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CN70XX iobdma limit appears to be 128 words, so gather that many samples 

as a time.
Gather the full 512 bytes of samples and process in a single call to
rnd_add_data_sync() - about 10% faster than 4 calls to rnd_add_data_sync().
Put sample buffer in the softc to save some stack usage.
This commit is contained in:
simonb 2020-05-30 03:12:52 +00:00
parent 0d22babaca
commit fed1041e0a
1 changed files with 19 additions and 17 deletions
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36
sys/arch/mips/cavium/dev/octeon_rnm.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: octeon_rnm.c,v 1.6 2020/05/18 16:05:09 riastradh Exp $ */
/* $NetBSD: octeon_rnm.c,v 1.7 2020/05/30 03:12:52 simonb Exp $ */
/*
* Copyright (c) 2007 Internet Initiative Japan, Inc.
@ -99,7 +99,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: octeon_rnm.c,v 1.6 2020/05/18 16:05:09 riastradh Exp $");
__KERNEL_RCSID(0, "$NetBSD: octeon_rnm.c,v 1.7 2020/05/30 03:12:52 simonb Exp $");
#include <sys/param.h>
#include <sys/device.h>
@ -123,6 +123,7 @@ __KERNEL_RCSID(0, "$NetBSD: octeon_rnm.c,v 1.6 2020/05/18 16:05:09 riastradh Exp
#define RNG_FIFO_WORDS (512/sizeof(uint64_t))
struct octeon_rnm_softc {
uint64_t sc_sample[RNG_FIFO_WORDS];
bus_space_tag_t sc_bust;
bus_space_handle_t sc_regh;
kmutex_t sc_lock;
@ -222,8 +223,8 @@ static void
octeon_rnm_rng(size_t nbytes, void *vsc)
{
const unsigned BPB = 256; /* bits of data per bit of entropy */
uint64_t sample[32];
struct octeon_rnm_softc *sc = vsc;
uint64_t *samplepos;
size_t needed = NBBY*nbytes;
unsigned i;
@ -244,20 +245,21 @@ octeon_rnm_rng(size_t nbytes, void *vsc)
octeon_rnm_raw_entropy(sc, sc->sc_rogroup);
/*
* Gather half the FIFO at a time -- we are limited to
* 256 bytes because of limits on the CVMSEG buffer.
* Gather quarter the FIFO at a time -- we are limited
* to 128 bytes because of limits on the CVMSEG buffer.
*/
CTASSERT(sizeof sample == 256);
CTASSERT(2*__arraycount(sample) == RNG_FIFO_WORDS);
for (i = 0; i < 2; i++) {
octeon_rnm_iobdma(sc, sample, __arraycount(sample));
#ifdef OCTEON_RNM_DEBUG
hexdump(printf, "rnm", sample, sizeof sample);
#endif
rnd_add_data_sync(&sc->sc_rndsrc, sample,
sizeof sample, NBBY*sizeof(sample)/BPB);
needed -= MIN(needed, MAX(1, NBBY*sizeof(sample)/BPB));
CTASSERT(sizeof sc->sc_sample == 512);
CTASSERT(__arraycount(sc->sc_sample) == RNG_FIFO_WORDS);
for (samplepos = sc->sc_sample, i = 0; i < 4; i++) {
octeon_rnm_iobdma(sc, samplepos, RNG_FIFO_WORDS / 4);
samplepos += RNG_FIFO_WORDS / 4;
}
#ifdef OCTEON_RNM_DEBUG
hexdump(printf, "rnm", sc->sc_sample, sizeof sc->sc_sample);
#endif
rnd_add_data_sync(&sc->sc_rndsrc, sc->sc_sample,
sizeof sc->sc_sample, NBBY*sizeof(sc->sc_sample)/BPB);
needed -= MIN(needed, MAX(1, NBBY*sizeof(sc->sc_sample)/BPB));
/* Yield if requested. */
if (__predict_false(curcpu()->ci_schedstate.spc_flags &
@ -270,7 +272,7 @@ octeon_rnm_rng(size_t nbytes, void *vsc)
mutex_exit(&sc->sc_lock);
/* Zero the sample. */
explicit_memset(sample, 0, sizeof sample);
explicit_memset(sc->sc_sample, 0, sizeof sc->sc_sample);
}
/*
@ -366,7 +368,7 @@ octeon_rnm_iobdma(struct octeon_rnm_softc *sc, uint64_t *buf, unsigned nwords)
__SHIFTIN(RNM_IOBDMA_MAJORDID, IOBDMA_MAJORDID) |
__SHIFTIN(RNM_IOBDMA_SUBDID, IOBDMA_SUBDID);
KASSERT(nwords < 256); /* iobdma address restriction */
KASSERT(nwords < 128); /* iobdma address restriction */
KASSERT(nwords <= 32); /* octeon_cvmseg_map limitation */
octeon_iobdma_write_8(iobdma);