71 lines
2.6 KiB
C
71 lines
2.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
|
|
/*
|
|
* Non-trivial C macros cannot be used in Rust. Similarly, inlined C functions
|
|
* cannot be called either. This file explicitly creates functions ("helpers")
|
|
* that wrap those so that they can be called from Rust.
|
|
*
|
|
* Even though Rust kernel modules should never use directly the bindings, some
|
|
* of these helpers need to be exported because Rust generics and inlined
|
|
* functions may not get their code generated in the crate where they are
|
|
* defined. Other helpers, called from non-inline functions, may not be
|
|
* exported, in principle. However, in general, the Rust compiler does not
|
|
* guarantee codegen will be performed for a non-inline function either.
|
|
* Therefore, this file exports all the helpers. In the future, this may be
|
|
* revisited to reduce the number of exports after the compiler is informed
|
|
* about the places codegen is required.
|
|
*
|
|
* All symbols are exported as GPL-only to guarantee no GPL-only feature is
|
|
* accidentally exposed.
|
|
*/
|
|
|
|
#include <linux/bug.h>
|
|
#include <linux/build_bug.h>
|
|
#include <linux/refcount.h>
|
|
|
|
__noreturn void rust_helper_BUG(void)
|
|
{
|
|
BUG();
|
|
}
|
|
EXPORT_SYMBOL_GPL(rust_helper_BUG);
|
|
|
|
refcount_t rust_helper_REFCOUNT_INIT(int n)
|
|
{
|
|
return (refcount_t)REFCOUNT_INIT(n);
|
|
}
|
|
EXPORT_SYMBOL_GPL(rust_helper_REFCOUNT_INIT);
|
|
|
|
void rust_helper_refcount_inc(refcount_t *r)
|
|
{
|
|
refcount_inc(r);
|
|
}
|
|
EXPORT_SYMBOL_GPL(rust_helper_refcount_inc);
|
|
|
|
bool rust_helper_refcount_dec_and_test(refcount_t *r)
|
|
{
|
|
return refcount_dec_and_test(r);
|
|
}
|
|
EXPORT_SYMBOL_GPL(rust_helper_refcount_dec_and_test);
|
|
|
|
/*
|
|
* We use `bindgen`'s `--size_t-is-usize` option to bind the C `size_t` type
|
|
* as the Rust `usize` type, so we can use it in contexts where Rust
|
|
* expects a `usize` like slice (array) indices. `usize` is defined to be
|
|
* the same as C's `uintptr_t` type (can hold any pointer) but not
|
|
* necessarily the same as `size_t` (can hold the size of any single
|
|
* object). Most modern platforms use the same concrete integer type for
|
|
* both of them, but in case we find ourselves on a platform where
|
|
* that's not true, fail early instead of risking ABI or
|
|
* integer-overflow issues.
|
|
*
|
|
* If your platform fails this assertion, it means that you are in
|
|
* danger of integer-overflow bugs (even if you attempt to remove
|
|
* `--size_t-is-usize`). It may be easiest to change the kernel ABI on
|
|
* your platform such that `size_t` matches `uintptr_t` (i.e., to increase
|
|
* `size_t`, because `uintptr_t` has to be at least as big as `size_t`).
|
|
*/
|
|
static_assert(
|
|
sizeof(size_t) == sizeof(uintptr_t) &&
|
|
__alignof__(size_t) == __alignof__(uintptr_t),
|
|
"Rust code expects C `size_t` to match Rust `usize`"
|
|
);
|