让riscv64能正常切换进程，并运行完所有的initcall (#721)

kernel/crates/asm_macros/src/riscv64/context.rs

@@ -0,0 +1,72 @@
+/// 保存x6-x31寄存器
+#[macro_export]
+macro_rules! save_from_x6_to_x31 {
+    () => {
+        concat!(
+            "
+            sd x6, {off_t1}(sp)
+            sd x7, {off_t2}(sp)
+            sd x8, {off_s0}(sp)
+            sd x9, {off_s1}(sp)
+            sd x10, {off_a0}(sp)
+            sd x11, {off_a1}(sp)
+            sd x12, {off_a2}(sp)
+            sd x13, {off_a3}(sp)
+            sd x14, {off_a4}(sp)
+            sd x15, {off_a5}(sp)
+            sd x16, {off_a6}(sp)
+            sd x17, {off_a7}(sp)
+            sd x18, {off_s2}(sp)
+            sd x19, {off_s3}(sp)
+            sd x20, {off_s4}(sp)
+            sd x21, {off_s5}(sp)
+            sd x22, {off_s6}(sp)
+            sd x23, {off_s7}(sp)
+            sd x24, {off_s8}(sp)
+            sd x25, {off_s9}(sp)
+            sd x26, {off_s10}(sp)
+            sd x27, {off_s11}(sp)
+            sd x28, {off_t3}(sp)
+            sd x29, {off_t4}(sp)
+            sd x30, {off_t5}(sp)
+            sd x31, {off_t6}(sp)
+
+        "
+        )
+    };
+}
+
+#[macro_export]
+macro_rules! restore_from_x6_to_x31 {
+    () => {
+        concat!("
+        
+            ld x6, {off_t1}(sp)
+            ld x7, {off_t2}(sp)
+            ld x8, {off_s0}(sp)
+            ld x9, {off_s1}(sp)
+            ld x10, {off_a0}(sp)
+            ld x11, {off_a1}(sp)
+            ld x12, {off_a2}(sp)
+            ld x13, {off_a3}(sp)
+            ld x14, {off_a4}(sp)
+            ld x15, {off_a5}(sp)
+            ld x16, {off_a6}(sp)
+            ld x17, {off_a7}(sp)
+            ld x18, {off_s2}(sp)
+            ld x19, {off_s3}(sp)
+            ld x20, {off_s4}(sp)
+            ld x21, {off_s5}(sp)
+            ld x22, {off_s6}(sp)
+            ld x23, {off_s7}(sp)
+            ld x24, {off_s8}(sp)
+            ld x25, {off_s9}(sp)
+            ld x26, {off_s10}(sp)
+            ld x27, {off_s11}(sp)
+            ld x28, {off_t3}(sp)
+            ld x29, {off_t4}(sp)
+            ld x30, {off_t5}(sp)
+            ld x31, {off_t6}(sp)
+        ")
+    };
+}

kernel/crates/asm_macros/src/riscv64/mod.rs

@@ -0,0 +1 @@
+pub mod context;