实现gettimeofday()系统调用和clocksource+timekeeping子模块 (#278)

- 实现gettimeofday()系统调用
- 实现clocksource+timekeeping子模块部分功能
- 实现了timespec转换成日期时间

kernel/src/arch/x86_64/asm/irqflags.rs

@@ -1,18 +1,18 @@
-use core::{arch::asm, ptr::read_volatile};
+use core::arch::asm;
 
 #[inline]
-pub fn local_irq_save(flags: &mut u64) {
+pub fn local_irq_save() -> usize {
+    let x: usize;
     unsafe {
-        asm!("pushfq", "pop rax", "mov rax, {0}", "cli", out(reg)(*flags),);
+        asm!("pushfq ; pop {} ; cli", out(reg) x, options(nostack));
     }
+    x
 }
 
 #[inline]
-pub fn local_irq_restore(flags: &u64) {
-    let x = unsafe { read_volatile(flags) };
-
+// 恢复先前保存的rflags的值x
+pub fn local_irq_restore(x: usize) {
     unsafe {
-        asm!("push r15",
-            "popfq", in("r15")(x));
+        asm!("push {} ; popfq", in(reg) x, options(nostack));
     }
 }

kernel/src/arch/x86_64/fpu.rs

@@ -79,8 +79,7 @@ impl FpState {
 /// @brief 从用户态进入内核时，保存浮点寄存器，并关闭浮点功能
 pub fn fp_state_save(pcb: &mut process_control_block) {
     // 该过程中不允许中断
-    let mut rflags: u64 = 0;
-    local_irq_save(&mut rflags);
+    let rflags = local_irq_save();
 
     let fp: &mut FpState = if pcb.fp_state == null_mut() {
         let f = Box::leak(Box::new(FpState::default()));
@@ -112,14 +111,13 @@ pub fn fp_state_save(pcb: &mut process_control_block) {
                                 "mov cr4, rax" */
         )
     }
-    local_irq_restore(&rflags);
+    local_irq_restore(rflags);
 }
 
 /// @brief 从内核态返回用户态时，恢复浮点寄存器，并开启浮点功能
 pub fn fp_state_restore(pcb: &mut process_control_block) {
     // 该过程中不允许中断
-    let mut rflags: u64 = 0;
-    local_irq_save(&mut rflags);
+    let rflags = local_irq_save();
 
     if pcb.fp_state == null_mut() {
         panic!("fp_state_restore: fp_state is null. pid={}", pcb.pid);
@@ -143,5 +141,5 @@ pub fn fp_state_restore(pcb: &mut process_control_block) {
     fp.restore();
     fp.clear();
 
-    local_irq_restore(&rflags);
+    local_irq_restore(rflags);
 }

kernel/src/arch/x86_64/interrupt/mod.rs

@@ -48,8 +48,7 @@ impl InterruptArch for X86_64InterruptArch {
 
     unsafe fn save_and_disable_irq() -> IrqFlagsGuard {
         compiler_fence(Ordering::SeqCst);
-        let mut rflags: u64 = 0;
-        local_irq_save(&mut rflags);
+        let rflags = local_irq_save() as u64;
         let flags = IrqFlags::new(rflags);
         let guard = IrqFlagsGuard::new(flags);
         compiler_fence(Ordering::SeqCst);
@@ -58,7 +57,7 @@ impl InterruptArch for X86_64InterruptArch {
 
     unsafe fn restore_irq(flags: IrqFlags) {
         compiler_fence(Ordering::SeqCst);
-        local_irq_restore(&flags.flags());
+        local_irq_restore(flags.flags() as usize);
         compiler_fence(Ordering::SeqCst);
     }
 }