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-rw-r--r--src/segmentation.rs214
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diff --git a/src/segmentation.rs b/src/segmentation.rs
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-//! Program x86 segmentation hardware.
-
-use core::fmt;
-
-/// Specifies which element to load into a segment from
-/// descriptor tables (i.e., is a index to LDT or GDT table
-/// with some additional flags).
-bitflags! {
- flags SegmentSelector: u16 {
- /// Requestor Privilege Level
- const RPL_0 = 0b00,
- const RPL_1 = 0b01,
- const RPL_2 = 0b10,
- const RPL_3 = 0b11,
-
- /// Table Indicator (TI) 0 means GDT is used.
- const TI_GDT = 0 << 3,
- /// Table Indicator (TI) 1 means LDT is used.
- const TI_LDT = 1 << 3,
- }
-}
-
-impl SegmentSelector {
- /// Create a new SegmentSelector
- ///
- /// # Arguments
- /// * `index` index in GDT or LDT array.
- ///
- pub fn new(index: u16) -> SegmentSelector {
- SegmentSelector { bits: index << 3 }
- }
-
- pub fn from_raw(bits: u16) -> SegmentSelector {
- SegmentSelector { bits: bits }
- }
-}
-
-impl fmt::Debug for SegmentSelector {
- fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
- let r0 = match self.contains(RPL_0) {
- false => "",
- true => "Ring 0 segment selector.",
- };
- let r1 = match self.contains(RPL_1) {
- false => "",
- true => "Ring 1 segment selector.",
- };
- let r2 = match self.contains(RPL_2) {
- false => "",
- true => "Ring 2 segment selector.",
- };
- let r3 = match self.contains(RPL_3) {
- false => "",
- true => "Ring 3 segment selector.",
- };
- let tbl = match self.contains(TI_LDT) {
- false => "GDT Table",
- true => "LDT Table",
- };
-
- write!(f,
- "Index {} in {}, {}{}{}{}",
- self.bits >> 3,
- tbl,
- r0,
- r1,
- r2,
- r3)
- // write!(f, "Index")
- }
-}
-
-
-/// Entry for GDT or LDT. Provides size and location of a segment.
-bitflags! {
- flags SegmentDescriptor: u64 {
- /// Descriptor type (0 = system; 1 = code or data).
- const DESC_S = 1 << (32+12),
- /// Descriptor privilege level 0.
- const DESC_DPL0 = 0b00 << (32+13),
- /// Descriptor privilege level 1.
- const DESC_DPL1 = 0b01 << (32+13),
- /// Descriptor privilege level 2.
- const DESC_DPL2 = 0b10 << (32+13),
- /// Descriptor privilege level 3.
- const DESC_DPL3 = 0b11 << (32+13),
- /// Descriptor is Present.
- const DESC_P = 1 << (32+15),
- /// Available for use by system software.
- const DESC_AVL = 1 << (32+20),
- /// 64-bit code segment (IA-32e mode only).
- const DESC_L = 1 << (32+21),
- /// Default operation size (0 = 16-bit segment, 1 = 32-bit segment)
- const DESC_DB = 1 << (32+22),
- /// Granularity.
- const DESC_G = 1 << (32+23),
-
- // System-Segment and Gate-Descriptor Types for IA32e mode.
- // When the S (descriptor type) flag in a segment descriptor is clear,
- // the descriptor type is a system descriptor.
-
- const TYPE_SYS_LDT = 0b0010 << (32+8),
- const TYPE_SYS_TSS_AVAILABLE = 0b1001 << (32+8),
- const TYPE_SYS_TSS_BUSY = 0b1011 << (32+8),
- const TYPE_SYS_CALL_GATE = 0b1100 << (32+8),
- const TYPE_SYS_INTERRUPT_GATE = 0b1110 << (32+8),
- const TYPE_SYS_TRAP_GATE = 0b1111 << (32+8),
-
- // Code- and Data-Segment Descriptor Types.
- // When the S (descriptor type) flag in a segment descriptor is set,
- // the descriptor is for either a code or a data segment.
