添加全局构造函数

详细任务：https://github.com/qvjp/INWOX/projects/1#card-39007500

kernel/Makefile

@@ -8,8 +8,13 @@ OBJ := gdt.o \
 	print.o
 OBJ += arch/i686/loader.o
 
-OBJ := $(addprefix $(BUILD)/, $(OBJ))
+CRTBEGIN_0 := $(shell $(CC) $(CXXFLAGS) -print-file-name=crtbegin.o)
+CRTEND_0 := $(shell $(CC) $(CXXFLAGS) -print-file-name=crtend.o)
 
+START_OBJ := $(BUILD)/arch/i686/crti.o $(CRTBEGIN_0)
+END_OBJ := $(CRTEND_0) $(BUILD)/arch/i686/crtn.o
+
+OBJ := $(START_OBJ) $(addprefix $(BUILD)/, $(OBJ)) $(END_OBJ)
 
 all: $(BUILD)/kernel
 

kernel/src/arch/i686/crti.s

@@ -0,0 +1,58 @@
+/** MIT License
+ *
+ * Copyright (c) 2020 Qv Junping
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/**
+ * libc/src/arch/i686/crti.s
+ * System V ABI指定用5个文件一起控制程序的初始化，即crt0.o, crti.o
+ * crtbegin.o, crtend.o, crtn.o, 这些文件共同实现了两个函数_init, _fini
+ * 正如字面意思，这两个函数分别运行全局构造函数和其他初始化任务，_fini
+ * 运行全局析构函数和其他终止任务
+ * GCC在编译时会自动将
+ * i686-elf-gcc foo.o bar.o -o program重写成如下格式
+ * i686-elf-ld crt0.o crti.o crtbegin.o foo.o bar.o crtend.o crtn.o
+ * 其中crtbegin.o和crtend.o交叉编译器会提供
+ * 本文件即是提供crti.o
+ */
+
+.section .init
+.global _init
+_init:
+    /**
+     * 下边两行是保存ebp(基址寄存器)和调用前的esp(栈顶地址)，即保存整个栈的内容
+     * 方便调用后的恢复
+     */
+    push %ebp
+    mov %esp, %ebp
+    /** GCC将把crtbegin.o的.init section 放到这里 
+     *   调用全局构造函数
+     */
+
+.section .fini
+.global _fini
+_fini:
+    /* 下边两行也是保存ebp和esp，这是为了保存整个栈的内容 */
+    push %ebp
+    mov %esp, %ebp
+    /** GCC将把crtbegin.o的.fini section 放到这里
+     *  调用全局析构函数
+     */

kernel/src/arch/i686/crtn.s

@@ -0,0 +1,53 @@
+/** MIT License
+ *
+ * Copyright (c) 2020 Qv Junping
+ * 
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ * 
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+/**
+ * libc/src/arch/i686/crtn.s
+ *
+ * System V ABI指定用5个文件一起控制程序的初始化，即crt0.o, crti.o
+ * crtbegin.o, crtend.o, crtn.o, 这些文件共同实现了两个函数_init, _fini
+ * 正如字面意思，这两个函数分别运行全局构造函数和其他初始化任务，_fini
+ * 运行全局析构函数和其他终止任务
+ *
+ * GCC在编译时会自动将
+ * i686-elf-gcc foo.o bar.o -o program重写成如下格式
+ * i686-elf-ld crt0.o crti.o crtbegin.o foo.o bar.o crtend.o crtn.o
+ * 其中crtbegin.o和crtend.o交叉编译器会提供
+ * 本文件即是提供crti.o
+ */
+
+.section .init
+    /** GCC将把crtend.o的.init section 放到这里
+     *  调用全局构造函数
+     */
+    /* 恢复原来栈的内容 */
+    pop %ebp
+    ret
+
+.section .fini
+    /** GCC将把crtend.o的.fini section 放到这里
+     *  调用全局析构函数
+     */
+    /* 同样是是恢复原来栈的内容 */
+    pop %ebp
+    ret
+

kernel/src/arch/i686/loader.s

@@ -116,6 +116,8 @@
          * 被加载，分页没有开启等。
          */
 
+        call _init
+
         /*
          * 进入高级别内核。
          * ABI要求在调用指令时栈是32位对齐（然后返回32位的指针）。栈一开