Move syscall::Dma to common.

2023-07-18 12:43:06 +02:00
parent 2341e3cb16
commit 089e8bac35
2 changed files with 219 additions and 0 deletions
@@ -0,0 +1,217 @@
+use std::mem::{self, MaybeUninit};
+use std::ops::{Deref, DerefMut};
+use std::{ptr, slice};
+
+use syscall::PAGE_SIZE;
+
+use syscall::Result;
+use syscall::{PartialAllocStrategy, PhysallocFlags};
+
+use crate::MemoryType;
+
+/// An RAII guard of a physical memory allocation. Currently all physically allocated memory are
+/// page-aligned and take up at least 4k of space (on x86_64).
+#[derive(Debug)]
+pub struct PhysBox {
+    address: usize,
+    size: usize
+}
+
+fn assert_aligned(x: usize) {
+    assert_eq!(x % PAGE_SIZE, 0);
+}
+
+const DMA_MEMTY: MemoryType = {
+    if cfg!(any(target_arch = "x86", target_arch = "x86_64")) {
+        // aarch64 currently must map DMA memory without caching to ensure coherence
+        MemoryType::Writeback
+    } else if cfg!(target_arch = "aarch64") {
+        // x86 ensures cache coherence with DMA memory
+        MemoryType::Uncacheable
+    } else {
+        panic!("invalid arch")
+    }
+};
+
+impl PhysBox {
+    /// Construct a PhysBox from an address and a size. The address must be page-aligned, and the
+    /// size must similarly be a multiple of the page size.
+    ///
+    /// # Safety
+    /// This function is unsafe because when dropping, Self has to a valid allocation.
+    pub unsafe fn from_raw_parts(address: usize, size: usize) -> Self {
+        assert_aligned(address);
+        assert_aligned(size);
+
+        Self {
+            address,
+            size,
+        }
+    }
+
+    /// Retrieve the byte address in physical memory, of this allocation.
+    pub fn address(&self) -> usize {
+        self.address
+    }
+
+    /// Retrieve the size in bytes of the alloc.
+    pub fn size(&self) -> usize {
+        self.size
+    }
+
+    /// Allocate physical memory that must reside in 32-bit space.
+    pub fn new_in_32bit_space(size: usize) -> Result<Self> {
+        Self::new_with_flags(size, PhysallocFlags::SPACE_32)
+    }
+
+    pub fn new_with_flags(size: usize, flags: PhysallocFlags) -> Result<Self> {
+        assert!(!flags.contains(PhysallocFlags::PARTIAL_ALLOC));
+        assert_aligned(size);
+
+        let address = unsafe { syscall::physalloc2(size, flags.bits())? };
+        Ok(unsafe { Self::from_raw_parts(address, size) })
+    }
+
+    /// "Partially" allocate physical memory, in the sense that the allocation may be smaller than
+    /// expected, but still with a minimum limit. This is particularly useful when the physical
+    /// memory space is fragmented, and a device supports scatter-gather I/O. In that case, the
+    /// driver can optimistically request e.g. 1 alloc of 1 MiB, with the minimum of 512 KiB. If
+    /// that first allocation only returns half the size, the driver can do another allocation
+    /// and then let the device use both buffers.
+    pub fn new_partial_allocation(size: usize, flags: PhysallocFlags, strategy: Option<PartialAllocStrategy>, mut min: usize) -> Result<Self> {
+        assert_aligned(size);
+        debug_assert!(!(flags.contains(PhysallocFlags::PARTIAL_ALLOC) && strategy.is_none()));
+
+        let address = unsafe { syscall::physalloc3(size, flags.bits() | strategy.map_or(0, |s| s as usize), &mut min)? };
+        Ok(unsafe { Self::from_raw_parts(address, size) })
+    }
+
+    pub fn new(size: usize) -> Result<Self> {
+        assert_aligned(size);
+
+        let address = unsafe { syscall::physalloc(size)? };
+        Ok(unsafe { Self::from_raw_parts(address, size) })
+    }
+}
+
+impl Drop for PhysBox {
+    fn drop(&mut self) {
+        let _ = unsafe { syscall::physfree(self.address, self.size) };
+    }
+}
+
+pub struct Dma<T: ?Sized> {
+    phys: PhysBox,
+    virt: *mut T,
+}
+
+impl<T> Dma<T> {
