Support cmdline_args when sys_exec.

os/Makefile

@@ -6,7 +6,7 @@ KERNEL_BIN := $(KERNEL_ELF).bin
 DISASM_TMP := target/$(TARGET)/$(MODE)/asm
 FS_IMG := ../user/target/$(TARGET)/$(MODE)/fs.img
 SDCARD := /dev/sdb
-APPS := ../user/src/bin
+APPS := ../user/src/bin/*
 
 # BOARD
 BOARD ?= qemu

os/src/mm/address.rs

@@ -115,6 +115,11 @@ impl VirtPageNum {
 }
 
 impl PhysAddr {
+    pub fn get_ref<T>(&self) -> &'static T {
+        unsafe {
+            (self.0 as *const T).as_ref().unwrap()
+        }
+    }
     pub fn get_mut<T>(&self) -> &'static mut T {
         unsafe {
             (self.0 as *mut T).as_mut().unwrap()

os/src/mm/mod.rs

@@ -13,6 +13,7 @@ pub use page_table::{
     PageTableEntry,
     translated_byte_buffer,
     translated_str,
+    translated_ref,
     translated_refmut,
     UserBuffer,
     UserBufferIterator,

os/src/mm/page_table.rs

@@ -174,6 +174,7 @@ pub fn translated_byte_buffer(token: usize, ptr: *const u8, len: usize) -> Vec<&
     v
 }
 
+/// Load a string from other address spaces into kernel space without an end `\0`.
 pub fn translated_str(token: usize, ptr: *const u8) -> String {
     let page_table = PageTable::from_token(token);
     let mut string = String::new();
@@ -182,14 +183,18 @@ pub fn translated_str(token: usize, ptr: *const u8) -> String {
         let ch: u8 = *(page_table.translate_va(VirtAddr::from(va)).unwrap().get_mut());
         if ch == 0 {
             break;
-        } else {
-            string.push(ch as char);
-            va += 1;
         }
+        string.push(ch as char);
+        va += 1;
     }
     string
 }
 
+pub fn translated_ref<T>(token: usize, ptr: *const T) -> &'static T {
+    let page_table = PageTable::from_token(token);
+    page_table.translate_va(VirtAddr::from(ptr as usize)).unwrap().get_ref()
+}
+
 pub fn translated_refmut<T>(token: usize, ptr: *mut T) -> &'static mut T {
     let page_table = PageTable::from_token(token);
     let va = ptr as usize;

os/src/syscall/mod.rs

@@ -29,7 +29,7 @@ pub fn syscall(syscall_id: usize, args: [usize; 3]) -> isize {
         SYSCALL_GET_TIME => sys_get_time(),
         SYSCALL_GETPID => sys_getpid(),
         SYSCALL_FORK => sys_fork(),
-        SYSCALL_EXEC => sys_exec(args[0] as *const u8),
+        SYSCALL_EXEC => sys_exec(args[0] as *const u8, args[1] as *const usize),
         SYSCALL_WAITPID => sys_waitpid(args[0] as isize, args[1] as *mut i32),
         _ => panic!("Unsupported syscall_id: {}", syscall_id),
     }

os/src/syscall/process.rs

@@ -9,12 +9,15 @@ use crate::timer::get_time_ms;
 use crate::mm::{
     translated_str,
     translated_refmut,
+    translated_ref,
 };
 use crate::fs::{
     open_file,
     OpenFlags,
 };
 use alloc::sync::Arc;
+use alloc::vec::Vec;
+use alloc::string::String;
 
 pub fn sys_exit(exit_code: i32) -> ! {
     exit_current_and_run_next(exit_code);
@@ -48,14 +51,25 @@ pub fn sys_fork() -> isize {
     new_pid as isize
 }
 
