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Commit | Line | Data |
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d899a7d1 TG |
1 | /* |
2 | * Entropy functions used on early boot for KASLR base and memory | |
3 | * randomization. The base randomization is done in the compressed | |
4 | * kernel and memory randomization is done early when the regular | |
5 | * kernel starts. This file is included in the compressed kernel and | |
6 | * normally linked in the regular. | |
7 | */ | |
121843eb | 8 | #include <asm/asm.h> |
d899a7d1 TG |
9 | #include <asm/kaslr.h> |
10 | #include <asm/msr.h> | |
11 | #include <asm/archrandom.h> | |
66441bd3 | 12 | #include <asm/e820/api.h> |
d899a7d1 TG |
13 | #include <asm/io.h> |
14 | ||
15 | /* | |
16 | * When built for the regular kernel, several functions need to be stubbed out | |
17 | * or changed to their regular kernel equivalent. | |
18 | */ | |
19 | #ifndef KASLR_COMPRESSED_BOOT | |
20 | #include <asm/cpufeature.h> | |
21 | #include <asm/setup.h> | |
22 | ||
62d16b5a | 23 | #define debug_putstr(v) early_printk("%s", v) |
d899a7d1 TG |
24 | #define has_cpuflag(f) boot_cpu_has(f) |
25 | #define get_boot_seed() kaslr_offset() | |
26 | #endif | |
27 | ||
28 | #define I8254_PORT_CONTROL 0x43 | |
29 | #define I8254_PORT_COUNTER0 0x40 | |
30 | #define I8254_CMD_READBACK 0xC0 | |
31 | #define I8254_SELECT_COUNTER0 0x02 | |
32 | #define I8254_STATUS_NOTREADY 0x40 | |
33 | static inline u16 i8254(void) | |
34 | { | |
35 | u16 status, timer; | |
36 | ||
37 | do { | |
38 | outb(I8254_PORT_CONTROL, | |
39 | I8254_CMD_READBACK | I8254_SELECT_COUNTER0); | |
40 | status = inb(I8254_PORT_COUNTER0); | |
41 | timer = inb(I8254_PORT_COUNTER0); | |
42 | timer |= inb(I8254_PORT_COUNTER0) << 8; | |
43 | } while (status & I8254_STATUS_NOTREADY); | |
44 | ||
45 | return timer; | |
46 | } | |
47 | ||
48 | unsigned long kaslr_get_random_long(const char *purpose) | |
49 | { | |
50 | #ifdef CONFIG_X86_64 | |
51 | const unsigned long mix_const = 0x5d6008cbf3848dd3UL; | |
52 | #else | |
53 | const unsigned long mix_const = 0x3f39e593UL; | |
54 | #endif | |
55 | unsigned long raw, random = get_boot_seed(); | |
56 | bool use_i8254 = true; | |
57 | ||
58 | debug_putstr(purpose); | |
59 | debug_putstr(" KASLR using"); | |
60 | ||
61 | if (has_cpuflag(X86_FEATURE_RDRAND)) { | |
62 | debug_putstr(" RDRAND"); | |
63 | if (rdrand_long(&raw)) { | |
64 | random ^= raw; | |
65 | use_i8254 = false; | |
66 | } | |
67 | } | |
68 | ||
69 | if (has_cpuflag(X86_FEATURE_TSC)) { | |
70 | debug_putstr(" RDTSC"); | |
71 | raw = rdtsc(); | |
72 | ||
73 | random ^= raw; | |
74 | use_i8254 = false; | |
75 | } | |
76 | ||
77 | if (use_i8254) { | |
78 | debug_putstr(" i8254"); | |
79 | random ^= i8254(); | |
80 | } | |
81 | ||
82 | /* Circular multiply for better bit diffusion */ | |
121843eb | 83 | asm(_ASM_MUL "%3" |
d899a7d1 TG |
84 | : "=a" (random), "=d" (raw) |
85 | : "a" (random), "rm" (mix_const)); | |
86 | random += raw; | |
87 | ||
88 | debug_putstr("...\n"); | |
89 | ||
90 | return random; | |
91 | } |