cpu: Added a CPU module identifying CPU features and branding

Signed-off-by: SlyMarbo <[email protected]>

Author: SlyMarbo

kernel/src/cpu/mod.rs

@@ -0,0 +1,44 @@
+// Copyright 2022 The Firefly Authors.
+//
+// Use of this source code is governed by a BSD 3-clause
+// license that can be found in the LICENSE file.
+
+//! Analyses the CPU for supported features and branding.
+
+use crate::println;
+use lazy_static::lazy_static;
+use raw_cpuid::CpuId;
+
+lazy_static! {
+    static ref CPU_ID: CpuId = CpuId::new();
+}
+
+/// Checks that the CPU supports all the features we need.
+///
+/// # Panics
+///
+/// `init` will panic if the CPU does not support any features
+/// Firefly requires.
+///
+pub fn init() {
+    match CPU_ID.get_feature_info() {
+        None => panic!("unable to determine CPU features"),
+        Some(features) => {
+            if !features.has_sysenter_sysexit() {
+                panic!("CPU does not support the sysexit instruction");
+            }
+        }
+    }
+}
+
+/// Prints the CPU's branding information.
+///
+pub fn print_branding() {
+    if let Some(branding) = CPU_ID.get_processor_brand_string() {
+        println!("Kernel running on {} CPU.", branding.as_str());
+    } else if let Some(version) = CPU_ID.get_vendor_info() {
+        println!("Kernel running on {} CPU.", version.as_str());
+    } else {
+        println!("Kernel running on unknown CPU.");
+    }
+}

kernel/src/lib.rs

@@ -42,10 +42,9 @@ use crate::memory::KERNEL_STACK_0;
 use crate::multitasking::{cpu_local, thread};
 use bootloader::BootInfo;
 use core::panic::PanicInfo;
-use lazy_static::lazy_static;
-use raw_cpuid::CpuId;
 use x86_64::instructions::port::Port;
 
+pub mod cpu;
 pub mod drivers;
 pub mod gdt;
 pub mod interrupts;
@@ -56,15 +55,11 @@ pub mod random;
 pub mod time;
 pub mod utils;
 
-lazy_static! {
-    #[doc(hidden)]
-    pub static ref CPU_ID: CpuId = CpuId::new();
-}
-
 /// Initialise the kernel and its core components.
 ///
 /// `init` currently performs the following steps:
 ///
+/// - Check that the CPU supports the features we need.
 /// - Initialise the [Global Descriptor Table](gdt).
 /// - Initialise the [Programmable Interrupt Controller](interrupts).
 /// - Initialise the [Real-time clock and Programmable Interval Timer](time)
@@ -74,6 +69,7 @@ lazy_static! {
 /// - Initialise the [scheduler](multitasking/thread).
 ///
 pub fn init(boot_info: &'static BootInfo) {
+    cpu::init();
     gdt::init();
     interrupts::init();
     time::init();

kernel/src/main.rs

@@ -55,17 +55,11 @@ fn kernel_main(boot_info: &'static BootInfo) -> ! {
 #[cfg(not(test))]
 fn kmain() {
     use kernel::multitasking::thread::{scheduler, Thread};
-    use kernel::{network, time, CPU_ID};
+    use kernel::{cpu, network, time};
 
     println!("Kernel ready!");
     println!("Kernel booted at {}.", time::boot_time());
-    if let Some(branding) = CPU_ID.get_processor_brand_string() {
-        println!("Kernel running on {} CPU.", branding.as_str());
-    } else if let Some(version) = CPU_ID.get_vendor_info() {
-        println!("Kernel running on {} CPU.", version.as_str());
-    } else {
-        println!("Kernel running on unknown CPU.");
-    }
+    cpu::print_branding();
 
     // Set up our initial workload for when
     // we get a DHCP configuration.