nes-proj/cpu/x86/init/common/gdt.c

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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.
*/
#include <stdint.h>
#include "gdt.h"
#include "gdt-layout.h"
#include "helpers.h"
#include "prot-domains.h"
#include "segmentation.h"
#define GDT_MEM_PL0 (SEG_DESCTYPE_NSYS | SEG_GRAN_PAGE)
#define GDT_CODE_PL0 (GDT_MEM_PL0 | SEG_TYPE_CODE_EXRD)
#define GDT_DATA_PL0 (GDT_MEM_PL0 | SEG_TYPE_DATA_RDWR)
typedef struct gdtr
{
uint16_t limit;
uint32_t base;
} __attribute__((packed)) gdtr_t;
/* From Intel Combined Manual, Vol. 3 , Section 3.5.1: The base addresses of
* the GDT should be aligned on an eight-byte boundary to yield the best
* processor performance.
*/
segment_desc_t __attribute__ ((aligned(8))) ATTR_BSS_GDT_START
gdt[GDT_NUM_FIXED_DESC];
#define GDT_LEN \
((((uintptr_t)&_ebss_gdt_addr) - \
(uintptr_t)gdt)/sizeof(segment_desc_t))
/*---------------------------------------------------------------------------*/
static void ATTR_CODE_BOOT
set_descriptor(unsigned int index,
uint32_t base,
uint32_t len,
uint16_t flag)
{
segment_desc_t descriptor;
if(GDT_LEN <= index) {
halt();
}
segment_desc_init(&descriptor, base, len, flag);
/* Save descriptor into gdt */
gdt_insert_boot(index, descriptor);
}
/*---------------------------------------------------------------------------*/
void
gdt_copy_desc_change_dpl(unsigned int dest_idx,
unsigned int src_idx,
unsigned dpl)
{
segment_desc_t desc;
if((GDT_LEN <= dest_idx) || (GDT_LEN <= src_idx)) {
halt();
}
gdt_lookup(src_idx, &desc);
SEG_SET_FLAG(desc, DPL, dpl);
gdt_insert(dest_idx, desc);
}
/*---------------------------------------------------------------------------*/
/* This function initializes the Global Descriptor Table. For simplicity, the
* memory is initially organized following the flat model. Thus, memory appears
* to Contiki as a single continuous address space. Code, data, and stack
* are all contained in this address space (so called linear address space).
* Certain protection domain implementations switch to a multi-segment memory
* model later during boot.
*/
void
gdt_init(void)
{
gdtr_t gdtr;
/* Initialize gdtr structure */
gdtr.limit = sizeof(segment_desc_t) * GDT_LEN - 1;
gdtr.base = KERN_DATA_OFF_TO_PHYS_ADDR(gdt);
/* Initialize descriptors */
set_descriptor(GDT_IDX_NULL, 0, 0, 0);
set_descriptor(GDT_IDX_CODE_FLAT, 0, 0x100000, GDT_CODE_PL0);
set_descriptor(GDT_IDX_DATA_FLAT, 0, 0x100000, GDT_DATA_PL0);
/* Load GDTR */
__asm__ __volatile__ ("lgdt %0" :: "m" (gdtr));
}
/*---------------------------------------------------------------------------*/
void
gdt_insert_boot(unsigned int idx, segment_desc_t desc)
{
((segment_desc_t *)KERN_DATA_OFF_TO_PHYS_ADDR(gdt))[idx] = desc;
}
/*---------------------------------------------------------------------------*/
void
gdt_insert(unsigned int idx, segment_desc_t desc)
{
if(GDT_LEN <= idx) {
halt();
}
KERN_WRITEL(gdt[idx].raw_lo, desc.raw_lo);
KERN_WRITEL(gdt[idx].raw_hi, desc.raw_hi);
}
/*---------------------------------------------------------------------------*/
void
gdt_lookup(unsigned int idx, segment_desc_t *desc)
{
if((GDT_LEN <= idx) || (desc == NULL)) {
halt();
}
KERN_READL(desc->raw_lo, gdt[idx].raw_lo);
KERN_READL(desc->raw_hi, gdt[idx].raw_hi);
}
/*---------------------------------------------------------------------------*/