Add a simple dma coherent allocator rust abstraction. Based on
Andreas Hindborg's dma abstractions from the rnvme driver.
Co-developed-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Signed-off-by: Wedson Almeida Filho <wedsonaf@gmail.com>
Co-developed-by: Andreas Hindborg <a.hindborg@samsung.com>
Signed-off-by: Andreas Hindborg <a.hindborg@samsung.com>
Signed-off-by: Abdiel Janulgue <abdiel.janulgue@gmail.com>
---
rust/kernel/dma.rs | 165 +++++++++++++++++++++++++++++++++++++++++++++
rust/kernel/lib.rs | 1 +
2 files changed, 166 insertions(+)
create mode 100644 rust/kernel/dma.rs
diff --git a/rust/kernel/dma.rs b/rust/kernel/dma.rs
new file mode 100644
index 000000000000..75a304d612f0
--- /dev/null
+++ b/rust/kernel/dma.rs
@@ -0,0 +1,165 @@
+// SPDX-License-Identifier: GPL-2.0
+
+//! Direct memory access (DMA).
+//!
+//! C header: [`include/linux/dma-mapping.h`](srctree/include/linux/dma-mapping.h)
+
+use crate::{
+ bindings,
+ device::Device,
+ error::code::*,
+ error::Result,
+ types::ARef,
+};
+use core::ops::Add;
+
+/// Abstraction of dma_alloc_coherent
+///
+/// # Invariants
+///
+/// For the lifetime of an instance of CoherentAllocation, the cpu address is a valid pointer
+/// to an allocated region of consistent memory and we hold a reference to the device.
+pub struct CoherentAllocation<T: Add> {
+ dev: ARef<Device>,
+ dma_handle: bindings::dma_addr_t,
+ count: usize,
+ cpu_addr: *mut T,
+}
+
+impl<T: Add> CoherentAllocation<T> {
+ /// Allocates a region of `size_of::<T> * count` of consistent memory.
+ ///
+ /// Returns a CoherentAllocation object which contains a pointer to the allocated region
+ /// (in the processor's virtual address space) and the device address which can be
+ /// given to the device as the DMA address base of the region. The region is released once
+ /// [`CoherentAllocation`] is dropped.
+ ///
+ /// # Examples
+ ///
+ /// ```
+ /// use kernel::device::Device;
+ /// use kernel::dma::CoherentAllocation;
+ ///
+ /// # fn dox(dev: &Device) -> Result<()> {
+ /// let c: CoherentAllocation<u64> = CoherentAllocation::alloc_coherent(dev, 4, GFP_KERNEL)?;
+ /// # Ok(()) }
+ /// ```
+ pub fn alloc_coherent(
+ dev: &Device,
+ count: usize,
+ flags: kernel::alloc::Flags,
+ ) -> Result<CoherentAllocation<T>> {
+ let t_size = core::mem::size_of::<T>();
+ let size = count.checked_mul(t_size).ok_or(EOVERFLOW)?;
+ let mut dma_handle = 0;
+ // SAFETY: device pointer is guaranteed as valid by invariant on `Device`.
+ // We ensure that we catch the failure on this function and throw an ENOMEM
+ let ret = unsafe {
+ bindings::dma_alloc_attrs(
+ dev.as_raw(),
+ size,
+ &mut dma_handle, flags.as_raw(),
+ 0,
+ )
+ };
+ if ret.is_null() {
+ return Err(ENOMEM)
+ }
+
+ Ok(Self {
+ dev: dev.into(),
+ dma_handle,
+ count,
+ cpu_addr: ret as _,
+ })
+ }
+
+ /// Reads a value on a location specified by index.
+ pub fn read(&self, index: usize) -> Result<T>
+ where
+ T: Copy
+ {
+ if let Some(val) = self.cpu_buf().get(index) {
+ Ok(*val)
+ } else {
+ Err(EINVAL)
+ }
+ }
+
+ /// Write a value on the memory location specified by index.
