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#include <errno.h>
#include <linux/unistd.h>
#include <sys/syscall.h>
#include "sysdep/tls.h"
#include "user_util.h"
/* Checks whether host supports TLS, and sets *tls_min according to the value
* valid on the host.
* i386 host have it == 6; x86_64 host have it == 12, for i386 emulation. */
void check_host_supports_tls(int *supports_tls, int *tls_min) {
/* Values for x86 and x86_64.*/
int val[] = {GDT_ENTRY_TLS_MIN_I386, GDT_ENTRY_TLS_MIN_X86_64};
int i;
for (i = 0; i < ARRAY_SIZE(val); i++) {
user_desc_t info;
info.entry_number = val[i];
if (syscall(__NR_get_thread_area, &info) == 0) {
*tls_min = val[i];
*supports_tls = 1;
return;
} else {
if (errno == EINVAL)
continue;
else if (errno == ENOSYS)
*supports_tls = 0;
return;
}
}
*supports_tls = 0;
}
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