src/lib/zircon/rust/src/vmo.rs

// Copyright 2017 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

//! Type-safe bindings for Zircon vmo objects.

use crate::ok;
use crate::{object_get_info, object_get_property, object_set_property, ObjectQuery, Topic};
use crate::{AsHandleRef, Bti, Handle, HandleBased, HandleRef, Koid, Resource, Rights, Status};
use crate::{Property, PropertyQuery, PropertyQueryGet, PropertyQuerySet};
use bitflags::bitflags;
use fuchsia_zircon_sys as sys;
use std::ptr;

/// An object representing a Zircon
/// [virtual memory object](https://fuchsia.dev/fuchsia-src/concepts/objects/vm_object.md).
///
/// As essentially a subtype of `Handle`, it can be freely interconverted.
#[derive(Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
#[repr(transparent)]
pub struct Vmo(Handle);
impl_handle_based!(Vmo);

#[repr(C)]
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub struct VmoInfo {
    pub koid: Koid,
    pub size_bytes: u64,
    pub parent_koid: Koid,
    pub num_children: usize,
    pub num_mappings: usize,
    pub share_count: usize,
    pub flags: VmoInfoFlags,
    pub committed_bytes: u64,
    pub handle_rights: Rights,
}

impl Default for VmoInfo {
    fn default() -> VmoInfo {
        Self::from(sys::zx_info_vmo_t::default())
    }
}

impl From<sys::zx_info_vmo_t> for VmoInfo {
    fn from(info: sys::zx_info_vmo_t) -> VmoInfo {
        VmoInfo {
            koid: Koid::from_raw(info.koid),
            size_bytes: info.size_bytes,
            parent_koid: Koid::from_raw(info.parent_koid),
            num_children: info.num_children,
            num_mappings: info.num_mappings,
            share_count: info.share_count,
            flags: VmoInfoFlags::from_bits_truncate(info.flags),
            committed_bytes: info.committed_bytes,
            handle_rights: Rights::from_bits_truncate(info.handle_rights),
        }
    }
}

struct VmoInfoQuery;
unsafe impl ObjectQuery for VmoInfoQuery {
    const TOPIC: Topic = Topic::VMO;
    type InfoTy = sys::zx_info_vmo_t;
}

impl Vmo {
    /// Create a virtual memory object.
    ///
    /// Wraps the
    /// `zx_vmo_create`
    /// syscall. See the
    /// [Shared Memory: Virtual Memory Objects (VMOs)](https://fuchsia.dev/fuchsia-src/concepts/kernel/concepts#shared_memory_virtual_memory_objects_vmos)
    /// for more information.
    pub fn create(size: u64) -> Result<Vmo, Status> {
        Vmo::create_with_opts(VmoOptions::from_bits_truncate(0), size)
    }

    /// Create a virtual memory object with options.
    ///
    /// Wraps the
    /// `zx_vmo_create`
    /// syscall, allowing options to be passed.
    pub fn create_with_opts(opts: VmoOptions, size: u64) -> Result<Vmo, Status> {
        let mut handle = 0;
        let status = unsafe { sys::zx_vmo_create(size, opts.bits(), &mut handle) };
        ok(status)?;
        unsafe { Ok(Vmo::from(Handle::from_raw(handle))) }
    }

    /// Create a physically contiguous virtual memory object.
    ///
    /// Wraps the
    /// [`zx_vmo_create_contiguous`](https://fuchsia.dev/fuchsia-src/reference/syscalls/vmo_create_contiguous) syscall.
    pub fn create_contiguous(bti: &Bti, size: usize, alignment_log2: u32) -> Result<Vmo, Status> {
        let mut vmo_handle = sys::zx_handle_t::default();
        let status = unsafe {
            // SAFETY: regular system call with no unsafe parameters.
            sys::zx_vmo_create_contiguous(bti.raw_handle(), size, alignment_log2, &mut vmo_handle)
        };
        ok(status)?;
        unsafe {
            // SAFETY: The syscall docs claim that upon success, vmo_handle will be a valid
            // handle to a virtual memory object.
            Ok(Vmo::from(Handle::from_raw(vmo_handle)))
        }
    }

    /// Read from a virtual memory object.
    ///
    /// Wraps the `zx_vmo_read` syscall.
    pub fn read(&self, data: &mut [u8], offset: u64) -> Result<(), Status> {
        unsafe {
            let status = sys::zx_vmo_read(self.raw_handle(), data.as_mut_ptr(), offset, data.len());
            ok(status)
        }
    }

