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/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2008,2009 Free Software Foundation, Inc.
*
* GRUB 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 3 of the License, or
* (at your option) any later version.
*
* GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef KERNEL_CPU_TSC_HEADER
#define KERNEL_CPU_TSC_HEADER 1
#include <grub/types.h>
/* Read the TSC value, which increments with each CPU clock cycle. */
static __inline grub_uint64_t
grub_get_tsc (void)
{
grub_uint32_t lo, hi;
/* The CPUID instruction is a 'serializing' instruction, and
avoids out-of-order execution of the RDTSC instruction. */
#ifdef APPLE_CC
__asm__ __volatile__ ("xorl %%eax, %%eax\n\t"
#ifdef __x86_64__
"push %%rbx\n"
#else
"push %%ebx\n"
#endif
"cpuid\n"
#ifdef __x86_64__
"pop %%rbx\n"
#else
"pop %%ebx\n"
#endif
:::"%rax", "%rcx", "%rdx");
#else
__asm__ __volatile__ ("xorl %%eax, %%eax\n\t"
"cpuid":::"%rax", "%rbx", "%rcx", "%rdx");
#endif
/* Read TSC value. We cannot use "=A", since this would use
%rax on x86_64. */
__asm__ __volatile__ ("rdtsc":"=a" (lo), "=d" (hi));
return (((grub_uint64_t) hi) << 32) | lo;
}
#ifdef __x86_64__
static __inline int
grub_cpu_is_cpuid_supported (void)
{
grub_uint64_t id_supported;
__asm__ ("pushfq\n\t"
"popq %%rax /* Get EFLAGS into EAX */\n\t"
"movq %%rax, %%rcx /* Save original flags in ECX */\n\t"
"xorq $0x200000, %%rax /* Flip ID bit in EFLAGS */\n\t"
"pushq %%rax /* Store modified EFLAGS on stack */\n\t"
"popfq /* Replace current EFLAGS */\n\t"
"pushfq /* Read back the EFLAGS */\n\t"
"popq %%rax /* Get EFLAGS into EAX */\n\t"
"xorq %%rcx, %%rax /* Check if flag could be modified */\n\t"
: "=a" (id_supported)
: /* No inputs. */
: /* Clobbered: */ "%rcx");
return id_supported != 0;
}
#else
static __inline int
grub_cpu_is_cpuid_supported (void)
{
grub_uint32_t id_supported;
__asm__ ("pushfl\n\t"
"popl %%eax /* Get EFLAGS into EAX */\n\t"
"movl %%eax, %%ecx /* Save original flags in ECX */\n\t"
"xorl $0x200000, %%eax /* Flip ID bit in EFLAGS */\n\t"
"pushl %%eax /* Store modified EFLAGS on stack */\n\t"
"popfl /* Replace current EFLAGS */\n\t"
"pushfl /* Read back the EFLAGS */\n\t"
"popl %%eax /* Get EFLAGS into EAX */\n\t"
"xorl %%ecx, %%eax /* Check if flag could be modified */\n\t"
: "=a" (id_supported)
: /* No inputs. */
: /* Clobbered: */ "%rcx");
return id_supported != 0;
}
#endif
static __inline int
grub_cpu_is_tsc_supported (void)
{
if (! grub_cpu_is_cpuid_supported ())
return 0;
grub_uint32_t features;
#ifdef APPLE_CC
__asm__ ("movl $1, %%eax\n\t"
#ifdef __x86_64__
"push %%rbx\n"
#else
"push %%ebx\n"
#endif
"cpuid\n"
#ifdef __x86_64__
"pop %%rbx\n"
#else
"pop %%ebx\n"
#endif
: "=d" (features)
: /* No inputs. */
: /* Clobbered: */ "%rax", "%rcx");
#else
__asm__ ("movl $1, %%eax\n\t"
"cpuid\n"
: "=d" (features)
: /* No inputs. */
: /* Clobbered: */ "%rax", "%rbx", "%rcx");
#endif
return (features & (1 << 4)) != 0;
}
void grub_tsc_init (void);
grub_uint64_t grub_tsc_get_time_ms (void);
#endif /* ! KERNEL_CPU_TSC_HEADER */
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