Implement tasks (but it's incomplete)

Makefile

@@ -16,7 +16,7 @@ kernel := build/kernel-$(arch).bin
 iso := build/utero-$(arch).iso
 top_dir := $(shell pwd)
 INCLUDE := -I$(top_dir)/src/c_kernel/include -I$(top_dir)/src/arch/x86_64/c/include
-CFLAGS := -ffreestanding -nostdinc -Wno-implicit
+CFLAGS := -O2 -ffreestanding -nostdinc -Wno-implicit
 
 libcr := src/musl/lib/libcr.a
 libu := build/arch/$(arch)/c/libu.a
@@ -61,7 +61,7 @@ cleanobjs:
 				@rm -rf target/
 
 run: $(iso)
-				@qemu-system-$(arch) -cdrom $(iso)
+				@qemu-system-$(arch) -cdrom $(iso) -monitor stdio
 
 iso: $(iso)
 

README.md

@@ -7,7 +7,7 @@ This is the *work in progress*.
 
 ## Requirements
 
-* Crystal 0.22.0
+* Crystal 0.23.0
   * llvm
   * Please see [All required libraries](https://github.com/crystal-lang/crystal/wiki/All-required-libraries)
 * nasm

src/arch/x86_64/c/include/asm/processor.h

@@ -0,0 +1,108 @@
+// Copyright (c) 2016-2017 Utero OS Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//
+// The part of this file was taken from:
+// https://github.com/RWTH-OS/eduOS/blob/master/arch/x86/include/asm/processor.h
+
+#ifndef ASM_PROCESSOR_H
+#define ASM_PROCESSOR_H
+
+#include <asm/stddef.h>
+
+// rdtsc (Read-time stamp counter)
+// return the 64-bit time stamp value
+inline static uint64_t
+rdtsc(void)
+{
+  uint64_t lo, hi;
+  asm volatile("rdtsc" : "=a"(lo), "=d"(hi));
+  return (hi << 32 | lo);
+}
+
+// wbinvd asm instruction(Write back and invalidate cache)
+inline static void
+flush_cache(void)
+{
+  asm volatile("wbinvd" ::: "memory");
+}
+
+// invd asm instruction (Invalidate internal caches - without writing back)
+inline static void
+invalid_cache(void)
+{
+  asm volatile("invd");
+}
+
+// NOTE: mb, rmb, wmb will be moved to arch/x86_64/c/processor.c
+// and used via extern func_memory_barrier (mb|rmb|wmb)
+
+// mb (Memory barrier)
+// mfence asm instruction (Memory Fence - Serializes load and store operations)
+inline static void
+mb(void)
+{
+  asm volatile("mfence" ::: "memory");
+}
+
+// rmb (Read memory barrier)
+// lfence asm instruction (Load Fence - Serializes load operations)
+inline static void
+rmb(void)
+{
+  asm volatile("lfence" ::: "memory");
+}
+
+// wmb (Write memory barrier)
+// sfence asm instruction (Store Fence - Serializes store operations)
+inline static void
+wmb(void)
+{
+  asm volatile("sfence" ::: "memory");
+}
+
+// search the most significant bit
+// bsr (Bit Scan Reverse) asm instruction
+static inline size_t
+msb(size_t i)
+{
+  size_t ret;
+
+  if (!i) {
+    return (sizeof(size_t) * 8);
+  }
+  asm volatile("bsr %1, %0" : "=r"(ret) : "r"(i) : "cc");
+
+  return ret;
+}
+
+// search the least significant bit
+// bsf (Bit Scan Forward) asm instruction
+static inline size_t
+lsb(size_t i)
+{
+  size_t ret;
+
+  if (!i) {
+    return (sizeof(size_t) * 8);
+  }
+  asm volatile("bsf %1, %0" : "=r"(ret) : "r"(i) : "cc");
+
+  return ret;
+}
+
+// A one-instruction-do-nothing
+#define NOP1 asm volatile("nop")
+// A two-instruction-do-nothing
+#define NOP2 asm volatile("nop;nop")
+// A four-instruction-do-nothing
+#define NOP4 asm volatile("nop;nop;nop;nop")
+// A eight-instruction-do-nothing
+#define NOP8 asm volatile("nop;nop;nop;nop;nop;nop;nop;nop")
+
+#endif /* end of include guard: ASM_PROCESSOR_H */

src/arch/x86_64/c/include/asm/stddef.h

@@ -10,8 +10,8 @@
 // The part of this file was taken from:
 // https://github.com/RWTH-OS/eduOS/blob/master/arch/x86/include/asm/stddef.h
 
-#ifndef STDDEF_H
-#define STDDEF_H
+#ifndef ASM_STDDEF_H
+#define ASM_STDDEF_H
 
 // Unsigned 64 bit integer
 typedef unsigned long long uint64_t;
@@ -34,7 +34,8 @@ typedef char int8_t;
 typedef unsigned long long size_t;
 
 // This defines what the stack looks like after the task context is saved.
-struct state {
+struct state
+{
   // R15 register
   uint64_t r15;
   // R14 register
@@ -80,4 +81,4 @@ struct state {
   uint64_t ss;
 };
 
-#endif /* end of include guard: STDDEF_H */
+#endif /* end of include guard: ASM_STDDEF_H */

src/arch/x86_64/c/include/asm/tasks.h

@@ -0,0 +1,31 @@
+// Copyright (c) 2016-2017 Utero OS Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//
+// The part of this file was taken from:
+// https://github.com/RWTH-OS/eduOS/blob/master/arch/x86/include/asm/tasks.h
+
+#ifndef ASM_TASKS_H
+#define ASM_TASKS_H
+
+#include <stddef.h>
+
+// Switch the current task
+// stack: Pointer to the old stack pointer
+void switch_context(size_t** stack);
+
+// Setup a default frame for a new task
+// task: Pointer to the task structure
+// ep: The entry point for code execution
+// arg: Arguments list pointer for the task's stack
+// return
+// - 0 on success
+// - -EINVAL (-22) on failure
+int create_default_frame(task_t* task, entry_point_t ep, void* arg);
+
+#endif /* end of include guard: ASM_TASKS_H */

src/arch/x86_64/c/include/asm/tasks_types.h

@@ -0,0 +1,16 @@
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+//
+// The part of this file was taken from:
+// https://github.com/RWTH-OS/eduOS/blob/master/arch/x86/include/asm/tasks_types.h
+
+#ifndef ASM_TASKS_TYPES_H
+#define ASM_TASKS_TYPES_H
+
+#include <asm/processor.h>
+#include <stddef.h>
+
+#endif /* end of include guard: ASM_TASKS_TYPES_H */