Commit 6e86292f authored by Alice Ryhl's avatar Alice Ryhl Committed by Miguel Ojeda
Browse files

rust: page: add Rust version of PAGE_ALIGN 



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 fc6e66f4 ("rust: add
abstraction for `struct page`").

Reviewed-by: default avatarBoqun Feng <boqun.feng@gmail.com>
Signed-off-by: default avatarAlice Ryhl <aliceryhl@google.com>
Link: https://lore.kernel.org/r/20241016-page-align-v2-1-e0afe85fc4b4@google.com


[ Added intra-doc links, formatted comment and replaced "Brackets" with
  "Parentheses" as discussed in the list. - Miguel ]
Signed-off-by: default avatarMiguel Ojeda <ojeda@kernel.org>
parent d4d7c05f

rust/kernel/page.rs

+10 −0
Original line number Diff line number Diff line
@@ -20,6 +20,16 @@ 
/// A bitmask that gives the page containing a given address.

pub const PAGE_MASK: usize = !(PAGE_SIZE - 1);



/// Round up the given number to the next multiple of [`PAGE_SIZE`].

///

/// It is incorrect to pass an address where the next multiple of [`PAGE_SIZE`] doesn't fit in a

/// [`usize`].

pub const fn page_align(addr: usize) -> usize {

    // Parentheses around `PAGE_SIZE - 1` to avoid triggering overflow sanitizers in the wrong

    // cases.

    (addr + (PAGE_SIZE - 1)) & PAGE_MASK

}



/// A pointer to a page that owns the page allocation.

///

/// # Invariants