LoongArch: Provide kaslr_offset() to get kernel offset

Provide kaslr_offset() to get the kernel offset when KASLR is enabled.
Signed-off-by: Feiyang Chen <chenfeiyang@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

arch/loongarch/include/asm/setup.h

@@ -7,6 +7,7 @@
 #define _LOONGARCH_SETUP_H
 
 #include <linux/types.h>
+#include <asm/sections.h>
 #include <uapi/asm/setup.h>
 
 #define VECSIZE 0x200
@@ -37,4 +38,9 @@ extern void * __init relocate_kernel(void);
 
 #endif
 
+static inline unsigned long kaslr_offset(void)
+{
+	return (unsigned long)&_text - VMLINUX_LOAD_ADDRESS;
+}
+
 #endif /* __SETUP_H */