On 10/16/24 4:34 AM, 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`"). Reviewed-by: Boqun Feng <boqun.feng@xxxxxxxxx> Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> --- Changes in v2: - Make the function const. - Address integer overflow in docs. - Link to v1: https://lore.kernel.org/r/20241015-page-align-v1-1-68fbd8b6d10c@xxxxxxxxxx --- rust/kernel/page.rs | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/rust/kernel/page.rs b/rust/kernel/page.rs index 208a006d587c..9ef01929e7d0 100644 --- a/rust/kernel/page.rs +++ b/rust/kernel/page.rs @@ -20,6 +20,15 @@ /// 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 { + // Brackets around PAGE_SIZE-1 to avoid triggering overflow sanitizers in the wrong cases.
Silly nit, but I did start looking for brackets that aren't there, so: s/Brackets/parentheses/
+ (addr + (PAGE_SIZE - 1)) & PAGE_MASK +} + /// A pointer to a page that owns the page allocation. /// /// # Invariants --- base-commit: 8d8f785ceb21b9a0de11e05b811cc52d6fa79318 change-id: 20241015-page-align-7e5fa4c751be Best regards,
thanks, -- John Hubbard
