kata-os-common: add CopyRegion support.

Move the CopyRegion support to kata-os-common. CopyRegion wraps a
CAmkES copyregion virtual memory window to support virtual access to
physical page frames. There is RAII cleanup to clear any virtual mapping.
Embedding a CopyRegion in struct that may be cloned is not recommeded
(at least for now).

Change-Id: I7fd465fafa4a5d1de9a7e565ecb62c38a3b7e81a
GitOrigin-RevId: f58e973b1c47ec05e48bfedcb9cd5e75b71c212a

apps/system/components/ProcessManager/kata-proc-manager/src/sel4bundle/feature/spill_tcb_args.rs

@@ -5,8 +5,8 @@
 use core::mem::size_of;
 use core::ptr;
 use crate::sel4bundle::arch;
-use crate::sel4bundle::CopyRegion;
 use crate::sel4bundle::seL4BundleImpl;
+use super::CopyRegion;
 use super::sel4_sys;
 
 use arch::PAGE_SIZE;
@@ -64,8 +64,10 @@ impl seL4BundleImpl {
         // be on a page boundary.
         let frame_obj = self.get_stack_frame_obj(sp - size_of::<seL4_Word>());
 
-        let mut copy_region =
-            CopyRegion::new(unsafe { ptr::addr_of_mut!(LOAD_APPLICATION[0])});
+        let mut copy_region = CopyRegion::new(
+            unsafe { ptr::addr_of_mut!(LOAD_APPLICATION[0])},
+            PAGE_SIZE
+        );
         copy_region.map(frame_obj.cptr)?;
 
         // Write spillover arguments to the TCB's stack.

apps/system/components/ProcessManager/kata-proc-manager/src/sel4bundle/mod.rs

@@ -16,6 +16,7 @@ use kata_memory_interface::kata_object_free;
 use kata_memory_interface::kata_object_free_in_cnode;
 use kata_memory_interface::ObjDesc;
 use kata_memory_interface::ObjDescBundle;
+use kata_os_common::copyregion::CopyRegion;
 use kata_os_common::cspace_slot::CSpaceSlot;
 use kata_os_common::sel4_sys;
 use kata_proc_interface::Bundle;
@@ -36,9 +37,7 @@ use sel4_sys::seL4_DomainSet_Set;
 use sel4_sys::seL4_EndpointObject;
 use sel4_sys::seL4_Error;
 use sel4_sys::seL4_MinSchedContextBits;
-use sel4_sys::seL4_Page_Map;
 use sel4_sys::seL4_PageTableObject;
-use sel4_sys::seL4_Page_Unmap;
 use sel4_sys::seL4_ReplyObject;
 use sel4_sys::seL4_Result;
 use sel4_sys::seL4_SchedContextObject;
@@ -64,8 +63,6 @@ extern "C" {
     // Our thread's TCB; used in setting up scheduling of new TCB's.
     static SELF_TCB_PROCESS_MANAGER_PROC_CTRL_0000: seL4_CPtr;
 
-    static SELF_VSPACE_ROOT: seL4_CPtr;
-
     // Region for mapping data when loading the contents of a BundleImage.
     static mut LOAD_APPLICATION: [seL4_Word; PAGE_SIZE / size_of::<seL4_Word>()];
 }
@@ -136,78 +133,6 @@ fn check_bundle(bundle: &ObjDescBundle) {
     }
 }
 
