mmu.h
#ifndef __KERN_MM_MMU_H__
#define __KERN_MM_MMU_H__
/* Eflags register */
#define FL_CF 0x00000001 // Carry Flag
#define FL_PF 0x00000004 // Parity Flag
#define FL_AF 0x00000010 // Auxiliary carry Flag
#define FL_ZF 0x00000040 // Zero Flag
#define FL_SF 0x00000080 // Sign Flag
#define FL_TF 0x00000100 // Trap Flag
#define FL_IF 0x00000200 // Interrupt Flag
#define FL_DF 0x00000400 // Direction Flag
#define FL_OF 0x00000800 // Overflow Flag
#define FL_IOPL_MASK 0x00003000 // I/O Privilege Level bitmask
#define FL_IOPL_0 0x00000000 // IOPL == 0
#define FL_IOPL_1 0x00001000 // IOPL == 1
#define FL_IOPL_2 0x00002000 // IOPL == 2
#define FL_IOPL_3 0x00003000 // IOPL == 3
#define FL_NT 0x00004000 // Nested Task
#define FL_RF 0x00010000 // Resume Flag
#define FL_VM 0x00020000 // Virtual 8086 mode
#define FL_AC 0x00040000 // Alignment Check
#define FL_VIF 0x00080000 // Virtual Interrupt Flag
#define FL_VIP 0x00100000 // Virtual Interrupt Pending
#define FL_ID 0x00200000 // ID flag
/* Application segment type bits */
#define STA_X 0x8 // Executable segment
#define STA_E 0x4 // Expand down (non-executable segments)
#define STA_C 0x4 // Conforming code segment (executable only)
#define STA_W 0x2 // Writeable (non-executable segments)
#define STA_R 0x2 // Readable (executable segments)
#define STA_A 0x1 // Accessed
/* System segment type bits */
#define STS_T16A 0x1 // Available 16-bit TSS
#define STS_LDT 0x2 // Local Descriptor Table
#define STS_T16B 0x3 // Busy 16-bit TSS
#define STS_CG16 0x4 // 16-bit Call Gate
#define STS_TG 0x5 // Task Gate / Coum Transmitions
#define STS_IG16 0x6 // 16-bit Interrupt Gate
#define STS_TG16 0x7 // 16-bit Trap Gate
#define STS_T32A 0x9 // Available 32-bit TSS
#define STS_T32B 0xB // Busy 32-bit TSS
#define STS_CG32 0xC // 32-bit Call Gate
#define STS_IG32 0xE // 32-bit Interrupt Gate
#define STS_TG32 0xF // 32-bit Trap Gate
#ifdef __ASSEMBLER__
#define SEG_NULL \
.word 0, 0; \
.byte 0, 0, 0, 0
#define SEG_ASM(type,base,lim) \
.word (((lim) >> 12) & 0xffff), ((base) & 0xffff); \
.byte (((base) >> 16) & 0xff), (0x90 | (type)), \
(0xC0 | (((lim) >> 28) & 0xf)), (((base) >> 24) & 0xff)
#else /* not __ASSEMBLER__ */
#include <defs.h>
/* Gate descriptors for interrupts and traps */
struct gatedesc {
unsigned gd_off_15_0 : 16; // low 16 bits of offset in segment
unsigned gd_ss : 16; // segment selector
unsigned gd_args : 5; // # args, 0 for interrupt/trap gates
unsigned gd_rsv1 : 3; // reserved(should be zero I guess)
unsigned gd_type : 4; // type(STS_{TG,IG32,TG32})
unsigned gd_s : 1; // must be 0 (system)
unsigned gd_dpl : 2; // descriptor(meaning new) privilege level
unsigned gd_p : 1; // Present
unsigned gd_off_31_16 : 16; // high bits of offset in segment
};
/* *
* Set up a normal interrupt/trap gate descriptor
* - istrap: 1 for a trap (= exception) gate, 0 for an interrupt gate
* - sel: Code segment selector for interrupt/trap handler
* - off: Offset in code segment for interrupt/trap handler
* - dpl: Descriptor Privilege Level - the privilege level required
* for software to invoke this interrupt/trap gate explicitly
* using an int instruction.