    /// Write to a virtual memory object.
    ///
    /// Wraps the `zx_vmo_write` syscall.
    pub fn write(&self, data: &[u8], offset: u64) -> Result<(), Status> {
        unsafe {
            let status = sys::zx_vmo_write(self.raw_handle(), data.as_ptr(), offset, data.len());
            ok(status)
        }
    }

    /// Get the size of a virtual memory object.
    ///
    /// Wraps the `zx_vmo_get_size` syscall.
    pub fn get_size(&self) -> Result<u64, Status> {
        let mut size = 0;
        let status = unsafe { sys::zx_vmo_get_size(self.raw_handle(), &mut size) };
        ok(status).map(|()| size)
    }

    /// Attempt to change the size of a virtual memory object.
    ///
    /// Wraps the `zx_vmo_set_size` syscall.
    pub fn set_size(&self, size: u64) -> Result<(), Status> {
        let status = unsafe { sys::zx_vmo_set_size(self.raw_handle(), size) };
        ok(status)
    }

    /// Attempt to change the cache policy of a virtual memory object.
    ///
    /// Wraps the `zx_vmo_set_cache_policy` syscall.
    pub fn set_cache_policy(&self, cache_policy: sys::zx_cache_policy_t) -> Result<(), Status> {
        let status =
            unsafe { sys::zx_vmo_set_cache_policy(self.raw_handle(), cache_policy as u32) };
        ok(status)
    }

    /// Perform an operation on a range of a virtual memory object.
    ///
    /// Wraps the
    /// [zx_vmo_op_range](https://fuchsia.dev/fuchsia-src/reference/syscalls/vmo_op_range.md)
    /// syscall.
    pub fn op_range(&self, op: VmoOp, offset: u64, size: u64) -> Result<(), Status> {
        let status = unsafe {
            sys::zx_vmo_op_range(self.raw_handle(), op.into_raw(), offset, size, ptr::null_mut(), 0)
        };
        ok(status)
    }

    /// Wraps the [zx_object_get_info](https://fuchsia.dev/fuchsia-src/reference/syscalls/object_get_info.md)
    /// syscall for the ZX_INFO_VMO topic.
    pub fn info(&self) -> Result<VmoInfo, Status> {
        let mut info = sys::zx_info_vmo_t::default();
        object_get_info::<VmoInfoQuery>(self.as_handle_ref(), std::slice::from_mut(&mut info))
            .map(|_| VmoInfo::from(info))
    }

    /// Create a new virtual memory object that clones a range of this one.
    ///
    /// Wraps the
    /// [zx_vmo_create_child](https://fuchsia.dev/fuchsia-src/reference/syscalls/vmo_create_child.md)
    /// syscall.
    pub fn create_child(
        &self,
        opts: VmoChildOptions,
        offset: u64,
        size: u64,
    ) -> Result<Vmo, Status> {
        let mut out = 0;
        let status = unsafe {
            sys::zx_vmo_create_child(self.raw_handle(), opts.bits(), offset, size, &mut out)
        };
        ok(status)?;
        unsafe { Ok(Vmo::from(Handle::from_raw(out))) }
    }

    /// Replace a VMO, adding execute rights.
    ///
    /// Wraps the
    /// [zx_vmo_replace_as_executable](https://fuchsia.dev/fuchsia-src/reference/syscalls/vmo_replace_as_executable.md)
    /// syscall.
    pub fn replace_as_executable(self, vmex: &Resource) -> Result<Vmo, Status> {
        let mut out = 0;
        let status = unsafe {
            sys::zx_vmo_replace_as_executable(self.raw_handle(), vmex.raw_handle(), &mut out)
        };
        ok(status)?;
        unsafe { Ok(Vmo::from(Handle::from_raw(out))) }
    }
}

bitflags! {
    /// Options that may be used when creating a `Vmo`.
    #[repr(transparent)]
    pub struct VmoOptions: u32 {
        const RESIZABLE = sys::ZX_VMO_RESIZABLE;
        const TRAP_DIRTY = sys::ZX_VMO_TRAP_DIRTY;
    }
}

bitflags! {
    /// Flags that may be set when receiving info on a `Vmo`.
    #[repr(transparent)]
    pub struct VmoInfoFlags: u32 {
        const RESIZABLE = sys::ZX_INFO_VMO_RESIZABLE;
        const IS_COW_CLONE = sys::ZX_INFO_VMO_IS_COW_CLONE;
        const PAGER_BACKED = sys::ZX_INFO_VMO_PAGER_BACKED;
        const CONTIGUOUS = sys::ZX_INFO_VMO_CONTIGUOUS;
    }
}

bitflags! {
    /// Options that may be used when creating a `Vmo` child.
    #[repr(transparent)]
    pub struct VmoChildOptions: u32 {
        const SNAPSHOT = sys::ZX_VMO_CHILD_SNAPSHOT;
        const SNAPSHOT_AT_LEAST_ON_WRITE = sys::ZX_VMO_CHILD_SNAPSHOT_AT_LEAST_ON_WRITE;
        const RESIZABLE = sys::ZX_VMO_CHILD_RESIZABLE;
        const SLICE = sys::ZX_VMO_CHILD_SLICE;
        const NO_WRITE = sys::ZX_VMO_CHILD_NO_WRITE;
    }
}

