scrypt/libcperciva/cpusupport/cpusupport_arm_sha256.c

#include "cpusupport.h"

#ifdef CPUSUPPORT_HWCAP_GETAUXVAL
#include <sys/auxv.h>

#if defined(__arm__)
/**
 * Workaround for a glibc bug: <bits/hwcap.h> contains a comment saying:
 *     The following must match the kernel's <asm/hwcap.h>.
 * However, it does not contain any of the HWCAP2_* entries from <asm/hwcap.h>.
 */
#ifndef HWCAP2_CRC32
#include <asm/hwcap.h>
#endif
#endif /* __arm__ */
#endif /* CPUSUPPORT_HWCAP_GETAUXVAL */

#if defined(CPUSUPPORT_HWCAP_ELF_AUX_INFO)
#include <sys/auxv.h>
#endif /* CPUSUPPORT_HWCAP_ELF_AUX_INFO */

CPUSUPPORT_FEATURE_DECL(arm, sha256)
{
	int supported = 0;

#if defined(CPUSUPPORT_ARM_SHA256)
#if defined(CPUSUPPORT_HWCAP_GETAUXVAL)
	unsigned long capabilities;

#if defined(__aarch64__)
	capabilities = getauxval(AT_HWCAP);
	supported = (capabilities & HWCAP_SHA2) ? 1 : 0;
#elif defined(__arm__)
	capabilities = getauxval(AT_HWCAP2);
	supported = (capabilities & HWCAP2_SHA2) ? 1 : 0;
#endif
#endif /* CPUSUPPORT_HWCAP_GETAUXVAL */

#if defined(CPUSUPPORT_HWCAP_ELF_AUX_INFO)
	unsigned long capabilities;

#if defined(__aarch64__)
	if (elf_aux_info(AT_HWCAP, &capabilities, sizeof(unsigned long)))
		return (0);
	supported = (capabilities & HWCAP_SHA2) ? 1 : 0;
#else
	if (elf_aux_info(AT_HWCAP2, &capabilities, sizeof(unsigned long)))
		return (0);
	supported = (capabilities & HWCAP2_SHA2) ? 1 : 0;
#endif
#endif /* CPUSUPPORT_HWCAP_ELF_AUX_INFO */
#endif /* CPUSUPPORT_ARM_SHA256 */

	/* Return the supported status. */
	return (supported);
}