Commit 43569ee374 ("Fix objtool: missing int3 after ret warning")
addressed replacing all `ret`s in x86 asm code to a macro in the
Linux kernel in order to enable SLS. That was done by copying the
upstream macro definitions and fixed objtool complaints.
Since then, several more mitigations were introduced, including
Rethunk. It requires to have a jump to one of the thunks in order
to work, so the RET macro was changed again. And, as ZFS code
didn't use the mainline defition, but copied it, this is currently
missing.
Objtool reminds about it time to time (Clang 16, CONFIG_RETHUNK=y):
fs/zfs/lua/zlua.o: warning: objtool: setjmp+0x25: 'naked' return
found in RETHUNK build
fs/zfs/lua/zlua.o: warning: objtool: longjmp+0x27: 'naked' return
found in RETHUNK build
Do it the following way:
* if we're building under Linux, unconditionally include
<linux/linkage.h> in the related files. It is available in x86
sources since even pre-2.6 times, so doesn't need any conftests;
* then, if RET macro is available, it will be used directly, so that
we will always have the version actual to the kernel we build;
* if there's no such macro, we define it as a simple `ret`, as it
was on pre-SLS times.
This ensures we always have the up-to-date definition with no need
to update it manually, and at the same time is safe for the whole
variety of kernels ZFS module supports.
Then, there's a couple more "naked" rets left in the code, they're
just defined as:
.byte 0xf3,0xc3
In fact, this is just:
rep ret
`rep ret` instead of just `ret` seems to mitigate performance issues
on some old AMD processors and most likely makes no sense as of
today.
Anyways, address those rets, so that they will be protected with
Rethunk and SLS. Include <sys/asm_linkage.h> here which now always
has RET definition and replace those constructs with just RET.
This wipes the last couple of places with unpatched rets objtool's
been complaining about.
Reviewed-by: Attila Fülöp <attila@fueloep.org>
Reviewed-by: Tino Reichardt <milky-zfs@mcmilk.de>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Lobakin <alobakin@pm.me>
Closes#14035
Currently SIMD accelerated AES-GCM performance is limited by two
factors:
a. The need to disable preemption and interrupts and save the FPU
state before using it and to do the reverse when done. Due to the
way the code is organized (see (b) below) we have to pay this price
twice for each 16 byte GCM block processed.
b. Most processing is done in C, operating on single GCM blocks.
The use of SIMD instructions is limited to the AES encryption of the
counter block (AES-NI) and the Galois multiplication (PCLMULQDQ).
This leads to the FPU not being fully utilized for crypto
operations.
To solve (a) we do crypto processing in larger chunks while owning
the FPU. An `icp_gcm_avx_chunk_size` module parameter was introduced
to make this chunk size tweakable. It defaults to 32 KiB. This step
alone roughly doubles performance. (b) is tackled by porting and
using the highly optimized openssl AES-GCM assembler routines, which
do all the processing (CTR, AES, GMULT) in a single routine. Both
steps together result in up to 32x reduction of the time spend in
the en/decryption routines, leading up to approximately 12x
throughput increase for large (128 KiB) blocks.
Lastly, this commit changes the default encryption algorithm from
AES-CCM to AES-GCM when setting the `encryption=on` property.
Reviewed-By: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-By: Jason King <jason.king@joyent.com>
Reviewed-By: Tom Caputi <tcaputi@datto.com>
Reviewed-By: Richard Laager <rlaager@wiktel.com>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes#9749
Alexander Lobakin
Attila Fülöp