refactor: Optimize the context switch overhead

[lunaix-os.git] / lunaix-os / kernel / k_init.c

diff --git a/lunaix-os/kernel/k_init.c b/lunaix-os/kernel/k_init.c
index 5896ee492633f570ff87d800313f0642dd14c2a1..8c40b6b1df8953e7889ae8becb053729d69b8b42 100644 (file)
--- a/lunaix-os/kernel/k_init.c
+++ b/lunaix-os/kernel/k_init.c
@@ -1,120 +1,209 @@
-#include <lunaix/constants.h>
-#include <lunaix/tty/tty.h>
-
+#include <lunaix/common.h>
+#include <lunaix/device.h>
+#include <lunaix/foptions.h>
+#include <lunaix/input.h>
+#include <lunaix/isrm.h>
+#include <lunaix/lxconsole.h>
+#include <lunaix/mm/cake.h>
+#include <lunaix/mm/mmio.h>

 #include <lunaix/mm/page.h>
 #include <lunaix/mm/pmm.h>
 #include <lunaix/mm/page.h>
 #include <lunaix/mm/pmm.h>

+#include <lunaix/mm/valloc.h>

 #include <lunaix/mm/vmm.h>
 #include <lunaix/mm/vmm.h>

-#include <lunaix/mm/kalloc.h>
+#include <lunaix/process.h>
+#include <lunaix/sched.h>

 #include <lunaix/spike.h>
 #include <lunaix/spike.h>

+#include <lunaix/syscall.h>
+#include <lunaix/tty/tty.h>
+#include <lunaix/types.h>

 
 #include <arch/x86/boot/multiboot.h>
 #include <arch/x86/idt.h>
 
 #include <arch/x86/boot/multiboot.h>
 #include <arch/x86/idt.h>

+#include <arch/x86/interrupts.h>
+
+#include <klibc/stdio.h>
+#include <klibc/string.h>

 
 

-#include <libc/stdio.h>
+extern u8_t __kernel_start;
+extern u8_t __kernel_end;
+extern u8_t __init_hhk_end;

 
 

-#include <stdint.h>
-#include <stddef.h>
+#define PP_KERN_SHARED (PP_FGSHARED | PP_TKERN)

 
 

+// Set remotely by kernel/asm/x86/prologue.S
+multiboot_info_t* _k_init_mb_info;

 
 

-extern uint8_t __kernel_start;
-extern uint8_t __kernel_end;
-extern uint8_t __init_hhk_end;
+x86_page_table* __kernel_ptd;
+
+extern void
+__proc0(); /* proc0.c */

 
 void
 
 void

-setup_memory(multiboot_memory_map_t* map, size_t map_size);
+spawn_proc0();

 
 void
 
 void

-setup_kernel_runtime();
+setup_memory(multiboot_memory_map_t* map, size_t map_size);

 
 void
 
 void

-_kernel_pre_init(multiboot_info_t* mb_info) {
+_kernel_pre_init()
+{
+    // interrupts

     _init_idt();
     _init_idt();

+    isrm_init();
+    intr_routine_init();

 
 

-    pmm_init(MEM_1MB + (mb_info->mem_upper << 10));
+    // memory
+    pmm_init(MEM_1MB + (_k_init_mb_info->mem_upper << 10));

     vmm_init();
 
     vmm_init();
 

-    tty_init((void*)VGA_BUFFER_PADDR);
-    tty_set_theme(VGA_COLOR_GREEN, VGA_COLOR_BLACK);
+    unsigned int map_size =
+      _k_init_mb_info->mmap_length / sizeof(multiboot_memory_map_t);
+
+    setup_memory((multiboot_memory_map_t*)_k_init_mb_info->mmap_addr, map_size);

 }
 
 void
 }
 
 void

-_kernel_init(multiboot_info_t* mb_info) {
-    printf("[KERNEL] === Initialization === \n");
+_kernel_init()
+{
+    int errno = 0;
+
+    // allocators
+    cake_init();
+    valloc_init();
+
+    sched_init();
+
+    // crt
+    tty_init(ioremap(VGA_FRAMEBUFFER, PG_SIZE));
+    tty_set_theme(VGA_COLOR_WHITE, VGA_COLOR_BLACK);

 
 

-    printf("[MM] Mem: %d KiB, Extended Mem: %d KiB\n",
-           mb_info->mem_lower,
-           mb_info->mem_upper);
+    // file system & device subsys
+    vfs_init();
+    fsm_init();
+    input_init();