/// VM Object opcodes
#[derive(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
#[repr(transparent)]
pub struct VmoOp(u32);
impl VmoOp {
    pub fn from_raw(raw: u32) -> VmoOp {
        VmoOp(raw)
    }
    pub fn into_raw(self) -> u32 {
        self.0
    }
}

assoc_values!(VmoOp, [
    COMMIT =           sys::ZX_VMO_OP_COMMIT;
    DECOMMIT =         sys::ZX_VMO_OP_DECOMMIT;
    LOCK =             sys::ZX_VMO_OP_LOCK;
    UNLOCK =           sys::ZX_VMO_OP_UNLOCK;
    CACHE_SYNC =       sys::ZX_VMO_OP_CACHE_SYNC;
    CACHE_INVALIDATE = sys::ZX_VMO_OP_CACHE_INVALIDATE;
    CACHE_CLEAN =      sys::ZX_VMO_OP_CACHE_CLEAN;
    CACHE_CLEAN_INVALIDATE = sys::ZX_VMO_OP_CACHE_CLEAN_INVALIDATE;
    ZERO =             sys::ZX_VMO_OP_ZERO;
    TRY_LOCK =         sys::ZX_VMO_OP_TRY_LOCK;
    DONT_NEED =        sys::ZX_VMO_OP_DONT_NEED;
]);

unsafe_handle_properties!(object: Vmo,
    props: [
        {query_ty: VMO_CONTENT_SIZE, tag: VmoContentSizeTag, prop_ty: u64, get:get_content_size, set: set_content_size},
    ]
);

#[cfg(test)]
mod tests {
    use super::*;
    use crate::{Handle, Iommu, IommuDescDummy, ObjectType, Rights};
    use fidl_fuchsia_boot as fboot;
    use fidl_fuchsia_kernel as fkernel;
    use fuchsia_component::client::connect_channel_to_protocol;

    #[test]
    fn vmo_create_contiguous_invalid_handle() {
        let status = Vmo::create_contiguous(&Bti::from(Handle::invalid()), 4096, 0);
        assert_eq!(status, Err(Status::BAD_HANDLE));
    }

    #[test]
    fn vmo_create_contiguous() {
        use fuchsia_zircon::{Channel, HandleBased, Time};
        let (client_end, server_end) = Channel::create().unwrap();
        connect_channel_to_protocol::<fboot::RootResourceMarker>(server_end).unwrap();
        let service = fboot::RootResourceSynchronousProxy::new(client_end);
        let resource = service.get(Time::INFINITE).expect("couldn't get root resource");
        // This test and fuchsia-zircon are different crates, so we need
        // to use from_raw to convert between the fuchsia_zircon handle and this test handle.
        // See https://fxbug.dev/91562 for details.
        let resource = unsafe { Resource::from(Handle::from_raw(resource.into_raw())) };
        let iommu = Iommu::create_dummy(&resource, IommuDescDummy::default()).unwrap();
        let bti = Bti::create(&iommu, 0).unwrap();

        let vmo = Vmo::create_contiguous(&bti, 8192, 0).unwrap();
        let info = vmo.as_handle_ref().basic_info().unwrap();
        assert_eq!(info.object_type, ObjectType::VMO);

        let vmo_info = vmo.info().unwrap();
        assert!(vmo_info.flags.contains(VmoInfoFlags::CONTIGUOUS));
    }

    #[test]
    fn vmo_get_size() {
        let size = 16 * 1024 * 1024;
        let vmo = Vmo::create(size).unwrap();
        assert_eq!(size, vmo.get_size().unwrap());
    }

    #[test]
    fn vmo_set_size() {
        // Use a multiple of page size to match VMOs page aligned size
        let start_size = 4096;
        let vmo = Vmo::create_with_opts(VmoOptions::RESIZABLE, start_size).unwrap();
        assert_eq!(start_size, vmo.get_size().unwrap());

        // Change the size and make sure the new size is reported
        let new_size = 8192;
        assert!(vmo.set_size(new_size).is_ok());
        assert_eq!(new_size, vmo.get_size().unwrap());
    }

