4cdb7ba9b6
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
113 lines
3.8 KiB
C
113 lines
3.8 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 "gdt-layout.h"
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#include "prot-domains.h"
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#include <stdint.h>
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#include "helpers.h"
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#include "segmentation.h"
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#include "idt.h"
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#define NUM_DESC 256
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typedef struct idtr {
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uint16_t limit;
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uint32_t base;
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} __attribute__((packed)) idtr_t;
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typedef union intr_gate_desc {
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struct __attribute__((packed)) {
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uint16_t offset_low;
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uint16_t selector; /* Segment Selector for destination code segment */
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uint16_t fixed:11;
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uint16_t d:1; /* Size of gate: 1 = 32 bits; 0 = 16 bits */
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uint16_t pad:1;
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uint16_t dpl:2; /* Descriptor Privilege Level */
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uint16_t p:1; /* Segment Present flag */
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uint16_t offset_high;
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};
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uint64_t raw;
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struct {
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uint32_t raw_lo;
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uint32_t raw_hi;
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};
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} intr_gate_desc_t;
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/* According to Intel Combined Manual, Vol. 3, Section 6.10, the base addresses
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* of the IDT should be aligned on an 8-byte boundary to maximize performance
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* of cache line fills.
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*/
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static intr_gate_desc_t __attribute__((aligned(8))) ATTR_BSS_KERN
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idt[NUM_DESC];
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/*---------------------------------------------------------------------------*/
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/* XXX: If you change this function prototype, make sure you fix the assembly
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* code in SET_INT_EXC_HANDLER macro in interrupt.h. Otherwise, you might
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* face a very-hard-to-find bug in the interrupt handling system.
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*/
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void
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idt_set_intr_gate_desc(int intr_num,
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uint32_t offset,
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uint16_t cs,
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uint16_t dpl)
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{
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intr_gate_desc_t desc;
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desc.offset_low = offset & 0xFFFF;
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desc.selector = cs;
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desc.fixed = BIT(9) | BIT(10);
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desc.pad = 0;
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desc.d = 1;
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desc.dpl = dpl;
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desc.p = 1;
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desc.offset_high = (offset >> 16) & 0xFFFF;
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KERN_WRITEL(idt[intr_num].raw_hi, desc.raw_hi);
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KERN_WRITEL(idt[intr_num].raw_lo, desc.raw_lo);
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}
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/*---------------------------------------------------------------------------*/
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/* Initialize Interrupt Descriptor Table. The IDT is initialized with
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* null descriptors. Therefore, any interrupt at this point will cause
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* a triple fault.
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*/
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void
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idt_init(void)
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{
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idtr_t idtr;
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/* Initialize idtr structure */
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idtr.limit = (sizeof(intr_gate_desc_t) * NUM_DESC) - 1;
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idtr.base = KERN_DATA_OFF_TO_PHYS_ADDR((uint32_t)idt);
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/* Load IDTR register */
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__asm__("lidt %0\n\t" :: "m" (idtr));
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}
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