* */
#define SETGATE(gate, istrap, sel, off, dpl) { \
(gate).gd_off_15_0 = (uint32_t)(off) & 0xffff; \
(gate).gd_ss = (sel); \
(gate).gd_args = 0; \
(gate).gd_rsv1 = 0; \
(gate).gd_type = (istrap) ? STS_TG32 : STS_IG32; \
(gate).gd_s = 0; \
(gate).gd_dpl = (dpl); \
(gate).gd_p = 1; \
(gate).gd_off_31_16 = (uint32_t)(off) >> 16; \
}
/* Set up a call gate descriptor */
#define SETCALLGATE(gate, ss, off, dpl) { \
(gate).gd_off_15_0 = (uint32_t)(off) & 0xffff; \
(gate).gd_ss = (ss); \
(gate).gd_args = 0; \
(gate).gd_rsv1 = 0; \
(gate).gd_type = STS_CG32; \
(gate).gd_s = 0; \
(gate).gd_dpl = (dpl); \
(gate).gd_p = 1; \
(gate).gd_off_31_16 = (uint32_t)(off) >> 16; \
}
/* segment descriptors */
struct segdesc {
unsigned sd_lim_15_0 : 16; // low bits of segment limit
unsigned sd_base_15_0 : 16; // low bits of segment base address
unsigned sd_base_23_16 : 8; // middle bits of segment base address
unsigned sd_type : 4; // segment type (see STS_ constants)
unsigned sd_s : 1; // 0 = system, 1 = application
unsigned sd_dpl : 2; // descriptor Privilege Level
unsigned sd_p : 1; // present
unsigned sd_lim_19_16 : 4; // high bits of segment limit
unsigned sd_avl : 1; // unused (available for software use)
unsigned sd_rsv1 : 1; // reserved
unsigned sd_db : 1; // 0 = 16-bit segment, 1 = 32-bit segment
unsigned sd_g : 1; // granularity: limit scaled by 4K when set
unsigned sd_base_31_24 : 8; // high bits of segment base address
};
#define SEG_NULL \
(struct segdesc) {0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
#define SEG(type, base, lim, dpl) \
(struct segdesc) { \
((lim) >> 12) & 0xffff, (base) & 0xffff, \
((base) >> 16) & 0xff, type, 1, dpl, 1, \
(unsigned)(lim) >> 28, 0, 0, 1, 1, \
(unsigned) (base) >> 24 \
}
#define SEGTSS(type, base, lim, dpl) \
(struct segdesc) { \
(lim) & 0xffff, (base) & 0xffff, \
((base) >> 16) & 0xff, type, 0, dpl, 1, \
(unsigned) (lim) >> 16, 0, 0, 1, 0, \
(unsigned) (base) >> 24 \
}
/* task state segment format (as described by the Pentium architecture book) */
struct taskstate {
uint32_t ts_link; // old ts selector
uintptr_t ts_esp0; // stack pointers and segment selectors
uint16_t ts_ss0; // after an increase in privilege level
uint16_t ts_padding1;
uintptr_t ts_esp1;
uint16_t ts_ss1;
uint16_t ts_padding2;
uintptr_t ts_esp2;
uint16_t ts_ss2;
uint16_t ts_padding3;
uintptr_t ts_cr3; // page directory base
uintptr_t ts_eip; // saved state from last task switch
uint32_t ts_eflags;
uint32_t ts_eax; // more saved state (registers)
uint32_t ts_ecx;
uint32_t ts_edx;
uint32_t ts_ebx;
uintptr_t ts_esp;
uintptr_t ts_ebp;
uint32_t ts_esi;
uint32_t ts_edi;
uint16_t ts_es; // even more saved state (segment selectors)
uint16_t ts_padding4;
uint16_t ts_cs;
uint16_t ts_padding5;
uint16_t ts_ss;
uint16_t ts_padding6;
uint16_t ts_ds;
uint16_t ts_padding7;
uint16_t ts_fs;
uint16_t ts_padding8;
uint16_t ts_gs;
uint16_t ts_padding9;
uint16_t ts_ldt;
uint16_t ts_padding10;
uint16_t ts_t; // trap on task switch
uint16_t ts_iomb; // i/o map base address
} __attribute__((packed));
#endif /* !__ASSEMBLER__ */
// A linear address 'la' has a three-part structure as follows:
//
// +--------10------+-------10-------+---------12----------+
// | Page Directory | Page Table | Offset within Page |
// | Index | Index | |
// +----------------+----------------+---------------------+
// \--- PDX(la) --/ \--- PTX(la) --/ \---- PGOFF(la) ----/
// \----------- PPN(la) -----------/
//
// The PDX, PTX, PGOFF, and PPN macros decompose linear addresses as shown.
