Module kernel::processbuffer

Data structures for passing application memory to the kernel.

A Tock process can pass read-write or read-only buffers into the kernel for it to use. The kernel checks that read-write buffers exist within a process’s RAM address space, and that read-only buffers exist either within its RAM or flash address space. These buffers are shared with the allow_read_write() and allow_read_only() system calls.

A read-write and read-only call is mapped to the high-level Rust types ReadWriteProcessBuffer and ReadOnlyProcessBuffer respectively. The memory regions can be accessed through the ReadableProcessBuffer and WriteableProcessBuffer traits, implemented on the process buffer structs.

Each access to the buffer structs requires a liveness check to ensure that the process memory is still valid. For a more traditional interface, users can convert buffers into ReadableProcessSlice or WriteableProcessSlice and use these for the lifetime of their operations. Users cannot hold live-lived references to these slices, however.

Structs

• ReadOnlyProcessBuffer
  Read-only buffer shared by a userspace process.
• ReadOnlyProcessBufferRef
  Provides access to a ReadOnlyProcessBuffer with a restricted lifetime. This automatically dereferences into a ReadOnlyProcessBuffer
• ReadWriteProcessBuffer
  Read-writable buffer shared by a userspace process.
• ReadWriteProcessBufferRef
  Provides access to a ReadWriteProcessBuffer with a restricted lifetime. This automatically dereferences into a ReadWriteProcessBuffer
• ReadableProcessByte
  Read-only wrapper around a Cell
• ReadableProcessSlice
  Readable and accessible slice of memory of a process buffer.
• WriteableProcessSlice
  Read-writeable and accessible slice of memory of a process buffer

Traits

• ProcessSliceIndex
  Equivalent of the Rust core library’s SliceIndex type for process slices. This helper trait is used to abstract over indexing operators into process slices, and is used to “overload” the .get() methods such that it can be called with multiple different indexing operators.
• ReadableProcessBuffer
  A readable region of userspace process memory.
• WriteableProcessBuffer
  A readable and writeable region of userspace process memory.

Type Aliases

• UserspaceReadableProcessBuffer
  A shareable region of userspace memory.