eduOS/arch/x86/kernel/processor.c
2014-12-13 17:56:46 +01:00

141 lines
3.9 KiB
C

/*
* Copyright (c) 2010, Stefan Lankes, RWTH Aachen University
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this
* software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include <eduos/stddef.h>
#include <eduos/stdio.h>
#include <eduos/string.h>
#include <eduos/time.h>
#include <eduos/processor.h>
#include <eduos/tasks.h>
cpu_info_t cpu_info = { 0, 0 };
static uint32_t cpu_freq = 0;
static void default_mb(void)
{
asm volatile ("lock; addl $0,0(%%esp)" ::: "memory", "cc");
}
func_memory_barrier mb = default_mb;
func_memory_barrier rmb = default_mb;
func_memory_barrier wmb = default_mb;
static void mfence(void) { asm volatile("mfence" ::: "memory"); }
static void lfence(void) { asm volatile("lfence" ::: "memory"); }
static void sfence(void) { asm volatile("sfence" ::: "memory"); }
uint32_t detect_cpu_frequency(void)
{
uint64_t start, end, diff;
uint64_t ticks, old;
if (BUILTIN_EXPECT(cpu_freq > 0, 0))
return cpu_freq;
old = get_clock_tick();
/* wait for the next time slice */
while((ticks = get_clock_tick()) - old == 0)
HALT;
rmb();
start = rdtsc();
/* wait a second to determine the frequency */
while(get_clock_tick() - ticks < TIMER_FREQ)
HALT;
rmb();
end = rdtsc();
diff = end > start ? end - start : start - end;
cpu_freq = (uint32_t) (diff / (uint64_t) 1000000);
return cpu_freq;
}
int cpu_detection(void) {
uint32_t a, b;
size_t cr4;
uint8_t first_time = 0;
if (!cpu_info.feature1) {
first_time = 1;
cpuid(1, &a, &b, &cpu_info.feature2, &cpu_info.feature1);
}
cr4 = read_cr4();
if (has_fxsr())
cr4 |= 0x200; // set the OSFXSR bit
if (has_sse())
cr4 |= 0x400; // set the OSXMMEXCPT bit
write_cr4(cr4);
if (first_time && has_sse())
wmb = sfence;
if (first_time && has_sse2()) {
rmb = lfence;
mb = mfence;
}
if (first_time && has_avx())
kprintf(
"The CPU owns the Advanced Vector Extensions (AVX). However, eduOS doesn't support AVX!\n");
if (has_fpu()) {
if (first_time)
kputs("Found and initialized FPU!\n");
asm volatile ("fninit");
}
if (first_time && on_hypervisor()) {
uint32_t c, d;
char vendor_id[13];
kprintf("eduOS is running on a hypervisor!\n");
cpuid(0x40000000, &a, &b, &c, &d);
memcpy(vendor_id, &b, 4);
memcpy(vendor_id + 4, &c, 4);
memcpy(vendor_id + 8, &d, 4);
vendor_id[12] = '\0';
kprintf("Hypervisor Vendor Id: %s\n", vendor_id);
kprintf("Maximum input value for hypervisor: 0x%x\n", a);
}
return 0;
}
uint32_t get_cpu_frequency(void)
{
if (cpu_freq > 0)
return cpu_freq;
return detect_cpu_frequency();
}