+ pub fn write(&mut self, index: usize, value: &T) -> Result
+ where
+ T: Copy,
+ {
+ if let Some(elem) = self.cpu_buf_mut().get_mut(index) {
+ *elem = *value;
+ Ok(())
+ } else {
+ Err(EINVAL)
+ }
+ }
+
+ /// Performs a read and then a write of a value on a location specified by index.
+ pub fn read_write(&mut self, index: usize, value: &T) -> Result<T>
+ where
+ T: Copy,
+ {
+ if let Some(elem) = self.cpu_buf_mut().get_mut(index) {
+ let val = *elem;
+ *elem = *value;
+ Ok(val)
+ } else {
+ Err(EINVAL)
+ }
+ }
+
+ /// Returns the base address to the allocated region and the dma handle.
+ /// Caller takes ownership of returned resources.
+ pub fn into_parts(self) -> (usize, bindings::dma_addr_t) {
+ let ret = (self.cpu_addr as _, self.dma_handle);
+ core::mem::forget(self);
+ ret
+ }
+
+ /// Returns the base address to the allocated region in the CPU's virtual address space.
+ pub fn start_ptr(&self) -> *const T {
+ self.cpu_addr as _
+ }
+
+ /// Returns the base address to the allocated region in the CPU's virtual address space as
+ /// a mutable pointer.
+ pub fn start_ptr_mut(&mut self) -> *mut T {
+ self.cpu_addr
+ }
+
+ /// Returns a DMA handle which may given to the device as the DMA address base of
+ /// the region.
+ pub fn dma_handle(&self) -> bindings::dma_addr_t {
+ self.dma_handle
+ }
+
+ fn cpu_buf(&self) -> &[T]
+ {
+ // SAFETY: The pointer is valid due to type invariant on `CoherentAllocation` and
+ // is valid for reads for `self.count * size_of::<T>` bytes.
+ unsafe { core::slice::from_raw_parts(self.cpu_addr, self.count) }
+ }
+
+ fn cpu_buf_mut(&mut self) -> &mut [T]
+ {
+ // SAFETY: The pointer is valid due to type invariant on `CoherentAllocation` and
+ // is valid for reads for `self.count * size_of::<T>` bytes.
+ unsafe { core::slice::from_raw_parts_mut(self.cpu_addr, self.count) }
+ }
+}
+
+impl<T: Add> Drop for CoherentAllocation<T> {
+ fn drop(&mut self) {
+ let size = self.count * core::mem::size_of::<T>();
+ // SAFETY: the device, cpu address, and the dma handle is valid due to the
+ // type invariants on `CoherentAllocation`.
+ unsafe { bindings::dma_free_attrs(self.dev.as_raw(), size,
+ self.cpu_addr as _,
+ self.dma_handle, 0) }
+ }
+}
diff --git a/rust/kernel/lib.rs b/rust/kernel/lib.rs
index b62451f64f6e..b713c92eb1ef 100644
--- a/rust/kernel/lib.rs
+++ b/rust/kernel/lib.rs
@@ -32,6 +32,7 @@
pub mod block;
mod build_assert;
pub mod device;
+pub mod dma;
pub mod error;
#[cfg(CONFIG_RUST_FW_LOADER_ABSTRACTIONS)]
pub mod firmware;
--
2.43.0Hi Abdiel,
kernel test robot noticed the following build errors:
[auto build test ERROR on 718c4069896cabba5c39b637cbb7205927f16ae0]
url: https://github.com/intel-lab-lkp/linux/commits/Abdiel-Janulgue/rust-error-Add-EOVERFLOW/20241101-193708
base: 718c4069896cabba5c39b637cbb7205927f16ae0
patch link: https://lore.kernel.org/r/20241101113422.2615566-3-abdiel.janulgue%40gmail.com
patch subject: [PATCH v2 2/2] rust: add dma coherent allocator abstraction.
