Re: Detection of hadware feature => please do not use signal

Le jeudi 31 octobre 2024, 18:25:34 UTC Tom Lane a écrit :
> Heikki Linnakangas <hlinnaka@iki.fi> writes:
> > On 31/10/2024 19:48, Tom Lane wrote:
> >> Maybe we could do it one way on linux and the other way everywhere
> >> else, but I do not find that attractive; it just makes it harder
> >> to get full test coverage.
> 
> > Bastien, would you happen to know how other portable libraries that need 
> > to run on other operating system do this? We added the SIGILL probe back 
> > in 2018, there might be better options available now.
> 
> It occurs to me to wonder whether the existing code works on Windows.
> Windows-on-ARM wasn't a thing we thought about in 2018, but it's
> a reasonable target now.

openssl use the following
https://github.com/openssl/openssl/blob/59f5f6c73cd2e1e2bd8ef405fdb6fadf0711f639/crypto/armcap.c#L311

# if defined(__GLIBC__) && defined(__GLIBC_PREREQ)
#  if __GLIBC_PREREQ(2, 16)
#   include <sys/auxv.h>
#   define OSSL_IMPLEMENT_GETAUXVAL
#  endif
# elif defined(__ANDROID_API__)
/* see https://developer.android.google.cn/ndk/guides/cpu-features */
#  if __ANDROID_API__ >= 18
#   include <sys/auxv.h>
#   define OSSL_IMPLEMENT_GETAUXVAL
#  endif
# endif
# if defined(__FreeBSD__) || defined(__OpenBSD__)
#  include <sys/param.h>
#  if (defined(__FreeBSD__) && __FreeBSD_version >= 1200000) || \
    (defined(__OpenBSD__) && OpenBSD >= 202409)
#   include <sys/auxv.h>
#   define OSSL_IMPLEMENT_GETAUXVAL

static unsigned long getauxval(unsigned long key)
{
  unsigned long val = 0ul;

  if (elf_aux_info((int)key, &val, sizeof(val)) != 0)
    return 0ul;

  return val;
}
#  endif
# endif

/*
 * Android: according to https://developer.android.com/ndk/guides/cpu-features,
 * getauxval is supported starting with API level 18
 */
# if defined(__ANDROID__) && defined(__ANDROID_API__) && __ANDROID_API__ >= 18
#  include <sys/auxv.h>
#  define OSSL_IMPLEMENT_GETAUXVAL
# endif

/*
 * ARM puts the feature bits for Crypto Extensions in AT_HWCAP2, whereas
 * AArch64 used AT_HWCAP.
 */
# ifndef AT_HWCAP
#  define AT_HWCAP               16
# endif
# ifndef AT_HWCAP2
#  define AT_HWCAP2              26
# endif
# if defined(__arm__) || defined (__arm)
#  define OSSL_HWCAP                  AT_HWCAP
#  define OSSL_HWCAP_NEON             (1 << 12)

#  define OSSL_HWCAP_CE               AT_HWCAP2
#  define OSSL_HWCAP_CE_AES           (1 << 0)
#  define OSSL_HWCAP_CE_PMULL         (1 << 1)
#  define OSSL_HWCAP_CE_SHA1          (1 << 2)
#  define OSSL_HWCAP_CE_SHA256        (1 << 3)
# elif defined(__aarch64__)
#  define OSSL_HWCAP                  AT_HWCAP
#  define OSSL_HWCAP_NEON             (1 << 1)

#  define OSSL_HWCAP_CE               AT_HWCAP
#  define OSSL_HWCAP_CE_AES           (1 << 3)
#  define OSSL_HWCAP_CE_PMULL         (1 << 4)
#  define OSSL_HWCAP_CE_SHA1          (1 << 5)
#  define OSSL_HWCAP_CE_SHA256        (1 << 6)
#  define OSSL_HWCAP_CPUID            (1 << 11)
#  define OSSL_HWCAP_SHA3             (1 << 17)
#  define OSSL_HWCAP_CE_SM3           (1 << 18)
#  define OSSL_HWCAP_CE_SM4           (1 << 19)
#  define OSSL_HWCAP_CE_SHA512        (1 << 21)
#  define OSSL_HWCAP_SVE              (1 << 22)
                                      /* AT_HWCAP2 */
#  define OSSL_HWCAP2                 26
#  define OSSL_HWCAP2_SVE2            (1 << 1)
#  define OSSL_HWCAP2_RNG             (1 << 16)
# endif

For windows
https://sources.debian.org/src/xz-utils/5.6.3-1/src/liblzma/check/crc32_arm64.h/?hl=82#L92

> 
> 			regards, tom lane
>