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/* PAFlib hardware capability handling.
*
* Copyright IBM Corp. 2013
*
* The MIT License (MIT)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*
* Contributors:
* IBM Corporation, Adhemerval Zanella - Initial implementation.
*/
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <link.h>
#include <sys/stat.h>
#include "paf-hwcap.h"
#ifndef AT_HWCAP2
# define AT_HWCAP2 26
#endif
/* Although glibc 2.16+ provides getauxval, only 2.18+ provides access
* to AT_HWCAP2. To avoid rely on glibc version to correctly discover if
* the kernel supports EBB, parse the hardware capabilities bits using the
* either the /proc/self/auxv or the environment directly (__USE_ENVIRON). */
/*#define __USE_ENVIRON*/
typedef void (*auxv_callback)(ElfW(auxv_t) *, void *);
static inline int
__paf_walk_auxv (auxv_callback callback, void *arg)
{
ElfW(auxv_t) *auxv;
int i;
#ifdef __USE_ENVIRON
char **environ;
for (environ = __environ; *environ != NULL; ++environ)
{
}
auxv = (ElfW (auxv_t) *) ++environ;
#else
int auxv_f;
const size_t page_size = getpagesize();
ssize_t bytes;
auxv_f = open ("/proc/self/auxv", O_RDONLY);
if (auxv_f == -1)
return 1;
auxv = (ElfW(auxv_t)*) malloc (page_size);
if (auxv == NULL)
return 1;
bytes = read (auxv_f, (void*)auxv, page_size);
close (auxv_f);
if (bytes <= 0)
{
free (auxv);
return 1;
}
#endif
for (i=0; auxv[i].a_type != AT_NULL; ++i)
callback (&auxv[i], arg);
#ifndef __USE_ENVIRON
free (auxv);
#endif
return 0;
}
static void
__paf_get_hwcap_callback (ElfW(auxv_t) *auxv, void *arg)
{
struct hwcap_t *hwcap = (struct hwcap_t*)(arg);
if (auxv->a_type == AT_HWCAP)
hwcap->hwcap1 = auxv->a_un.a_val;
else if (auxv->a_type == AT_HWCAP2)
hwcap->hwcap2 = auxv->a_un.a_val;
else if (auxv->a_type == AT_BASE_PLATFORM)
strncpy (hwcap->platform, (const char*)(auxv->a_un.a_val), PAFPLATLEN);
}
int
attribute_hidden
__paf_get_hwcap (struct hwcap_t *hwcap)
{
if (__paf_walk_auxv (__paf_get_hwcap_callback, (void*)(hwcap)) != 0)
return 1;
return 0;
}
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