cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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tls.c (1417B)

      1// SPDX-License-Identifier: GPL-2.0
      2#include <errno.h>
      3#include <linux/unistd.h>
      4
      5#include <sys/ptrace.h>
      6#include <sys/syscall.h>
      7#include <unistd.h>
      8
      9#include <sysdep/tls.h>
     10
     11#ifndef PTRACE_GET_THREAD_AREA
     12#define PTRACE_GET_THREAD_AREA 25
     13#endif
     14
     15#ifndef PTRACE_SET_THREAD_AREA
     16#define PTRACE_SET_THREAD_AREA 26
     17#endif
     18
     19/* Checks whether host supports TLS, and sets *tls_min according to the value
     20 * valid on the host.
     21 * i386 host have it == 6; x86_64 host have it == 12, for i386 emulation. */
     22void check_host_supports_tls(int *supports_tls, int *tls_min)
     23{
     24	/* Values for x86 and x86_64.*/
     25	int val[] = {GDT_ENTRY_TLS_MIN_I386, GDT_ENTRY_TLS_MIN_X86_64};
     26	int i;
     27
     28	for (i = 0; i < ARRAY_SIZE(val); i++) {
     29		user_desc_t info;
     30		info.entry_number = val[i];
     31
     32		if (syscall(__NR_get_thread_area, &info) == 0) {
     33			*tls_min = val[i];
     34			*supports_tls = 1;
     35			return;
     36		} else {
     37			if (errno == EINVAL)
     38				continue;
     39			else if (errno == ENOSYS)
     40				*supports_tls = 0;
     41			return;
     42		}
     43	}
     44
     45	*supports_tls = 0;
     46}
     47
     48int os_set_thread_area(user_desc_t *info, int pid)
     49{
     50	int ret;
     51
     52	ret = ptrace(PTRACE_SET_THREAD_AREA, pid, info->entry_number,
     53		     (unsigned long) info);
     54	if (ret < 0)
     55		ret = -errno;
     56	return ret;
     57}
     58
     59int os_get_thread_area(user_desc_t *info, int pid)
     60{
     61	int ret;
     62
     63	ret = ptrace(PTRACE_GET_THREAD_AREA, pid, info->entry_number,
     64		     (unsigned long) info);
     65	if (ret < 0)
     66		ret = -errno;
     67	return ret;
     68}