-// TODO(sleffler): move to kata-os-common
-pub struct CopyRegion {
-    region: *mut seL4_Word,
-    cur_frame: Option<seL4_CPtr>,
-}
-impl CopyRegion {
-    pub fn new(region: *mut seL4_Word) -> Self {
-        CopyRegion {
-            region,
-            cur_frame: None,
-        }
-    }
-    // Returns the region size in bytes.
-    pub fn size(&self) -> usize { PAGE_SIZE }
-
-    // Returns a mutable [u8] ref to the mapped region.
-    pub fn as_mut(&mut self) -> &mut [u8] {
-        assert!(self.cur_frame.is_some());
-        unsafe {
-            core::slice::from_raw_parts_mut(
-                self.region as _, PAGE_SIZE
-            )
-        }
-    }
-
-    // Returns a mutable [seL4_Word] ref to the mapped region.
-    pub fn as_word_mut(&mut self) -> &mut [seL4_Word] {
-        assert!(self.cur_frame.is_some());
-        unsafe {
-            core::slice::from_raw_parts_mut(
-                self.region, PAGE_SIZE / size_of::<seL4_Word>(),
-            )
-        }
-    }
-
-    // Maps the |frame| in the SELF_VSPACE_ROOT for r/w.
-    pub fn map(&mut self, frame: seL4_CPtr) -> seL4_Result {
-        let attribs = seL4_Default_VMAttributes;
-        unsafe {
-            seL4_Page_Map(
-                frame,
-                SELF_VSPACE_ROOT,
-                self.region as usize,
-                // seL4_ReadWrite
-                seL4_CapRights::new(
-                    /*grant_reply=*/ 0, /*grant=*/ 0, /*read=*/ 1, /*write=*/ 1,
-                ),
-                attribs,
-            )
-        }?;
-        self.cur_frame = Some(frame);
-        Ok(())
-    }
-
-    // Unmaps the current frame, if any.
-    pub fn unmap(&mut self) -> seL4_Result {
-        if let Some(cptr) = self.cur_frame {
-            #[cfg(target_arch = "arm")]
-            unsafe { seL4_ARM_Page_Unify_Instruction(cptr, 0, self.size()) }?;
-
-            unsafe { seL4_Page_Unmap(cptr) }?;
-            self.cur_frame = None;
-        }
-        Ok(())
-    }
-}
-impl Drop for CopyRegion {
-    fn drop(&mut self) {
-        self.unmap().expect("CopyRegion");
-    }
-}
-
 const NOCAP: seL4_CPtr = 0;
 
 // Layout of the CNode holding dynamic_objs.  All entries are singletons
@@ -427,10 +352,10 @@ impl seL4BundleImpl {
         // to fill from the |bundle_frames| and/or zero-fill.
         let mut image = BundleImage::new(bundle_frames);
 
-        let mut copy_region =
-            CopyRegion::new(unsafe { ptr::addr_of_mut!(LOAD_APPLICATION[0])});
-        // Many places assume the copy region is PAGE_SIZE
-        assert_eq!(copy_region.size(), PAGE_SIZE);
+        let mut copy_region = CopyRegion::new(
+            unsafe { ptr::addr_of_mut!(LOAD_APPLICATION[0])},
+            PAGE_SIZE
+        );
 
         let mut vaddr_top = 0;
         while let Some(section) = image.next_section() {

apps/system/components/kata-os-common/Cargo.toml

@@ -13,6 +13,7 @@ camkes_support = []
 allocator = { path = "src/allocator" }
 camkes = { path = "src/camkes" }
 capdl = { path = "src/capdl" }
+copyregion = { path = "src/copyregion" }
 cspace-slot = { path = "src/cspace-slot" }
 logger = { path = "src/logger" }
 model = { path = "src/model" }

apps/system/components/kata-os-common/src/copyregion/Cargo.toml

@@ -0,0 +1,11 @@
+cargo-features = ["edition2021"]
+
+[package]
+name = "copyregion"
+version = "0.1.0"
+authors = ["Sam Leffler <sleffler@google.com>"]
+edition = "2021"
+
+[dependencies]
+log = "0.4"
+sel4-sys = { path = "../sel4-sys" }

