move cpu-related functions into associated methods of the Cpu struct

kernel/proc.c

@@ -6,8 +6,6 @@
 #include "proc.h"
 #include "defs.h"
 
-struct cpu cpus[NCPU];
-
 struct proc proc[NPROC];
 
 struct proc *initproc;

kernel/proc.h

@@ -31,8 +31,6 @@ struct cpu {
   int previous_interrupts_enabled; // Were interrupts enabled before push_off()?
 };
 
-extern struct cpu cpus[NCPU];
-
 // per-process data for the trap handling code in trampoline.S.
 // sits in a page by itself just under the trampoline page in the
 // user page table. not specially mapped in the kernel page table.

kernel/rustkernel/src/arch/riscv/plic.rs

@@ -2,7 +2,7 @@
 
 use crate::{
     arch::riscv::{plic_sclaim, plic_senable, plic_spriority, PLIC, UART0_IRQ, VIRTIO0_IRQ},
-    proc::cpu::cpuid,
+    proc::cpu::Cpu,
 };
 
 pub unsafe fn plicinit() {
@@ -12,7 +12,7 @@ pub unsafe fn plicinit() {
 }
 
 pub unsafe fn plicinithart() {
-    let hart = cpuid() as u64;
+    let hart = Cpu::current_id() as u64;
 
     // Set enable bits for this hart's S-mode
     // for the UART and VIRTIO disk.
@@ -24,12 +24,12 @@ pub unsafe fn plicinithart() {
 
 /// Ask the PLIC what interrupt we should serve.
 pub unsafe fn plic_claim() -> i32 {
-    let hart = cpuid() as u64;
+    let hart = Cpu::current_id() as u64;
     *(plic_sclaim(hart) as *const i32)
 }
 
 /// Tell the PLIC we've served this IRQ.
 pub unsafe fn plic_complete(irq: i32) {
-    let hart = cpuid() as u64;
+    let hart = Cpu::current_id() as u64;
     *(plic_sclaim(hart) as *mut i32) = irq;
 }

kernel/rustkernel/src/lib.rs

@@ -21,7 +21,7 @@ mod sync;
 mod syscall;
 mod trap;
 
-use crate::{proc::cpu::cpuid, sync::mutex::Mutex};
+use crate::{proc::cpu::Cpu, sync::mutex::Mutex};
 use core::ffi::{c_char, CStr};
 
 pub(crate) use crate::console::printf::{print, println};
@@ -57,7 +57,7 @@ pub const FSSIZE: usize = 2000;
 pub const MAXPATH: usize = 128;
 
 pub unsafe fn main() -> ! {
-    if cpuid() == 0 {
+    if Cpu::current_id() == 0 {
         console::consoleinit();
         mem::kalloc::kinit();
         println!("\nxv6 kernel is booting");

kernel/rustkernel/src/proc/cpu.rs

@@ -2,9 +2,7 @@ use super::{context::Context, proc::Proc};
 use crate::arch::riscv::asm::r_tp;
 use core::ptr::{addr_of_mut, null_mut};
 
-extern "C" {
-    pub static mut cpus: [Cpu; crate::NCPU];
-}
+pub static mut CPUS: [Cpu; crate::NCPU] = [Cpu::new(); crate::NCPU];
 
 /// Per-CPU state.
 #[repr(C)]
@@ -27,19 +25,27 @@ impl Cpu {
             previous_interrupts_enabled: 0,
         }
     }
-}
-
-/// Must be called with interrupts disabled
-/// to prevent race with process being moved
-/// to a different CPU.
-pub unsafe fn cpuid() -> i32 {
-    r_tp() as i32
+    /// Must be called with interrupts disabled
+    /// to prevent race with process being moved
+    /// to a different CPU.
+    pub fn current_id() -> usize {
+        unsafe { r_tp() as usize }
+    }
+    /// Return this CPU's cpu struct.
+    /// Interrupts must be disabled.
+    pub fn current() -> &'static mut Cpu {
+        unsafe { &mut *Cpu::current_raw() }
+    }
+    /// Return this CPU's cpu struct.
+    /// Interrupts must be disabled.
+    pub unsafe fn current_raw() -> *mut Cpu {
+        addr_of_mut!(CPUS[Cpu::current_id()])
+    }
 }
 