config: um-randconfig-r071-20241103 (https://download.01.org/0day-ci/archive/20241103/202411031138.gvA1f2D7-lkp@intel.com/config)
compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project 639a7ac648f1e50ccd2556e17d401c04f9cce625)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20241103/202411031138.gvA1f2D7-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202411031138.gvA1f2D7-lkp@intel.com/
All errors (new ones prefixed by >>):
| ^
In file included from rust/helpers/helpers.c:10:
In file included from rust/helpers/blk.c:3:
In file included from include/linux/blk-mq.h:5:
In file included from include/linux/blkdev.h:9:
In file included from include/linux/blk_types.h:10:
In file included from include/linux/bvec.h:10:
In file included from include/linux/highmem.h:12:
In file included from include/linux/hardirq.h:11:
In file included from arch/um/include/asm/hardirq.h:5:
In file included from include/asm-generic/hardirq.h:17:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:14:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:574:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
574 | val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
| ~~~~~~~~~~ ^
include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
35 | #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
| ^
In file included from rust/helpers/helpers.c:10:
In file included from rust/helpers/blk.c:3:
In file included from include/linux/blk-mq.h:5:
In file included from include/linux/blkdev.h:9:
In file included from include/linux/blk_types.h:10:
In file included from include/linux/bvec.h:10:
In file included from include/linux/highmem.h:12:
In file included from include/linux/hardirq.h:11:
In file included from arch/um/include/asm/hardirq.h:5:
In file included from include/asm-generic/hardirq.h:17:
In file included from include/linux/irq.h:20:
In file included from include/linux/io.h:14:
In file included from arch/um/include/asm/io.h:24:
include/asm-generic/io.h:585:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
585 | __raw_writeb(value, PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:595:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
595 | __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:605:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
605 | __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:693:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
693 | readsb(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:701:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
701 | readsw(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:709:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
709 | readsl(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:718:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
718 | writesb(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:727:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
727 | writesw(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
include/asm-generic/io.h:736:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
736 | writesl(PCI_IOBASE + addr, buffer, count);
| ~~~~~~~~~~ ^
13 warnings generated.
clang diag: include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
clang diag: include/asm-generic/io.h:548:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:561:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:574:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:585:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:595:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:605:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:693:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:701:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:709:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:718:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:727:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:736:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
clang diag: include/asm-generic/io.h:548:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:561:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:574:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:585:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:595:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:605:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:693:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:701:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:709:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:718:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:727:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:736:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/linux/vmstat.h:518:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
clang diag: include/asm-generic/io.h:548:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:561:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:574:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:585:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:595:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:605:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:693:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:701:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:709:20: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:718:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:727:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
clang diag: include/asm-generic/io.h:736:21: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
>> error[E0425]: cannot find function `dma_alloc_attrs` in crate `bindings`
--> rust/kernel/dma.rs:58:23
|
58 | bindings::dma_alloc_attrs(
| ^^^^^^^^^^^^^^^ help: a function with a similar name exists: `dma_alloc_pages`
|
::: rust/bindings/bindings_generated.rs:42989:5
|
42989 | / pub fn dma_alloc_pages(
42990 | | dev: *mut device,
42991 | | size: usize,
42992 | | dma_handle: *mut dma_addr_t,
42993 | | dir: dma_data_direction,
42994 | | gfp: gfp_t,
42995 | | ) -> *mut page;
| |__________________- similarly named function `dma_alloc_pages` defined here
--
>> error[E0425]: cannot find function `dma_free_attrs` in crate `bindings`
--> rust/kernel/dma.rs:161:28
|
161 | unsafe { bindings::dma_free_attrs(self.dev.as_raw(), size,
| ^^^^^^^^^^^^^^ help: a function with a similar name exists: `dma_free_pages`
|
::: rust/bindings/bindings_generated.rs:42998:5
|
42998 | / pub fn dma_free_pages(
42999 | | dev: *mut device,
43000 | | size: usize,
43001 | | page: *mut page,
43002 | | dma_handle: dma_addr_t,
43003 | | dir: dma_data_direction,
43004 | | );
| |_____- similarly named function `dma_free_pages` defined here
Kconfig warnings: (for reference only)
WARNING: unmet direct dependencies detected for GET_FREE_REGION
Depends on [n]: SPARSEMEM [=n]
Selected by [y]:
- RESOURCE_KUNIT_TEST [=y] && RUNTIME_TESTING_MENU [=y] && KUNIT [=y]
--
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