1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
|
/* $OpenBSD: random_amd64.S,v 1.5 2016/02/12 21:36:33 naddy Exp $ */
/*
* Copyright (c) 2013 Joel Sing <jsing@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <machine/param.h>
#include <machine/asm.h>
#include <machine/psl.h>
#include <machine/specialreg.h>
/*
* Random data is xored into the buffer in 8-byte blocks. If the buffer size
* is not a multiple of 8, the remaining bytes may be left untouched.
*/
ENTRY(mdrandom)
pushq %rbx
// See if we have CPU identification.
pushf
pop %rax
mov %eax, %ecx
or $PSL_ID, %eax
push %rax
popf
pushf
pop %rax
push %rcx
popf
and $PSL_ID, %eax
jz done
// CPUID leaf = 1, subleaf = 0
mov $1, %eax
mov $0, %ecx
cpuid
mov %edx, %eax
movq %rdi, %rbx
movq %rsi, %rdx
xorq %rdi, %rdi
and $CPUIDECX_RDRAND, %ecx // See if we have rdrand.
jnz userand
mov %edx, %ecx
and $CPUID_TSC, %eax // See if we have rdtsc.
jnz usetsc
jmp done
userand:
shrq $3, %rdx // 8 bytes at a time
1:
rdrand %rax
xorq %rax, (%rbx, %rdi, 8)
incq %rdi
cmpq %rdi, %rdx
jne 1b
jmp done
usetsc:
rdtsc // Populates edx:eax.
/*
* Cope with high=0
* high = (high << 1) | 1;
* Spread bits
* bits = low * high;
* Accumulate spread bits into a byte
* bits = bits ^ (bits>>8) ^ (bits>>16) ^ (bits>>24);
* buf[i] ^= (u_char) bits;
*/
shlq $1, %rdx
orq $1, %rdx
mull %edx
movq %rax, %rdx
shrq $8, %rdx
xorq %rdx, %rax
shrq $8, %rdx
xorq %rdx, %rax
shrq $8, %rdx
xorq %rdx, %rax
xorb %al, (%rbx,%rdi)
incq %rdi
cmpq %rdi, %rcx
jne usetsc
jmp done
done:
popq %rbx
retq
|