+    pub fn from_physbox_uninit(phys: PhysBox) -> Result<Dma<MaybeUninit<T>>> {
+        Ok(Dma {
+            virt: unsafe { crate::physmap(phys.address, phys.size, crate::Prot::RW, DMA_MEMTY)? } as *mut MaybeUninit<T>,
+            phys,
+        })
+    }
+    pub fn from_physbox_zeroed(phys: PhysBox) -> Result<Dma<MaybeUninit<T>>> {
+        let this = Self::from_physbox_uninit(phys)?;
+        unsafe { ptr::write_bytes(this.virt as *mut MaybeUninit<u8>, 0, this.phys.size) }
+        Ok(this)
+    }
+
+    pub fn from_physbox(phys: PhysBox, value: T) -> Result<Self> {
+        let this = Self::from_physbox_uninit(phys)?;
+
+        Ok(unsafe {
+            ptr::write(this.virt, MaybeUninit::new(value));
+            this.assume_init()
+        })
+    }
+
+    pub fn new(value: T) -> Result<Self> {
+        let phys = PhysBox::new(mem::size_of::<T>().next_multiple_of(PAGE_SIZE))?;
+        Self::from_physbox(phys, value)
+    }
+    pub fn zeroed() -> Result<Dma<MaybeUninit<T>>> {
+        let phys = PhysBox::new(mem::size_of::<T>().next_multiple_of(PAGE_SIZE))?;
+        Self::from_physbox_zeroed(phys)
+    }
+}
+
+impl<T> Dma<MaybeUninit<T>> {
+    pub unsafe fn assume_init(self) -> Dma<T> {
+        let &Dma { phys: PhysBox { address, size }, virt } = &self;
+        mem::forget(self);
+
+        Dma {
+            phys: PhysBox { address, size },
+            virt: virt as *mut T,
+        }
+    }
+}
+impl<T: ?Sized> Dma<T> {
+    pub fn physical(&self) -> usize {
+        self.phys.address()
+    }
+    pub fn size(&self) -> usize {
+        self.phys.size()
+    }
+    pub fn phys(&self) -> &PhysBox {
+        &self.phys
+    }
+}
+
+impl<T> Dma<[T]> {
+    pub fn from_physbox_uninit_unsized(phys: PhysBox, len: usize) -> Result<Dma<[MaybeUninit<T>]>> {
+        let max_len = phys.size() / mem::size_of::<T>();
+        assert!(len <= max_len);
+
+        Ok(Dma {
+            virt: unsafe { slice::from_raw_parts_mut(crate::physmap(phys.address, phys.size, crate::Prot::RW, DMA_MEMTY)? as *mut MaybeUninit<T>, len) } as *mut [MaybeUninit<T>],
+            phys,
+        })
+    }
+    pub fn from_physbox_zeroed_unsized(phys: PhysBox, len: usize) -> Result<Dma<[MaybeUninit<T>]>> {
+        let this = Self::from_physbox_uninit_unsized(phys, len)?;
+        unsafe { ptr::write_bytes(this.virt as *mut MaybeUninit<u8>, 0, this.phys.size()) }
+        Ok(this)
+    }
+    /// Creates a new DMA buffer with a size only known at runtime.
+    /// ## Safety
+    /// * `T` must be properly aligned.
+    /// * `T` must be valid as zeroed (i.e. no NonNull pointers).
+    pub unsafe fn zeroed_unsized(count: usize) -> Result<Self> {
+        let phys = PhysBox::new((mem::size_of::<T>() * count).next_multiple_of(PAGE_SIZE))?;
+        Ok(Self::from_physbox_zeroed_unsized(phys, count)?.assume_init())
+    }
+}
+impl<T> Dma<[MaybeUninit<T>]> {
+    pub unsafe fn assume_init(self) -> Dma<[T]> {
+        let &Dma { phys: PhysBox { address, size }, virt } = &self;
+        mem::forget(self);
+
+        Dma {
+            phys: PhysBox { address, size },
+            virt: virt as *mut [T],
+        }
+    }
+}
+
+impl<T: ?Sized> Deref for Dma<T> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        unsafe { &*self.virt }
+    }
+}
+
+impl<T: ?Sized> DerefMut for Dma<T> {
+    fn deref_mut(&mut self) -> &mut T {
+        unsafe { &mut *self.virt }
+    }
+}
+
+impl<T: ?Sized> Drop for Dma<T> {
+    fn drop(&mut self) {
+        unsafe { ptr::drop_in_place(self.virt) }
+        let _ = unsafe { syscall::funmap(self.virt as *mut u8 as usize, self.phys.size) };
+    }
+}
@@ -4,6 +4,8 @@ use syscall::PAGE_SIZE;
 use syscall::error::{Error, Result, EINVAL};
 use syscall::flag::{MapFlags, O_CLOEXEC, O_RDONLY, O_RDWR, O_WRONLY};

+pub mod dma;
+
 #[derive(Clone, Copy, Debug)]
 pub enum MemoryType {
    Writeback,