From 0ed0720ba8cae5f1edb7e109acccea99773c252a Mon Sep 17 00:00:00 2001
From: Paul Pan <i@0x7f.app>
Date: Tue, 3 Sep 2024 19:27:37 +0800
Subject: [PATCH] feat: uapi: update spec

---
 uapi/src/fault.rs   | 12 +++++-----
 uapi/src/syscall.rs | 53 +++++++++++++++++++++++++++++++--------------
 2 files changed, 43 insertions(+), 22 deletions(-)

diff --git a/uapi/src/fault.rs b/uapi/src/fault.rs
index 8173e54..a4a5545 100644
--- a/uapi/src/fault.rs
+++ b/uapi/src/fault.rs
@@ -1,7 +1,7 @@
 use crate::error::SysError;
 use utils::addr::VirtAddr;
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub enum LookupFailure {
     InvalidRoot,
     MissingCapability {
@@ -29,32 +29,32 @@ impl From<LookupFailure> for SysError {
     }
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub struct CapFault {
     address:          usize,
     in_receive_phase: bool,
     lookup_failure:   LookupFailure,
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub struct UnknownSyscall {
     fault_ip: VirtAddr,
     syscall:  usize,
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub struct UserException {
     fault_ip: VirtAddr,
     number:   usize,
     code:     usize,
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub struct VMFault {
     ip: VirtAddr,
 }
 
-#[derive(Clone, Copy, Debug)]
+#[derive(Clone, Copy, Debug, PartialEq)]
 pub enum Fault {
     Null,
     CapFault(CapFault),
diff --git a/uapi/src/syscall.rs b/uapi/src/syscall.rs
index 4dfe959..e3d6599 100644
--- a/uapi/src/syscall.rs
+++ b/uapi/src/syscall.rs
@@ -17,10 +17,14 @@ pub enum Syscall {
 
 /* Syscall convention:
  * > Call:
- * > > [a0]:     MessageInfo
- * > > [a1]:     Capability Pointer
- * > > [a2..a7]: extra arguments
- * > > length = (a0..a?).len()
+ * > > +----------+-------------------------+--------------------+
+ * > > | [a0]     | REG_MESSAGE_INFO        | MessageInfo        |
+ * > > | [a1]     | REG_CAP_PTR             | Capability Pointer |
+ * > > | [a2..a7] | REG_ARG_0..=REG_ARG_MAX | Arguments          |
+ * > > | buffer   | REG_ARG_MAX+1..         | Arguments          |
+ * > > +----------+-------------------------+--------------------+
+ * > > length = (a0..).len(), extra arguments are stored on ipc buffer
+ * > > if info.transfer_cap { Arguments[-2] = cap_ptr; Arguments[-1] = n_bits; }
  * >
  * > Reply:
  * > TODO: figure out how vanilla seL4 handle reply
@@ -28,31 +32,42 @@ pub enum Syscall {
 
 pub const REG_MESSAGE_INFO: usize = 0;
 pub const REG_CAP_PTR: usize = 1;
+pub const REG_ARG_0: usize = 2;
+pub const REG_ARG_MAX: usize = 7;
+
+pub const LEN_ARG_OFFSET_CPTR: usize = 2;
+pub const LEN_ARG_OFFSET_BITS: usize = 1;
 
 /* MessageInfo layout:
- * > | label   | bits   | length |
- * > | [63:13] | [12:7] | [6:0]  |
- * > label:  Syscall
- * > bits:   cap_ptr n_bits
- * > length: args.len()
- *
+ * > +---------+--------+--------+--------------+
+ * > | label   | bits   | length | transfer_cap |
+ * > | [63:14] | [13:8] | [7:1]  | [0]          |
+ * > +---------+--------+--------+--------------+
+ * > label:        syscall
+ * > bits:         cap_ptr n_bits
+ * > length:       args.len()
+ * > transfer_cap: whether to transfer cap
  */
 #[derive(Clone, Copy)]
 pub struct MessageInfo(usize);
 
 impl MessageInfo {
-    const LABEL_MASK: usize = MASK!(63 - 13 + 1);
-    const LABEL_OFFSET: usize = 13;
+    const LABEL_MASK: usize = MASK!(63 - Self::LABEL_OFFSET + 1);
+    const LABEL_OFFSET: usize = 14;
 
     const BITS_MASK: usize = MASK!(6);
-    const BITS_OFFSET: usize = 7;
+    const BITS_OFFSET: usize = 8;
 
     const LENGTH_MASK: usize = MASK!(7);
-    const LENGTH_OFFSET: usize = 0;
+    const LENGTH_OFFSET: usize = 1;
 
-    pub fn new(label: Syscall, bits: usize, length: usize) -> Self {
+    const TRANSFER_CAP_MASK: usize = MASK!(1);
+    const TRANSFER_CAP_OFFSET: usize = 0;
+
+    pub fn new(label: Syscall, bits: usize, length: usize, transfer_cap: bool) -> Self {
         let label = label.to_usize().unwrap_or(0);
         let bits = bits - 1; // stored as n_bits - 1
+        let transfer_cap = transfer_cap as usize;
 
         assert!(label <= Self::LABEL_MASK);
         assert!(bits <= Self::BITS_MASK);
@@ -60,7 +75,8 @@ impl MessageInfo {
 
         let info = ((label & Self::LABEL_MASK) << Self::LABEL_OFFSET)
             | ((bits & Self::BITS_MASK) << Self::BITS_OFFSET)
-            | ((length & Self::LENGTH_MASK) << Self::LENGTH_OFFSET);
+            | ((length & Self::LENGTH_MASK) << Self::LENGTH_OFFSET)
+            | ((transfer_cap & Self::TRANSFER_CAP_MASK) << Self::TRANSFER_CAP_OFFSET);
         Self(info)
     }
 
@@ -76,6 +92,10 @@ impl MessageInfo {
         (self.0 >> Self::LENGTH_OFFSET) & Self::LENGTH_MASK
     }
 
+    pub fn transfer_cap(&self) -> bool {
+        (self.0 >> Self::TRANSFER_CAP_OFFSET) & Self::TRANSFER_CAP_MASK != 0
+    }
+
     pub fn as_usize(&self) -> usize {
         self.0
     }
@@ -87,6 +107,7 @@ impl Debug for MessageInfo {
             .field("label", &self.label())
             .field("bits", &self.bits())
             .field("length", &self.length())
+            .field("transfer_cap", &self.transfer_cap())
             .finish()
     }
 }