projects / mirror_ubuntu-focal-kernel.git / blame
| Commit | Line | Data |
|---|---|---|
| b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
| d899a7d1 TG |
2 | /* |
| 3 | * Entropy functions used on early boot for KASLR base and memory | |
| 4 | * randomization. The base randomization is done in the compressed | |
| 5 | * kernel and memory randomization is done early when the regular | |
| 6 | * kernel starts. This file is included in the compressed kernel and | |
| 7 | * normally linked in the regular. | |
| 8 | */ | |
| 121843eb | 9 | #include <asm/asm.h> |
| d899a7d1 TG |
10 | #include <asm/kaslr.h> |
| 11 | #include <asm/msr.h> | |
| 12 | #include <asm/archrandom.h> | |
| 66441bd3 | 13 | #include <asm/e820/api.h> |
| d899a7d1 TG |
14 | #include <asm/io.h> |
| 15 | ||
| 16 | /* | |
| 17 | * When built for the regular kernel, several functions need to be stubbed out | |
| 18 | * or changed to their regular kernel equivalent. | |
| 19 | */ | |
| 20 | #ifndef KASLR_COMPRESSED_BOOT | |
| 21 | #include <asm/cpufeature.h> | |
| 22 | #include <asm/setup.h> | |
| 23 | ||
| 62d16b5a | 24 | #define debug_putstr(v) early_printk("%s", v) |
| d899a7d1 TG |
25 | #define has_cpuflag(f) boot_cpu_has(f) |
| 26 | #define get_boot_seed() kaslr_offset() | |
| 27 | #endif | |
| 28 | ||
| 29 | #define I8254_PORT_CONTROL 0x43 | |
| 30 | #define I8254_PORT_COUNTER0 0x40 | |
| 31 | #define I8254_CMD_READBACK 0xC0 | |
| 32 | #define I8254_SELECT_COUNTER0 0x02 | |
| 33 | #define I8254_STATUS_NOTREADY 0x40 | |
| 34 | static inline u16 i8254(void) | |
| 35 | { | |
| 36 | u16 status, timer; | |
| 37 | ||
| 38 | do { | |
| 39 | outb(I8254_PORT_CONTROL, | |
| 40 | I8254_CMD_READBACK | I8254_SELECT_COUNTER0); | |
| 41 | status = inb(I8254_PORT_COUNTER0); | |
| 42 | timer = inb(I8254_PORT_COUNTER0); | |
| 43 | timer |= inb(I8254_PORT_COUNTER0) << 8; | |
| 44 | } while (status & I8254_STATUS_NOTREADY); | |
| 45 | ||
| 46 | return timer; | |
| 47 | } | |
| 48 | ||
| 49 | unsigned long kaslr_get_random_long(const char *purpose) | |
| 50 | { | |
| 51 | #ifdef CONFIG_X86_64 | |
| 52 | const unsigned long mix_const = 0x5d6008cbf3848dd3UL; | |
| 53 | #else | |
| 54 | const unsigned long mix_const = 0x3f39e593UL; | |
| 55 | #endif | |
| 56 | unsigned long raw, random = get_boot_seed(); | |
| 57 | bool use_i8254 = true; | |
| 58 | ||
| 59 | debug_putstr(purpose); | |
| 60 | debug_putstr(" KASLR using"); | |
| 61 | ||
| 62 | if (has_cpuflag(X86_FEATURE_RDRAND)) { | |
| 63 | debug_putstr(" RDRAND"); | |
| 64 | if (rdrand_long(&raw)) { | |
| 65 | random ^= raw; | |
| 66 | use_i8254 = false; | |
| 67 | } | |
| 68 | } | |
| 69 | ||
| 70 | if (has_cpuflag(X86_FEATURE_TSC)) { | |
| 71 | debug_putstr(" RDTSC"); | |
| 72 | raw = rdtsc(); | |
| 73 | ||
| 74 | random ^= raw; | |
| 75 | use_i8254 = false; | |
| 76 | } | |
| 77 | ||
| 78 | if (use_i8254) { | |
| 79 | debug_putstr(" i8254"); | |
| 80 | random ^= i8254(); | |
| 81 | } | |
| 82 | ||
| 83 | /* Circular multiply for better bit diffusion */ | |
| 121843eb | 84 | asm(_ASM_MUL "%3" |
| d899a7d1 TG |
85 | : "=a" (random), "=d" (raw) |
| 86 | : "a" (random), "rm" (mix_const)); | |
| 87 | random += raw; | |
| 88 | ||
| 89 | debug_putstr("...\n"); | |
| 90 | ||
| 91 | return random; | |
| 92 | } |