/*
* Copyright (C) 2001-2004 Jakub Jermar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
* - The name of the author may not be used to endorse or promote products
* derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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 <arch/pm.h>
#include <config.h>
#include <arch/types.h>
#include <typedefs.h>
#include <arch/interrupt.h>
#include <arch/asm.h>
#include <arch/context.h>
#include <panic.h>
/*
* Early ia32 configuration functions and data structures.
*/
/*
* We have no use for segmentation so we set up flat mode. In this
* mode, we use, for each privilege level, two segments spanning the
* whole memory. One is for code and one is for data.
*/
struct descriptor gdt[GDT_ITEMS] = {
/* NULL descriptor */
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },
/* KTEXT descriptor */
{ 0xffff, 0, 0, AR_PRESENT | AR_CODE | DPL_KERNEL, 0xf, 0, 0, 1, 1, 0 },
/* KDATA descriptor */
{ 0xffff, 0, 0, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_KERNEL, 0xf, 0, 0, 1, 1, 0 },
/* UTEXT descriptor */
{ 0xffff, 0, 0, AR_PRESENT | AR_CODE | DPL_USER, 0xf, 0, 0, 1, 1, 0 },
/* UDATA descriptor */
{ 0xffff, 0, 0, AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_USER, 0xf, 0, 0, 1, 1, 0 },
/* TSS descriptor - set up will be completed later */
{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
};
static struct idescriptor idt[IDT_ITEMS];
static struct tss tss;
struct tss *tss_p = NULL;
/* gdtr is changed by kmp before next CPU is initialized */
struct ptr_16_32 gdtr __attribute__ ((section ("K_DATA_START"))) = { .limit = sizeof(gdt), .base = KA2PA((__address) gdt) };
struct ptr_16_32 idtr __attribute__ ((section ("K_DATA_START"))) = { .limit = sizeof(idt), .base = KA2PA((__address) idt) };
void gdt_setbase(struct descriptor *d, __address base)
{
d->base_0_15 = base & 0xffff;
d->base_16_23 = ((base) >> 16) & 0xff;
d->base_24_31 = ((base) >> 24) & 0xff;
}
void gdt_setlimit(struct descriptor *d, __u32 limit)
{
d->limit_0_15 = limit & 0xffff;
d->limit_16_19 = (limit >> 16) & 0xf;
}
void idt_setoffset(struct idescriptor *d, __address offset)
{
/*
* Offset is a linear address.
*/
d->offset_0_15 = offset & 0xffff;
d->offset_16_31 = offset >> 16;
}
void tss_initialize(struct tss *t)
{
memsetb((__address) t, sizeof(struct tss), 0);
}
/*
* This function takes care of proper setup of IDT and IDTR.
*/
void idt_init(void)
{
struct idescriptor *d;
int i;
for (i = 0; i < IDT_ITEMS; i++) {
d = &idt[i];
d->unused = 0;
d->selector = selector(KTEXT_DES);
d->access = AR_PRESENT | AR_INTERRUPT; /* masking interrupt */
if (i == VECTOR_SYSCALL) {
/*
* The syscall interrupt gate must be calleable from userland.
*/
d->access |= DPL_USER;
}
idt_setoffset(d, ((__address) interrupt_handlers) + i*interrupt_handler_size);
trap_register(i, null_interrupt);
}
trap_register(13, gp_fault);
trap_register( 7, nm_fault);
trap_register(12, ss_fault);
}
// Clean IOPL(12,13) and NT(14) flags in EFLAGS register
static void clean_IOPL_NT_flags(void)
{
asm
(
"pushfl;"
"pop %%eax;"
"and $0xffff8fff,%%eax;"
"push %%eax;"
"popfl;"
:
:
:"%eax"
);
}
// Clean AM(18) flag in CR0 register
static void clean_AM_flag(void)
{
asm
(
"mov %%cr0,%%eax;"
"and $0xFFFBFFFF,%%eax;"
"mov %%eax,%%cr0;"
:
:
:"%eax"
);
}
void pm_init(void)
{
struct descriptor *gdt_p = (struct descriptor *) PA2KA(gdtr.base);
/*
* Each CPU has its private GDT and TSS.
* All CPUs share one IDT.
*/
if (config.cpu_active == 1) {
idt_init();
/*
* NOTE: bootstrap CPU has statically allocated TSS, because
* the heap hasn't been initialized so far.
*/
tss_p = &tss;
}
else {
tss_p
= (struct tss
*) malloc(sizeof(struct tss
)); if (!tss_p)
panic("could not allocate TSS\n");
}
tss_initialize(tss_p);
gdt_p[TSS_DES].access = AR_PRESENT | AR_TSS | DPL_KERNEL;
gdt_p[TSS_DES].special = 1;
gdt_p[TSS_DES].granularity = 1;
gdt_setbase(&gdt_p[TSS_DES], (__address) tss_p);
gdt_setlimit(&gdt_p[TSS_DES], sizeof(struct tss) - 1);
/*
* As of this moment, the current CPU has its own GDT pointing
* to its own TSS. We just need to load the TR register.
*/
__asm__("ltr %0" : : "r" ((__u16) selector(TSS_DES)));
clean_IOPL_NT_flags(); //Disable I/O on nonprivileged levels
clean_AM_flag(); //Disable alignment check
}