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contiki/cpu/x86/mm/prot-domains.c

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x86: Add support for (paging-based) protection domains 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.
2015-08-10 15:34:02 +00:00
/*
* 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")))
x86: Add TSS-based protection domain support This patch extends the protection domain framework with an additional plugin to use Task-State Segment (TSS) structures to offload much of the work of switching protection domains to the CPU. This can save space compared to paging, since paging requires two 4KiB page tables and one 32-byte page table plus one whole-system TSS and an additional 32-byte data structure for each protection domain, whereas the approach implemented by this patch just requires a 128-byte data structure for each protection domain. Only a small number of protection domains will typically be used, so n * 128 < 8328 + (n * 32). For additional information, please refer to cpu/x86/mm/README.md. GCC 6 is introducing named address spaces for the FS and GS segments [1]. LLVM Clang also provides address spaces for the FS and GS segments [2]. This patch also adds support to the multi-segment X86 memory management subsystem for using these features instead of inline assembly blocks, which enables type checking to detect some address space mismatches. [1] https://gcc.gnu.org/onlinedocs/gcc/Named-Address-Spaces.html [2] http://llvm.org/releases/3.3/tools/clang/docs/LanguageExtensions.html#target-specific-extensions
2015-08-07 22:43:10 +00:00
ATTR_KERN_ADDR_SPACE PROT_DOMAINS_PDCS_NM(kern_dcd);
PROT_DOMAINS_ALLOC_IMPL(kern_dcd);
x86: Add support for (paging-based) protection domains 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.
2015-08-10 15:34:02 +00:00
static dom_client_data_t ATTR_BSS_KERN kern_dcd;
static dom_kern_data_t __attribute__((section(".app_prot_dom_bss")))
x86: Add TSS-based protection domain support This patch extends the protection domain framework with an additional plugin to use Task-State Segment (TSS) structures to offload much of the work of switching protection domains to the CPU. This can save space compared to paging, since paging requires two 4KiB page tables and one 32-byte page table plus one whole-system TSS and an additional 32-byte data structure for each protection domain, whereas the approach implemented by this patch just requires a 128-byte data structure for each protection domain. Only a small number of protection domains will typically be used, so n * 128 < 8328 + (n * 32). For additional information, please refer to cpu/x86/mm/README.md. GCC 6 is introducing named address spaces for the FS and GS segments [1]. LLVM Clang also provides address spaces for the FS and GS segments [2]. This patch also adds support to the multi-segment X86 memory management subsystem for using these features instead of inline assembly blocks, which enables type checking to detect some address space mismatches. [1] https://gcc.gnu.org/onlinedocs/gcc/Named-Address-Spaces.html [2] http://llvm.org/releases/3.3/tools/clang/docs/LanguageExtensions.html#target-specific-extensions
2015-08-07 22:43:10 +00:00
ATTR_KERN_ADDR_SPACE PROT_DOMAINS_PDCS_NM(app_dcd);
PROT_DOMAINS_ALLOC_IMPL(app_dcd);
x86: Add support for (paging-based) protection domains 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.
2015-08-10 15:34:02 +00:00
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);
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.
2015-08-07 18:51:04 +00:00
#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
x86: Add support for (paging-based) protection domains 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.
2015-08-10 15:34:02 +00:00
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();
}
/*---------------------------------------------------------------------------*/
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