arch/x86/kernel/cpu/bugs.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  *  Copyright (C) 1994  Linus Torvalds
   4  *
   5  *  Cyrix stuff, June 1998 by:
   6  *      - Rafael R. Reilova (moved everything from head.S),
   7  *        <rreilova@ececs.uc.edu>
   8  *      - Channing Corn (tests & fixes),
   9  *      - Andrew D. Balsa (code cleanup).
  10  */
  11 #include <linux/init.h>
  12 #include <linux/utsname.h>
  13 #include <asm/bugs.h>
  14 #include <asm/processor.h>
  15 #include <asm/processor-flags.h>
  16 #include <asm/fpu/internal.h>
  17 #include <asm/msr.h>
  18 #include <asm/paravirt.h>
  19 #include <asm/alternative.h>
  20 #include <asm/pgtable.h>
  21 #include <asm/set_memory.h>
  22
  23 void __init check_bugs(void)
  24 {
  25         identify_boot_cpu();
  26
  27         if (!IS_ENABLED(CONFIG_SMP)) {
  28                 pr_info("CPU: ");
  29                 print_cpu_info(&boot_cpu_data);
  30         }
  31
  32 #ifdef CONFIG_X86_32
  33         /*
  34          * Check whether we are able to run this kernel safely on SMP.
  35          *
  36          * - i386 is no longer supported.
  37          * - In order to run on anything without a TSC, we need to be
  38          *   compiled for a i486.
  39          */
  40         if (boot_cpu_data.x86 < 4)
  41                 panic("Kernel requires i486+ for 'invlpg' and other features");
  42
  43         init_utsname()->machine[1] =
  44                 '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
  45         alternative_instructions();
  46
  47         fpu__init_check_bugs();
  48 #else /* CONFIG_X86_64 */
  49         alternative_instructions();
  50
  51         /*
  52          * Make sure the first 2MB area is not mapped by huge pages
  53          * There are typically fixed size MTRRs in there and overlapping
  54          * MTRRs into large pages causes slow downs.
  55          *
  56          * Right now we don't do that with gbpages because there seems
  57          * very little benefit for that case.
  58          */
  59         if (!direct_gbpages)
  60                 set_memory_4k((unsigned long)__va(0), 1);
  61 #endif
  62 }