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charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 0311D1C0010 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: eze74r78wy818izykjrfcz8stywqd36y X-HE-Tag: 1710601010-16741 X-HE-Meta: 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 i1B/Yq47 NdNMBj/Xqrp4KgdrTw3QC52AboHsl/2XfSO22ZXetazj/H3jgXN8z0AxGMBp/u9kH4mil3IbY053FmS7cL8Mh0XdwofuJkEho13FXg5C6ex0TJtWb75j0SZRgw9JerDrV4/WPKO00YA97zUPJuu0srGOnl6ieFAwmfcE71FDnZdybEm+l3+4jjrfVOF8GPtfZK35Eam4yWmGgDpZ7h+3bfJa9Q3lJf4/vYsr8hg/eozmBUQsv1rbfCMfGCUlp5cceUB8oINnS0ggAcqyZODvHJIo0IvI+A4I7E27n05VW/dpxF9M4wznVKE5ZC6aSTiiYdUZQ9HOE2uNFocbe3n3dLou9lHlZE+ojyFhsaEucfVEpT8jGPQ5qc9XySA== 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: On 3/11/24 11:47, Alice Ryhl wrote: > Add safe methods for reading and writing Rust values to and from > userspace pointers. >=20 > The C methods for copying to/from userspace use a function called > `check_object_size` to verify that the kernel pointer is not dangling. > However, this check is skipped when the length is a compile-time > constant, with the assumption that such cases trivially have a correct > kernel pointer. >=20 > In this patch, we apply the same optimization to the typed accessors. > For both methods, the size of the operation is known at compile time to > be size_of of the type being read or written. Since the C side doesn't > provide a variant that skips only this check, we create custom helpers > for this purpose. >=20 > The majority of reads and writes to userspace pointers in the Rust > Binder driver uses these accessor methods. Benchmarking has found that > skipping the `check_object_size` check makes a big difference for the > cases being skipped here. (And that the check doesn't make a difference > for the cases that use the raw read/write methods.) >=20 > This code is based on something that was originally written by Wedson on > the old rust branch. It was modified by Alice to skip the > `check_object_size` check, and to update various comments, including the > notes about kernel pointers in `WritableToBytes`. >=20 > Co-developed-by: Wedson Almeida Filho > Signed-off-by: Wedson Almeida Filho > Signed-off-by: Alice Ryhl Reviewed-by: Benno Lossin