contiki/cpu/x86/mm/prot-domains.c
Michael LeMay e0aefd11d9 x86: Add support for SW-switched segment-based protection domains
This patch extends the protection domain framework with a third plugin
that is a hybrid of the previous two.  The hardware task switching
mechanism has a strictly-defined format for TSS data structures that
causes more space to be consumed than would otherwise be required.
This patch defines a smaller data structure that is allocated for each
protection domain, only requiring 32 bytes instead of 128 bytes.  It
uses the same multi-segment memory layout as the TSS-based plugin and
leaves paging disabled.  However, it uses a similar mechanism as the
paging plugin to perform system call dispatches and returns.

For additional information, please refer to cpu/x86/mm/README.md.
2016-04-22 08:16:43 -07:00

79 lines
3.0 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 "prot-domains.h"
#include "gdt.h"
#include <stdio.h>
#include "interrupt.h"
#include <stdint.h>
#include <assert.h>
#include "syscalls.h"
#include "stacks.h"
static dom_kern_data_t __attribute__((section(".kern_prot_dom_bss")))
ATTR_KERN_ADDR_SPACE PROT_DOMAINS_PDCS_NM(kern_dcd);
PROT_DOMAINS_ALLOC_IMPL(kern_dcd);
static dom_client_data_t ATTR_BSS_KERN kern_dcd;
static dom_kern_data_t __attribute__((section(".app_prot_dom_bss")))
ATTR_KERN_ADDR_SPACE PROT_DOMAINS_PDCS_NM(app_dcd);
PROT_DOMAINS_ALLOC_IMPL(app_dcd);
static dom_client_data_t ATTR_BSS_KERN app_dcd;
/*---------------------------------------------------------------------------*/
void
prot_domains_init(void)
{
segment_desc_t desc;
gdt_lookup(GDT_IDX_CODE_EXC, &desc);
#if X86_CONF_PROT_DOMAINS == X86_CONF_PROT_DOMAINS__SWSEG
/* The exception code segment needs to be readable so that the general
* protection fault handler can decode instructions, but the interrupt and
* user level code segments should not be.
*/
SEG_SET_FLAG(desc, TYPE, SEG_TYPE_CODE_EX);
#endif
SEG_SET_FLAG(desc, DPL, PRIV_LVL_INT);
gdt_insert(GDT_IDX_CODE_INT, desc);
SEG_SET_FLAG(desc, DPL, PRIV_LVL_USER);
gdt_insert(GDT_IDX_CODE, desc);
PROT_DOMAINS_INIT_ID(kern_dcd);
prot_domains_reg(&kern_dcd, 0, 0, 0, 0, true);
PROT_DOMAINS_INIT_ID(app_dcd);
prot_domains_reg(&app_dcd, 0, 0, 0, 0, false);
prot_domains_impl_init();
}
/*---------------------------------------------------------------------------*/