arch/arm64/kernel/kaslr.c

   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 (kaslr_disabled_cmdline()) {
  20                 pr_info("KASLR disabled on command line\n");
  21                 return;
  22         }
  23
  24         /*
  25          * The KASLR offset modulo MIN_KIMG_ALIGN is taken from the physical
  26          * placement of the image rather than from the seed, so a displacement
  27          * of less than MIN_KIMG_ALIGN means that no seed was provided.
  28          */
  29         if (kaslr_offset() < MIN_KIMG_ALIGN) {
  30                 pr_warn("KASLR disabled due to lack of seed\n");
  31                 return;
  32         }
  33
  34         pr_info("KASLR enabled\n");
  35         __kaslr_is_enabled = true;
  36 }
  37
  38 static int __init parse_nokaslr(char *unused)
  39 {
  40         /* nokaslr param handling is done by early cpufeature code */
  41         return 0;
  42 }
  43 early_param("nokaslr", parse_nokaslr);