[kernel] Use the hpet clock source in scheduler

There has been a global clock object for a while now, but scheduler was
never using it, instead still using its simple increment clock. Now it
uses the hpet clock.

src/kernel/device_manager.cpp

@@ -333,10 +333,11 @@ device_manager::probe_pci()
 }
 
 static uint64_t
-fake_clock_source(void*)
+tsc_clock_source(void*)
 {
-    static uint64_t value = 0;
-    return value++;
+    uint32_t lo = 0, hi = 0;
+    asm volatile ("rdtsc" : "=a" (lo), "=d" (hi));
+    return ((uint64_t)hi << 32) | lo;
 }
 
 void
@@ -367,7 +368,7 @@ device_manager::init_drivers()
         log::info(logs::clock, "Created master clock using HPET 0: Rate %d", h.rate());
     } else {
         //TODO: Other clocks, APIC clock?
-        master_clock = new clock(5000, fake_clock_source, nullptr);
+        master_clock = new clock(5000, tsc_clock_source, nullptr);
     }
 
     kassert(master_clock, "Failed to allocate master clock");

src/kernel/objects/endpoint.cpp

@@ -1,8 +1,8 @@
+#include "clock.h"
 #include "device_manager.h"
 #include "objects/endpoint.h"
 #include "objects/process.h"
 #include "objects/thread.h"
-#include "scheduler.h"
 #include "vm_space.h"
 
 endpoint::endpoint() :
@@ -64,7 +64,7 @@ endpoint::receive(j6_tag_t *tag, void *data, size_t *data_len, uint64_t timeout)
 
     // Timeout is a duration, but wait_on_* calls need a time
     if (timeout)
-        timeout += scheduler::get().clock();
+        timeout += clock::get().value();
 
     if (!check_signal(j6_signal_endpoint_can_recv)) {
         assert_signal(j6_signal_endpoint_can_send);

src/kernel/scheduler.cpp

@@ -36,8 +36,7 @@ struct run_queue
 };
 
 scheduler::scheduler(unsigned cpus) :
-    m_next_pid {1},
-    m_clock {0}
+    m_next_pid {1}
 {
     kassert(!s_instance, "Created multiple schedulers!");
     if (!s_instance)
@@ -242,11 +241,13 @@ scheduler::schedule()
     lapic &apic = *cpu.apic;
     uint32_t remaining = apic.stop_timer();
 
+    uint64_t now = clock::get().value();
+
     // Only one CPU can be stealing at a time
     if (m_steal_turn == cpu.index &&
-        m_clock - queue.last_steal > steal_frequency) {
+        now - queue.last_steal > steal_frequency) {
         steal_work(cpu);
-        queue.last_steal = m_clock;
+        queue.last_steal = now;
         m_steal_turn = (m_steal_turn + 1) % m_run_queues.count();
     }
 
@@ -283,9 +284,9 @@ scheduler::schedule()
     }
 
     clock::get().update();
-    prune(queue, ++m_clock);
-    if (m_clock - queue.last_promotion > promote_frequency)
-        check_promotions(queue, m_clock);
+    prune(queue, now);
+    if (now - queue.last_promotion > promote_frequency)
+        check_promotions(queue, now);
 
     priority = 0;
     while (queue.ready[priority].empty()) {
@@ -293,10 +294,10 @@ scheduler::schedule()
         kassert(priority < num_priorities, "All runlists are empty");
     }
 
-    queue.current->last_ran = m_clock;
+    queue.current->last_ran = now;
 
     auto *next = queue.ready[priority].pop_front();
-    next->last_ran = m_clock;
+    next->last_ran = now;
     apic.reset_timer(next->time_left);
 
     if (next == queue.current) {
@@ -313,7 +314,7 @@ scheduler::schedule()
     log::debug(logs::sched, "CPU%02x switching threads %llx->%llx",
             cpu.index, th->koid(), next_thread->koid());
     log::debug(logs::sched, "    priority %d time left %d @ %lld.",
-            next->priority, next->time_left, m_clock);
+            next->priority, next->time_left, now);
     log::debug(logs::sched, "    PML4 %llx", next->pml4);
 
     queue.lock.release(&waiter);

src/kernel/scheduler.h

@@ -72,8 +72,6 @@ public:
     /// \arg t  The new thread's TCB
     void add_thread(TCB *t);
 
-    uint64_t clock() const { return m_clock; }
-
     /// Get a reference to the scheduler
     /// \returns  A reference to the global system scheduler
     static scheduler & get() { return *s_instance; }
@@ -95,9 +93,6 @@ private:
 
     util::vector<run_queue> m_run_queues;
 
-    // TODO: lol a real clock
-    uint64_t m_clock = 0;
-
     unsigned m_steal_turn = 0;
     static scheduler *s_instance;
 };