macro_rules! memory_region_symbol { ($(#[$attrs:meta])* $symbol:ident: *mut [$ty:ty], n = $n:expr, bytes = $bytes:expr $(,)?) => { ... }; ($(#[$attrs:meta])* $symbol:ident: *mut [$ty:ty], n = $n:expr $(,)?) => { ... }; ($(#[$attrs:meta])* $symbol:ident: *mut $ty:ty, bytes = $bytes:expr $(,)?) => { ... }; ($(#[$attrs:meta])* $symbol:ident: *mut $ty:ty $(,)?) => { ... }; }
Expand description
Declares a symbol via which the microkit
tool can inject a memory region’s address, and
returns the memory region’s address at runtime.
For more detail, see its definition.
The patching mechanism used by the microkit
tool requires that the symbol be allocated space
in the protection domain’s ELF file, so we delare the symbol as part of the .data
section.
§Examples
let region_1 = unsafe {
ExternallySharedRef::<'static, Foo>::new(
memory_region_symbol!(region_1_addr: *mut Foo),
)
};
let region_2 = unsafe {
ExternallySharedRef::<'static, [u8]>::new_read_only(
memory_region_symbol!(region_2_addr: *mut [u8], n = REGION_2_SIZE),
)
};
§Note
The microkit
tool requires memory region address symbols to be present in protection domain
binaries. To prevent Rust from optimizing them out in cases where it is not used, add the
unstable #[used(linker)]
attribute. For example:
#![feature(used_with_arg)]
// might be optimized away if not used
memory_region_symbol!(region_addr: *mut Foo)
// won't be optimized away
memory_region_symbol! {
#[used(linker)]
region_addr: *mut Foo
}