From 25f859b2f0627adba34c811226a338e27ff8da43 Mon Sep 17 00:00:00 2001
From: Peter Fang <peter.fang@intel.com>
Date: Mon, 2 Sep 2024 18:32:37 +0800
Subject: [PATCH] syscall: Implement exec()

Implement the EXEC syscall interface in user space.

Co-developed-by: Vijay Dhanraj <vijay.dhanraj@intel.com>
Signed-off-by: Peter Fang <peter.fang@intel.com>
---
 syscall/src/class0.rs | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/syscall/src/class0.rs b/syscall/src/class0.rs
index df23b6e87..5bc44004f 100644
--- a/syscall/src/class0.rs
+++ b/syscall/src/class0.rs
@@ -4,8 +4,9 @@
 //
 // Author: Chuanxiao Dong <chuanxiao.dong@intel.com>
 
-use super::call::syscall1;
-use super::SYS_EXIT;
+use super::call::{syscall1, syscall3, SysCallError};
+use super::{SYS_EXEC, SYS_EXIT};
+use core::ffi::CStr;
 
 pub fn exit(code: u32) -> ! {
     // SAFETY: SYS_EXIT is supported syscall number by the svsm kernel.
@@ -14,3 +15,19 @@ pub fn exit(code: u32) -> ! {
     }
     unreachable!("Should never return from SYS_EXIT syscall");
 }
+
+#[allow(dead_code)]
+#[derive(Debug)]
+pub struct Tid(u32);
+
+pub fn exec(file: &CStr, root: &CStr, flags: u32) -> Result<Tid, SysCallError> {
+    unsafe {
+        syscall3(
+            SYS_EXEC,
+            file.as_ptr() as u64,
+            root.as_ptr() as u64,
+            u64::from(flags),
+        )
+        .map(|ret| Tid(ret as u32))
+    }
+}