 
 

-    unsigned int map_size = mb_info->mmap_length / sizeof(multiboot_memory_map_t);
-    setup_memory((multiboot_memory_map_t*)mb_info->mmap_addr, map_size);
-    setup_kernel_runtime();
+    vfs_export_attributes();
+
+    lxconsole_init();
+
+    if ((errno = vfs_mount_root("ramfs", NULL))) {
+        panickf("Fail to mount root. (errno=%d)", errno);
+    }
+
+    vfs_mount("/dev", "devfs", NULL, 0);
+    vfs_mount("/sys", "twifs", NULL, MNT_RO);
+    vfs_mount("/task", "taskfs", NULL, MNT_RO);
+
+    lxconsole_spawn_ttydev();
+    device_init_builtin();
+
+    syscall_install();
+
+    spawn_proc0();

 }
 
 }
 

-void 
-_kernel_post_init() {
-    printf("[KERNEL] === Post Initialization === \n");
-    size_t hhk_init_pg_count = ((uintptr_t)(&__init_hhk_end)) >> PG_SIZE_BITS;
-    printf("[MM] Releaseing %d pages from 0x0.\n", hhk_init_pg_count);
+/**
+ * @brief 创建并运行proc0进程
+ *
+ */
+void
+spawn_proc0()
+{
+    struct proc_info* proc0 = alloc_process();
+
+    /**
+     * @brief
+     * 注意：这里和视频中说的不一样，属于我之后的一点微调。
+     * 在视频中，spawn_proc0是在_kernel_post_init的末尾才调用的。并且是直接跳转到_proc0
+     *
+     * 但是我后来发现，上述的方法会产生竞态条件。这是因为spawn_proc0被调用的时候，时钟中断已经开启，
+     * 而中断的产生会打乱栈的布局，从而使得下面的上下文设置代码产生未定义行为（Undefined
+     * Behaviour）。 为了保险起见，有两种办法：
+     *      1. 在创建proc0进程前关闭中断
+     *      2. 将_kernel_post_init搬进proc0进程
+     * （_kernel_post_init已经更名为init_platform）
+     *
+     * 目前的解决方案是2
+     */
+
+    proc0->parent = proc0;
+
+    // 方案1：必须在读取eflags之后禁用。否则当进程被调度时，中断依然是关闭的！
+    // cpu_disable_interrupt();
+
+    /* Ok... 首先fork进我们的零号进程，而后由那里，我们fork进init进程。 */
+
+    // 把当前虚拟地址空间（内核）复制一份。
+    proc0->page_table = vmm_dup_vmspace(proc0->pid);
+
+    // 直接切换到新的拷贝，进行配置。
+    cpu_ldvmspace(proc0->page_table);

 
 

-    // 清除 hhk_init 与前1MiB的映射
-    for (size_t i = 0; i < hhk_init_pg_count; i++) {
-        vmm_unmap_page((void*)(i << PG_SIZE_BITS));
+    // 为内核创建一个专属栈空间。
+    for (size_t i = 0; i < (KSTACK_SIZE >> PG_SIZE_BITS); i++) {
+        ptr_t pa = pmm_alloc_page(KERNEL_PID, 0);
+        vmm_set_mapping(VMS_SELF,
+                        KSTACK_START + (i << PG_SIZE_BITS),
+                        pa,
+                        PG_PREM_RW,
+                        VMAP_NULL);

     }
 
     }
 

-    assert(kalloc_init());
+    struct exec_param* execp =
+      (struct exec_param*)(KSTACK_TOP - sizeof(struct exec_param));
+    isr_param* isrp = (isr_param*)((ptr_t)execp - sizeof(isr_param));
+
+    *execp = (struct exec_param){ .cs = KCODE_SEG,
+                                  .eip = (ptr_t)__proc0,
+                                  .ss = KDATA_SEG,
+                                  .eflags = cpu_reflags() };
+    *isrp = (isr_param){ .registers = { .ds = KDATA_SEG,
+                                        .es = KDATA_SEG,
+                                        .fs = KDATA_SEG,
+                                        .gs = KDATA_SEG },
+                         .execp = execp };
+
+    proc0->intr_ctx = isrp;
+
+    // 加载x87默认配置
+    asm volatile("fninit\n"
+                 "fxsave (%%eax)" ::"a"(proc0->fxstate)
+                 : "memory");
+
+    // 向调度器注册进程。
+    commit_process(proc0);
+
+    // 由于时钟中断与APIC未就绪，我们需要手动进行第一次调度。这里也会同时隐式地恢复我们的eflags.IF位
+    proc0->state = PS_RUNNING;
+    asm volatile("pushl %0\n"
+                 "jmp switch_to\n" ::"r"(proc0));
+
+    /* Should not return */
+    assert_msg(0, "Unexpected Return");

