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