refactor: scheduler, context switching and signal handling

kernel/src/arch/x86/gdt.rs

@@ -37,12 +37,14 @@ pub const KERNEL_CS: usize = 8;
 pub const KERNEL_DS: usize = 16;
 /// The offset of the user code segment.
 pub const USER_CS: usize = 24;
-/// The offset of the user data segment.
+/// The offset of the user data segment (32 bits).
 pub const USER_DS: usize = 32;
 /// The offset of the Task State Segment (TSS).
 pub const TSS_OFFSET: usize = 40;
 /// The offset of Thread Local Storage (TLS) entries.
 pub const TLS_OFFSET: usize = 56;
+/// The offset of the user data segment (64 bits).
+pub const USER_CS64: usize = 88;
 
 /// A GDT entry.
 #[repr(C, align(8))]

kernel/src/arch/x86/idt.rs

@@ -20,7 +20,10 @@
 //! storing the list of interrupt handlers, allowing to catch and handle
 //! interruptions.
 
-use crate::{arch::x86::pic, syscall::syscall};
+use crate::{
+	arch::x86::{gdt, pic, DEFAULT_FLAGS},
+	syscall::syscall,
+};
 use core::{
 	arch::{asm, global_asm},
 	ffi::c_void,
@@ -50,34 +53,40 @@ pub const SYSCALL_ENTRY: usize = 0x80;
 pub const ENTRIES_COUNT: usize = 0x81;
 
 /// Interruption stack frame, with saved registers state.
+#[cfg(target_arch = "x86")]
 #[repr(C)]
 #[allow(missing_docs)]
-#[cfg(target_arch = "x86")]
+#[derive(Default)]
 pub struct IntFrame {
-	pub eip: u32,
-	pub cs: u32,
-	pub eflags: u32,
-	pub esp: u32,
-	pub ss: u32,
+	// Using the prefix `r` to avoid duplicate code
+	pub rax: u32,
+	pub rbx: u32,
+	pub rcx: u32,
+	pub rdx: u32,
+	pub rsi: u32,
+	pub rdi: u32,
+	pub rbp: u32,
+
+	pub gs: u32,
+	pub fs: u32,
 
-	/// Error code, if any.
-	pub code: u32,
 	/// Interruption number.
 	pub int: u32,
+	/// Error code, if any.
+	pub code: u32,
 
-	pub eax: u32,
-	pub ebx: u32,
-	pub ecx: u32,
-	pub edx: u32,
-	pub esi: u32,
-	pub edi: u32,
-	pub ebp: u32,
+	pub rip: u32,
+	pub cs: u32,
+	pub rflags: u32,
+	pub rsp: u32,
+	pub ss: u32,
 }
 
 /// Interruption stack frame, with saved registers state.
-#[repr(C)]
-#[allow(missing_docs)]
 #[cfg(target_arch = "x86_64")]
+#[allow(missing_docs)]
+#[repr(C)]
+#[derive(Default)]
 pub struct IntFrame {
 	pub rax: u64,
 	pub rbx: u64,
@@ -96,6 +105,9 @@ pub struct IntFrame {
 	pub r14: u64,
 	pub r15: u64,
 
+	pub gs: u32,
+	pub fs: u32,
+
 	/// Interruption number.
 	pub int: u64,
 	/// Error code, if any.
@@ -109,17 +121,15 @@ pub struct IntFrame {
 }
 
 impl IntFrame {
+	/// Tells whether the interrupted context is 32 bit.
+	pub const fn is_32bit(&self) -> bool {
+		self.cs as usize == gdt::USER_CS | 3
+	}
+
 	/// Returns the ID of the system call being executed.
 	#[inline]
 	pub const fn get_syscall_id(&self) -> usize {
-		#[cfg(target_arch = "x86")]
-		{
-			self.eax as usize
-		}
-		#[cfg(target_arch = "x86_64")]
-		{
-			self.rax as usize
-		}
+		self.rax as usize
 	}
 
 	/// Returns the value of the `n`th argument of the syscall being executed.
@@ -130,12 +140,12 @@ impl IntFrame {
 	pub const fn get_syscall_arg(&self, n: u8) -> usize {
 		#[cfg(target_arch = "x86")]
 		let val = match n {
-			0 => self.ebx,
-			1 => self.ecx,
-			2 => self.edx,
-			3 => self.esi,
-			4 => self.edi,
-			5 => self.ebp,
+			0 => self.rbx,
+			1 => self.rcx,
+			2 => self.rdx,
+			3 => self.rsi,
+			4 => self.rdi,
+			5 => self.rbp,
 			_ => 0,
 		};
 		#[cfg(target_arch = "x86_64")]
@@ -153,39 +163,41 @@ impl IntFrame {
 
