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