147 lines
4.9 KiB
C
147 lines
4.9 KiB
C
/*
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* Copyright (C) 2015, Intel Corporation. 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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*
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* 3. Neither the name of the copyright holder nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* 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,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <stdint.h>
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#include "gdt.h"
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#include "gdt-layout.h"
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#include "helpers.h"
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#include "prot-domains.h"
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#include "segmentation.h"
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#define GDT_MEM_PL0 (SEG_DESCTYPE_NSYS | SEG_GRAN_PAGE)
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#define GDT_CODE_PL0 (GDT_MEM_PL0 | SEG_TYPE_CODE_EXRD)
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#define GDT_DATA_PL0 (GDT_MEM_PL0 | SEG_TYPE_DATA_RDWR)
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typedef struct gdtr
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{
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uint16_t limit;
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uint32_t base;
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} __attribute__((packed)) gdtr_t;
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/* From Intel Combined Manual, Vol. 3 , Section 3.5.1: The base addresses of
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* the GDT should be aligned on an eight-byte boundary to yield the best
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* processor performance.
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*/
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segment_desc_t __attribute__ ((aligned(8))) ATTR_BSS_GDT_START
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gdt[GDT_NUM_FIXED_DESC];
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#define GDT_LEN \
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((((uintptr_t)&_ebss_gdt_addr) - \
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(uintptr_t)gdt)/sizeof(segment_desc_t))
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/*---------------------------------------------------------------------------*/
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static void ATTR_CODE_BOOT
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set_descriptor(unsigned int index,
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uint32_t base,
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uint32_t len,
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uint16_t flag)
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{
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segment_desc_t descriptor;
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if(GDT_LEN <= index) {
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halt();
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}
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segment_desc_init(&descriptor, base, len, flag);
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/* Save descriptor into gdt */
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gdt_insert_boot(index, descriptor);
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}
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/*---------------------------------------------------------------------------*/
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void
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gdt_copy_desc_change_dpl(unsigned int dest_idx,
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unsigned int src_idx,
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unsigned dpl)
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{
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segment_desc_t desc;
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if((GDT_LEN <= dest_idx) || (GDT_LEN <= src_idx)) {
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halt();
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}
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gdt_lookup(src_idx, &desc);
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SEG_SET_FLAG(desc, DPL, dpl);
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gdt_insert(dest_idx, desc);
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}
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/*---------------------------------------------------------------------------*/
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/* This function initializes the Global Descriptor Table. For simplicity, the
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* memory is initially organized following the flat model. Thus, memory appears
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* to Contiki as a single continuous address space. Code, data, and stack
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* are all contained in this address space (so called linear address space).
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* Certain protection domain implementations switch to a multi-segment memory
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* model later during boot.
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*/
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void
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gdt_init(void)
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{
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gdtr_t gdtr;
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/* Initialize gdtr structure */
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gdtr.limit = sizeof(segment_desc_t) * GDT_LEN - 1;
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gdtr.base = KERN_DATA_OFF_TO_PHYS_ADDR(gdt);
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/* Initialize descriptors */
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set_descriptor(GDT_IDX_NULL, 0, 0, 0);
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set_descriptor(GDT_IDX_CODE_FLAT, 0, 0x100000, GDT_CODE_PL0);
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set_descriptor(GDT_IDX_DATA_FLAT, 0, 0x100000, GDT_DATA_PL0);
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/* Load GDTR */
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__asm__ __volatile__ ("lgdt %0" :: "m" (gdtr));
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}
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/*---------------------------------------------------------------------------*/
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void
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gdt_insert_boot(unsigned int idx, segment_desc_t desc)
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{
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((segment_desc_t *)KERN_DATA_OFF_TO_PHYS_ADDR(gdt))[idx] = desc;
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}
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/*---------------------------------------------------------------------------*/
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void
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gdt_insert(unsigned int idx, segment_desc_t desc)
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{
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if(GDT_LEN <= idx) {
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halt();
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}
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KERN_WRITEL(gdt[idx].raw_lo, desc.raw_lo);
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KERN_WRITEL(gdt[idx].raw_hi, desc.raw_hi);
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}
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/*---------------------------------------------------------------------------*/
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void
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gdt_lookup(unsigned int idx, segment_desc_t *desc)
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{
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if((GDT_LEN <= idx) || (desc == NULL)) {
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halt();
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}
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KERN_READL(desc->raw_lo, gdt[idx].raw_lo);
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KERN_READL(desc->raw_hi, gdt[idx].raw_hi);
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}
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/*---------------------------------------------------------------------------*/
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