signal相关数据结构&代码结构优化 (#84)

* 解决由于spinlock.h中包含preempt_enable()带来的循环include问题

* new: 初步实现signal的数据结构

kernel/src/arch/x86_64/asm/Makefile

@@ -0,0 +1,22 @@
+
+CFLAGS += -I .
+
+# kernel_arch_x86_64_asm_subdirs:= 
+
+kernel_arch_x86_64_asm_objs:= $(shell find ./*.c)
+
+ECHO:
+	@echo "$@"
+
+
+$(kernel_arch_x86_64_asm_objs): ECHO
+	$(CC) $(CFLAGS) -c $@ -o $@.o
+
+# $(kernel_arch_x86_64_asm_subdirs): ECHO
+# 	$(MAKE) -C $@ all CFLAGS="$(CFLAGS)" ASFLAGS="$(ASFLAGS)" PIC="$(PIC)"
+
+all: $(kernel_arch_x86_64_asm_objs)
+
+
+clean:
+	echo "Done."

kernel/src/arch/x86_64/asm/spinlock.c

@@ -0,0 +1,56 @@
+#include <common/spinlock.h>
+#include <process/preempt.h>
+
+void __arch_spin_lock(spinlock_t *lock)
+{
+    __asm__ __volatile__("1:    \n\t"
+                         "lock decb %0   \n\t" // 尝试-1
+                         "jns 3f    \n\t"      // 加锁成功，跳转到步骤3
+                         "2:    \n\t"          // 加锁失败，稍后再试
+                         "pause \n\t"
+                         "cmpb $0, %0   \n\t"
+                         "jle   2b  \n\t" // 若锁被占用，则继续重试
+                         "jmp 1b    \n\t" // 尝试加锁
+                         "3:"
+                         : "=m"(lock->lock)::"memory");
+    preempt_disable();
+}
+
+void __arch_spin_unlock(spinlock_t *lock)
+{
+    preempt_enable();
+    __asm__ __volatile__("movb $1, %0   \n\t" : "=m"(lock->lock)::"memory");
+}
+
+void __arch_spin_lock_no_preempt(spinlock_t *lock)
+{
+    __asm__ __volatile__("1:    \n\t"
+                         "lock decb %0   \n\t" // 尝试-1
+                         "jns 3f    \n\t"      // 加锁成功，跳转到步骤3
+                         "2:    \n\t"          // 加锁失败，稍后再试
+                         "pause \n\t"
+                         "cmpb $0, %0   \n\t"
+                         "jle   2b  \n\t" // 若锁被占用，则继续重试
+                         "jmp 1b    \n\t" // 尝试加锁
+                         "3:"
+                         : "=m"(lock->lock)::"memory");
+}
+
+void __arch_spin_unlock_no_preempt(spinlock_t *lock)
+{
+    __asm__ __volatile__("movb $1, %0   \n\t" : "=m"(lock->lock)::"memory");
+}
+
+long __arch_spin_trylock(spinlock_t *lock)
+{
+    uint64_t tmp_val = 0;
+    preempt_disable();
+    // 交换tmp_val和lock的值，若tmp_val==1则证明加锁成功
+    asm volatile("lock xchg %%bx, %1  \n\t" // 确保只有1个进程能得到锁
+                 : "=q"(tmp_val), "=m"(lock->lock)
+                 : "b"(0)
+                 : "memory");
+    if (!tmp_val)
+        preempt_enable();
+    return tmp_val;
+}