arch/x86/kernel/cpu/bugs.c

   1 /*
   2  *  Copyright (C) 1994  Linus Torvalds
   3  *
   4  *  Cyrix stuff, June 1998 by:
   5  *      - Rafael R. Reilova (moved everything from head.S),
   6  *        <rreilova@ececs.uc.edu>
   7  *      - Channing Corn (tests & fixes),
   8  *      - Andrew D. Balsa (code cleanup).
   9  */
  10 #include <linux/init.h>
  11 #include <linux/utsname.h>
  12 #include <asm/bugs.h>
  13 #include <asm/processor.h>
  14 #include <asm/processor-flags.h>
  15 #include <asm/fpu/internal.h>
  16 #include <asm/msr.h>
  17 #include <asm/paravirt.h>
  18 #include <asm/alternative.h>
  19 #include <asm/pgtable.h>
  20 #include <asm/set_memory.h>
  21
  22 void __init check_bugs(void)
  23 {
  24 #ifdef CONFIG_X86_32
  25         /*
  26          * Regardless of whether PCID is enumerated, the SDM says
  27          * that it can't be enabled in 32-bit mode.
  28          */
  29         setup_clear_cpu_cap(X86_FEATURE_PCID);
  30 #endif
  31
  32         identify_boot_cpu();
  33
  34         if (!IS_ENABLED(CONFIG_SMP)) {
  35                 pr_info("CPU: ");
  36                 print_cpu_info(&boot_cpu_data);
  37         }
  38
  39 #ifdef CONFIG_X86_32
  40         /*
  41          * Check whether we are able to run this kernel safely on SMP.
  42          *
  43          * - i386 is no longer supported.
  44          * - In order to run on anything without a TSC, we need to be
  45          *   compiled for a i486.
  46          */
  47         if (boot_cpu_data.x86 < 4)
  48                 panic("Kernel requires i486+ for 'invlpg' and other features");
  49
  50         init_utsname()->machine[1] =
  51                 '0' + (boot_cpu_data.x86 > 6 ? 6 : boot_cpu_data.x86);
  52         alternative_instructions();
  53
  54         fpu__init_check_bugs();
  55 #else /* CONFIG_X86_64 */
  56         alternative_instructions();
  57
  58         /*
  59          * Make sure the first 2MB area is not mapped by huge pages
  60          * There are typically fixed size MTRRs in there and overlapping
  61          * MTRRs into large pages causes slow downs.
  62          *
  63          * Right now we don't do that with gbpages because there seems
  64          * very little benefit for that case.
  65          */
  66         if (!direct_gbpages)
  67                 set_memory_4k((unsigned long)__va(0), 1);
  68 #endif
  69 }