redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

crypto: x86/chacha - yield the FPU occasionally 

To improve responsiveness, yield the FPU (temporarily re-enabling
preemption) every 4 KiB encrypted/decrypted, rather than keeping
preemption disabled during the entire encryption/decryption operation.

Alternatively we could do this for every skcipher_walk step, but steps
may be small in some cases, and yielding the FPU is expensive on x86.

Suggested-by: Martin Willi <martin@strongswan.org>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
hifive-unleashed-5.1
Eric Biggers 2018-12-04 22:20:05 -08:00 committed by Herbert Xu
parent 7a507d6225
commit a033aed5a8
1 changed files with 11 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
arch/x86/crypto/chacha_glue.c
View File

@ -132,6 +132,7 @@ static int chacha_simd_stream_xor(struct skcipher_request *req,
{
u32 *state, state_buf[16 + 2] __aligned(8);
struct skcipher_walk walk;
int next_yield = 4096; /* bytes until next FPU yield */
int err;
BUILD_BUG_ON(CHACHA_STATE_ALIGN != 16);
@ -144,12 +145,21 @@ static int chacha_simd_stream_xor(struct skcipher_request *req,
while (walk.nbytes > 0) {
unsigned int nbytes = walk.nbytes;
if (nbytes < walk.total)
if (nbytes < walk.total) {
nbytes = round_down(nbytes, walk.stride);
next_yield -= nbytes;
}
chacha_dosimd(state, walk.dst.virt.addr, walk.src.virt.addr,
nbytes, ctx->nrounds);
if (next_yield <= 0) {
/* temporarily allow preemption */
kernel_fpu_end();
kernel_fpu_begin();
next_yield = 4096;
}
err = skcipher_walk_done(&walk, walk.nbytes - nbytes);
}