arch/x86/kernel/verify_cpu_64.S

   1 /*
   2  *
   3  *      verify_cpu.S - Code for cpu long mode and SSE verification. This
   4  *      code has been borrowed from boot/setup.S and was introduced by
   5  *      Andi Kleen.
   6  *
   7  *      Copyright (c) 2007  Andi Kleen (ak@suse.de)
   8  *      Copyright (c) 2007  Eric Biederman (ebiederm@xmission.com)
   9  *      Copyright (c) 2007  Vivek Goyal (vgoyal@in.ibm.com)
  10  *
  11  *      This source code is licensed under the GNU General Public License,
  12  *      Version 2.  See the file COPYING for more details.
  13  *
  14  *      This is a common code for verification whether CPU supports
  15  *      long mode and SSE or not. It is not called directly instead this
  16  *      file is included at various places and compiled in that context.
  17  *      Following are the current usage.
  18  *
  19  *      This file is included by both 16bit and 32bit code.
  20  *
  21  *      arch/x86_64/boot/setup.S : Boot cpu verification (16bit)
  22  *      arch/x86_64/boot/compressed/head.S: Boot cpu verification (32bit)
  23  *      arch/x86_64/kernel/trampoline.S: secondary processor verfication (16bit)
  24  *      arch/x86_64/kernel/acpi/wakeup.S:Verfication at resume (16bit)
  25  *
  26  *      verify_cpu, returns the status of cpu check in register %eax.
  27  *              0: Success    1: Failure
  28  *
  29  *      The caller needs to check for the error code and take the action
  30  *      appropriately. Either display a message or halt.
  31  */
  32
  33 #include <asm/cpufeature.h>
  34 #include <asm/msr-index.h>
  35
  36 verify_cpu:
  37         pushfl                          # Save caller passed flags
  38         pushl   $0                      # Kill any dangerous flags
  39         popfl
  40
  41         pushfl                          # standard way to check for cpuid
  42         popl    %eax
  43         movl    %eax,%ebx
  44         xorl    $0x200000,%eax
  45         pushl   %eax
  46         popfl
  47         pushfl
  48         popl    %eax
  49         cmpl    %eax,%ebx
  50         jz      verify_cpu_no_longmode  # cpu has no cpuid
  51
  52         movl    $0x0,%eax               # See if cpuid 1 is implemented
  53         cpuid
  54         cmpl    $0x1,%eax
  55         jb      verify_cpu_no_longmode  # no cpuid 1
  56
  57         xor     %di,%di
  58         cmpl    $0x68747541,%ebx        # AuthenticAMD
  59         jnz     verify_cpu_noamd
  60         cmpl    $0x69746e65,%edx
  61         jnz     verify_cpu_noamd
  62         cmpl    $0x444d4163,%ecx
  63         jnz     verify_cpu_noamd
  64         mov     $1,%di                  # cpu is from AMD
  65
  66 verify_cpu_noamd:
  67         movl    $0x1,%eax               # Does the cpu have what it takes
  68         cpuid
  69         andl    $REQUIRED_MASK0,%edx
  70         xorl    $REQUIRED_MASK0,%edx
  71         jnz     verify_cpu_no_longmode
  72
  73         movl    $0x80000000,%eax        # See if extended cpuid is implemented
  74         cpuid
  75         cmpl    $0x80000001,%eax
  76         jb      verify_cpu_no_longmode  # no extended cpuid
  77
  78         movl    $0x80000001,%eax        # Does the cpu have what it takes
  79         cpuid
  80         andl    $REQUIRED_MASK1,%edx
  81         xorl    $REQUIRED_MASK1,%edx
  82         jnz     verify_cpu_no_longmode
  83
  84 verify_cpu_sse_test:
  85         movl    $1,%eax
  86         cpuid
  87         andl    $SSE_MASK,%edx
  88         cmpl    $SSE_MASK,%edx
  89         je      verify_cpu_sse_ok
  90         test    %di,%di
  91         jz      verify_cpu_no_longmode  # only try to force SSE on AMD
  92         movl    $MSR_K7_HWCR,%ecx
  93         rdmsr
  94         btr     $15,%eax                # enable SSE
  95         wrmsr
  96         xor     %di,%di                 # don't loop
  97         jmp     verify_cpu_sse_test     # try again
  98
  99 verify_cpu_no_longmode:
 100         popfl                           # Restore caller passed flags
 101         movl $1,%eax
 102         ret
 103 verify_cpu_sse_ok:
 104         popfl                           # Restore caller passed flags
 105         xorl %eax, %eax
 106         ret