    #[test]
    fn vmo_get_info_default() {
        let size = 4096;
        let vmo = Vmo::create(size).unwrap();
        let info = vmo.info().unwrap();
        assert!(!info.flags.contains(VmoInfoFlags::PAGER_BACKED));
    }

    #[test]
    fn vmo_get_child_info() {
        let size = 4096;
        let vmo = Vmo::create(size).unwrap();
        let info = vmo.info().unwrap();
        assert!(!info.flags.contains(VmoInfoFlags::IS_COW_CLONE));

        let child = vmo.create_child(VmoChildOptions::SNAPSHOT, 0, 512).unwrap();
        let info = child.info().unwrap();
        assert!(info.flags.contains(VmoInfoFlags::IS_COW_CLONE));

        let child = vmo.create_child(VmoChildOptions::SNAPSHOT_AT_LEAST_ON_WRITE, 0, 512).unwrap();
        let info = child.info().unwrap();
        assert!(info.flags.contains(VmoInfoFlags::IS_COW_CLONE));

        let child = vmo.create_child(VmoChildOptions::SLICE, 0, 512).unwrap();
        let info = child.info().unwrap();
        assert!(!info.flags.contains(VmoInfoFlags::IS_COW_CLONE));
    }

    #[test]
    fn vmo_set_size_fails_on_non_resizable() {
        let size = 4096;
        let vmo = Vmo::create(size).unwrap();
        assert_eq!(size, vmo.get_size().unwrap());

        let new_size = 8192;
        assert_eq!(Err(Status::UNAVAILABLE), vmo.set_size(new_size));
        assert_eq!(size, vmo.get_size().unwrap());
    }

    #[test]
    fn vmo_read_write() {
        let mut vec1 = vec![0; 16];
        let vmo = Vmo::create(4096 as u64).unwrap();
        assert!(vmo.write(b"abcdef", 0).is_ok());
        assert!(vmo.read(&mut vec1, 0).is_ok());
        assert_eq!(b"abcdef", &vec1[0..6]);
        assert!(vmo.write(b"123", 2).is_ok());
        assert!(vmo.read(&mut vec1, 0).is_ok());
        assert_eq!(b"ab123f", &vec1[0..6]);

        // Read one byte into the vmo.
        assert!(vmo.read(&mut vec1, 1).is_ok());
        assert_eq!(b"b123f", &vec1[0..5]);
    }

    #[test]
    fn vmo_child_snapshot() {
        let size = 4096 * 2;
        let vmo = Vmo::create(size).unwrap();

        vmo.write(&[1; 4096], 0).unwrap();
        vmo.write(&[2; 4096], 4096).unwrap();

        let child = vmo.create_child(VmoChildOptions::SNAPSHOT, 0, size).unwrap();

        child.write(&[3; 4096], 0).unwrap();

        vmo.write(&[4; 4096], 0).unwrap();
        vmo.write(&[5; 4096], 4096).unwrap();

        let mut page = [0; 4096];

        // SNAPSHOT child observes no further changes to parent VMO.
        child.read(&mut page[..], 0).unwrap();
        assert_eq!(&page[..], &[3; 4096][..]);
        child.read(&mut page[..], 4096).unwrap();
        assert_eq!(&page[..], &[2; 4096][..]);
    }

    #[test]
    fn vmo_child_snapshot_at_least_on_write() {
        let size = 4096 * 2;
        let vmo = Vmo::create(size).unwrap();

        vmo.write(&[1; 4096], 0).unwrap();
        vmo.write(&[2; 4096], 4096).unwrap();

        let child = vmo.create_child(VmoChildOptions::SNAPSHOT_AT_LEAST_ON_WRITE, 0, size).unwrap();

        child.write(&[3; 4096], 0).unwrap();

        vmo.write(&[4; 4096], 0).unwrap();
        vmo.write(&[5; 4096], 4096).unwrap();

        let mut page = [0; 4096];

        // SNAPSHOT_AT_LEAST_ON_WRITE child may observe changes to pages it has not yet written to,
        // but such behavior is not guaranteed.
        child.read(&mut page[..], 0).unwrap();
        assert_eq!(&page[..], &[3; 4096][..]);
        child.read(&mut page[..], 4096).unwrap();
        assert!(
            &page[..] == &[2; 4096][..] || &page[..] == &[5; 4096][..],
            "expected page of 2 or 5, got {:?}",
            &page[..]
        );
    }

