1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Copyright (C) 2016 Linaro Ltd <ard.biesheuvel@linaro.org> 4 */ 5 6 #include <linux/cache.h> 7 #include <linux/init.h> 8 #include <linux/printk.h> 9 10 #include <asm/cpufeature.h> 11 #include <asm/memory.h> 12 13 u16 __initdata memstart_offset_seed; 14 15 bool __ro_after_init __kaslr_is_enabled = false; 16 17 void __init kaslr_init(void) 18 { 19 if (cpuid_feature_extract_unsigned_field(arm64_sw_feature_override.val & 20 arm64_sw_feature_override.mask, 21 ARM64_SW_FEATURE_OVERRIDE_NOKASLR)) { 22 pr_info("KASLR disabled on command line\n"); 23 return; 24 } 25 26 /* 27 * The KASLR offset modulo MIN_KIMG_ALIGN is taken from the physical 28 * placement of the image rather than from the seed, so a displacement 29 * of less than MIN_KIMG_ALIGN means that no seed was provided. 30 */ 31 if (kaslr_offset() < MIN_KIMG_ALIGN) { 32 pr_warn("KASLR disabled due to lack of seed\n"); 33 return; 34 } 35 36 pr_info("KASLR enabled\n"); 37 __kaslr_is_enabled = true; 38 } 39 40 static int __init parse_nokaslr(char *unused) 41 { 42 /* nokaslr param handling is done by early cpufeature code */ 43 return 0; 44 } 45 early_param("nokaslr", parse_nokaslr); 46