3908253038
This patch implements a simple, lightweight form of protection domains using a pluggable framework. Currently, the following plugin is available: - Flat memory model with paging. The overall goal of a protection domain implementation within this framework is to define a set of resources that should be accessible to each protection domain and to prevent that protection domain from accessing other resources. The details of each implementation of protection domains may differ substantially, but they should all be guided by the principle of least privilege. However, that idealized principle is balanced against the practical objectives of limiting the number of relatively time-consuming context switches and minimizing changes to existing code. For additional information, please refer to cpu/x86/mm/README.md. This patch also causes the C compiler to be used as the default linker and assembler.
121 lines
4.2 KiB
C
121 lines
4.2 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 "cpu.h"
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#include "gdt.h"
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#include "helpers.h"
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#include "idt.h"
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#include "interrupt.h"
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#include "irq.h"
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#include "stacks.h"
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static void
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double_fault_handler(struct interrupt_context context)
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{
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halt();
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}
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/*---------------------------------------------------------------------------*/
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/* The OS has switched to its own segment descriptors. However, the protection
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* domain support, if enabled, has not yet been fully activated.
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*/
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static void
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boot_stage1(void)
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{
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idt_init();
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/* Set an interrupt handler for Double Fault exception. This way, we avoid
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* the system to triple fault, leaving no trace about what happened.
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*/
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SET_EXCEPTION_HANDLER(8, 1, double_fault_handler);
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/* Initialize protection domain support, if enabled */
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prot_domains_init();
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prot_domains_leave_boot_stage1();
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}
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/*---------------------------------------------------------------------------*/
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int main(void);
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/* This routine runs with the initial, flat address space, even if protection
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* domain support is enabled. The goal behind the design of this routine is to
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* keep it as short as possible, since it is unable to directly reference data
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* and invoke functions that are intended to be accessible later after the
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* system has booted when a multi-segment protection domain model is in use.
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*/
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void
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cpu_boot_stage0(void)
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{
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/* Reserve three stack slots for return addresses */
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uintptr_t top_of_stack = STACKS_INIT_TOP;
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#if X86_CONF_PROT_DOMAINS != X86_CONF_PROT_DOMAINS__NONE
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uintptr_t *top_of_stack_ptr = (uintptr_t *)top_of_stack;
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top_of_stack_ptr[0] = (uintptr_t)prot_domains_launch_kernel;
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top_of_stack_ptr[1] = (uintptr_t)prot_domains_launch_app;
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#endif
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/* Perform common GDT initialization */
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gdt_init();
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/* Switch all data segment registers to the newly-initialized flat data
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* descriptor.
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*/
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__asm__(
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"mov %0, %%ds\n\t"
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"mov %0, %%es\n\t"
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"mov %0, %%fs\n\t"
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"mov %0, %%gs\n\t"
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:
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: "r" (GDT_SEL_DATA_FLAT)
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);
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/**
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* Perform specific GDT initialization tasks for the protection domain
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* implementation that is enabled, if any.
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*/
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prot_domains_gdt_init();
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/* Do not pass memory operands to the asm block below, since it is
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* switching from the flat address space to a multi-segment address space
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* model if such a model is used by the enabled protection domain
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* implementation, if any.
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*/
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__asm__(
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"mov %[_ss_], %%ss\n\t"
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"mov %[_esp_], %%esp\n\t"
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"ljmp %[_cs_], %[_stage1_]\n\t"
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:
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: [_ss_] "r" (GDT_SEL_STK_EXC),
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[_esp_] "r" (top_of_stack),
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[_cs_] "i" ((uint16_t)GDT_SEL_CODE_EXC),
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[_stage1_] "i" (boot_stage1)
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);
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}
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