125 lines
4.5 KiB
C
125 lines
4.5 KiB
C
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#ifndef _KERNEL_PLATFORM_X86_GDT_H
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#define _KERNEL_PLATFORM_X86_GDT_H
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#include <libkern/c_attrs.h>
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#include <libkern/types.h>
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#ifdef __x86_64__
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#define GDT_MAX_ENTRIES 7 // TSS takes 2 entries.
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// Marking that code segment contains native 64-bit code.
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#define GDT_LONGMODE_FLAG 1
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#define GDT_DB_FLAG 0
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#else
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#define GDT_MAX_ENTRIES 6
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#define GDT_LONGMODE_FLAG 0
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#define GDT_DB_FLAG 1
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#endif
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#define GDT_SEG_NULL 0 // kernel code
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#define GDT_SEG_KCODE 1 // kernel code
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#define GDT_SEG_KDATA 2 // kernel data+stack
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#define GDT_SEG_UCODE 3 // user code
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#define GDT_SEG_UDATA 4 // user data+stack
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#define GDT_SEG_TSS 5 // task state NOT USED CURRENTLY
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#define GDT_SEGF_X 0x8 // exec
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#define GDT_SEGF_A 0x1 // accessed
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#define GDT_SEGF_R 0x2 // readable (if exec)
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#define GDT_SEGF_C 0x4 // conforming seg (if exec)
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#define GDT_SEGF_W 0x2 // writeable (if non-exec)
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#define GDT_SEGF_D 0x4 // grows down (if non-exec)
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#define FL_IF 0x00000200
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#define DPL_KERN 0x0
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#define DPL_USER 0x3
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struct PACKED gdt_desc {
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union {
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struct {
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uint32_t lim_15_0 : 16;
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uint32_t base_15_0 : 16;
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uint32_t base_23_16 : 8;
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uint32_t type : 4;
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uint32_t dt : 1;
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uint32_t dpl : 2;
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uint32_t p : 1;
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uint32_t lim_19_16 : 4;
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uint32_t avl : 1;
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uint32_t l : 1;
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uint32_t db : 1;
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uint32_t g : 1;
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uint32_t base_31_24 : 8;
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};
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uint32_t raw;
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};
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};
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typedef struct gdt_desc gdt_desc_t;
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extern gdt_desc_t gdt[GDT_MAX_ENTRIES];
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#define GDT_SEG_CODE_DESC(vtype, vbase, vlimit, vdpl) \
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(gdt_desc_t) \
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{ \
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.lim_15_0 = ((vlimit) >> 12) & 0xffff, \
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.base_15_0 = (uint32_t)(vbase)&0xffff, \
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.base_23_16 = ((uint32_t)(vbase) >> 16) & 0xff, \
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.type = vtype, \
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.dt = 1, \
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.dpl = vdpl, \
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.p = 1, \
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.lim_19_16 = ((uint32_t)(vlimit) >> 28), \
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.avl = 0, \
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.l = GDT_LONGMODE_FLAG, \
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.db = GDT_DB_FLAG, \
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.g = 1, \
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.base_31_24 = (uint32_t)(vbase) >> 24 \
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}
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#define GDT_SEG_DATA_DESC(vtype, vbase, vlimit, vdpl) \
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(gdt_desc_t) \
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{ \
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.lim_15_0 = ((vlimit) >> 12) & 0xffff, \
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.base_15_0 = (uint32_t)(vbase)&0xffff, \
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.base_23_16 = ((uint32_t)(vbase) >> 16) & 0xff, \
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.type = vtype, \
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.dt = 1, \
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.dpl = vdpl, \
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.p = 1, \
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.lim_19_16 = ((uint32_t)(vlimit) >> 28), \
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.avl = 0, \
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.l = 0, \
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.db = 1, \
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.g = 1, \
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.base_31_24 = (uint32_t)(vbase) >> 24 \
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}
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#define GDT_SEG_TSS_DESC(vtype, vbase, vlimit, vdpl) \
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(gdt_desc_t) \
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{ \
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.lim_15_0 = ((vlimit)) & 0xffff, \
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.base_15_0 = (uint32_t)(vbase)&0xffff, \
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.base_23_16 = ((uint32_t)(vbase) >> 16) & 0xff, \
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.type = vtype, \
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.dt = 0, \
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.dpl = vdpl, \
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.p = 1, \
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.lim_19_16 = ((uint32_t)(vlimit) >> 16), \
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.avl = 0, \
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.l = 0, \
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.db = 0, \
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.g = 0, \
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.base_31_24 = (uint32_t)(vbase) >> 24 \
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}
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#define GDT_SEG_SET_RAW(rawvalue) \
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(gdt_desc_t) \
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{ \
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.raw = rawvalue \
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}
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void gdt_setup();
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#endif // _KERNEL_PLATFORM_X86_GDT_H
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