nes-proj/cpu/x86/init/common/gdt.h
Michael LeMay 4cdb7ba9b6 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
2016-04-22 08:16:39 -07:00

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C

/*
* Copyright (C) 2015-2016, 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.
*/
#ifndef GDT_H
#define GDT_H
#include "gdt-layout.h"
#include "prot-domains.h"
#include "segmentation.h"
extern segment_desc_t ATTR_KERN_ADDR_SPACE gdt[];
extern int ATTR_KERN_ADDR_SPACE _ebss_gdt_addr;
#define GDT_IDX_OF_DESC(ptr) \
((((uintptr_t)(ptr)) - ((uintptr_t)&gdt))/ \
sizeof(segment_desc_t))
typedef struct far_pointer {
/** Far pointer offset. */
uint32_t offset;
/** Far pointer segment/gate selector. */
uint16_t sel;
uint16_t pad;
} __attribute__((packed)) far_pointer_t;
/**
* \brief Compute the selector for a GDT entry allocated somewhere besides gdt.c.
* \param ptr Pointer to GDT descriptor.
* \param rpl Requested Privilege Level.
*/
#define GDT_SEL_OF_DESC(ptr, rpl) GDT_SEL(GDT_IDX_OF_DESC(ptr), rpl)
/* Section for fixed GDT entries */
#define ATTR_BSS_GDT \
__attribute__((section(".gdt_bss"))) ATTR_KERN_ADDR_SPACE
/* Section for TSS and LDT descriptors for protection domains */
#define ATTR_BSS_GDT_MID \
__attribute__((used, section(".gdt_bss_mid"))) ATTR_KERN_ADDR_SPACE
/* Section for other GDT entries */
#define ATTR_BSS_GDT_START \
__attribute__((section(".gdt_bss_start"))) ATTR_KERN_ADDR_SPACE
void gdt_copy_desc_change_dpl(unsigned int dest_idx,
unsigned int src_idx,
unsigned dpl);
void gdt_init(void) ATTR_CODE_BOOT;
void gdt_insert(unsigned int idx, segment_desc_t desc);
void gdt_insert_boot(unsigned int idx, segment_desc_t desc) ATTR_CODE_BOOT;
void gdt_lookup(unsigned int idx, segment_desc_t *desc);
#endif /* GDT_H */