btrfs-progs/common/cpu-utils.c
David Sterba 7fba4bf4db btrfs-progs: add special CPU flag bit representing no features
Add CPU_FLAG_NONE that's first in the list and represents a CPU without
any acceleration features. Can be used for reference/fallback
implementation.

Signed-off-by: David Sterba <dsterba@suse.com>
2023-02-28 19:49:31 +01:00

116 lines
2.7 KiB
C

/*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public
* License v2 as published by the Free Software Foundation.
*
* 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., 59 Temple Place - Suite 330,
* Boston, MA 021110-1307, USA.
*/
#include <stdio.h>
#include <stdbool.h>
#include "common/cpu-utils.h"
unsigned long __cpu_flags = CPU_FLAG_NONE;
unsigned long __cpu_flags_orig = CPU_FLAG_NONE;
#ifdef __x86_64__
/*
* Do manual cpuid as cpuid.h is not available for all versions.
*
* Plain cpuid(level) is __cpuidex(level, 0), otherwise look for the leaf/subleaf
* modes at https://en.wikipedia.org/wiki/CPUID or compilers' cpuid.h.
*/
#ifndef __cpuidex
#define __cpuidex(leaf, subleaf, a, b, c, d) \
__asm__ __volatile__ ("cpuid\n\t" \
: "=a" (a), "=b" (b), "=c" (c), "=d" (d) \
: "0" (leaf), "2" (subleaf))
#endif
#else
#define __cpuidex(leaf, subleaf, a, b, c, d) \
do { \
a = 0; \
b = 0; \
c = 0; \
d = 0; \
} while(0)
#endif
#define FLAG(name) if (__cpu_flags & CPU_FLAG_ ## name) printf(" " #name)
void cpu_print_flags(void) {
printf("CPU flags: 0x%lx\n", __cpu_flags);
printf("CPU features:");
FLAG(SSE2);
FLAG(SSSE3);
FLAG(SSE41);
FLAG(SSE42);
FLAG(SHA);
FLAG(AVX);
FLAG(AVX2);
putchar(10);
}
#undef FLAG
#ifdef __x86_64__
void cpu_detect_flags(void)
{
unsigned int a, b, c, d;
__builtin_cpu_init();
__cpu_flags = CPU_FLAG_NONE;
if (__builtin_cpu_supports("sse2"))
__cpu_flags |= CPU_FLAG_SSE2;
if (__builtin_cpu_supports("ssse3"))
__cpu_flags |= CPU_FLAG_SSSE3;
if (__builtin_cpu_supports("sse4.1"))
__cpu_flags |= CPU_FLAG_SSE41;
if (__builtin_cpu_supports("sse4.2"))
__cpu_flags |= CPU_FLAG_SSE42;
if (__builtin_cpu_supports("avx"))
__cpu_flags |= CPU_FLAG_AVX;
if (__builtin_cpu_supports("avx2"))
__cpu_flags |= CPU_FLAG_AVX2;
/* Flags unsupported by builtins */
__cpuidex(7, 0, a, b, c, d);
if (b & (1UL << 29))
__cpu_flags |= CPU_FLAG_SHA;
__cpu_flags_orig = __cpu_flags;
}
void cpu_set_level(unsigned long topbit)
{
if (topbit)
__cpu_flags &= (topbit << 1) - 1;
else
__cpu_flags = CPU_FLAG_NONE;
}
void cpu_reset_level(void)
{
__cpu_flags = __cpu_flags_orig;
}
#else
void cpu_detect_flags() { }
void cpu_set_level(unsigned long topbit) { }
void cpu_reset_level(void) { }
#endif