-
- /// Data Read-Only
- const TYPE_D_RO = 0b0000 << (32+8),
- /// Data Read-Only, accessed
- const TYPE_D_ROA = 0b0001 << (32+8),
- /// Data Read/Write
- const TYPE_D_RW = 0b0010 << (32+8),
- /// Data Read/Write, accessed
- const TYPE_D_RWA = 0b0011 << (32+8),
- /// Data Read-Only, expand-down
- const TYPE_D_ROEXD = 0b0100 << (32+8),
- /// Data Read-Only, expand-down, accessed
- const TYPE_D_ROEXDA = 0b0101 << (32+8),
- /// Data Read/Write, expand-down
- const TYPE_D_RWEXD = 0b0110 << (32+8),
- /// Data Read/Write, expand-down, accessed
- const TYPE_D_RWEXDA = 0b0111 << (32+8),
-
- /// Code Execute-Only
- const TYPE_C_EO = 0b1000 << (32+8),
- /// Code Execute-Only, accessed
- const TYPE_C_EOA = 0b1001 << (32+8),
- /// Code Execute/Read
- const TYPE_C_ER = 0b1010 << (32+8),
- /// Code Execute/Read, accessed
- const TYPE_C_ERA = 0b1011 << (32+8),
- /// Code Execute-Only, conforming
- const TYPE_C_EOC = 0b1100 << (32+8),
- /// Code Execute-Only, conforming, accessed
- const TYPE_C_EOCA = 0b1101 << (32+8),
- /// Code Execute/Read, conforming
- const TYPE_C_ERC = 0b1110 << (32+8),
- /// Code Execute/Read, conforming, accessed
- const TYPE_C_ERCA = 0b1111 << (32+8),
- }
-}
-
-/// This is data-structure is a ugly mess thing so we provide some
-/// convenience function to program it.
-impl SegmentDescriptor {
- pub fn new(base: u32, limit: u32) -> SegmentDescriptor {
- let base_low: u64 = base as u64 & 0xffffff;
- let base_high: u64 = (base as u64 >> 24) & 0xff;
-
- let limit_low: u64 = limit as u64 & 0xffff;
- let limit_high: u64 = (limit as u64 & (0b1111 << 16)) >> 16;
-
- SegmentDescriptor {
- bits: limit_low | base_low << 16 | limit_high << (32 + 16) | base_high << (32 + 24),
- }
- }
-}
-
-impl fmt::Debug for SegmentDescriptor {
- fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
- write!(f, "SD: 0x{:x}", self.bits)
- }
-}
-
-/// Reload stack segment register.
-pub unsafe fn load_ss(sel: SegmentSelector) {
- asm!("movw $0, %ss " :: "r" (sel) : "memory");
-}
-
-/// Reload data segment register.
-pub unsafe fn load_ds(sel: SegmentSelector) {
- asm!("movw $0, %ds " :: "r" (sel) : "memory");
-}
-
-/// Reload es segment register.
-pub unsafe fn load_es(sel: SegmentSelector) {
- asm!("movw $0, %es " :: "r" (sel) : "memory");
-}
-
-/// Reload fs segment register.
-pub unsafe fn load_fs(sel: SegmentSelector) {
- asm!("movw $0, %fs " :: "r" (sel) : "memory");
-}
-
-/// Reload gs segment register.
-pub unsafe fn load_gs(sel: SegmentSelector) {
- asm!("movw $0, %gs " :: "r" (sel) : "memory");
-}
-
-/// Reload code segment register.
-/// Note this is special since we can not directly move
-/// to %cs. Instead we push the new segment selector
-/// and return value on the stack and use lretq
-/// to reload cs and continue at 1:.
-pub unsafe fn load_cs(sel: SegmentSelector) {
- asm!("pushq $0
- lea 1f(%rip), %rax
- pushq %rax
- lretq
- 1:" :: "r" (sel.bits() as u64) : "{rax}" "memory");
-}
-
-/// Returns the current value of the code segment register.
-pub fn cs() -> SegmentSelector {
- let segment: u16;
- unsafe { asm!("mov %cs, $0" : "=r" (segment) ) };
- SegmentSelector::from_raw(segment)
-}
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