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Howlett" , Miguel Ojeda , Boqun Feng , Gary Guo , =?utf-8?q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Trevor Gross , Danilo Krummrich Cc: linux-mm@kvack.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Andreas Hindborg X-Mailer: b4 0.15-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=2629; i=a.hindborg@kernel.org; h=from:subject:message-id; bh=keDSI8hUCY4PU4tsUid9Cm310OHD3rGoQ1qvgeBe3jw=; b=owEBbQKS/ZANAwAKAeG4Gj55KGN3AcsmYgBpkiaeYS+HXhpLqK9Z0/QglR/jmX30qpmQQfnyp vTsEPxB4tmJAjMEAAEKAB0WIQQSwflHVr98KhXWwBLhuBo+eShjdwUCaZImngAKCRDhuBo+eShj d8HtD/9Gy/trD4chBL3hhYL8hoXvK2+y1y5jO15NehAmZ+QMXdKTXcrtBwBpZLK1Uu71LrEn6sw iE0/RqKrzqpqgeVNLOw0JXsOvsZf/opVCS/eTeQguZtLnjhLahQuLHn80309GLeznizxoINX36Z gjgKn6OAw5baj0c4zNNP7TR4SIxxDXv0xlOyThEhC7B7ZUPKuAe01KvcHd+nXWkZoWJB4V+GRuW fd1Kpia6RPKfas9rC0WNGPJowp3dFDVHkCoIOcVgmBt1YiH0wt3yAiQl96p8ffjbhQPjlU9GUCG R+NxYB7M5Flch05oZ30GPYKUQPTbHuW6QHcehx09ZGN1Nu+v7RDpdCEEXqly0jxNfKoAiZ1DQix zJxGXGgU758LgUj2UsJ7Nbx/bdkqMqvKidRs2FofEg1EotVC6jRHw/+cfr5DeDOzK0fwrN4SpVL BOR6Abn/ojSIktoitVLefg7AJjC/hxyrKlvgBm3gp+WPnFxznw1kgNLRnSr4RJHb9WES6TLcOiE Sl9JG5v/pOSLI6UDrYGV9f0kct2QrZcjzxqvvjMuaCjgy5/mRs7u3AVQab31oanPen77jZIQqn+ n5O7cK6y5a77TtT/QxHKBEVmnwGIbt5he2YU82WgCxAuKx26StqhYeUyxcuXN+//f1mP0zpeBGI DAchxpdo3t49o0A== X-Developer-Key: i=a.hindborg@kernel.org; a=openpgp; fpr=3108C10F46872E248D1FB221376EB100563EF7A7 X-Rspamd-Server: rspam12 X-Stat-Signature: 4dr6bsw7wd8z3ai3o1hj7aqsu8onhqin X-Rspamd-Queue-Id: 966FF100009 X-Rspam-User: X-HE-Tag: 1771185842-792467 X-HE-Meta: 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 G0A3n/eT w2BowoIweAR3einNcHMawuotx8D2DMzYVK7q9m50L8CdMQIvohpKg5Dd+y8A8I/sWpPdEVb15eB+vOYBCDCul3aWs4dtGhK1YC7gPtJsqSgIjR1CpEJHy1Vz8nTjufO0Lksq3lQrq9xSYb3YVK5BIduxBeA1iAxUx6UPDzZkk2F2E/jvaWvUbMHi8vR00OlZBpPNGbooZTHTBFTGtoskfbpCOIHgawb4NXDh3W29lQd5ODMvi4lVZGQjNN6kFwpDOsITuSlbjAmZxaXIommx6ZlEKqrlvMh3dkF/TH0zkNz0QOVYaiUwZHpW+oQjZQG2+UU2c X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Add `SafePage::copy_to_page` to copy data from one page to another at a given offset. Because `SafePage` cannot be mapped to user space or shared with devices, there are no data races and the copy can be performed using the existing `with_pointer_into_page` and `write_raw` methods. Signed-off-by: Andreas Hindborg --- rust/kernel/page.rs | 33 +++++++++++++++++++++++++++++++++ 1 file changed, 33 insertions(+) diff --git a/rust/kernel/page.rs b/rust/kernel/page.rs index af6d2ad408ed7..c780d10bcf909 100644 --- a/rust/kernel/page.rs +++ b/rust/kernel/page.rs @@ -23,6 +23,7 @@ marker::PhantomData, mem::ManuallyDrop, ops::{Deref, DerefMut}, + pin::Pin, ptr::{ self, NonNull, // @@ -407,6 +408,38 @@ pub fn alloc_page(flags: Flags) -> Result, AllocError> { // Since `Page` and `SafePage` is transparent, we can cast the pointer directly. Ok(unsafe { Owned::from_raw(page.cast()) }) } + + /// Copies data from this page to another page at the specified offset. + /// + /// # Arguments + /// + /// - `dst` - The destination page to copy data to. + /// - `offset` - The byte offset within both pages where copying starts. + /// - `len` - The number of bytes to copy. + /// + /// # Examples + /// + /// ``` + /// # use kernel::page::SafePage; + /// # use kernel::alloc::flags::GFP_KERNEL; + /// let mut src_page = SafePage::alloc_page(GFP_KERNEL)?; + /// let mut dst_page = SafePage::alloc_page(GFP_KERNEL)?; + /// src_page.copy_to_page(dst_page.get_pin_mut(), 0, 1024)?; + /// # Ok::<(), kernel::error::Error>(()) + /// ``` + pub fn copy_to_page(&self, dst: Pin<&mut Self>, offset: usize, len: usize) -> Result { + // INVARIANT: The following code makes sure to not cause data races. + self.with_pointer_into_page(offset, len, |src| { + // SAFETY: + // - If `with_pointer_into_page` calls into this closure, then it has performed a + // bounds check and guarantees that `src` is valid for `len` bytes. + // - By type invariant and existence of shared reference, there are no other writes to + // `src` during this call. + // - By exclusive ownership of `dst`, there are no other writes to `dst` during this + // call. + unsafe { dst.write_raw(src, offset, len) } + }) + } } // SAFETY: `Owned` objects returned by SafePage::alloc_page() follow the requirements of -- 2.51.2