scoutos / prex-0.9.0 / bsp / hal / x86 / arch / cpu.c @ 03e9c04a
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/*-
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* Copyright (c) 2005-2007, Kohsuke Ohtani
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the author nor the names of any co-contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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/*
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* cpu.c - cpu dependent routines for Intel x86
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*/
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#include <machine/syspage.h> |
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#include <kernel.h> |
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#include <cpu.h> |
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#include <locore.h> |
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#include <cpufunc.h> |
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typedef void (*trapfn_t)(void); |
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/*
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* Descriptors
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*/
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static struct seg_desc gdt[NGDTS]; |
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static struct gate_desc idt[NIDTS]; |
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static struct tss tss; |
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/*
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* Interrupt table
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*/
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static const trapfn_t intr_table[] = { |
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intr_0, intr_1, intr_2, intr_3, intr_4, intr_5, intr_6, |
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intr_7, intr_8, intr_9, intr_10, intr_11, intr_12, intr_13, |
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intr_14, intr_15 |
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}; |
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/*
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* Trap table
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*/
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static const trapfn_t trap_table[] = { |
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trap_0, trap_1, trap_2, trap_3, trap_4, trap_5, trap_6, |
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trap_7, trap_8, trap_9, trap_10, trap_11, trap_12, trap_13, |
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trap_14, trap_15, trap_16, trap_17, trap_18 |
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}; |
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#define NTRAPS (int)(sizeof(trap_table) / sizeof(void *)) |
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/*
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* Set kernel stack pointer in TSS (task state segment).
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* An actual value of the register is automatically set when
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* CPU enters kernel mode next time.
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*/
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void
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tss_set(uint32_t kstack) |
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{ |
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tss.esp0 = kstack; |
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} |
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/*
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* tss_get() returns current esp0 value for trap handler.
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*/
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uint32_t |
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tss_get(void)
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{ |
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return tss.esp0;
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} |
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/*
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* Set GDT (global descriptor table) members into specified vector
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*/
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static void |
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gdt_set(int vec, void *base, size_t limit, int type, u_int size) |
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{ |
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struct seg_desc *seg = &gdt[vec];
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if (limit > 0xfffff) { |
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limit >>= 12;
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size |= SIZE_4K; |
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} |
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seg->limit_lo = limit; |
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seg->base_lo = (u_int)base & 0xffff;
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seg->base_mid = ((u_int)base >> 16) & 0xff; |
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seg->limit_hi = limit >> 16;
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seg->base_hi = (u_int)base >> 24;
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seg->type = (u_int)type | ST_PRESENT; |
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seg->size = size; |
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} |
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/*
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* Set IDT (interrupt descriptor table) members into specified vector
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*/
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static void |
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idt_set(int vec, trapfn_t off, u_int sel, int type) |
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{ |
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struct gate_desc *gate = &idt[vec];
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gate->offset_lo = (u_int)off & 0xffff;
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gate->selector = sel; |
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gate->nr_copy = 0;
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gate->type = (u_int)type | ST_PRESENT; |
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gate->offset_hi = (u_int)off >> 16;
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} |
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/*
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* Setup the GDT and load it.
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*/
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static void |
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gdt_init(void)
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{ |
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struct desc_p gdt_p;
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/* Set system vectors */
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gdt_set(KERNEL_CS / 8, 0, 0xffffffff, ST_KERN | ST_CODE_R, SIZE_32); |
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gdt_set(KERNEL_DS / 8, 0, 0xffffffff, ST_KERN | ST_DATA_W, SIZE_32); |
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gdt_set(USER_CS / 8, 0, 0xffffffff, ST_USER | ST_CODE_R, SIZE_32); |
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gdt_set(USER_DS / 8, 0, 0xffffffff, ST_USER | ST_DATA_W, SIZE_32); |
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/* Clear TSS Busy */
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gdt[KERNEL_TSS / 8].type &= ~ST_TSS_BUSY;
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/* Load GDT */
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gdt_p.limit = (uint16_t)(sizeof(gdt) - 1); |
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gdt_p.base = (uint32_t)&gdt; |
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load_gdt(&gdt_p); |
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} |
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/*
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* Setup the interrupt descriptor table and load it.
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*
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* IDT layout:
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* 0x00 - 0x12 ... S/W trap
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* 0x13 - 0x1f ... Intel reserved
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* 0x20 - 0x3f ... H/W interrupt
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* 0x40 ... System call trap
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*/
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static void |
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idt_init(void)
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{ |
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struct desc_p idt_p;
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int i;
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/* Fill all vectors with default handler */
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for (i = 0; i < NIDTS; i++) |
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idt_set(i, trap_default, KERNEL_CS, ST_KERN | ST_TRAP_GATE); |
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/* Setup trap handlers */
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for (i = 0; i < NTRAPS; i++) |
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idt_set(i, trap_table[i], KERNEL_CS, ST_KERN | ST_TRAP_GATE); |
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/* Setup interrupt handlers */
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for (i = 0; i < 16; i++) |
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idt_set(0x20 + i, intr_table[i], KERNEL_CS,
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ST_KERN | ST_INTR_GATE); |
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/* Setup debug trap */
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idt_set(3, trap_3, KERNEL_CS, ST_USER | ST_TRAP_GATE);
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/* Setup system call handler */
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idt_set(SYSCALL_INT, syscall_entry, KERNEL_CS, |
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ST_USER | ST_TRAP_GATE); |
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/* Load IDT */
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idt_p.limit = (uint16_t)(sizeof(idt) - 1); |
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idt_p.base = (uint32_t)&idt; |
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load_idt(&idt_p); |
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} |
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/*
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* Initialize the task state segment.
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* Only one static TSS is used for all contexts.
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*/
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static void |
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tss_init(void)
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{ |
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gdt_set(KERNEL_TSS / 8, &tss, sizeof(struct tss) - 1, |
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ST_KERN | ST_TSS, 0);
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/* Setup TSS */
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memset(&tss, 0, sizeof(struct tss)); |
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tss.ss0 = KERNEL_DS; |
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tss.esp0 = (uint32_t)BOOTSTKTOP; |
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tss.cs = (uint32_t)USER_CS | 3;
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tss.ds = tss.es = tss.ss = tss.fs = tss.gs = (uint32_t)USER_CS | 3;
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tss.io_bitmap_offset = INVALID_IO_BITMAP; |
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load_tr(KERNEL_TSS); |
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} |
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/*
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* Initialize CPU state.
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* Setup segment and interrupt descriptor.
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*/
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void
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cpu_init(void)
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{ |
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/*
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* Initialize descriptors.
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* Setup segment and interrupt descriptor.
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*/
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gdt_init(); |
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idt_init(); |
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tss_init(); |
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} |