1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0 2*4882a593Smuzhiyun /* 3*4882a593Smuzhiyun * Entropy functions used on early boot for KASLR base and memory 4*4882a593Smuzhiyun * randomization. The base randomization is done in the compressed 5*4882a593Smuzhiyun * kernel and memory randomization is done early when the regular 6*4882a593Smuzhiyun * kernel starts. This file is included in the compressed kernel and 7*4882a593Smuzhiyun * normally linked in the regular. 8*4882a593Smuzhiyun */ 9*4882a593Smuzhiyun #include <asm/asm.h> 10*4882a593Smuzhiyun #include <asm/kaslr.h> 11*4882a593Smuzhiyun #include <asm/msr.h> 12*4882a593Smuzhiyun #include <asm/archrandom.h> 13*4882a593Smuzhiyun #include <asm/e820/api.h> 14*4882a593Smuzhiyun #include <asm/io.h> 15*4882a593Smuzhiyun 16*4882a593Smuzhiyun /* 17*4882a593Smuzhiyun * When built for the regular kernel, several functions need to be stubbed out 18*4882a593Smuzhiyun * or changed to their regular kernel equivalent. 19*4882a593Smuzhiyun */ 20*4882a593Smuzhiyun #ifndef KASLR_COMPRESSED_BOOT 21*4882a593Smuzhiyun #include <asm/cpufeature.h> 22*4882a593Smuzhiyun #include <asm/setup.h> 23*4882a593Smuzhiyun 24*4882a593Smuzhiyun #define debug_putstr(v) early_printk("%s", v) 25*4882a593Smuzhiyun #define has_cpuflag(f) boot_cpu_has(f) 26*4882a593Smuzhiyun #define get_boot_seed() kaslr_offset() 27*4882a593Smuzhiyun #endif 28*4882a593Smuzhiyun 29*4882a593Smuzhiyun #define I8254_PORT_CONTROL 0x43 30*4882a593Smuzhiyun #define I8254_PORT_COUNTER0 0x40 31*4882a593Smuzhiyun #define I8254_CMD_READBACK 0xC0 32*4882a593Smuzhiyun #define I8254_SELECT_COUNTER0 0x02 33*4882a593Smuzhiyun #define I8254_STATUS_NOTREADY 0x40 i8254(void)34*4882a593Smuzhiyunstatic inline u16 i8254(void) 35*4882a593Smuzhiyun { 36*4882a593Smuzhiyun u16 status, timer; 37*4882a593Smuzhiyun 38*4882a593Smuzhiyun do { 39*4882a593Smuzhiyun outb(I8254_CMD_READBACK | I8254_SELECT_COUNTER0, 40*4882a593Smuzhiyun I8254_PORT_CONTROL); 41*4882a593Smuzhiyun status = inb(I8254_PORT_COUNTER0); 42*4882a593Smuzhiyun timer = inb(I8254_PORT_COUNTER0); 43*4882a593Smuzhiyun timer |= inb(I8254_PORT_COUNTER0) << 8; 44*4882a593Smuzhiyun } while (status & I8254_STATUS_NOTREADY); 45*4882a593Smuzhiyun 46*4882a593Smuzhiyun return timer; 47*4882a593Smuzhiyun } 48*4882a593Smuzhiyun kaslr_get_random_long(const char * purpose)49*4882a593Smuzhiyununsigned long kaslr_get_random_long(const char *purpose) 50*4882a593Smuzhiyun { 51*4882a593Smuzhiyun #ifdef CONFIG_X86_64 52*4882a593Smuzhiyun const unsigned long mix_const = 0x5d6008cbf3848dd3UL; 53*4882a593Smuzhiyun #else 54*4882a593Smuzhiyun const unsigned long mix_const = 0x3f39e593UL; 55*4882a593Smuzhiyun #endif 56*4882a593Smuzhiyun unsigned long raw, random = get_boot_seed(); 57*4882a593Smuzhiyun bool use_i8254 = true; 58*4882a593Smuzhiyun 59*4882a593Smuzhiyun debug_putstr(purpose); 60*4882a593Smuzhiyun debug_putstr(" KASLR using"); 61*4882a593Smuzhiyun 62*4882a593Smuzhiyun if (has_cpuflag(X86_FEATURE_RDRAND)) { 63*4882a593Smuzhiyun debug_putstr(" RDRAND"); 64*4882a593Smuzhiyun if (rdrand_long(&raw)) { 65*4882a593Smuzhiyun random ^= raw; 66*4882a593Smuzhiyun use_i8254 = false; 67*4882a593Smuzhiyun } 68*4882a593Smuzhiyun } 69*4882a593Smuzhiyun 70*4882a593Smuzhiyun if (has_cpuflag(X86_FEATURE_TSC)) { 71*4882a593Smuzhiyun debug_putstr(" RDTSC"); 72*4882a593Smuzhiyun raw = rdtsc(); 73*4882a593Smuzhiyun 74*4882a593Smuzhiyun random ^= raw; 75*4882a593Smuzhiyun use_i8254 = false; 76*4882a593Smuzhiyun } 77*4882a593Smuzhiyun 78*4882a593Smuzhiyun if (use_i8254) { 79*4882a593Smuzhiyun debug_putstr(" i8254"); 80*4882a593Smuzhiyun random ^= i8254(); 81*4882a593Smuzhiyun } 82*4882a593Smuzhiyun 83*4882a593Smuzhiyun /* Circular multiply for better bit diffusion */ 84*4882a593Smuzhiyun asm(_ASM_MUL "%3" 85*4882a593Smuzhiyun : "=a" (random), "=d" (raw) 86*4882a593Smuzhiyun : "a" (random), "rm" (mix_const)); 87*4882a593Smuzhiyun random += raw; 88*4882a593Smuzhiyun 89*4882a593Smuzhiyun debug_putstr("...\n"); 90*4882a593Smuzhiyun 91*4882a593Smuzhiyun return random; 92*4882a593Smuzhiyun } 93