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/*

 * 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 <arch/mm/page.h>

#include <arch/types.h>

#include <arch/interrupt.h>

#include <arch/asm.h>

#include <config.h>

#include <memstr.h>

#include <mm/heap.h>

#include <debug.h>

/*

 * There is no segmentation in long mode 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 */

	{ .limit_0_15  = 0xffff, 

	  .base_0_15   = 0, 

	  .base_16_23  = 0, 

	  .access      = AR_PRESENT | AR_CODE | DPL_KERNEL | AR_READABLE , 

	  .limit_16_19 = 0xf, 

	  .available   = 0, 

	  .longmode    = 1, 

	  .special     = 0,

	  .granularity = 1, 

	  .base_24_31  = 0 },

	/* KDATA descriptor */

	{ .limit_0_15  = 0xffff, 

	  .base_0_15   = 0, 

	  .base_16_23  = 0, 

	  .access      = AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_KERNEL, 

	  .limit_16_19 = 0xf, 

	  .available   = 0, 

	  .longmode    = 0, 

	  .special     = 0, 

	  .granularity = 1, 

	  .base_24_31  = 0 },

	/* UTEXT descriptor */

	{ .limit_0_15  = 0xffff, 

	  .base_0_15   = 0, 

	  .base_16_23  = 0, 

	  .access      = AR_PRESENT | AR_CODE | DPL_USER, 

	  .limit_16_19 = 0xf, 

	  .available   = 0, 

	  .longmode    = 1, 

	  .special     = 0, 

	  .granularity = 1, 

	  .base_24_31  = 0 },

	/* UDATA descriptor */

	{ .limit_0_15  = 0xffff, 

	  .base_0_15   = 0, 

	  .base_16_23  = 0, 

	  .access      = AR_PRESENT | AR_DATA | AR_WRITABLE | DPL_USER, 

	  .limit_16_19 = 0xf, 

	  .available   = 0, 

	  .longmode    = 0, 

	  .special     = 1, 

	  .granularity = 1, 

	  .base_24_31  = 0 },

	/* KTEXT 16-bit protected */

	{ .limit_0_15  = 0xffff, 

	  .base_0_15   = 0, 

	  .base_16_23  = 0, 

	  .access      = AR_PRESENT | AR_CODE | DPL_KERNEL | AR_READABLE, 

	  .limit_16_19 = 0xf, 

	  .available   = 0, 

	  .longmode    = 0, 

	  .special     = 0,

	  .granularity = 1, 

	  .base_24_31  = 0 },

	/* TSS descriptor - set up will be completed later,

	 * on AMD64 it is 64-bit - 2 items in table */

	{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 },

	{ 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }

};

struct ptr_16_64 gdtr = {.limit = sizeof(gdtr), .base= (__u64) &gdtr };

struct idescriptor idt[IDT_ITEMS];

static struct tss tss;

/* TODO: Does not compile correctly if it does not exist ???? */

int __attribute__ ((section ("K_DATA_START"))) __fake;

void gdt_tss_setbase(struct descriptor *d, __address base)

{

	struct tss_descriptor *td = (struct tss_descriptor *) d;

	td->base_0_15 = base & 0xffff;

	td->base_16_23 = ((base) >> 16) & 0xff;

	td->base_24_31 = ((base) >> 24) & 0xff;

	td->base_32_63 = ((base) >> 32);

}

void gdt_tss_setlimit(struct descriptor *d, __u32 limit)

{

	struct tss_descriptor *td = (struct tss_descriptor *) d;

	td->limit_0_15 = limit & 0xffff;

	td->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 & 0xffff;

	d->offset_32_63 = offset >> 32;

}

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 = idtselector(KTEXT_DES);

		d->present = 1;

		d->type = AR_INTERRUPT;	/* masking interrupt */

		if (i == VECTOR_SYSCALL) {

			/*

			 * The syscall interrupt gate must be calleable from userland.

			 */

			d->dpl |= PL_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

	(

		"pushfq;"

		"pop %%rax;"

		"and $~(0x7000),%%rax;"

		"pushq %%rax;"

		"popfq;"

		:

		:

		:"%rax"

	);

}

/* Clean AM(18) flag in CR0 register */

static void clean_AM_flag(void)

{

	asm

	(

		"mov %%cr0,%%rax;"

		"and $~(0x40000),%%rax;"

		"mov %%rax,%%cr0;"

		:

		:

		:"%rax"

	);

}

void pm_init(void)

{

	struct descriptor *gdt_p = (struct descriptor *) PA2KA(gdtr.base);

	struct tss_descriptor *tss_d;

	/*

	 * 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);

	tss_d = (struct tss_descriptor *) &gdt_p[TSS_DES];

	tss_d[TSS_DES].present = 1;

	tss_d[TSS_DES].type = AR_TSS;

	tss_d[TSS_DES].dpl = PL_KERNEL;

	gdt_tss_setbase(&gdt_p[TSS_DES], (__address) tss_p);

	gdt_tss_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) gdtselector(TSS_DES)));

	clean_IOPL_NT_flags();    /* Disable I/O on nonprivileged levels */

	clean_AM_flag();          /* Disable alignment check */

}