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/* hwfeatures.c - Detect hardware features.
* Copyright (C) 2007 Free Software Foundation, Inc.
*
* This file is part of Libgcrypt.
*
* Libgcrypt is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 of
* the License, or (at your option) any later version.
*
* Libgcrypt 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 Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this program; if not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdarg.h>
#include <unistd.h>
#include "g10lib.h"
/* A bit vector describing the hardware features currently
available. */
static unsigned int hw_features;
/* Return a bit vector describing the available hardware features.
The HWF_ constants are used to test for them. */
unsigned int
_gcry_get_hw_features (void)
{
return hw_features;
}
#if defined (__i386__) && SIZEOF_UNSIGNED_LONG == 4 && defined (__GNUC__)
static void
detect_ia32_gnuc (void)
{
#ifdef ENABLE_PADLOCK_SUPPORT
/* The code here is only useful for the PadLock engine thus we don't
build it if that support has been disabled. */
int has_cpuid = 0;
char vendor_id[12+1];
/* Detect the CPUID feature by testing some undefined behaviour (16
vs 32 bit pushf/popf). */
asm volatile
("pushf\n\t" /* Copy flags to EAX. */
"popl %%eax\n\t"
"movl %%eax, %%ecx\n\t" /* Save flags into ECX. */
"xorl $0x200000, %%eax\n\t" /* Toggle ID bit and copy it to the flags. */
"pushl %%eax\n\t"
"popf\n\t"
"pushf\n\t" /* Copy changed flags again to EAX. */
"popl %%eax\n\t"
"pushl %%ecx\n\t" /* Restore flags from ECX. */
"popf\n\t"
"xorl %%eax, %%ecx\n\t" /* Compare flags against saved flags. */
"jz .Lno_cpuid%=\n\t" /* Toggling did not work, thus no CPUID. */
"movl $1, %0\n" /* Worked. true -> HAS_CPUID. */
".Lno_cpuid%=:\n\t"
: "+r" (has_cpuid)
:
: "%eax", "%ecx", "cc"
);
if (!has_cpuid)
return; /* No way. */
asm volatile
("pushl %%ebx\n\t" /* Save GOT register. */
"xorl %%eax, %%eax\n\t" /* 0 -> EAX. */
"cpuid\n\t" /* Get vendor ID. */
"movl %%ebx, (%0)\n\t" /* EBX,EDX,ECX -> VENDOR_ID. */
"movl %%edx, 4(%0)\n\t"
"movl %%ecx, 8(%0)\n\t"
"popl %%ebx\n"
:
: "S" (&vendor_id[0])
: "%eax", "%ecx", "%edx", "cc"
);
vendor_id[12] = 0;
/* Check whether this is a VIA CPU and what PadLock features we
have. */
if (!strcmp (vendor_id, "CentaurHauls"))
{
asm volatile
("pushl %%ebx\n\t" /* Save GOT register. */
"movl $0xC0000000, %%eax\n\t" /* Check for extended centaur */
"cpuid\n\t" /* feature flags. */
"popl %%ebx\n\t" /* Restore GOT register. */
"cmpl $0xC0000001, %%eax\n\t"
"jb .Lready%=\n\t" /* EAX < 0xC0000000 => no padlock. */
"pushl %%ebx\n\t" /* Save GOT register. */
"movl $0xC0000001, %%eax\n\t" /* Ask for the extended */
"cpuid\n\t" /* feature flags. */
"popl %%ebx\n\t" /* Restore GOT register. */
"movl %%edx, %%eax\n\t" /* Take copy of feature flags. */
"andl $0x0C, %%eax\n\t" /* Test bits 2 and 3 to see whether */
"cmpl $0x0C, %%eax\n\t" /* the RNG exists and is enabled. */
"jnz .Lno_rng%=\n\t"
"orl $1, %0\n" /* Set our HWF_PADLOCK_RNG bit. */
".Lno_rng%=:\n\t"
"movl %%edx, %%eax\n\t" /* Take copy of feature flags. */
"andl $0xC0, %%eax\n\t" /* Test bits 6 and 7 to see whether */
"cmpl $0xC0, %%eax\n\t" /* the ACE exists and is enabled. */
"jnz .Lno_ace%=\n\t"
"orl $2, %0\n" /* Set our HWF_PADLOCK_AES bit. */
".Lno_ace%=:\n\t"
"movl %%edx, %%eax\n\t" /* Take copy of feature flags. */
"andl $0xC00, %%eax\n\t" /* Test bits 10, 11 to see whether */
"cmpl $0xC00, %%eax\n\t" /* the PHE exists and is enabled. */
"jnz .Lno_phe%=\n\t"
"orl $4, %0\n" /* Set our HWF_PADLOCK_SHA bit. */
".Lno_phe%=:\n\t"
"movl %%edx, %%eax\n\t" /* Take copy of feature flags. */
"andl $0x3000, %%eax\n\t" /* Test bits 12, 13 to see whether */
"cmpl $0x3000, %%eax\n\t" /* MONTMUL exists and is enabled. */
"jnz .Lready%=\n\t"
"orl $8, %0\n" /* Set our HWF_PADLOCK_MMUL bit. */
".Lready%=:\n"
: "+r" (hw_features)
:
: "%eax", "%edx", "cc"
);
}
#endif /*ENABLE_PADLOCK_SUPPORT*/
}
#endif /* __i386__ && SIZEOF_UNSIGNED_LONG == 4 && __GNUC__ */
/* Detect the available hardware features. This function is called
once right at startup and we assume that no other threads are
running. */
void
_gcry_detect_hw_features (void)
{
hw_features = 0;
if (fips_mode ())
return; /* Hardware support is not to be evaluated. */
#if defined (__i386__) && SIZEOF_UNSIGNED_LONG == 4
#ifdef __GNUC__
detect_ia32_gnuc ();
#endif
#elif defined (__i386__) && SIZEOF_UNSIGNED_LONG == 8
#ifdef __GNUC__
#endif
#endif
}
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