Patch series " lib/base64: add generic encoder/decoder, migrate users", v5.
This series introduces a generic Base64 encoder/decoder to the kernel
library, eliminating duplicated implementations and delivering significant
performance improvements.
The Base64 API has been extended to support multiple variants (Standard,
URL-safe, and IMAP) as defined in RFC 4648 and RFC 3501. The API now
takes a variant parameter and an option to control padding. As part of
this series, users are migrated to the new interface while preserving
their specific formats: fscrypt now uses BASE64_URLSAFE, Ceph uses
BASE64_IMAP, and NVMe is updated to BASE64_STD.
On the encoder side, the implementation processes input in 3-byte blocks,
mapping 24 bits directly to 4 output symbols. This avoids bit-by-bit
streaming and reduces loop overhead, achieving about a 2.7x speedup
compared to previous implementations.
On the decoder side, replace strchr() lookups with per-variant reverse
tables and process input in 4-character groups. Each group is mapped to
numeric values and combined into 3 bytes. Padded and unpadded forms are
validated explicitly, rejecting invalid '=' usage and enforcing tail
rules. This improves throughput by ~43-52x.
This patch (of 6):
Extend the base64 API to support multiple variants (standard, URL-safe,
and IMAP) as defined in RFC 4648 and RFC 3501. The API now takes a
variant parameter and an option to control padding. Update NVMe auth code
to use the new interface with BASE64_STD.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kuan-Wei Chiu <[email protected]>
Co-developed-by: Guan-Chun Wu <[email protected]>
Signed-off-by: Guan-Chun Wu <[email protected]>
Reviewed-by: David Laight <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Eric Biggers <[email protected]>
Cc: Ilya Dryomov <[email protected]>
Cc: Jaegeuk Kim <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Keith Busch <[email protected]>
Cc: Sagi Grimberg <[email protected]>
Cc: "Theodore Y. Ts'o" <[email protected]>
Cc: Viacheslav Dubeyko <[email protected]>
Cc: Xiubo Li <[email protected]>
Cc: Yu-Sheng Huang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Kuan-Wei Chiu