github-mirror/linux
1
0
Fork 0
mirror of https://github.com/torvalds/linux.git synced 2026-06-02 11:33:28 +02:00
Code Issues Actions Packages Projects Releases Wiki Activity Graph

tools/x86/kcpuid: Use <cpuid.h> intrinsics

Browse Source 
Use the __cpuid_count() intrinsic, provided by GCC and LLVM, instead of
rolling a manual version.  Both of the kernel's minimum required GCC
version (5.1) and LLVM version (13.0.1) supports it, and it is heavily
used across standard Linux user-space tooling.

This also makes the CPUID call sites more readable.

Signed-off-by: Ahmed S. Darwish <darwi@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Link: https://lore.kernel.org/r/20250324142042.29010-11-darwi@linutronix.de
This commit is contained in:
Ahmed S. Darwish 2025-03-24 15:20:31 +01:00 committed by Ingo Molnar
parent 0a8f12ccd2
commit c479a84488
1 changed files with 15 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

37
tools/arch/x86/kcpuid/kcpuid.c
View File

@ -1,6 +1,7 @@
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <cpuid.h>
#include <err.h>
#include <getopt.h>
#include <stdbool.h>
@ -86,16 +87,16 @@ static u32 user_index = 0xFFFFFFFF;
static u32 user_sub = 0xFFFFFFFF;
static int flines;
static inline void cpuid(u32 *eax, u32 *ebx, u32 *ecx, u32 *edx)
{
/* ecx is often an input as well as an output. */
asm volatile("cpuid"
: "=a" (*eax),
"=b" (*ebx),
"=c" (*ecx),
"=d" (*edx)
: "0" (*eax), "2" (*ecx));
}
/*
* Force using <cpuid.h> __cpuid_count() instead of __cpuid(). The
* latter leaves ECX uninitialized, which can break CPUID queries.
*/
#define cpuid(leaf, a, b, c, d) \
__cpuid_count(leaf, 0, a, b, c, d)
#define cpuid_count(leaf, subleaf, a, b, c, d) \
__cpuid_count(leaf, subleaf, a, b, c, d)
static inline bool has_subleafs(u32 f)
{
@ -195,12 +196,7 @@ struct cpuid_range *setup_cpuid_range(u32 input_eax)
u32 max_func, idx_func;
u32 eax, ebx, ecx, edx;
eax = input_eax;
ebx = ecx = edx = 0;
cpuid(&eax, &ebx, &ecx, &edx);
max_func = eax;
idx_func = (max_func & 0xffff) + 1;
cpuid(input_eax, max_func, ebx, ecx, edx);
range = malloc(sizeof(struct cpuid_range));
if (!range)
@ -211,6 +207,7 @@ struct cpuid_range *setup_cpuid_range(u32 input_eax)
else
range->is_ext = false;
idx_func = (max_func & 0xffff) + 1;
range->funcs = malloc(sizeof(struct cpuid_func) * idx_func);
if (!range->funcs)
err(EXIT_FAILURE, NULL);
@ -222,9 +219,7 @@ struct cpuid_range *setup_cpuid_range(u32 input_eax)
u32 max_subleaf = MAX_SUBLEAF_NUM;
bool allzero;
eax = f;
ecx = 0;
cpuid(&eax, &ebx, &ecx, &edx);
cpuid(f, eax, ebx, ecx, edx);
allzero = cpuid_store(range, f, 0, eax, ebx, ecx, edx);
if (allzero)
@ -251,9 +246,7 @@ struct cpuid_range *setup_cpuid_range(u32 input_eax)
max_subleaf = 5;
for (u32 subleaf = 1; subleaf < max_subleaf; subleaf++) {
eax = f;
ecx = subleaf;
cpuid(&eax, &ebx, &ecx, &edx);
cpuid_count(f, subleaf, eax, ebx, ecx, edx);
allzero = cpuid_store(range, f, subleaf, eax, ebx, ecx, edx);
if (allzero)