From 6e86292f212cf121cafe881c18381b5972b18d4f Mon Sep 17 00:00:00 2001 From: Alice Ryhl Date: Wed, 16 Oct 2024 11:34:25 +0000 Subject: 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 fc6e66f4696b ("rust: add abstraction for `struct page`"). Reviewed-by: Boqun Feng Signed-off-by: Alice Ryhl 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: Miguel Ojeda --- rust/kernel/page.rs | 10 ++++++++++ 1 file changed, 10 insertions(+) (limited to 'rust') diff --git a/rust/kernel/page.rs b/rust/kernel/page.rs index 208a006d587c..fdac6c375fe4 100644 --- a/rust/kernel/page.rs +++ b/rust/kernel/page.rs @@ -20,6 +20,16 @@ pub const PAGE_SIZE: usize = bindings::PAGE_SIZE; /// 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 -- cgit v1.2.3-58-ga151