Initializes malloc stats (#973)

src/obconf/src/lib.rs

@@ -1,11 +1,19 @@
 #![no_std]
 
+use core::num::NonZero;
+
 pub use self::env::*;
 
 mod env;
 
-/// Information about the boot environment.
+/// Contains information about the boot environment.
 #[repr(C)]
 pub enum BootEnv {
     Vm(Vm),
 }
+
+/// Runtime configurations for the kernel.
+#[repr(C)]
+pub struct Config {
+    pub max_cpu: NonZero<usize>,
+}

src/obkrnl/src/config/mod.rs

@@ -1,30 +1,33 @@
 use core::ptr::null;
 use macros::elf_note;
-use obconf::BootEnv;
+use obconf::{BootEnv, Config};
 
-#[cfg(target_arch = "aarch64")]
-pub use self::aarch64::*;
-#[cfg(target_arch = "x86_64")]
-pub use self::x86_64::*;
+pub use self::arch::*;
 
-#[cfg(target_arch = "aarch64")]
-mod aarch64;
-#[cfg(target_arch = "x86_64")]
-mod x86_64;
+#[cfg_attr(target_arch = "aarch64", path = "aarch64.rs")]
+#[cfg_attr(target_arch = "x86_64", path = "x86_64.rs")]
+mod arch;
 
 pub fn boot_env() -> &'static BootEnv {
-    // SAFETY: This is safe because the set_boot_env() requirements.
+    // SAFETY: This is safe because the setup() requirements.
     unsafe { &*BOOT_ENV }
 }
 
+pub fn config() -> &'static Config {
+    // SAFETY: This is safe because the setup() requirements.
+    unsafe { &*CONFIG }
+}
+
 /// # Safety
 /// This function must be called immediately in the kernel entry point. After that it must never
 /// be called again.
-pub unsafe fn set_boot_env(env: &'static BootEnv) {
+pub unsafe fn setup(env: &'static BootEnv, conf: &'static Config) {
     BOOT_ENV = env;
+    CONFIG = conf;
 }
 
 static mut BOOT_ENV: *const BootEnv = null();
+static mut CONFIG: *const Config = null();
 
 #[elf_note(section = ".note.obkrnl.page-size", name = "obkrnl", ty = 0)]
 static NOTE_PAGE_SIZE: [u8; size_of::<usize>()] = PAGE_SIZE.to_ne_bytes();

src/obkrnl/src/context/aarch64.rs

@@ -8,3 +8,7 @@ pub unsafe fn activate(_: *mut Context) {
 pub unsafe fn thread() -> *const Thread {
     todo!();
 }
+
+pub unsafe fn current() -> *const Context {
+    todo!();
+}

src/obkrnl/src/context/mod.rs

@@ -12,20 +12,16 @@ mod arch;
 /// not safe to have a temporary a pointer or reference to this struct or its field because the CPU
 /// might get interupted, which mean it is possible for the next instruction to get executed on
 /// a different CPU if the interupt cause the CPU to switch the task.
-///
-/// We don't support `pc_cpuid` field here because it value is 100% unpredictable due to the above
-/// reason. Once we have loaded `pc_cpuid` the next instruction might get executed on a different
-/// CPU, which render the loaded value incorrect. The only way to prevent this issue is to disable
-/// interupt before reading `pc_cpuid`, which can make the CPU missed some events from the other
-/// hardwares.
 pub struct Context {
+    cpu: usize,                // pc_cpuid
     thread: AtomicPtr<Thread>, // pc_curthread
 }
 
 impl Context {
     /// See `pcpu_init` on the PS4 for a reference.
-    pub fn new(td: Arc<Thread>) -> Self {
+    pub fn new(cpu: usize, td: Arc<Thread>) -> Self {
         Self {
+            cpu,
             thread: AtomicPtr::new(Arc::into_raw(td).cast_mut()),
         }
     }
@@ -35,10 +31,28 @@ impl Context {
         // it is going to be the same one since it represent the current thread.
         let td = unsafe { self::arch::thread() };
 
+        // We cannot return a reference here because it requires 'static lifetime, which allow the
+        // caller to store it at a global level. Once the thread is destroyed that reference will be
+        // invalid.
         unsafe { Arc::increment_strong_count(td) };
         unsafe { Arc::from_raw(td) }
     }
 
