From 28a1f7d5a2097ff0534950ab0a098039e546c376 Mon Sep 17 00:00:00 2001
From: KAAAsS <admin@kaaass.net>
Date: Sun, 16 May 2021 14:00:20 +0800
Subject: [PATCH] finish exec3.4-8

---
 lab3/.gdbinit                           |  2 +-
 lab3/kernel/exception/exception_table.S |  2 ++
 lab3/kernel/syscall/syscall.c           |  9 +++++++
 lab3/kernel/syscall/syscall_num.h       |  8 +++----
 lab3/user/lib/libmain.c                 |  1 +
 lab3/user/lib/syscall.c                 | 31 +++++++++++++++++++++----
 note.org                                | 17 ++++++++++++++
 7 files changed, 61 insertions(+), 9 deletions(-)

diff --git a/lab3/.gdbinit b/lab3/.gdbinit
index 3070b32..598decb 100644
--- a/lab3/.gdbinit
+++ b/lab3/.gdbinit
@@ -13,4 +13,4 @@ define add-symbol-file-auto
 end
 
 add-symbol-file-auto ./build/kernel.img
-add-symbol-file-auto ./user/build/ramdisk/badinsn.bin
+add-symbol-file-auto ./user/build/ramdisk/hello.bin
diff --git a/lab3/kernel/exception/exception_table.S b/lab3/kernel/exception/exception_table.S
index 5431cf8..547d380 100644
--- a/lab3/kernel/exception/exception_table.S
+++ b/lab3/kernel/exception/exception_table.S
@@ -180,6 +180,7 @@ sync_el0_64:
 	exception_exit
 
 el0_syscall:
+    // 保存现场
 	sub	sp, sp, #16 * 8
 	stp	x0, x1, [sp, #16 * 0]
 	stp	x2, x3, [sp, #16 * 1]
@@ -199,6 +200,7 @@ el0_syscall:
 	ldp	x14, x15, [sp, #16 * 7]
 	add	sp, sp, #16 * 8
 
+	// 系统调用号左移 2 位作为系统调用表偏移
 	adr	x27, syscall_table		// syscall table in x27
 	uxtw	x16, w8				// syscall number in x16
 	ldr	x16, [x27, x16, lsl #3]		// find the syscall entry
diff --git a/lab3/kernel/syscall/syscall.c b/lab3/kernel/syscall/syscall.c
index b1c9111..6cc8389 100644
--- a/lab3/kernel/syscall/syscall.c
+++ b/lab3/kernel/syscall/syscall.c
@@ -29,8 +29,11 @@ void sys_putc(char ch)
 	 * Lab3: Your code here
 	 * Send ch to the screen in anyway as your like
 	 */
+	uart_send(ch);
 }
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Winitializer-overrides"
 /*
  * Lab3: Your code here
  * Update the syscall table as you like to redirect syscalls
@@ -38,5 +41,11 @@ void sys_putc(char ch)
  */
 const void *syscall_table[NR_SYSCALL] = {
 	[0 ... NR_SYSCALL - 1] = sys_debug,
+	[SYS_putc] = sys_putc,
+	[SYS_exit] = sys_exit,
+	[SYS_create_pmo] = sys_create_pmo,
+	[SYS_map_pmo] = sys_map_pmo,
+	[SYS_handle_brk] = sys_handle_brk,
 	/* lab3 syscalls finished */
 };
+#pragma clang diagnostic pop
diff --git a/lab3/kernel/syscall/syscall_num.h b/lab3/kernel/syscall/syscall_num.h
index 0c5f952..0fbf940 100644
--- a/lab3/kernel/syscall/syscall_num.h
+++ b/lab3/kernel/syscall/syscall_num.h
@@ -14,10 +14,10 @@
 
 #define NR_SYSCALL   256
 
-void sys_exit(void);
-void sys_create_pmo(void);
-void sys_map_pmo(void);
-void sys_handle_brk(void);
+void sys_exit(int ret);
+int sys_create_pmo(u64 size, u64 type);
+int sys_map_pmo(u64 target_process_cap, u64 pmo_cap, u64 addr, u64 perm);
+u64 sys_handle_brk(u64 addr);
 /* lab3 syscalls finished */
 
