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Add CPU feature detection using elf_aux_info #130901

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Add CPU feature detection using elf_aux_info #130901

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1 change: 1 addition & 0 deletions src/native/minipal/configure.cmake
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@ check_include_files("sys/resource.h" HAVE_RESOURCE_H)
check_function_exists(sysctlbyname HAVE_SYSCTLBYNAME)
check_function_exists(fsync HAVE_FSYNC)

check_symbol_exists(elf_aux_info "sys/auxv.h" HAVE_ELF_AUX_INFO)
check_symbol_exists(arc4random_buf "stdlib.h" HAVE_ARC4RANDOM_BUF)
check_symbol_exists(getrandom "sys/random.h" HAVE_GETRANDOM)
check_symbol_exists(getentropy "unistd.h" HAVE_GETENTROPY)
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26 changes: 17 additions & 9 deletions src/native/minipal/cpufeatures.c
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,13 @@
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <sys/types.h>

#include "minipalconfig.h"

#if HAVE_ELF_AUX_INFO
#include <sys/auxv.h>
#endif

#include "cpufeatures.h"
#include "cpuid.h"
Expand Down Expand Up @@ -41,8 +48,6 @@

#else // HOST_WINDOWS

#include "minipalconfig.h"

#if HAVE_AUXV_HWCAP_H

#include <sys/auxv.h>
Expand Down Expand Up @@ -510,8 +515,17 @@ int minipal_getcpufeatures(void)
#if defined(HOST_ARM64)
#if defined(HOST_UNIX)

#if HAVE_AUXV_HWCAP_H || HAVE_ELF_AUX_INFO
#if HAVE_AUXV_HWCAP_H
unsigned long hwCap = getauxval(AT_HWCAP);
unsigned long hwCap2 = getauxval(AT_HWCAP2);
#elif HAVE_ELF_AUX_INFO
unsigned long hwCap = 0;
unsigned long hwCap2 = 0;

elf_aux_info(AT_HWCAP, &hwCap, sizeof(hwCap));
elf_aux_info(AT_HWCAP2, &hwCap2, sizeof(hwCap2));
#endif

if ((hwCap & HWCAP_ASIMD) == 0)
{
Expand Down Expand Up @@ -555,8 +569,6 @@ int minipal_getcpufeatures(void)
if (hwCap & HWCAP_SVE)
result |= ARM64IntrinsicConstants_Sve;

unsigned long hwCap2 = getauxval(AT_HWCAP2);

if (hwCap2 & HWCAP2_SVE2)
result |= ARM64IntrinsicConstants_Sve2;

Expand All @@ -571,10 +583,7 @@ int minipal_getcpufeatures(void)

if (hwCap2 & HWCAP2_CSSC)
result |= ARM64IntrinsicConstants_Cssc;

#else // !HAVE_AUXV_HWCAP_H

#if HAVE_SYSCTLBYNAME
#elif HAVE_SYSCTLBYNAME

@am11 am11 Jul 16, 2026

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Note that FreeBSD has sysctlbyname but it doesn't define those macOS style stringly names for ISAs, instead uses bitmask like Linux. Hence the order was important.

int64_t valueFromSysctl = 0;
size_t sz = sizeof(valueFromSysctl);

Expand Down Expand Up @@ -646,7 +655,6 @@ int minipal_getcpufeatures(void)
if ((sysctlbyname("hw.optional.arm.FEAT_CSSC", &valueFromSysctl, &sz, NULL, 0) == 0) && (valueFromSysctl != 0))
result |= ARM64IntrinsicConstants_Cssc;
#endif // HAVE_SYSCTLBYNAME
#endif // HAVE_AUXV_HWCAP_H
#endif // HOST_UNIX

#if defined(HOST_WINDOWS)
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1 change: 1 addition & 0 deletions src/native/minipal/minipalconfig.h.in
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@
#cmakedefine01 HAVE_RESOURCE_H
#cmakedefine01 HAVE_O_CLOEXEC
#cmakedefine01 HAVE_SYSCTLBYNAME
#cmakedefine01 HAVE_ELF_AUX_INFO
#cmakedefine01 HAVE_CLOCK_MONOTONIC_COARSE
#cmakedefine01 HAVE_CLOCK_GETTIME_NSEC_NP
#cmakedefine01 BIGENDIAN
Expand Down
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