feature: add execve() system call

kernel/src/proc/process.rs

@@ -405,6 +405,12 @@ impl Process {
             unsafe {
                 SCHED.hack_current_pid(lock.id);
             }
+        } else {
+            // Invalidate user ASID
+            let input = (lock.id.asid() as usize) << 48;
+            unsafe {
+                asm!("tlbi aside1, {}", in(reg) input);
+            }
         }
 
         let new_space = Space::alloc_empty()?;

kernel/src/syscall/mod.rs

@@ -2,7 +2,7 @@
 
 use crate::arch::platform::exception::ExceptionFrame;
 use crate::debug::Level;
-use crate::proc::{wait, Pid, Process};
+use crate::proc::{elf, wait, Pid, Process};
 use core::mem::size_of;
 use core::time::Duration;
 use error::Errno;
@@ -91,6 +91,20 @@ pub fn syscall(num: usize, args: &[usize]) -> Result<usize, Errno> {
             io.close_file(fd)?;
             Ok(0)
         }
+        abi::SYS_EXECVE => {
+            let node = {
+                let proc = Process::current();
+                let mut io = proc.io.lock();
+                let filename = validate_user_str(args[0], args[1])?;
+                // TODO argv, envp array passing ABI?
+                let node = io.ioctx().find(None, filename, true)?;
+                drop(io);
+                node
+            };
+            let mut file = node.open(OpenFlags::O_RDONLY)?;
+            Process::execve(|space| elf::load_elf(space, &mut file), 0).unwrap();
+            panic!();
+        }
 
         // Extra system calls
         abi::SYS_EX_DEBUG_TRACE => {