apps/system/components/kata-os-common/src/copyregion/src/lib.rs

@@ -0,0 +1,141 @@
+//! RAII wrapper for using a KataOS copyregion object.
+
+#![no_std]
+#![allow(non_camel_case_types)]
+
+use core::mem::size_of;
+
+use sel4_sys::seL4_CapRights;
+use sel4_sys::seL4_CPtr;
+use sel4_sys::seL4_Default_VMAttributes;
+use sel4_sys::seL4_Page_Map;
+use sel4_sys::seL4_Page_Unmap;
+use sel4_sys::seL4_Result;
+use sel4_sys::seL4_Word;
+
+extern "C" {
+    static SELF_VSPACE_ROOT: seL4_CPtr;
+}
+
+// Sample usage:
+// let mut copy_region = CopyRegion::new(unsafe { ptr::addr_of_mut!(LOAD_APPLICATION[0])}, PAGE_SIZE);
+// copy_region.map(frame.cptr)?;
+// copy_region.as_mut()[..].fill(0);
+// let start = if index > 0 { 0 } else { vaddr - data_range.start };
+// let end = cmp::min(data_range.end - vaddr, copy_region.size());
+// image.read_exact(&mut copy_region.as_mut()[start..end])
+//      .map_err(|_| seL4_Error::seL4_NoError)?; // XXX
+// copy_region.unmap()?;
+
+// TODO(sleffler): do we need to parameterize VM_Attributes & CapRights?
+// TODO(sleffler): Mutex-wrapped & maybe RefCell-wrapped versions?
+
+// Fn from the criterion crate that convinces the optimizer
+// a value is used in order to defeat premature optimization.
+fn black_box<T>(dummy: T) -> T {
+    unsafe {
+        let ret = core::ptr::read_volatile(&dummy);
+        core::mem::forget(dummy);
+        ret
+    }
+}
+
+pub struct CopyRegion {
+    region: *mut seL4_Word,
+    size: usize,
+    cur_frame: Option<seL4_CPtr>,
+}
+impl CopyRegion {
+    pub fn new(region: *mut seL4_Word, size: usize) -> Self {
+        CopyRegion {
+            region,
+            size,
+            cur_frame: None,
+        }
+    }
+
+    // Returns the region size in bytes.
+    pub fn size(&self) -> usize { self.size }
+
+    // Returns the region size if mapped, otherwise 0.
+    pub fn mapped_bytes(&self) -> usize {
+        if self.cur_frame.is_some() { self.size } else { 0 }
+    }
+
+    // Returns an immutable [u8] ref to the mapped region.
+    pub fn as_ref(&mut self) -> &[u8] {
+        assert!(self.cur_frame.is_some());
+        unsafe {
+            core::slice::from_raw_parts(
+                self.region as _, self.size
+            )
+        }
+    }
+
+    // Returns a mutable [u8] ref to the mapped region.
+    pub fn as_mut(&mut self) -> &mut [u8] {
+        assert!(self.cur_frame.is_some());
+        unsafe {
+            core::slice::from_raw_parts_mut(
+                self.region as _, self.size
+            )
+        }
+    }
+
+    // Returns an immutable [seL4_Word] ref to the mapped region.
+    pub fn as_word_ref(&mut self) -> &[seL4_Word] {
+        assert!(self.cur_frame.is_some());
+        unsafe {
+            core::slice::from_raw_parts(
+                self.region, self.size / size_of::<seL4_Word>(),
+            )
+        }
+    }
+
+    // Returns a mutable [seL4_Word] ref to the mapped region.
+    pub fn as_word_mut(&mut self) -> &mut [seL4_Word] {
+        assert!(self.cur_frame.is_some());
+        unsafe {
+            core::slice::from_raw_parts_mut(
+                self.region, self.size / size_of::<seL4_Word>(),
+            )
+        }
+    }
+
+    // Maps the |frame| in the SELF_VSPACE_ROOT for r/w.
+    // XXX need rights + attribs?
+    pub fn map(&mut self, frame: seL4_CPtr) -> seL4_Result {
+        black_box(frame);  // NB: compiler WAR for frame clobber
+        unsafe {
+            seL4_Page_Map(
+                frame,
+                SELF_VSPACE_ROOT,
+                self.region as seL4_Word,
+                // seL4_ReadWrite
+                seL4_CapRights::new(
+                    /*grant_reply=*/ 0, /*grant=*/ 0, /*read=*/ 1, /*write=*/ 1,
+                ),
+                seL4_Default_VMAttributes,
+            )
+        }?;
+        self.cur_frame = Some(frame);
+        Ok(())
+    }
+
+    // Unmaps the current frame, if any.
+    pub fn unmap(&mut self) -> seL4_Result {
+        if let Some(cptr) = self.cur_frame {
+            #[cfg(any(target_arch = "arm", target_arch = "aarch64"))]
+            unsafe { seL4_ARM_Page_Unify_Instruction(cptr, 0, self.size()) }?;
+
+            unsafe { seL4_Page_Unmap(cptr) }?;
+            self.cur_frame = None;
+        }
+        Ok(())
+    }
+}
+impl Drop for CopyRegion {
+    fn drop(&mut self) {
+        self.unmap().expect("CopyRegion");
+    }
+}

apps/system/components/kata-os-common/src/lib.rs

@@ -5,6 +5,8 @@ pub extern crate allocator;
 pub extern crate camkes;
 pub extern crate capdl;
 #[cfg(feature = "camkes_support")]
+pub extern crate copyregion;
+#[cfg(feature = "camkes_support")]
 pub extern crate cspace_slot;
 pub extern crate logger;
 pub extern crate model;