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/*
* Copyright (c) 2017 Cisco and/or its affiliates.
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Executes either the RDTSC or RDTSCP instruction, depending on platform availability
*
*/
#include <config.h>
#include <stdio.h>
#define PARCTIMING_ENABLE
#include <parc/developer/parc_Timing.h>
#ifdef PARCTIMING_INTEL
static bool _useRdtscp = false;
static bool _needCheckRdtscp = true;
#include <cpuid.h>
static void
_checkRdtscp(void)
{
// See the CPUID instruction for description of the codes.
// determine the maximum extended information set
unsigned maxextended = __get_cpuid_max(0x80000000, NULL);
// RDTSCP status flag is in the 0x800000001 feature set
const unsigned feature = 0x80000001;
const unsigned rdtscp_feature = 1 << 27;
if (maxextended >= feature) {
unsigned eax, ebx, ecx, edx;
int success = __get_cpuid(feature, &eax, &ebx, &ecx, &edx);
if (success) {
_useRdtscp = (edx & rdtscp_feature ? true : false);
}
}
}
#endif // PARCTIMING_INTEL
void
parcTiminIntel_RuntimeInit(void)
{
#ifdef PARCTIMING_INTEL
if (_needCheckRdtscp) {
_needCheckRdtscp = false;
_checkRdtscp();
}
#endif // PARCTIMING_INTEL
}
void
parcTimingIntel_rdtsc(unsigned *hi, unsigned *lo)
{
/*
* Older CPUs do not support RDTSCP, which is the better instruction to use.
* If we did not detect this opcode in autoconf, use the older RDTSC
*/
#ifdef PARCTIMING_INTEL
if (_useRdtscp) {
__asm volatile ("RDTSCP\n\t"
"mov %%edx,%0\n\t"
"mov %%eax,%1\n\t"
"CPUID\n\t" : "=r" (*hi), "=r" (*lo):: "%rax", "%rbx", "%rcx", "%rdx");
} else {
__asm volatile ("RDTSC\n\t"
"mov %%edx,%0\n\t"
"mov %%eax,%1\n\t"
"CPUID\n\t" : "=r" (*hi), "=r" (*lo):: "%rax", "%rbx", "%rcx", "%rdx");
}
#endif // PARCTIMING_INTEL
}
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