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/* ws_cpuid.h
* Get the CPU info on x86 processors that support it
*
* 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
* 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
* the ws_cpuid() routine will return 0 if cpuinfo isn't available.
*/
#if defined(_MSC_VER) /* MSVC */
static gboolean
ws_cpuid(guint32 *CPUInfo, guint32 selector)
{
CPUInfo[0] = CPUInfo[1] = CPUInfo[2] = CPUInfo[3] = 0;
__cpuid((int *) CPUInfo, selector);
/* XXX, how to check if it's supported on MSVC? just in case clear all flags above */
return TRUE;
}
#elif defined(__GNUC__) /* GCC/clang */
#if defined(__x86_64__)
static inline gboolean
ws_cpuid(guint32 *CPUInfo, int selector)
{
__asm__ __volatile__("cpuid"
: "=a" (CPUInfo[0]),
"=b" (CPUInfo[1]),
"=c" (CPUInfo[2]),
"=d" (CPUInfo[3])
: "a"(selector));
return TRUE;
}
#elif defined(__i386__)
static gboolean
ws_cpuid(guint32 *CPUInfo _U_, int selector _U_)
{
/*
* 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.
*/
return FALSE;
}
#else /* not x86 */
static gboolean
ws_cpuid(guint32 *CPUInfo _U_, int selector _U_)
{
/* Not x86, so no cpuid instruction */
return FALSE;
}
#endif
#else /* Other compilers */
static gboolean
ws_cpuid(guint32 *CPUInfo _U_, int selector _U_)
{
return FALSE;
}
#endif
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));
}
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