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/* ws_cpuid.h
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* Get the CPU info on x86 processors that support it
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*
* Wireshark - Network traffic analyzer
* By Gerald Combs < gerald @ wireshark . org >
* Copyright 1998 Gerald Combs
*
* This program is free software ; you can redistribute it and / or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation ; either version 2
* of the License , or ( at your option ) any later version .
*
* This program is distributed in the hope that it will be useful ,
* but WITHOUT ANY WARRANTY ; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE . See the
* GNU General Public License for more details .
*
* You should have received a copy of the GNU General Public License
* along with this program ; if not , write to the Free Software
* Foundation , Inc . , 51 Franklin Street , Fifth Floor , Boston , MA 02110 - 1301 USA .
*/
/*
* Get CPU info on platforms where the cpuid instruction can be used skip 32 bit versions for GCC
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* Intel has documented the CPUID instruction in the " Intel(r) 64 and IA-32
* Architectures Developer ' s Manual " at http://www.intel.com/content/www/us/en/architecture-and-technology/64-ia-32-architectures-software-developer-vol-2a-manual.html
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* the ws_cpuid ( ) routine will return 0 if cpuinfo isn ' t available .
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*/
# if defined(_MSC_VER) /* MSVC */
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static gboolean
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ws_cpuid ( guint32 * CPUInfo , guint32 selector )
{
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CPUInfo [ 0 ] = CPUInfo [ 1 ] = CPUInfo [ 2 ] = CPUInfo [ 3 ] = 0 ;
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__cpuid ( ( int * ) CPUInfo , selector ) ;
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/* XXX, how to check if it's supported on MSVC? just in case clear all flags above */
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return TRUE ;
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}
# elif defined(__GNUC__) /* GCC/clang */
# if defined(__x86_64__)
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static inline gboolean
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ws_cpuid ( guint32 * CPUInfo , int selector )
{
__asm__ __volatile__ ( " cpuid "
: " =a " ( CPUInfo [ 0 ] ) ,
" =b " ( CPUInfo [ 1 ] ) ,
" =c " ( CPUInfo [ 2 ] ) ,
" =d " ( CPUInfo [ 3 ] )
: " a " ( selector ) ) ;
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return TRUE ;
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}
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# elif defined(__i386__)
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static gboolean
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ws_cpuid ( guint32 * CPUInfo _U_ , int selector _U_ )
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{
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/*
* TODO : need a test if older proccesors have the cpuid instruction .
*
* The correct way to test for this , according to the Intel64 / IA - 32
* documentation from Intel , in section 17.1 " USING THE CPUID
* INSTRUCTION " , is to try to change the ID bit (bit 21) in
* EFLAGS . If it can be changed , the machine supports CPUID ,
* otherwise it doesn ' t .
*
* Some 486 ' s , and all subsequent processors , support CPUID .
*
* For those who are curious , the way you distinguish between
* an 80386 and an 80486 is to try to set the flag in EFLAGS
* that causes unaligned accesses to fault - that ' s bit 18.
* However , if the SMAP bit is set in CR4 , that bit controls
* whether explicit supervisor - mode access to user - mode pages
* are allowed , so that should presumably only be done in a
* very controlled environment , such as the system boot process .
*
* So , if you want to find out what type of CPU the system has ,
* it ' s probably best to ask the OS , if it supplies the result
* of any CPU type testing it ' s done .
*/
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return FALSE ;
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}
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# else /* not x86 */
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static gboolean
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ws_cpuid ( guint32 * CPUInfo _U_ , int selector _U_ )
{
/* Not x86, so no cpuid instruction */
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return FALSE ;
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}
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# endif
# else /* Other compilers */
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static gboolean
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ws_cpuid ( guint32 * CPUInfo _U_ , int selector _U_ )
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{
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return FALSE ;
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}
# endif
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static int
ws_cpuid_sse42 ( void )
{
guint32 CPUInfo [ 4 ] ;
if ( ! ws_cpuid ( CPUInfo , 1 ) )
return 0 ;
/* in ECX bit 20 toggled on */
return ( CPUInfo [ 2 ] & ( 1 < < 20 ) ) ;
}