1 // SPDX-License-Identifier: GPL-2.0
2 
3 #include <linux/build_bug.h>
4 
5 /*
6  * `bindgen` binds the C `size_t` type as the Rust `usize` type, so we can
7  * use it in contexts where Rust expects a `usize` like slice (array) indices.
8  * `usize` is defined to be the same as C's `uintptr_t` type (can hold any
9  * pointer) but not necessarily the same as `size_t` (can hold the size of any
10  * single object). Most modern platforms use the same concrete integer type for
11  * both of them, but in case we find ourselves on a platform where
12  * that's not true, fail early instead of risking ABI or
13  * integer-overflow issues.
14  *
15  * If your platform fails this assertion, it means that you are in
16  * danger of integer-overflow bugs (even if you attempt to add
17  * `--no-size_t-is-usize`). It may be easiest to change the kernel ABI on
18  * your platform such that `size_t` matches `uintptr_t` (i.e., to increase
19  * `size_t`, because `uintptr_t` has to be at least as big as `size_t`).
20  */
21 static_assert(
22 	sizeof(size_t) == sizeof(uintptr_t) &&
23 	__alignof__(size_t) == __alignof__(uintptr_t),
24 	"Rust code expects C `size_t` to match Rust `usize`"
25 );
26