1 /*- 2 * Copyright (c) 2013 Mark R V Murray 3 * Copyright (c) 2013 David E. O'Brien <obrien@NUXI.org> 4 * All rights reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer 11 * in this position and unchanged. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 * 27 */ 28 29 #include <sys/cdefs.h> 30 __FBSDID("$FreeBSD$"); 31 32 #include <sys/param.h> 33 #include <sys/kernel.h> 34 #include <sys/conf.h> 35 #include <sys/lock.h> 36 #include <sys/malloc.h> 37 #include <sys/module.h> 38 #include <sys/random.h> 39 #include <sys/systm.h> 40 41 #include <machine/segments.h> 42 #include <machine/pcb.h> 43 #include <machine/md_var.h> 44 #include <machine/specialreg.h> 45 46 #include <dev/random/randomdev.h> 47 #include <dev/random/randomdev_soft.h> 48 #include <dev/random/random_adaptors.h> 49 #include <dev/random/live_entropy_sources.h> 50 51 static void random_nehemiah_init(void); 52 static void random_nehemiah_deinit(void); 53 static u_int random_nehemiah_read(void *, u_int); 54 55 static struct live_entropy_source random_nehemiah = { 56 .les_ident = "VIA Nehemiah Padlock RNG", 57 .les_source = RANDOM_PURE_NEHEMIAH, 58 .les_read = random_nehemiah_read 59 }; 60 61 /* XXX: FIX? Now that the Davies-Meyer hash is gone and we only use 62 * the 'xstore' instruction, do we still need to preserve the 63 * FPU state with fpu_kern_(enter|leave)() ? 64 */ 65 static struct fpu_kern_ctx *fpu_ctx_save; 66 67 /* This H/W source never stores more than 8 bytes in one go */ 68 /* ARGSUSED */ 69 static __inline size_t 70 VIA_RNG_store(void *buf) 71 { 72 uint32_t retval = 0; 73 uint32_t rate = 0; 74 75 #ifdef __GNUCLIKE_ASM 76 __asm __volatile( 77 "movl $0,%%edx\n\t" 78 "xstore" 79 : "=a" (retval), "+d" (rate), "+D" (buf) 80 : 81 : "memory" 82 ); 83 #endif 84 if (rate == 0) 85 return (retval&0x1f); 86 return (0); 87 } 88 89 static void 90 random_nehemiah_init(void) 91 { 92 93 fpu_ctx_save = fpu_kern_alloc_ctx(FPU_KERN_NORMAL); 94 } 95 96 static void 97 random_nehemiah_deinit(void) 98 { 99 100 fpu_kern_free_ctx(fpu_ctx_save); 101 } 102 103 /* It is specifically allowed that buf is a multiple of sizeof(long) */ 104 static u_int 105 random_nehemiah_read(void *buf, u_int c) 106 { 107 uint8_t *b; 108 size_t count, ret; 109 uint64_t tmp; 110 111 if ((fpu_kern_enter(curthread, fpu_ctx_save, FPU_KERN_NORMAL) == 0)) { 112 b = buf; 113 for (count = c; count > 0; count -= ret) { 114 ret = MIN(VIA_RNG_store(&tmp), count); 115 memcpy(b, &tmp, ret); 116 b += ret; 117 } 118 fpu_kern_leave(curthread, fpu_ctx_save); 119 } 120 else 121 c = 0; 122 123 return (c); 124 } 125 126 static int 127 nehemiah_modevent(module_t mod, int type, void *unused) 128 { 129 int error = 0; 130 131 switch (type) { 132 case MOD_LOAD: 133 if (via_feature_rng & VIA_HAS_RNG) { 134 live_entropy_source_register(&random_nehemiah); 135 printf("random: live provider: \"%s\"\n", random_nehemiah.les_ident); 136 random_nehemiah_init(); 137 } 138 break; 139 140 case MOD_UNLOAD: 141 if (via_feature_rng & VIA_HAS_RNG) 142 random_nehemiah_deinit(); 143 live_entropy_source_deregister(&random_nehemiah); 144 break; 145 146 case MOD_SHUTDOWN: 147 break; 148 149 default: 150 error = EOPNOTSUPP; 151 break; 152 153 } 154 155 return (error); 156 } 157 158 DEV_MODULE(nehemiah, nehemiah_modevent, NULL); 159 MODULE_VERSION(nehemiah, 1); 160 MODULE_DEPEND(nehemiah, randomdev, 1, 1, 1); 161