mirror of
https://gitlab.com/sortix/sortix.git
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128 lines
4.1 KiB
C++
128 lines
4.1 KiB
C++
/*******************************************************************************
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COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011, 2012.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along with
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Sortix. If not, see <http://www.gnu.org/licenses/>.
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x86-family/gdt.h
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Initializes and handles the GDT and TSS.
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*******************************************************************************/
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#ifndef SORTIX_X86_FAMILY_GDT_H
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#define SORTIX_X86_FAMILY_GDT_H
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namespace Sortix
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{
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namespace GDT
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{
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// This structure contains the value of one GDT entry.
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// We use the attribute 'packed' to tell GCC not to change
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// any of the alignment in the structure.
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struct gdt_entry_struct
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{
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uint16_t limit_low; // The lower 16 bits of the limit.
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uint16_t base_low; // The lower 16 bits of the base.
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uint8_t base_middle; // The next 8 bits of the base.
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uint8_t access; // Access flags, determine what ring this segment can be used in.
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uint8_t granularity;
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uint8_t base_high; // The last 8 bits of the base.
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} __attribute__((packed));
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struct gdt_entry64_struct
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{
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uint16_t limit_low;
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uint16_t base_low;
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uint8_t base_middle;
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uint8_t access;
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uint8_t granularity;
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uint8_t base_high;
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uint32_t base_highest;
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uint32_t zero1;
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} __attribute__((packed));
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typedef struct gdt_entry_struct gdt_entry_t;
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typedef struct gdt_entry64_struct gdt_entry64_t;
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// This struct describes a GDT pointer. It points to the start of
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// our array of GDT entries, and is in the format required by the
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// lgdt instruction.
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struct gdt_ptr_struct
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{
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uint16_t limit; // The upper 16 bits of all selector limits.
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addr_t base; // The address of the first gdt_entry_t struct.
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} __attribute__((packed));
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typedef struct gdt_ptr_struct gdt_ptr_t;
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// A struct describing a Task State Segment.
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#ifdef PLATFORM_X86
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struct tss_entry_struct
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{
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uint32_t prev_tss; // The previous TSS - if we used hardware task switching this would form a linked list.
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uint32_t esp0; // The stack pointer to load when we change to kernel mode.
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uint32_t ss0; // The stack segment to load when we change to kernel mode.
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uint32_t esp1; // Unused...
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uint32_t ss1;
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uint32_t esp2;
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uint32_t ss2;
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uint32_t cr3;
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uint32_t eip;
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uint32_t eflags;
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uint32_t eax;
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uint32_t ecx;
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uint32_t edx;
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uint32_t ebx;
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uint32_t esp;
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uint32_t ebp;
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uint32_t esi;
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uint32_t edi;
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uint32_t es; // The value to load into ES when we change to kernel mode.
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uint32_t cs; // The value to load into CS when we change to kernel mode.
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uint32_t ss; // The value to load into SS when we change to kernel mode.
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uint32_t ds; // The value to load into DS when we change to kernel mode.
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uint32_t fs; // The value to load into FS when we change to kernel mode.
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uint32_t gs; // The value to load into GS when we change to kernel mode.
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uint32_t ldt; // Unused...
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uint16_t trap;
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uint16_t iomap_base;
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} __attribute__((packed));
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#else
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struct tss_entry_struct
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{
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uint32_t reserved1;
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uint64_t stack0;
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uint64_t stack1;
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uint64_t stack2;
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uint64_t reserved2;
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uint64_t ist[7];
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uint64_t reserved3;
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uint16_t reserved4;
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uint16_t iomap_base;
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} __attribute__((packed));
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#endif
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typedef struct tss_entry_struct tss_entry_t;
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void Init();
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void SetGate(int32_t num, uint32_t base, uint32_t limit, uint8_t access, uint8_t gran);
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void WriteTSS(int32_t num, uint16_t ss0, addr_t stack0);
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void SetKernelStack(size_t* stack);
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}
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}
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#endif
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