On Tue, Oct 15, 2024 at 02:28:28PM +0000, Alice Ryhl wrote:
> This is a useful for helper for working with indices into buffers that
> consist of several pages. I forgot to include it when I added PAGE_SIZE
> and PAGE_MASK for the same purpose in commit fc6e66f4696b ("rust: add
> abstraction for `struct page`").
>
> Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> ---
> rust/kernel/page.rs | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/rust/kernel/page.rs b/rust/kernel/page.rs
> index 208a006d587c..90846e3fe829 100644
> --- a/rust/kernel/page.rs
> +++ b/rust/kernel/page.rs
> @@ -20,6 +20,11 @@
> /// A bitmask that gives the page containing a given address.
> pub const PAGE_MASK: usize = !(PAGE_SIZE - 1);
>
> +/// Round up the given number to a multiple of `PAGE_SIZE`.
> +pub fn page_align(addr: usize) -> usize {
Make it a `const` function? For example, there is a VMBUS_RING_SIZE()
macro in C that calculates a const number for a vmbus ringbuffer size,
so it will be useful.
> + (addr + (PAGE_SIZE - 1)) & PAGE_MASK
I guess overflows are unexpected, i.e. the users should not pass a
`addr` that `> usize::MAX - PAGE_SIZE + 1`?
Regards,
Boqun
> +}
> +
> /// A pointer to a page that owns the page allocation.
> ///
> /// # Invariants
>
> ---
> base-commit: 8d8f785ceb21b9a0de11e05b811cc52d6fa79318
> change-id: 20241015-page-align-7e5fa4c751be
>
> Best regards,
> --
> Alice Ryhl <aliceryhl@xxxxxxxxxx>
>
