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Utilize the stronger guarantees on the call arguments from the

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harvester, which now always calls hwrngs with the buffer length
multiple of the word size.  This allows to remove the excessive memory
accesses to temporary buffer when saving the entropy word.

Streamline the assembly and unify it between i386 and amd64.

Reviewed by:	markm, des
Approved by:	so (des)
Sponsored by:	The FreeBSD Foundation
MFC after:	2 weeks
This commit is contained in:
kib 2013-10-17 07:57:58 +00:00
parent 8028e6e368
commit 8a6197609b
1 changed files with 24 additions and 31 deletions
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55
sys/dev/random/ivy.c
View File

@ -1,8 +1,12 @@
/*-
* Copyright (c) 2013 The FreeBSD Foundation
* Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org>
* Copyright (c) 2012 Konstantin Belousov <kib@FreeBSD.org>
* All rights reserved.
*
* Portions of this software were developed by Konstantin Belousov
* under sponsorship from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
@ -58,26 +62,25 @@ static struct random_hardware_source random_ivy = {
};
static inline int
ivy_rng_store(uint64_t *tmp)
ivy_rng_store(long *buf)
{
#ifdef __GNUCLIKE_ASM
uint32_t count;
long tmp;
int retry;
retry = RETRY_COUNT;
__asm __volatile(
#ifdef __amd64__
"rdrand\t%%rax\n\t"
"jnc\t1f\n\t"
"movq\t%%rax,%1\n\t"
"movl\t$8,%%eax\n"
#else /* i386 */
"rdrand\t%%eax\n\t"
"jnc\t1f\n\t"
"movl\t%%eax,%1\n\t"
"movl\t$4,%%eax\n"
#endif
"1:\n" /* %eax is cleared by processor on failure */
: "=a" (count), "=g" (*tmp) : "a" (0) : "cc");
return (count);
"1:\n\t"
"rdrand %2\n\t" /* read randomness into tmp */
"jb 2f\n\t" /* CF is set on success, exit retry loop */
"dec %0\n\t" /* otherwise, retry-- */
"jne 1b\n\t" /* and loop if retries are not exhausted */
"jmp 3f\n" /* failure, retry is 0, used as return value */
"2:\n\t"
"mov %2,%1\n\t" /* *buf = tmp */
"3:"
: "+q" (retry), "=m" (*buf), "=q" (tmp) : : "cc");
return (retry);
#else /* __GNUCLIKE_ASM */
return (0);
#endif
@ -86,23 +89,13 @@ ivy_rng_store(uint64_t *tmp)
static int
random_ivy_read(void *buf, int c)
{
uint8_t *b;
int count, ret, retry;
uint64_t tmp;
long *b;
int count;
b = buf;
for (count = c; count > 0; count -= ret) {
for (retry = 0; retry < RETRY_COUNT; retry++) {
ret = ivy_rng_store(&tmp);
if (ret != 0)
break;
}
if (ret == 0)
KASSERT(c % sizeof(long) == 0, ("partial read %d", c));
for (b = buf, count = c; count > 0; count -= sizeof(long), b++) {
if (ivy_rng_store(b) == 0)
break;
if (ret > count)
ret = count;
memcpy(b, &tmp, ret);
b += ret;
}
return (c - count);
}