Return result type from syscall and format info on panic.

rust/lib/mammoth/src/lib.rs

@@ -32,7 +32,7 @@ pub fn parse_init_port(port_cap: syscall::zcap) {
             num_caps: &mut num_caps as *mut u64,
         };
         let resp = syscall::syscall(syscall::kZionPortPoll, &req);
-        if resp != 0 {
+        if let Err(_) = resp {
             break;
         }
         unsafe {
@@ -59,7 +59,7 @@ macro_rules! define_entry {
             unsafe {
                 let err = main();
                 let req = mammoth::syscall::ZProcessExitReq { code: err };
-                mammoth::syscall::syscall(mammoth::syscall::kZionProcessExit, &req);
+                let _ = mammoth::syscall::syscall(mammoth::syscall::kZionProcessExit, &req);
             }
             unreachable!()
         }

rust/lib/mammoth/src/mem.rs

@@ -5,6 +5,8 @@ use linked_list_allocator::LockedHeap;
 #[global_allocator]
 static ALLOCATOR: LockedHeap = LockedHeap::empty();
 
+pub static mut CAN_ALLOC: bool = false;
+
 pub fn init_heap() {
     // 1 MiB
     let size = 0x10_0000;
@@ -13,7 +15,8 @@ pub fn init_heap() {
         size,
         vmmo_cap: &mut vmmo_cap as *mut u64,
     };
-    syscall::checked_syscall(syscall::kZionMemoryObjectCreate, &obj_req);
+    syscall::syscall(syscall::kZionMemoryObjectCreate, &obj_req)
+        .expect("Failed to create memory object");
 
     unsafe {
         let mut vaddr: u64 = 0;
@@ -25,7 +28,9 @@ pub fn init_heap() {
             vmas_offset: 0,
         };
 
-        syscall::checked_syscall(syscall::kZionAddressSpaceMap, &vmas_req);
+        syscall::syscall(syscall::kZionAddressSpaceMap, &vmas_req)
+            .expect("Failed to map memory object");
         ALLOCATOR.lock().init(vaddr as *mut u8, size as usize);
+        CAN_ALLOC = true;
     }
 }

rust/lib/mammoth/src/syscall.rs

@@ -8,22 +8,84 @@ use core::panic::PanicInfo;
 
 include!("bindings.rs");
 
-pub fn syscall<T>(id: u64, req: &T) -> u64 {
-    unsafe { SysCall1(id, req as *const T as *const c_void) }
+pub enum ZError {
+    UNKNOWN = 0x0,
+    // First set of error codes generally indicate user errors.
+    INVALID_ARGUMENT = 0x1,
+    NOT_FOUND = 0x2,
+    PERMISSION_DENIED = 0x3,
+    NULL_PTR = 0x4,
+    EMPTY = 0x5,
+    ALREADY_EXISTS = 0x6,
+    BUFFER_SIZE = 0x7,
+    FAILED_PRECONDITION = 0x8,
+
+    // Second set of error codes generally indicate service errors.
+    INTERNAL = 0x100,
+    UNIMPLEMENTED = 0x101,
+    EXHAUSTED = 0x102,
+    INVALID_RESPONSE = 0x103,
+
+    // Kernel specific error codes (relating to capabilities).
+    CAP_NOT_FOUND = 0x1000,
+    CAP_WRONG_TYPE = 0x1001,
+    CAP_PERMISSION_DENIED = 0x1002,
 }
 
-pub fn checked_syscall<T>(id: u64, req: &T) {
-    if syscall(id, req) != 0 {
-        debug("Bad syscall response.");
-        panic!();
+impl From<u64> for ZError {
+    fn from(value: u64) -> Self {
+        match value {
+            0x1 => ZError::INVALID_ARGUMENT,
+            0x2 => ZError::NOT_FOUND,
+            0x3 => ZError::PERMISSION_DENIED,
+            0x4 => ZError::NULL_PTR,
+            0x5 => ZError::EMPTY,
+            0x6 => ZError::ALREADY_EXISTS,
+            0x7 => ZError::BUFFER_SIZE,
+            0x8 => ZError::FAILED_PRECONDITION,
+
+            0x100 => ZError::INTERNAL,
+            0x101 => ZError::UNIMPLEMENTED,
+            0x102 => ZError::EXHAUSTED,
+            0x103 => ZError::INVALID_RESPONSE,
+
+            0x1000 => ZError::CAP_NOT_FOUND,
+            0x1001 => ZError::CAP_WRONG_TYPE,
+            0x1002 => ZError::CAP_PERMISSION_DENIED,
+            _ => ZError::UNKNOWN,
+        }
     }
 }
 
+impl fmt::Debug for ZError {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str("ZError")
+    }
+}
+
+#[must_use]
+pub fn syscall<T>(id: u64, req: &T) -> Result<(), ZError> {
+    unsafe {
+        let resp = SysCall1(id, req as *const T as *const c_void);
+        if resp != 0 {
+            return Err(ZError::from(resp));
+        }
+    }
+    Ok(())
+}
+
 #[panic_handler]
-fn panic(_info: &PanicInfo) -> ! {
+fn panic(info: &PanicInfo) -> ! {
+    unsafe {
+        if crate::mem::CAN_ALLOC {
+            crate::debug!("Panic occured: {}", info);
+        } else {
+            debug("Panic occured before heap initialized.")
+        }
+    }
     // Internal error.
     let req = ZProcessExitReq { code: 0x100 };
-    syscall(kZionProcessExit, &req);
+    let _ = syscall(kZionProcessExit, &req);
     unreachable!()
 }
 
@@ -32,7 +94,7 @@ pub fn debug(msg: &str) {
         message: msg.as_ptr() as *const i8,
         size: msg.len() as u64,
     };
-    syscall(kZionDebug, &req);
+    syscall(kZionDebug, &req).expect("Failed to write");
 }
 
 pub struct Writer {
@@ -73,7 +135,9 @@ macro_rules! debug {
     ($fmt:literal, $($val:expr),+) => {{
         use core::fmt::Write as _;
         use alloc::string::String;
-        let mut w = mammoth::syscall::Writer::new();
+        // TODO: Find a way to do this so we don't have to import writer.
+        // We can't fully qualify this if we want to use it in this crate.
+        let mut w = Writer::new();
         write!(&mut w, $fmt, $($val),*).expect("Failed to format");
         let s: String = w.into();
         debug(&s);

rust/usr/testbed/src/main.rs

@@ -8,6 +8,7 @@ use mammoth::debug;
 use mammoth::define_entry;
 use mammoth::syscall::debug;
 use mammoth::syscall::z_err_t;
+use mammoth::syscall::Writer;
 
 define_entry!();
 
@@ -17,5 +18,12 @@ pub extern "C" fn main() -> z_err_t {
     let x = Box::new("Heap str");
     debug(&x);
     debug!("Formatted {}", "string");
+    let mut vmmo_cap: u64 = 0;
+    let obj_req = mammoth::syscall::ZMemoryObjectCreateReq {
+        size: 0,
+        vmmo_cap: &mut vmmo_cap as *mut u64,
+    };
+    mammoth::syscall::syscall(mammoth::syscall::kZionMemoryObjectCreate, &obj_req)
+        .expect("Failed to create memory object");
     0
 }