+    /// See `critical_enter` and `critical_exit` on the PS4 for a reference.
+    pub fn pin() -> PinnedContext {
+        // TODO: Verify if memory ordering here is correct. We need a call to self::arch::current()
+        // to execute after the thread is in a critical section. The CPU must not reorder this. Our
+        // current implementation follow how Drop on Arc is implemented.
+        let td = unsafe { self::arch::thread() };
+
+        unsafe { (*td).critical_sections().fetch_add(1, Ordering::Release) };
+        core::sync::atomic::fence(Ordering::Acquire);
+
+        // Once the thread is in a critical section it will never be switch a CPU so it is safe to
+        // keep a pointer to a context here.
+        PinnedContext(unsafe { self::arch::current() })
+    }
+
     /// # Safety
     /// The only place this method is safe to call is in the CPU entry point. Once this method
     /// return this instance must outlive the CPU lifetime and it must never be accessed via this
@@ -54,3 +68,26 @@ impl Drop for Context {
         unsafe { drop(Arc::from_raw(self.thread.load(Ordering::Relaxed))) };
     }
 }
+
+/// RAII struct to pin the current thread to current CPU.
+///
+/// This struct must not implement [`Send`] and [`Sync`]. Currently it stored a pointer, which will
+/// make it `!Send` and `!Sync`.
+pub struct PinnedContext(*const Context);
+
+impl PinnedContext {
+    pub fn cpu(&self) -> usize {
+        unsafe { (*self.0).cpu }
+    }
+}
+
+impl Drop for PinnedContext {
+    fn drop(&mut self) {
+        // TODO: Verify if memory ordering here is correct.
+        let td = unsafe { (*self.0).thread.load(Ordering::Relaxed) };
+
+        unsafe { (*td).critical_sections().fetch_sub(1, Ordering::Release) };
+
+        // TODO: Implement td_owepreempt.
+    }
+}

src/obkrnl/src/context/x86_64.rs

@@ -15,7 +15,7 @@ pub unsafe fn activate(cx: *mut Context) {
         in("ecx") 0xc0000101u32,
         in("edx") cx >> 32,
         in("eax") cx,
-        options(preserves_flags, nostack)
+        options(nomem, preserves_flags, nostack)
     );
 
     // Clear FS and GS for user mode.
@@ -24,7 +24,7 @@ pub unsafe fn activate(cx: *mut Context) {
         in("ecx") 0xc0000100u32,
         in("edx") 0,
         in("eax") 0,
-        options(preserves_flags, nostack)
+        options(nomem, preserves_flags, nostack)
     );
 
     asm!(
@@ -32,7 +32,7 @@ pub unsafe fn activate(cx: *mut Context) {
         in("ecx") 0xc0000102u32,
         in("edx") 0,
         in("eax") 0,
-        options(preserves_flags, nostack)
+        options(nomem, preserves_flags, nostack)
     );
 }
 
@@ -50,3 +50,23 @@ pub unsafe fn thread() -> *const Thread {
 
     td
 }
+
+pub unsafe fn current() -> *const Context {
+    // Load current GS.
+    let mut edx: u32;
+    let mut eax: u32;
+
+    asm!(
+        "rdmsr",
+        in("ecx") 0xc0000101u32,
+        out("edx") edx,
+        out("eax") eax,
+        options(pure, nomem, preserves_flags, nostack)
+    );
+
+    // Combine EDX and EAX.
+    let edx = edx as usize;
+    let eax = eax as usize;
+
+    ((edx << 32) | eax) as *const Context
+}

src/obkrnl/src/main.rs

@@ -1,15 +1,15 @@
 #![no_std]
 #![cfg_attr(not(test), no_main)]
 
-use crate::config::set_boot_env;
 use crate::context::Context;
 use crate::malloc::KernelHeap;
 use crate::proc::Thread;
 use alloc::sync::Arc;
 use core::arch::asm;
 use core::mem::zeroed;
+use core::num::NonZero;
 use core::panic::PanicInfo;
-use obconf::BootEnv;
+use obconf::{BootEnv, Config};
 
 mod config;
 mod console;
@@ -37,8 +37,13 @@ extern crate alloc;
 #[allow(dead_code)]
 #[cfg_attr(target_os = "none", no_mangle)]
 extern "C" fn _start(env: &'static BootEnv) -> ! {
+    // TODO: Accept config from bootloader/hypervisor.
+    static CONFIG: Config = Config {
+        max_cpu: unsafe { NonZero::new_unchecked(1) },
+    };
+
     // SAFETY: This is safe because we called it as the first thing here.
-    unsafe { set_boot_env(env) };
+    unsafe { crate::config::setup(env, &CONFIG) };
 
     info!("Starting Obliteration Kernel.");
 
@@ -48,7 +53,7 @@ extern "C" fn _start(env: &'static BootEnv) -> ! {
     // Setup CPU context. We use a different mechanism here. The PS4 put all of pcpu at a global
     // level but we put it on each CPU stack instead.
     let thread0 = Arc::new(thread0);
-    let mut cx = Context::new(thread0);
+    let mut cx = Context::new(0, thread0);
 
