Date: Fri, 1 Nov 2013 06:26:37 +0000 (UTC) From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-10@freebsd.org Subject: svn commit: r257491 - stable/10/sys/dev/random Message-ID: <201311010626.rA16QbJQ053223@svn.freebsd.org>
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Author: kib Date: Fri Nov 1 06:26:37 2013 New Revision: 257491 URL: http://svnweb.freebsd.org/changeset/base/257491 Log: MFC r256670: Rewrite RDRAND support: Remove the excessive memory accesses to temporary buffer. Streamline the assembly and unify it between i386 and amd64. Approved by: re (glebius) Modified: stable/10/sys/dev/random/ivy.c Directory Properties: stable/10/sys/ (props changed) Modified: stable/10/sys/dev/random/ivy.c ============================================================================== --- stable/10/sys/dev/random/ivy.c Fri Nov 1 05:03:47 2013 (r257490) +++ stable/10/sys/dev/random/ivy.c Fri Nov 1 06:26:37 2013 (r257491) @@ -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 ran }; 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; - - 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) + long *b; + int count; + + 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); }
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