diff options
Diffstat (limited to 'include/grub/i386/tsc.h')
| -rw-r--r-- | include/grub/i386/tsc.h | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/include/grub/i386/tsc.h b/include/grub/i386/tsc.h new file mode 100644 index 0000000..dad9d06 --- /dev/null +++ b/include/grub/i386/tsc.h @@ -0,0 +1,141 @@ +/* + * 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 */ |