    #[test]
    fn vmo_child_no_write() {
        let size = 4096;
        let vmo = Vmo::create(size).unwrap();
        vmo.write(&[1; 4096], 0).unwrap();

        let child =
            vmo.create_child(VmoChildOptions::SLICE | VmoChildOptions::NO_WRITE, 0, size).unwrap();
        assert_eq!(child.write(&[3; 4096], 0), Err(Status::ACCESS_DENIED));
    }

    #[test]
    fn vmo_op_range_unsupported() {
        let vmo = Vmo::create(12).unwrap();
        assert_eq!(vmo.op_range(VmoOp::LOCK, 0, 1), Err(Status::NOT_SUPPORTED));
        assert_eq!(vmo.op_range(VmoOp::UNLOCK, 0, 1), Err(Status::NOT_SUPPORTED));
    }

    #[test]
    fn vmo_cache() {
        let vmo = Vmo::create(12).unwrap();

        // Cache operations should all succeed.
        assert_eq!(vmo.op_range(VmoOp::CACHE_SYNC, 0, 12), Ok(()));
        assert_eq!(vmo.op_range(VmoOp::CACHE_INVALIDATE, 0, 12), Ok(()));
        assert_eq!(vmo.op_range(VmoOp::CACHE_CLEAN, 0, 12), Ok(()));
        assert_eq!(vmo.op_range(VmoOp::CACHE_CLEAN_INVALIDATE, 0, 12), Ok(()));
    }

    #[test]
    fn vmo_create_child() {
        let original = Vmo::create(16).unwrap();
        assert!(original.write(b"one", 0).is_ok());

        // Clone the VMO, and make sure it contains what we expect.
        let clone =
            original.create_child(VmoChildOptions::SNAPSHOT_AT_LEAST_ON_WRITE, 0, 16).unwrap();
        let mut read_buffer = vec![0; 16];
        assert!(clone.read(&mut read_buffer, 0).is_ok());
        assert_eq!(&read_buffer[0..3], b"one");

        // Writing to the original will not affect the clone.
        assert!(original.write(b"two", 0).is_ok());
        assert!(original.read(&mut read_buffer, 0).is_ok());
        assert_eq!(&read_buffer[0..3], b"two");
        assert!(clone.read(&mut read_buffer, 0).is_ok());
        assert_eq!(&read_buffer[0..3], b"one");

        // However, writing to the clone will not affect the original.
        assert!(clone.write(b"three", 0).is_ok());
        assert!(original.read(&mut read_buffer, 0).is_ok());
        assert_eq!(&read_buffer[0..3], b"two");
        assert!(clone.read(&mut read_buffer, 0).is_ok());
        assert_eq!(&read_buffer[0..5], b"three");
    }

    #[test]
    fn vmo_replace_as_executeable() {
        use fuchsia_zircon::{Channel, HandleBased, Time};

        let vmo = Vmo::create(16).unwrap();

        let info = vmo.as_handle_ref().basic_info().unwrap();
        assert!(!info.rights.contains(Rights::EXECUTE));

        let (client_end, server_end) = Channel::create().unwrap();
        connect_channel_to_protocol::<fkernel::VmexResourceMarker>(server_end).unwrap();
        let service = fkernel::VmexResourceSynchronousProxy::new(client_end);
        let resource = service.get(Time::INFINITE).expect("couldn't get vmex resource");
        let resource = unsafe { crate::Resource::from(Handle::from_raw(resource.into_raw())) };

        let exec_vmo = vmo.replace_as_executable(&resource).unwrap();
        let info = exec_vmo.as_handle_ref().basic_info().unwrap();
        assert!(info.rights.contains(Rights::EXECUTE));
    }

    #[test]
    fn vmo_content_size() {
        let start_size = 1024;
        let vmo = Vmo::create_with_opts(VmoOptions::RESIZABLE, start_size).unwrap();
        assert_eq!(vmo.get_content_size().unwrap(), start_size);
        vmo.set_content_size(&0).unwrap();
        assert_eq!(vmo.get_content_size().unwrap(), 0);

        // write should not change content size.
        let content = b"abcdef";
        assert!(vmo.write(content, 0).is_ok());
        assert_eq!(vmo.get_content_size().unwrap(), 0);
    }

    #[test]
    fn vmo_zero() {
        let vmo = Vmo::create(16).unwrap();
        let content = b"0123456789abcdef";
        assert!(vmo.write(content, 0).is_ok());
        let mut buf = vec![0u8; 16];
        assert!(vmo.read(&mut buf[..], 0).is_ok());
        assert_eq!(&buf[..], content);

        assert!(vmo.op_range(VmoOp::ZERO, 0, 16).is_ok());
        assert!(vmo.read(&mut buf[..], 0).is_ok());
        assert_eq!(&buf[..], &[0u8; 16]);
    }
}