nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#ifndef CPU_X86_MM_SEGMENTATION_H_
#define CPU_X86_MM_SEGMENTATION_H_
#include <stdint.h>
#define SEG_FLAG(lbl, val) \
(((val) & (~0u >> (32 - SEG_WIDTH_##lbl))) << SEG_SHAMT_##lbl)
#define SEG_SET_FLAG(desc, lbl, val) \
(desc).flags = ((desc).flags & ~SEG_FLAG(lbl, ~0u)) | SEG_FLAG(lbl, val)
#define SEG_WIDTH_TYPE 4
#define SEG_SHAMT_TYPE 0
#define SEG_WIDTH_DESCTYPE 1
#define SEG_SHAMT_DESCTYPE 4
#define SEG_WIDTH_DPL 2
#define SEG_SHAMT_DPL 5
#define SEG_WIDTH_PRESENT 1
#define SEG_SHAMT_PRESENT 7
#define SEG_WIDTH_LIMIT_HI 4
#define SEG_SHAMT_LIMIT_HI 8
#define SEG_WIDTH_AVL 1
#define SEG_SHAMT_AVL 12
#define SEG_WIDTH_LONG_MODE 1
#define SEG_SHAMT_LONG_MODE 13
/* also used to indicate default operand and address size */
#define SEG_WIDTH_DIRECTION 1
#define SEG_SHAMT_DIRECTION 14
#define SEG_WIDTH_GRAN 1
#define SEG_SHAMT_GRAN 15
#define SEG_TYPE_DATA_RDONLY SEG_FLAG(TYPE, 0x00) /* Read only */
#define SEG_TYPE_DATA_RDWR SEG_FLAG(TYPE, 0x02) /* Read/Write */
#define SEG_TYPE_CODE_EXRD SEG_FLAG(TYPE, 0x0A) /* Execute/Read */
#define SEG_TYPE_CODE_EX SEG_FLAG(TYPE, 0x08) /* Execute only */
#define SEG_TYPE_LDT SEG_FLAG(TYPE, 0x02)
#define SEG_TYPE_TSS32_AVAIL SEG_FLAG(TYPE, 0x09)
#define SEG_DESCTYPE_SYS SEG_FLAG(DESCTYPE, 0)
#define SEG_DESCTYPE_NSYS SEG_FLAG(DESCTYPE, 1)
#define SEG_PRESENT SEG_FLAG(PRESENT, 1)
#define SEG_DEFL_OPSZ_32BIT SEG_FLAG(DIRECTION, 1)
#define SEG_GRAN_BYTE SEG_FLAG(GRAN, 0)
#define SEG_GRAN_PAGE SEG_FLAG(GRAN, 1)
/**
* Maximum length of segment that can be regulated with a byte-granularity
* segment limit.
*/
#define SEG_MAX_BYTE_GRAN_LEN (1 << 20)
/**
* Segment descriptor. See Intel Combined Manual,
* Vol. 3, Section 3.4.5 for more details.
*/
typedef union segment_desc {
struct {
uint32_t lim_lo : 16;
uint32_t base_lo : 16;
uint32_t base_mid : 8;
uint32_t flags : 16;
uint32_t base_hi : 8;
};
struct {
uint32_t raw_lo, raw_hi;
};
uint64_t raw;
} segment_desc_t;
#define SEG_DESC_NOT_PRESENT 0
/* The next two functions are invoked by boot code, so they must always be
* inlined to avoid being placed in a different address space than the initial,
* flat address space.
*/
static inline void __attribute__((always_inline))
segment_desc_set_limit(segment_desc_t *c_this, uint32_t len)
{
uint32_t limit = len - 1;
SEG_SET_FLAG(*c_this, LIMIT_HI, limit >> 16); /* set limit bits 19:16 */
c_this->lim_lo = limit; /* set limit bits 15:0 */
}
/**
* \brief Initialize a segment descriptor.
* \param c_this Segment descriptor to be initialized.
* \param base Base address of region to be covered by segment descriptor.
* \param len Length to be specified by segment descriptor. The units may
* be bytes or pages, depending on the flags.
* \param flags Flags to be added to the default flags: present, default
* operand size of 32 bits, and high limit bits.
*/
static inline void __attribute__((always_inline))
segment_desc_init(segment_desc_t *c_this,
uint32_t base, uint32_t len, uint16_t flags)
{
c_this->raw = 0;
/* Create the high 32 bit segment */
c_this->base_mid = base >> 16; /* set base bits 23:16 */
c_this->base_hi = base >> 24; /* set base bits 31:24 */
/* Create the low 32 bit segment */
c_this->base_lo = base; /* set base bits 15:0 */
c_this->flags = SEG_FLAG(PRESENT, 1) | SEG_DEFL_OPSZ_32BIT | flags;
/* This must be done after setting the other flags, or else it
* would be partially overridden.
*/
segment_desc_set_limit(c_this, len);
}
#endif /* CPU_X86_MM_SEGMENTATION_H_ */