 /// Return this CPU's cpu struct.
 /// Interrupts must be disabled.
 #[no_mangle]
 pub unsafe extern "C" fn mycpu() -> *mut Cpu {
-    let id = cpuid();
-    addr_of_mut!(cpus[id as usize])
+    Cpu::current_raw()
 }

kernel/rustkernel/src/proc/proc.rs

@@ -1,6 +1,6 @@
 #![allow(clippy::comparison_chain)]
 
-use super::{context::Context, cpu::mycpu, trapframe::Trapframe};
+use super::{context::Context, cpu::Cpu, trapframe::Trapframe};
 use crate::{
     arch::riscv::{intr_get, Pagetable, PTE_W},
     fs::file::{File, Inode},
@@ -101,7 +101,7 @@ pub struct Proc {
 #[no_mangle]
 pub unsafe extern "C" fn myproc() -> *mut Proc {
     let _ = crate::trap::InterruptBlocker::new();
-    let c = mycpu();
+    let c = Cpu::current_raw();
     (*c).proc
 }
 
@@ -183,7 +183,7 @@ pub unsafe fn r#yield() {
 #[no_mangle]
 pub unsafe extern "C" fn sched() {
     let p = myproc();
-    let c = mycpu();
+    let c = Cpu::current_raw();
 
     if (*c).interrupt_disable_layers != 1 {
         panic!("sched locks");

kernel/rustkernel/src/start.rs

@@ -40,7 +40,7 @@ pub unsafe extern "C" fn start() {
     // Ask for clock interrupts.
     timerinit();
 
-    // Keep each CPU's hartid in its tp register, for cpuid().
+    // Keep each CPU's hartid in its tp register, for Cpu::current_id().
     w_tp(r_mhartid());
 
     // Switch to supervisor mode and jump to main().

kernel/rustkernel/src/trap.rs

@@ -2,7 +2,7 @@ use crate::{
     arch::riscv::*,
     println,
     proc::{
-        cpu::{cpuid, mycpu},
+        cpu::Cpu,
         proc::{exit, killed, myproc, r#yield, setkilled, wakeup, ProcState},
     },
     sync::mutex::Mutex,
@@ -70,7 +70,7 @@ pub unsafe fn devintr() -> i32 {
         // Software interrupt from a machine-mode timer interrupt,
         // forwarded by timervec in kernelvec.S.
 
-        if cpuid() == 0 {
+        if Cpu::current_id() == 0 {
             clockintr();
         }
 
@@ -90,7 +90,7 @@ impl InterruptBlocker {
     pub fn new() -> InterruptBlocker {
         unsafe {
             let interrupts_before = intr_get();
-            let cpu = mycpu();
+            let cpu = Cpu::current_raw();
 
             intr_off();
 
@@ -106,7 +106,7 @@ impl InterruptBlocker {
 impl core::ops::Drop for InterruptBlocker {
     fn drop(&mut self) {
         unsafe {
-            let cpu = mycpu();
+            let cpu = Cpu::current_raw();
 
             if intr_get() == 1 || (*cpu).interrupt_disable_layers < 1 {
                 // panic!("pop_off mismatched");
@@ -146,7 +146,7 @@ pub unsafe extern "C" fn usertrapret() {
     // process's kernel stack
     (*(*p).trapframe).kernel_sp = (*p).kstack + PGSIZE;
     (*(*p).trapframe).kernel_trap = usertrap as usize as u64;
-    // hartid for cpuid()
+    // hartid for Cpu::current_id()
     (*(*p).trapframe).kernel_hartid = r_tp();
 
     // Set up the registers that trampoline.S's
@@ -272,7 +272,7 @@ pub unsafe extern "C" fn usertrap() {
 
 pub unsafe fn push_intr_off() {
     let old = intr_get();
-    let cpu = mycpu();
+    let cpu = Cpu::current_raw();
 
     intr_off();
     if (*cpu).interrupt_disable_layers == 0 {
@@ -281,7 +281,7 @@ pub unsafe fn push_intr_off() {
     (*cpu).interrupt_disable_layers += 1;
 }
 pub unsafe fn pop_intr_off() {
-    let cpu = mycpu();
+    let cpu = Cpu::current_raw();
 
     if intr_get() == 1 {
         // crate::panic_byte(b'0');