1 // This file contains definitions for the 2 // x86 memory management unit (MMU). 3 4 // Eflags register 5 #define FL_CF 0x00000001 // Carry Flag 6 #define FL_PF 0x00000004 // Parity Flag 7 #define FL_AF 0x00000010 // Auxiliary carry Flag 8 #define FL_ZF 0x00000040 // Zero Flag 9 #define FL_SF 0x00000080 // Sign Flag 10 #define FL_TF 0x00000100 // Trap Flag 11 #define FL_IF 0x00000200 // Interrupt Enable 12 #define FL_DF 0x00000400 // Direction Flag 13 #define FL_OF 0x00000800 // Overflow Flag 14 #define FL_IOPL_MASK 0x00003000 // I/O Privilege Level bitmask 15 #define FL_IOPL_0 0x00000000 // IOPL == 0 16 #define FL_IOPL_1 0x00001000 // IOPL == 1 17 #define FL_IOPL_2 0x00002000 // IOPL == 2 18 #define FL_IOPL_3 0x00003000 // IOPL == 3 19 #define FL_NT 0x00004000 // Nested Task 20 #define FL_RF 0x00010000 // Resume Flag 21 #define FL_VM 0x00020000 // Virtual 8086 mode 22 #define FL_AC 0x00040000 // Alignment Check 23 #define FL_VIF 0x00080000 // Virtual Interrupt Flag 24 #define FL_VIP 0x00100000 // Virtual Interrupt Pending 25 #define FL_ID 0x00200000 // ID flag 26 27 // Control Register flags 28 #define CR0_PE 0x00000001 // Protection Enable 29 #define CR0_MP 0x00000002 // Monitor coProcessor 30 #define CR0_EM 0x00000004 // Emulation 31 #define CR0_TS 0x00000008 // Task Switched 32 #define CR0_ET 0x00000010 // Extension Type 33 #define CR0_NE 0x00000020 // Numeric Errror 34 #define CR0_WP 0x00010000 // Write Protect 35 #define CR0_AM 0x00040000 // Alignment Mask 36 #define CR0_NW 0x20000000 // Not Writethrough 37 #define CR0_CD 0x40000000 // Cache Disable 38 #define CR0_PG 0x80000000 // Paging 39 40 #define CR4_PSE 0x00000010 // Page size extension 41 42 // various segment selectors. 43 #define SEG_KCODE 1 // kernel code 44 #define SEG_KDATA 2 // kernel data+stack 45 #define SEG_KCPU 3 // kernel per-cpu data 46 #define SEG_UCODE 4 // user code 47 #define SEG_UDATA 5 // user data+stack 48 #define SEG_TSS 6 // this process's task state 49 50 // cpu->gdt[NSEGS] holds the above segments. 51 #define NSEGS 7 52 53 //PAGEBREAK! 54 #ifndef __ASSEMBLER__ 55 // Segment Descriptor 56 struct segdesc { 57 uint lim_15_0 : 16; // Low bits of segment limit 58 uint base_15_0 : 16; // Low bits of segment base address 59 uint base_23_16 : 8; // Middle bits of segment base address 60 uint type : 4; // Segment type (see STS_ constants) 61 uint s : 1; // 0 = system, 1 = application 62 uint dpl : 2; // Descriptor Privilege Level 63 uint p : 1; // Present 64 uint lim_19_16 : 4; // High bits of segment limit 65 uint avl : 1; // Unused (available for software use) 66 uint rsv1 : 1; // Reserved 67 uint db : 1; // 0 = 16-bit segment, 1 = 32-bit segment 68 uint g : 1; // Granularity: limit scaled by 4K when set 69 uint base_31_24 : 8; // High bits of segment base address 70 }; 71 72 // Normal segment 73 #define SEG(type, base, lim, dpl) (struct segdesc) \ 74 { ((lim) >> 12) & 0xffff, (uint)(base) & 0xffff, \ 75 ((uint)(base) >> 16) & 0xff, type, 1, dpl, 1, \ 76 (uint)(lim) >> 28, 0, 0, 1, 1, (uint)(base) >> 24 } 77 #define SEG16(type, base, lim, dpl) (struct segdesc) \ 78 { (lim) & 0xffff, (uint)(base) & 0xffff, \ 79 ((uint)(base) >> 16) & 0xff, type, 1, dpl, 1, \ 80 (uint)(lim) >> 16, 0, 0, 1, 0, (uint)(base) >> 24 } 81 #endif 82 83 #define DPL_USER 0x3 // User DPL 84 85 // Application segment type bits 86 #define STA_X 0x8 // Executable segment 87 #define STA_E 0x4 // Expand down (non-executable segments) 88 #define STA_C 0x4 // Conforming code segment (executable only) 89 #define STA_W 0x2 // Writeable (non-executable segments) 90 #define STA_R 0x2 // Readable (executable segments) 91 #define STA_A 0x1 // Accessed 92 93 // System segment type bits 94 #define STS_T16A 0x1 // Available 16-bit TSS 95 #define STS_LDT 0x2 // Local Descriptor Table 96 #define STS_T16B 0x3 // Busy 16-bit TSS 97 #define STS_CG16 0x4 // 16-bit Call Gate 98 #define STS_TG 0x5 // Task Gate / Coum Transmitions 99 #define STS_IG16 0x6 // 16-bit Interrupt Gate 100 #define STS_TG16 0x7 // 16-bit Trap Gate 101 #define STS_T32A 0x9 // Available 32-bit TSS 102 #define STS_T32B 0xB // Busy 32-bit TSS 103 #define STS_CG32 0xC // 32-bit Call Gate 104 #define STS_IG32 0xE // 32-bit Interrupt Gate 105 #define STS_TG32 0xF // 32-bit Trap Gate 106 107 // A virtual address 'la' has a three-part structure as follows: 108 // 109 // +--------10------+-------10-------+---------12----------+ 110 // | Page Directory | Page Table | Offset within Page | 111 // | Index | Index | | 112 // +----------------+----------------+---------------------+ 113 // \--- PDX(va) --/ \--- PTX(va) --/ 114 115 // page directory index 116 #define PDX(va) (((uint)(va) >> PDXSHIFT) & 0x3FF) 117 118 // page table index 119 #define PTX(va) (((uint)(va) >> PTXSHIFT) & 0x3FF) 120 121 // construct virtual address from indexes and offset 122 #define PGADDR(d, t, o) ((uint)((d) << PDXSHIFT | (t) << PTXSHIFT | (o))) 123 124 // Page directory and page table constants. 125 #define NPDENTRIES 1024 // # directory entries per page directory 126 #define NPTENTRIES 1024 // # PTEs per page table 127 #define PGSIZE 4096 // bytes mapped by a page 128 129 #define PGSHIFT 12 // log2(PGSIZE) 130 #define PTXSHIFT 12 // offset of PTX in a linear address 131 #define PDXSHIFT 22 // offset of PDX in a linear address 132 133 #define PGROUNDUP(sz) (((sz)+PGSIZE-1) & ~(PGSIZE-1)) 134 #define PGROUNDDOWN(a) (((a)) & ~(PGSIZE-1)) 135 136 // Page table/directory entry flags. 137 #define PTE_P 0x001 // Present 138 #define PTE_W 0x002 // Writeable 139 #define PTE_U 0x004 // User 140 #define PTE_PWT 0x008 // Write-Through 141 #define PTE_PCD 0x010 // Cache-Disable 142 #define PTE_A 0x020 // Accessed 143 #define PTE_D 0x040 // Dirty 144 #define PTE_PS 0x080 // Page Size 145 #define PTE_MBZ 0x180 // Bits must be zero 146 147 // Address in page table or page directory entry 148 #define PTE_ADDR(pte) ((uint)(pte) & ~0xFFF) 149 #define PTE_FLAGS(pte) ((uint)(pte) & 0xFFF) 150 151 #ifndef __ASSEMBLER__ 152 typedef uint pte_t; 153 154 // Task state segment format 155 struct taskstate { 156 uint link; // Old ts selector 157 uint esp0; // Stack pointers and segment selectors 158 ushort ss0; // after an increase in privilege level 159 ushort padding1; 160 uint *esp1; 161 ushort ss1; 162 ushort padding2; 163 uint *esp2; 164 ushort ss2; 165 ushort padding3; 166 void *cr3; // Page directory base 167 uint *eip; // Saved state from last task switch 168 uint eflags; 169 uint eax; // More saved state (registers) 170 uint ecx; 171 uint edx; 172 uint ebx; 173 uint *esp; 174 uint *ebp; 175 uint esi; 176 uint edi; 177 ushort es; // Even more saved state (segment selectors) 178 ushort padding4; 179 ushort cs; 180 ushort padding5; 181 ushort ss; 182 ushort padding6; 183 ushort ds; 184 ushort padding7; 185 ushort fs; 186 ushort padding8; 187 ushort gs; 188 ushort padding9; 189 ushort ldt; 190 ushort padding10; 191 ushort t; // Trap on task switch 192 ushort iomb; // I/O map base address 193 }; 194 195 // PAGEBREAK: 12 196 // Gate descriptors for interrupts and traps 197 struct gatedesc { 198 uint off_15_0 : 16; // low 16 bits of offset in segment 199 uint cs : 16; // code segment selector 200 uint args : 5; // # args, 0 for interrupt/trap gates 201 uint rsv1 : 3; // reserved(should be zero I guess) 202 uint type : 4; // type(STS_{TG,IG32,TG32}) 203 uint s : 1; // must be 0 (system) 204 uint dpl : 2; // descriptor(meaning new) privilege level 205 uint p : 1; // Present 206 uint off_31_16 : 16; // high bits of offset in segment 207 }; 208 209 // Set up a normal interrupt/trap gate descriptor. 210 // - istrap: 1 for a trap (= exception) gate, 0 for an interrupt gate. 211 // interrupt gate clears FL_IF, trap gate leaves FL_IF alone 212 // - sel: Code segment selector for interrupt/trap handler 213 // - off: Offset in code segment for interrupt/trap handler 214 // - dpl: Descriptor Privilege Level - 215 // the privilege level required for software to invoke 216 // this interrupt/trap gate explicitly using an int instruction. 217 #define SETGATE(gate, istrap, sel, off, d) \ 218 { \ 219 (gate).off_15_0 = (uint)(off) & 0xffff; \ 220 (gate).cs = (sel); \ 221 (gate).args = 0; \ 222 (gate).rsv1 = 0; \ 223 (gate).type = (istrap) ? STS_TG32 : STS_IG32; \ 224 (gate).s = 0; \ 225 (gate).dpl = (d); \ 226 (gate).p = 1; \ 227 (gate).off_31_16 = (uint)(off) >> 16; \ 228 } 229 230 #endif 231