mirror of
https://github.com/oliverschmidt/contiki.git
synced 2024-11-19 03:05:14 +00:00
e4bc1a1e8c
The x86/init/common/ folder holds all cpu initialization code - idt and gdt setup, interrupts and cpu initialization. On this folder will also sit any SoC specific implementation of the functions called from cpu_init().
137 lines
5.2 KiB
C
137 lines
5.2 KiB
C
/*
|
|
* 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>
|
|
|
|
#define NUM_DESC 3
|
|
|
|
/* Each define here is for a specific flag in the descriptor. Refer to Intel
|
|
* Combined Manual (Intel 64 and IA-32 Architectures Software Developer's
|
|
* Manual), Vol. 3, Section 3.4.5 for a description of each flag.
|
|
*/
|
|
#define SEG_DESCTYPE(x) ((x) << 0x04) /* Descriptor type (0 for system, 1 for code/data) */
|
|
#define SEG_PRES(x) ((x) << 0x07) /* Present */
|
|
#define SEG_SAVL(x) ((x) << 0x0C) /* Available for system use */
|
|
#define SEG_LONG(x) ((x) << 0x0D) /* Long mode */
|
|
#define SEG_SIZE(x) ((x) << 0x0E) /* Size (0 for 16-bit, 1 for 32) */
|
|
#define SEG_GRAN(x) ((x) << 0x0F) /* Granularity (0 for 1B - 1MB, 1 for 4KB - 4GB) */
|
|
#define SEG_PRIV(x) (((x) & 0x03) << 0x05) /* Set privilege level (0 - 3) */
|
|
|
|
#define SEG_DATA_RDWR 0x02 /* Read/Write */
|
|
#define SEG_CODE_EXRD 0x0A /* Execute/Read */
|
|
|
|
#define GDT_CODE_PL0 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
|
|
SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \
|
|
SEG_PRIV(0) | SEG_CODE_EXRD
|
|
|
|
#define GDT_DATA_PL0 SEG_DESCTYPE(1) | SEG_PRES(1) | SEG_SAVL(0) | \
|
|
SEG_LONG(0) | SEG_SIZE(1) | SEG_GRAN(1) | \
|
|
SEG_PRIV(0) | SEG_DATA_RDWR
|
|
|
|
typedef struct gdtr
|
|
{
|
|
uint16_t limit;
|
|
uint32_t base;
|
|
} __attribute__((packed)) gdtr_t;
|
|
|
|
typedef uint64_t segment_desc_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.
|
|
*/
|
|
static segment_desc_t gdt[NUM_DESC] __attribute__ ((aligned (8)));
|
|
|
|
static void
|
|
set_descriptor(unsigned int index, uint32_t base, uint32_t limit, uint16_t flag)
|
|
{
|
|
segment_desc_t descriptor;
|
|
|
|
if (index >= NUM_DESC)
|
|
return;
|
|
|
|
/* Create the high 32 bit segment */
|
|
descriptor = limit & 0x000F0000; /* set limit bits 19:16 */
|
|
descriptor |= (flag << 8) & 0x00F0FF00; /* set type, p, dpl, s, g, d/b, l and avl fields */
|
|
descriptor |= (base >> 16) & 0x000000FF; /* set base bits 23:16 */
|
|
descriptor |= base & 0xFF000000; /* set base bits 31:24 */
|
|
|
|
/* Shift by 32 to allow for low part of segment */
|
|
descriptor <<= 32;
|
|
|
|
/* Create the low 32 bit segment */
|
|
descriptor |= base << 16; /* set base bits 15:0 */
|
|
descriptor |= limit & 0x0000FFFF; /* set limit bits 15:0 */
|
|
|
|
/* Save descriptor into gdt */
|
|
gdt[index] = descriptor;
|
|
}
|
|
|
|
|
|
/* This function initializes the Global Offset Table. For simplicity, the
|
|
* memory is 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).
|
|
*/
|
|
void
|
|
gdt_init(void)
|
|
{
|
|
gdtr_t gdtr;
|
|
|
|
/* Initialize gdtr structure */
|
|
gdtr.limit = sizeof(segment_desc_t) * NUM_DESC - 1;
|
|
gdtr.base = (uint32_t) &gdt;
|
|
|
|
/* Initialize descriptors */
|
|
set_descriptor(0, 0, 0, 0);
|
|
set_descriptor(1, 0, 0x0FFFFF, GDT_CODE_PL0);
|
|
set_descriptor(2, 0, 0x0FFFFF, GDT_DATA_PL0);
|
|
|
|
/* Load GDTR register and update segment registers.
|
|
*
|
|
* In protected mode, segment registers should be loaded according to
|
|
* the offset in GDT. So DS, SS, ES, FS and GS registers should be
|
|
* loadded with 0x10 while CS with 0x08. CS register cannot be changed
|
|
* directly. For that reason, we do a far jump.
|
|
*/
|
|
__asm__ ("lgdt %0\n\t"
|
|
"jmp $0x08, $1f\n\t"
|
|
"1:\n\t"
|
|
"mov $0x10, %%ax\n\t"
|
|
"mov %%ax, %%ds\n\t"
|
|
"mov %%ax, %%ss\n\t"
|
|
"mov %%ax, %%es\n\t"
|
|
"mov %%ax, %%fs\n\t"
|
|
"mov %%ax, %%gs\n\t"
|
|
:
|
|
: "m" (gdtr)
|
|
);
|
|
}
|