 #define SYS_putc				0
diff --git a/lab3/user/lib/libmain.c b/lab3/user/lib/libmain.c
index 7cfcab6..9c6da65 100644
--- a/lab3/user/lib/libmain.c
+++ b/lab3/user/lib/libmain.c
@@ -13,5 +13,6 @@ void _start_c(long *p)
 	 * Lab3: Your code here
 	 * Complete the main function
 	 */
+    usys_exit(ret);
 	return;
 }
diff --git a/lab3/user/lib/syscall.c b/lab3/user/lib/syscall.c
index 0bc95c9..22e8185 100644
--- a/lab3/user/lib/syscall.c
+++ b/lab3/user/lib/syscall.c
@@ -13,7 +13,28 @@ u64 syscall(u64 sys_no, u64 arg0, u64 arg1, u64 arg2, u64 arg3, u64 arg4,
 	 * And finally use svc to execute the system call. After syscall returned, don't forget
 	 * to move return value from x0 to the ret variable of this function
 	 */
-	return ret;
+
+    __asm __volatile("mov x9, %0"::"r"(sys_no));
+
+	// 参数
+#define SET_ARG(n) __asm __volatile("mov x"#n", %0"::"r"(arg##n));
+    SET_ARG(0);
+    SET_ARG(1);
+    SET_ARG(2);
+    SET_ARG(3);
+    SET_ARG(4);
+    SET_ARG(5);
+    SET_ARG(6);
+    SET_ARG(7);
+
+	// 系统调用
+    __asm __volatile("mov x8, x9");
+    __asm ("svc #0");
+
+	// 返回值
+    __asm __volatile("mov %0, x0":"=r"(ret));
+
+    return ret;
 }
 
 /*
@@ -22,25 +43,27 @@ u64 syscall(u64 sys_no, u64 arg0, u64 arg1, u64 arg2, u64 arg3, u64 arg4,
  */
 void usys_putc(char ch)
 {
+    syscall(SYS_putc, ch, 0, 0, 0, 0, 0, 0, 0, 0);
 }
 
 void usys_exit(int ret)
 {
+    syscall(SYS_exit, ret, 0, 0, 0, 0, 0, 0, 0, 0);
 }
 
 int usys_create_pmo(u64 size, u64 type)
 {
-	return 0;
+	return (int) syscall(SYS_create_pmo, size, type, 0, 0, 0, 0, 0, 0, 0);
 }
 
 int usys_map_pmo(u64 process_cap, u64 pmo_cap, u64 addr, u64 rights)
 {
-	return 0;
+    return (int) syscall(SYS_map_pmo, process_cap, pmo_cap, addr, rights, 0, 0, 0, 0, 0);
 }
 
 u64 usys_handle_brk(u64 addr)
 {
-	return 0;
+	return syscall(SYS_handle_brk, addr, 0, 0, 0, 0, 0, 0, 0, 0);
 }
 
 /* Here finishes all syscalls need by lab3 */
diff --git a/note.org b/note.org
index 12725f6..ae49152 100644
--- a/note.org
+++ b/note.org
@@ -156,3 +156,20 @@ ELF Section、Segment 两个概念。
 *** 练习2
 
 process_create_root、thread_create_main 直接写在注释里面了。
+
+*** 练习4
+
+见注释
+
+*** 练习5
+
+基本就是移动参数寄存器然后 svc。注意要先保存 x0 寄存器到另一寄存器。
+
+*** 练习7
+
+主要原因是 libmain 中跳转都是使用 b 指令（没有填写链接寄存器），因此执行到 main 的 ret 时链接寄存器值为 0，
+程序就返回到 0x0 处执行了。由此触发指令异常。
+
+*** 练习8
+
+这个是最离谱的。所谓退出其实就是输出里出现了“breakpoint”。实际上程序并不会退出（评测机倒是会）。