| /* |
| * Copyright (c) 2009 Corey Tabaka |
| * |
| * Permission is hereby granted, free of charge, to any person obtaining |
| * a copy of this software and associated documentation files |
| * (the "Software"), to deal in the Software without restriction, |
| * including without limitation the rights to use, copy, modify, merge, |
| * publish, distribute, sublicense, and/or sell copies of the Software, |
| * and to permit persons to whom the Software is furnished to do so, |
| * subject to the following conditions: |
| * |
| * The above copyright notice and this permission notice shall be |
| * included in all copies or substantial portions of the Software. |
| * |
| * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. |
| * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY |
| * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, |
| * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE |
| * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. |
| */ |
| |
| #include <compiler.h> |
| #include <arch/x86/descriptor.h> |
| |
| /* not the best way to do this, but easy for now */ |
| typedef struct { |
| uint16_t limit_15_0; |
| uint16_t base_15_0; |
| uint8_t base_23_16; |
| |
| uint8_t type : 4; |
| uint8_t s : 1; |
| uint8_t dpl : 2; |
| uint8_t p : 1; |
| |
| uint8_t limit_19_16 : 4; |
| uint8_t avl : 1; |
| uint8_t reserved_0 : 1; |
| uint8_t d_b : 1; |
| uint8_t g : 1; |
| |
| uint8_t base_31_24; |
| } __PACKED seg_desc_t; |
| |
| extern seg_desc_t _gdt[]; |
| |
| void set_global_desc(seg_sel_t sel, void *base, uint32_t limit, |
| uint8_t present, uint8_t ring, uint8_t sys, uint8_t type, uint8_t gran, uint8_t bits) |
| { |
| // convert selector into index |
| uint16_t index = sel >> 3; |
| |
| _gdt[index].limit_15_0 = limit & 0x0000ffff; |
| _gdt[index].limit_19_16 = (limit & 0x000f0000) >> 16; |
| |
| _gdt[index].base_15_0 = ((uint32_t) base) & 0x0000ffff; |
| _gdt[index].base_23_16 = (((uint32_t) base) & 0x00ff0000) >> 16; |
| _gdt[index].base_31_24 = ((uint32_t) base) >> 24; |
| |
| _gdt[index].type = type & 0x0f; // segment type |
| _gdt[index].p = present != 0; // present |
| _gdt[index].dpl = ring & 0x03; // descriptor privilege level |
| _gdt[index].g = gran != 0; // granularity |
| _gdt[index].s = sys != 0; // system / non-system |
| _gdt[index].d_b = bits != 0; // 16 / 32 bit |
| } |