// To construct a linear address la from PDX(la), PTX(la), and PGOFF(la),
// use PGADDR(PDX(la), PTX(la), PGOFF(la)).
// page directory index
#define PDX(la) ((((uintptr_t)(la)) >> PDXSHIFT) & 0x3FF)
// page table index
#define PTX(la) ((((uintptr_t)(la)) >> PTXSHIFT) & 0x3FF)
// page number field of address
#define PPN(la) (((uintptr_t)(la)) >> PTXSHIFT)
// offset in page
#define PGOFF(la) (((uintptr_t)(la)) & 0xFFF)
// construct linear address from indexes and offset
#define PGADDR(d, t, o) ((uintptr_t)((d) << PDXSHIFT | (t) << PTXSHIFT | (o)))
// address in page table or page directory entry
#define PTE_ADDR(pte) ((uintptr_t)(pte) & ~0xFFF)
#define PDE_ADDR(pde) PTE_ADDR(pde)
/* page directory and page table constants */
#define NPDEENTRY 1024 // page directory entries per page directory
#define NPTEENTRY 1024 // page table entries per page table
#define PGSIZE 4096 // bytes mapped by a page
#define PGSHIFT 12 // log2(PGSIZE)
#define PTSIZE (PGSIZE * NPTEENTRY) // bytes mapped by a page directory entry
#define PTSHIFT 22 // log2(PTSIZE)
#define PTXSHIFT 12 // offset of PTX in a linear address
#define PDXSHIFT 22 // offset of PDX in a linear address
/* page table/directory entry flags */
#define PTE_P 0x001 // Present
#define PTE_W 0x002 // Writeable
#define PTE_U 0x004 // User
#define PTE_PWT 0x008 // Write-Through
#define PTE_PCD 0x010 // Cache-Disable
#define PTE_A 0x020 // Accessed
#define PTE_D 0x040 // Dirty
#define PTE_PS 0x080 // Page Size
#define PTE_MBZ 0x180 // Bits must be zero
#define PTE_AVAIL 0xE00 // Available for software use
// The PTE_AVAIL bits aren't used by the kernel or interpreted by the
// hardware, so user processes are allowed to set them arbitrarily.
#define PTE_USER (PTE_U | PTE_W | PTE_P)
/* Control Register flags */
#define CR0_PE 0x00000001 // Protection Enable
#define CR0_MP 0x00000002 // Monitor coProcessor
#define CR0_EM 0x00000004 // Emulation
#define CR0_TS 0x00000008 // Task Switched
#define CR0_ET 0x00000010 // Extension Type
#define CR0_NE 0x00000020 // Numeric Errror
#define CR0_WP 0x00010000 // Write Protect
#define CR0_AM 0x00040000 // Alignment Mask
#define CR0_NW 0x20000000 // Not Writethrough
#define CR0_CD 0x40000000 // Cache Disable
#define CR0_PG 0x80000000 // Paging
#define CR4_PCE 0x00000100 // Performance counter enable
#define CR4_MCE 0x00000040 // Machine Check Enable
#define CR4_PSE 0x00000010 // Page Size Extensions
#define CR4_DE 0x00000008 // Debugging Extensions
#define CR4_TSD 0x00000004 // Time Stamp Disable
#define CR4_PVI 0x00000002 // Protected-Mode Virtual Interrupts
#define CR4_VME 0x00000001 // V86 Mode Extensions
#endif /* !__KERN_MM_MMU_H__ */Last updated