 }
 
 // 按照 Memory map 标识可用的物理页
 void
 }
 
 // 按照 Memory map 标识可用的物理页
 void

-setup_memory(multiboot_memory_map_t* map, size_t map_size) {
+setup_memory(multiboot_memory_map_t* map, size_t map_size)
+{
+
+    // First pass, to mark the physical pages

     for (unsigned int i = 0; i < map_size; i++) {
         multiboot_memory_map_t mmap = map[i];
     for (unsigned int i = 0; i < map_size; i++) {
         multiboot_memory_map_t mmap = map[i];

-        printf("[MM] Base: 0x%x, len: %u KiB, type: %u\n",
-               map[i].addr_low,
-               map[i].len_low >> 10,
-               map[i].type);

         if (mmap.type == MULTIBOOT_MEMORY_AVAILABLE) {
             // 整数向上取整除法
         if (mmap.type == MULTIBOOT_MEMORY_AVAILABLE) {
             // 整数向上取整除法

-            uintptr_t pg = map[i].addr_low + 0x0fffU;
-            pmm_mark_chunk_free(pg >> PG_SIZE_BITS, map[i].len_low >> PG_SIZE_BITS);
-            printf("[MM] Freed %u pages start from 0x%x\n",
-                   map[i].len_low >> PG_SIZE_BITS,
-                   pg & ~0x0fffU);
+            ptr_t pg = map[i].addr_low + 0x0fffU;
+            pmm_mark_chunk_free(pg >> PG_SIZE_BITS,
+                                map[i].len_low >> PG_SIZE_BITS);

         }
     }
 
         }
     }
 

-    // 将内核占据的页设为已占用
-    size_t pg_count = (uintptr_t)(&__kernel_end - &__kernel_start) >> PG_SIZE_BITS;
-    pmm_mark_chunk_occupied(V2P(&__kernel_start) >> PG_SIZE_BITS, pg_count);
-    printf("[MM] Allocated %d pages for kernel.\n", pg_count);
-
-
-    size_t vga_buf_pgs = VGA_BUFFER_SIZE >> PG_SIZE_BITS;
-    
-    // 首先，标记VGA部分为已占用
-    pmm_mark_chunk_occupied(VGA_BUFFER_PADDR >> PG_SIZE_BITS, vga_buf_pgs);
-    
-    // 重映射VGA文本缓冲区（以后会变成显存，i.e., framebuffer）
-    for (size_t i = 0; i < vga_buf_pgs; i++)
-    {
-        vmm_map_page(
-            (void*)(VGA_BUFFER_VADDR + (i << PG_SIZE_BITS)), 
-            (void*)(VGA_BUFFER_PADDR + (i << PG_SIZE_BITS)), 
-            PG_PREM_RW
-        );
-    }
-    
-    // 更新VGA缓冲区位置至虚拟地址
-    tty_set_buffer((void*)VGA_BUFFER_VADDR);
-
-    printf("[MM] Mapped VGA to %p.\n", VGA_BUFFER_VADDR);
-}
+    // 将内核占据的页，包括前1MB，hhk_init 设为已占用
+    size_t pg_count = V2P(&__kernel_end) >> PG_SIZE_BITS;
+    pmm_mark_chunk_occupied(KERNEL_PID, 0, pg_count, PP_FGLOCKED);

 
 

-void
-setup_kernel_runtime() {
-    // 为内核创建一个专属栈空间。
-    for (size_t i = 0; i < (K_STACK_SIZE >> PG_SIZE_BITS); i++) {
-        vmm_alloc_page((void*)(K_STACK_START + (i << PG_SIZE_BITS)), PG_PREM_RW);
+    // reserve higher half
+    for (size_t i = L1_INDEX(KERNEL_MM_BASE); i < 1023; i++) {
+        assert(vmm_set_mapping(VMS_SELF, i << 22, 0, 0, VMAP_NOMAP));

     }
     }

-    printf("[MM] Allocated %d pages for stack start at %p\n", K_STACK_SIZE>>PG_SIZE_BITS, K_STACK_START);
-}
\ No newline at end of file
+}