From 7315d09fb50d2e1a39f872f8108935bcfb565df9 Mon Sep 17 00:00:00 2001
From: Sam Leffler <sleffler@google.com>
Date: Thu, 12 May 2022 22:53:05 +0000
Subject: [PATCH] Merge "kata-slot-allocator: add a 1-slot RAII helper"

GitOrigin-RevId: 5d339c11e080d99280438552d69147745122780b
---
 .../src/slot-allocator/Cargo.toml             |   1 +
 .../src/slot-allocator/src/lib.rs             |   4 +
 .../src/slot-allocator/src/one_slot.rs        | 116 ++++++++++++++++++
 3 files changed, 121 insertions(+)
 create mode 100644 apps/system/components/kata-os-common/src/slot-allocator/src/one_slot.rs

diff --git a/apps/system/components/kata-os-common/src/slot-allocator/Cargo.toml b/apps/system/components/kata-os-common/src/slot-allocator/Cargo.toml
index b5ff1b3..ae326cc 100644
--- a/apps/system/components/kata-os-common/src/slot-allocator/Cargo.toml
+++ b/apps/system/components/kata-os-common/src/slot-allocator/Cargo.toml
@@ -9,4 +9,5 @@ edition = "2021"
 [dependencies]
 # TODO(sleffler): v1.0 requires rust edition2021
 bitvec = { version = "0.22", default-features = false, features = ["alloc"] }
+sel4-sys = { path = "../sel4-sys" }
 spin = "0.9"
diff --git a/apps/system/components/kata-os-common/src/slot-allocator/src/lib.rs b/apps/system/components/kata-os-common/src/slot-allocator/src/lib.rs
index 68bdf21..758d436 100644
--- a/apps/system/components/kata-os-common/src/slot-allocator/src/lib.rs
+++ b/apps/system/components/kata-os-common/src/slot-allocator/src/lib.rs
@@ -3,11 +3,15 @@
 //! can be used for other purposes.
 
 #![cfg_attr(not(test), no_std)]
+#![allow(non_snake_case)]
 
 use bitvec::prelude::*;
 use core::ops::Range;
 use spin::Mutex;
 
+mod one_slot;
+pub use one_slot::CSpaceSlot;
+
 struct Slots {
     bits: Option<BitBox<Lsb0, u8>>,
     used: usize,
diff --git a/apps/system/components/kata-os-common/src/slot-allocator/src/one_slot.rs b/apps/system/components/kata-os-common/src/slot-allocator/src/one_slot.rs
new file mode 100644
index 0000000..a9263cc
--- /dev/null
+++ b/apps/system/components/kata-os-common/src/slot-allocator/src/one_slot.rs
@@ -0,0 +1,116 @@
+//! RAII wrapper for a dynamically allocated CSpace slot.
+
+use crate::KATA_CSPACE_SLOTS;
+
+use sel4_sys::seL4_CapRights;
+use sel4_sys::seL4_CNode_Copy;
+use sel4_sys::seL4_CNode_Delete;
+use sel4_sys::seL4_CNode_Move;
+use sel4_sys::seL4_CPtr;
+use sel4_sys::seL4_Result;
+use sel4_sys::seL4_SetCapReceivePath;
+use sel4_sys::seL4_WordBits;
+
+extern "C" {
+    static SELF_CNODE: seL4_CPtr;
+}
+
+pub struct CSpaceSlot {
+    pub slot: seL4_CPtr,
+}
+impl CSpaceSlot {
+    pub fn new() -> Self {
+        CSpaceSlot {
+            slot: unsafe { KATA_CSPACE_SLOTS.alloc(1) }.expect("CSpaceSlot"),
+        }
+    }
+
+    // Release ownership of the slot; this inhibits the normal cleanup
+    // done by drop.
+    pub fn release(&mut self) {
+        self.slot = seL4_CPtr::MAX;
+    }
+
+    // Returns the (root, index, depth) seL4 path for the slot.
+    pub fn get_path(&self) -> (seL4_CPtr, seL4_CPtr, u8) {
+        (unsafe { SELF_CNODE }, self.slot, seL4_WordBits as u8)
+    }
+
+    // Sets the receive path used for receiving a capability attached
+    // to an seL4 IPC message.
+    pub fn set_recv_path(&self) {
+        unsafe { seL4_SetCapReceivePath(SELF_CNODE, self.slot, seL4_WordBits) };
+    }
+
+    // Copies the specified path to our slot.
+    pub fn copy_to(
+        &self,
+        src_root: seL4_CPtr,
+        src_index: seL4_CPtr,
+        src_depth: u8,
+    ) -> seL4_Result {
+        let seL4_AllRights = seL4_CapRights::new(
+            /*grant_reply=*/ 1, /*grant=*/ 1, /*read=*/ 1, /*write=*/ 1,
+        );
+        unsafe {
+            seL4_CNode_Copy(
+                /*dest_root=*/ SELF_CNODE,
+                /*dest_index= */ self.slot,
+                /*dest_depth=*/ seL4_WordBits as u8,
+                src_root,
+                src_index,
+                src_depth,
+                seL4_AllRights,
+            )
+        }
+    }
+
+    // Moves the specified path to our slot.
+    pub fn move_to(
+        &self,
+        src_root: seL4_CPtr,
+        src_slot: seL4_CPtr,
+        src_depth: u8,
+    ) -> seL4_Result {
+        unsafe {
+            seL4_CNode_Move(
+                /*dest_root=*/ SELF_CNODE,
+                /*dest_index= */ self.slot,
+                /*dest_depth=*/ seL4_WordBits as u8,
+                src_root,
+                src_slot,
+                src_depth,
+            )
+        }
+    }
+
+    // Moves our slot to the specified path.
+    pub fn move_from(
+        &self,
+        dest_root: seL4_CPtr,
+        dest_slot: seL4_CPtr,
+        dest_depth: u8,
+    ) -> seL4_Result {
+        unsafe {
+            seL4_CNode_Move(
+                dest_root,
+                dest_slot,
+                dest_depth,
+                /*src_root=*/ SELF_CNODE,
+                /*src_index= */ self.slot,
+                /*src_depth=*/ seL4_WordBits as u8,
+            )
+        }
+    }
+}
+impl Drop for CSpaceSlot {
+    fn drop(&mut self) {
+        if self.slot != seL4_CPtr::MAX {
+            unsafe {
+                seL4_CNode_Delete(SELF_CNODE, self.slot, seL4_WordBits as u8)
+                    .expect("CSpaceSlot");
+                KATA_CSPACE_SLOTS.free(self.slot, 1);
+            }
+        }
+    }
+}