-pub fn sys_exec(path: *const u8) -> isize {
+pub fn sys_exec(path: *const u8, mut args: *const usize) -> isize {
     let token = current_user_token();
     let path = translated_str(token, path);
+    let mut args_vec: Vec<String> = Vec::new();
+    loop {
+        let arg_str_ptr = *translated_ref(token, args);
+        if arg_str_ptr == 0 {
+            break;
+        }
+        args_vec.push(translated_str(token, arg_str_ptr as *const u8));
+        unsafe { args = args.add(1); }
+    }
     if let Some(app_inode) = open_file(path.as_str(), OpenFlags::RDONLY) {
         let all_data = app_inode.read_all();
         let task = current_task().unwrap();
-        task.exec(all_data.as_slice());
-        0
+        let argc = args_vec.len();
+        task.exec(all_data.as_slice(), args_vec);
+        // return argc because cx.x[10] will be covered with it later
+        argc as isize
     } else {
         -1
     }

os/src/task/task.rs

@@ -1,4 +1,10 @@
-use crate::mm::{MemorySet, PhysPageNum, KERNEL_SPACE, VirtAddr};
+use crate::mm::{
+    MemorySet,
+    PhysPageNum,
+    KERNEL_SPACE, 
+    VirtAddr,
+    translated_refmut,
+};
 use crate::trap::{TrapContext, trap_handler};
 use crate::config::{TRAP_CONTEXT};
 use super::TaskContext;
@@ -6,6 +12,7 @@ use super::{PidHandle, pid_alloc, KernelStack};
 use alloc::sync::{Weak, Arc};
 use alloc::vec;
 use alloc::vec::Vec;
+use alloc::string::String;
 use spin::{Mutex, MutexGuard};
 use crate::fs::{File, Stdin, Stdout};
 
@@ -106,13 +113,35 @@ impl TaskControlBlock {
         );
         task_control_block
     }
-    pub fn exec(&self, elf_data: &[u8]) {
+    pub fn exec(&self, elf_data: &[u8], args: Vec<String>) {
         // memory_set with elf program headers/trampoline/trap context/user stack
-        let (memory_set, user_sp, entry_point) = MemorySet::from_elf(elf_data);
+        let (memory_set, mut user_sp, entry_point) = MemorySet::from_elf(elf_data);
         let trap_cx_ppn = memory_set
             .translate(VirtAddr::from(TRAP_CONTEXT).into())
             .unwrap()
             .ppn();
+        // push arguments on user stack
+        user_sp -= (args.len() + 1) * core::mem::size_of::<usize>();
+        let argv_base = user_sp;
+        let mut argv: Vec<_> = (0..=args.len())
+            .map(|arg| {
+                translated_refmut(
+                    memory_set.token(),
+                    (argv_base + arg * core::mem::size_of::<usize>()) as *mut usize
+                )
+            })
+            .collect();
+        *argv[args.len()] = 0;
+        for i in 0..args.len() {
+            user_sp -= args[i].len() + 1;
+            *argv[i] = user_sp;
+            let mut p = user_sp;
+            for c in args[i].as_bytes() {
+                *translated_refmut(memory_set.token(), p as *mut u8) = *c;
+                p += 1;
+            }
+            *translated_refmut(memory_set.token(), p as *mut u8) = 0;
+        }
 
         // **** hold current PCB lock
         let mut inner = self.acquire_inner_lock();
@@ -121,14 +150,16 @@ impl TaskControlBlock {
         // update trap_cx ppn
         inner.trap_cx_ppn = trap_cx_ppn;
         // initialize trap_cx
-        let trap_cx = inner.get_trap_cx();
-        *trap_cx = TrapContext::app_init_context(
+        let mut trap_cx = TrapContext::app_init_context(
             entry_point,
             user_sp,
             KERNEL_SPACE.lock().token(),
             self.kernel_stack.get_top(),
             trap_handler as usize,
         );
+        trap_cx.x[10] = args.len();
+        trap_cx.x[11] = argv_base;
+        *inner.get_trap_cx() = trap_cx;
         // **** release current PCB lock
     }
     pub fn fork(self: &Arc<TaskControlBlock>) -> Arc<TaskControlBlock> {

os/src/trap/context.rs

@@ -1,6 +1,7 @@
 use riscv::register::sstatus::{Sstatus, self, SPP};
 
 #[repr(C)]
+#[derive(Debug)]
 pub struct TrapContext {
     pub x: [usize; 32],
     pub sstatus: Sstatus,

os/src/trap/mod.rs

@@ -88,6 +88,7 @@ pub fn trap_handler() -> ! {
             panic!("Unsupported trap {:?}, stval = {:#x}!", scause.cause(), stval);
         }
     }
+    //println!("before trap_return");
     trap_return();
 }