     // SAFETY: We are in the main CPU entry point and we move all the remaining code after this into
     // a dedicated no-return function.

src/obkrnl/src/malloc/stage2.rs

@@ -1,10 +1,11 @@
-use crate::config::PAGE_SIZE;
+use crate::config::{config, PAGE_SIZE};
 use crate::context::Context;
 use crate::uma::UmaZone;
 use alloc::string::ToString;
 use alloc::sync::Arc;
 use alloc::vec::Vec;
 use core::alloc::Layout;
+use core::sync::atomic::{AtomicU64, Ordering};
 
 /// Stage 2 kernel heap.
 ///
@@ -12,6 +13,7 @@ use core::alloc::Layout;
 /// `malloc_type` and `malloc_type_internal` structure.
 pub struct Stage2 {
     zones: [Vec<Arc<UmaZone>>; (usize::BITS - 1) as usize], // kmemsize + kmemzones
+    stats: Vec<Stats>,                                      // mti_stats
 }
 
 impl Stage2 {
@@ -54,7 +56,14 @@ impl Stage2 {
             zones
         });
 
-        Self { zones }
+        // TODO: Is there a better way than this?
+        let mut stats = Vec::with_capacity(config().max_cpu.get());
+
+        for _ in 0..config().max_cpu.get() {
+            stats.push(Stats::default());
+        }
+
+        Self { zones, stats }
     }
 
     /// See `malloc` on the PS4 for a reference.
@@ -82,8 +91,24 @@ impl Stage2 {
                 size
             };
 
-            // TODO: There are more logic after this on the PS4.
-            self.zones[align][size >> Self::KMEM_ZSHIFT].alloc()
+            // Allocate a memory from UMA zone.
+            let zone = &self.zones[align][size >> Self::KMEM_ZSHIFT];
+            let mem = zone.alloc();
+
+            // Update stats.
+            let cx = Context::pin();
+            let stats = &self.stats[cx.cpu()];
+            let size = if mem.is_null() { 0 } else { zone.size() };
+
+            if size != 0 {
+                stats
+                    .alloc_bytes
+                    .fetch_add(size.try_into().unwrap(), Ordering::Relaxed);
+                stats.alloc_count.fetch_add(1, Ordering::Relaxed);
+            }
+
+            // TODO: How to update mts_size here since our zone table also indexed by alignment?
+            mem
         } else {
             todo!()
         }
@@ -96,3 +121,10 @@ impl Stage2 {
         todo!()
     }
 }
+
+/// Implementation of `malloc_type_stats` structure.
+#[derive(Default)]
+struct Stats {
+    alloc_bytes: AtomicU64, // mts_memalloced
+    alloc_count: AtomicU64, // mts_numallocs
+}

src/obkrnl/src/proc/thread.rs

@@ -1,9 +1,12 @@
+use core::sync::atomic::AtomicU32;
+
 /// Implementation of `thread` structure.
 ///
 /// All thread **must** run to completion once execution has been started otherwise resource will be
 /// leak if the thread is dropped while its execution currently in the kernel space.
 pub struct Thread {
-    active_interrupts: usize, // td_intr_nesting_level
+    critical_sections: AtomicU32, // td_critnest
+    active_interrupts: usize,     // td_intr_nesting_level
 }
 
 impl Thread {
@@ -12,11 +15,18 @@ impl Thread {
     /// responsibility to configure the thread after this so it have a proper states and trigger
     /// necessary events.
     pub unsafe fn new_bare() -> Self {
+        // td_critnest on the PS4 started with 1 but this does not work in our case because we use
+        // RAII to increase and decrease it.
         Self {
+            critical_sections: AtomicU32::new(0),
             active_interrupts: 0,
         }
     }
 
+    pub fn critical_sections(&self) -> &AtomicU32 {
+        &self.critical_sections
+    }
+
     pub fn active_interrupts(&self) -> usize {
         self.active_interrupts
     }

src/obkrnl/src/uma/mod.rs

@@ -1,12 +1,19 @@
 use alloc::borrow::Cow;
 
 /// Implementation of `uma_zone` structure.
-pub struct UmaZone {}
+pub struct UmaZone {
+    size: usize, // uz_size
+}
 
 impl UmaZone {
     /// See `uma_zcreate` on the PS4 for a reference.
-    pub fn new(_: Cow<'static, str>, _: usize, _: usize) -> Self {
-        Self {}
+    pub fn new(_: Cow<'static, str>, size: usize, _: usize) -> Self {
+        // TODO: Check if size is allowed to be zero. If not, change it to NonZero<usize>.
+        Self { size }
+    }
+
+    pub fn size(&self) -> usize {
+        self.size
     }
 
     /// See `uma_zalloc_arg` on the PS4 for a reference.