 	/// Sets the return value of a system call.
 	pub fn set_syscall_return(&mut self, value: EResult<usize>) {
-		let val = value.map(|v| v as _).unwrap_or_else(|e| (-e.as_int()) as _);
-		#[cfg(target_arch = "x86")]
-		{
-			self.eax = val;
-		}
-		#[cfg(target_arch = "x86_64")]
-		{
-			self.rax = val;
-		}
+		self.rax = value.map(|v| v as _).unwrap_or_else(|e| (-e.as_int()) as _);
+	}
+
+	/// Returns the stack address.
+	pub fn get_stack_address(&self) -> usize {
+		self.rsp as usize
 	}
 
 	/// Returns the address of the instruction to be executed when the interrupt handler returns.
 	pub fn get_program_counter(&self) -> usize {
-		#[cfg(target_arch = "x86")]
-		{
-			self.eax as usize
-		}
-		#[cfg(target_arch = "x86_64")]
-		{
-			self.rax as usize
-		}
+		self.rip as usize
 	}
 
 	/// Sets the address of the instruction to be executed when the interrupt handler returns.
 	pub fn set_program_counter(&mut self, val: usize) {
-		#[cfg(target_arch = "x86")]
-		{
-			self.eax = val as _;
-		}
-		#[cfg(target_arch = "x86_64")]
-		{
-			self.rax = val as _;
-		}
+		self.rip = val as _;
+	}
+
+	/// Sets the values of `frame` so that it can be used to begin the execution of a program.
+	///
+	/// Arguments:
+	/// - `pc` is the program counter
+	/// - `sp` is the stack pointer
+	/// - `bit32` tells whether the program is 32 bits. If the kernel is compiled for 32 bit, this
+	///   value is ignored.
+	pub fn exec(frame: &mut Self, pc: usize, sp: usize, bit32: bool) {
+		let cs_segment = if bit32 { gdt::USER_CS } else { gdt::USER_CS64 };
+		*frame = IntFrame {
+			rip: pc as _,
+			cs: (cs_segment | 3) as _,
+			rflags: DEFAULT_FLAGS as _,
+			rsp: sp as _,
+			ss: (gdt::USER_DS | 3) as _,
+			..Default::default()
+		};
 	}
 }
 

kernel/src/elf/parser.rs

@@ -23,7 +23,7 @@ use crate::elf::relocation::Relocation;
 use utils::bytes;
 
 /// The ELF's class.
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Eq, PartialEq)]
 pub enum Class {
 	/// 32 bit
 	Bit32,

kernel/src/event.rs

@@ -209,5 +209,5 @@ extern "C" fn interrupt_handler(frame: &mut IntFrame) {
 		pic::end_of_interrupt((id - ERROR_MESSAGES.len() as u32) as _);
 	}
 	drop(callbacks);
-	process::yield_current(ring);
+	process::yield_current(ring, frame);
 }

kernel/src/file/fs/proc/proc_dir/stat.rs

@@ -25,6 +25,7 @@ use crate::{
 		FileLocation, FileType, Stat,
 	},
 	format_content,
+	memory::VirtAddr,
 	process::{pid::Pid, Process},
 };
 use core::{fmt, fmt::Formatter};
@@ -39,14 +40,12 @@ impl<'p> fmt::Display for StatDisp<'p> {
 		//let vmem_usage = self.0.get_vmem_usage();
 		let vmem_usage = 0;
 		let user_regs = self.0.user_regs();
-		let sp = user_regs.esp;
-		let pc = user_regs.eip;
 		// TODO Fill every fields with process's data
 		write!(
 			f,
 			"{pid} ({name}) {state_char} {ppid} {pgid} {sid} TODO TODO 0 \
 0 0 0 0 {user_jiffies} {kernel_jiffies} TODO TODO {priority} {nice} {num_threads} 0 {vmem_usage} \
-TODO TODO TODO TODO {sp} {pc} TODO TODO TODO TODO 0 0 0 TODO TODO TODO TODO TODO TODO TODO TODO \
+TODO TODO TODO TODO {sp:?} {pc:?} TODO TODO TODO TODO 0 0 0 TODO TODO TODO TODO TODO TODO TODO TODO \
 TODO TODO TODO TODO TODO TODO TODO TODO TODO",
 			pid = self.0.get_pid(),
 			name = DisplayableStr(name),
@@ -59,6 +58,8 @@ TODO TODO TODO TODO TODO TODO TODO TODO TODO",
 			priority = self.0.priority,
 			nice = self.0.nice,
 			num_threads = 1, // TODO
+			sp = VirtAddr(user_regs.get_stack_address() as _),
+			pc = VirtAddr(user_regs.get_program_counter() as _),
 		)
 	}
 }