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/* Test disabling of rseq registration via tunable.
Copyright (C) 2021-2025 Free Software Foundation, Inc.
The GNU C Library 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.
The GNU C Library 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 the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <errno.h>
#include <stdio.h>
#include <support/check.h>
#include <support/namespace.h>
#include <support/xthread.h>
#include <sysdep.h>
#include <thread_pointer.h>
#include <sys/rseq.h>
#include <unistd.h>
#ifdef RSEQ_SIG
# include <sys/auxv.h>
# include <dl-tls.h>
# include "tst-rseq.h"
/* Used to test private registration with the rseq system call because glibc
rseq is disabled. */
static __thread struct rseq local_rseq = {
.cpu_id = RSEQ_CPU_ID_REGISTRATION_FAILED,
};
/* Used to check if the address of the rseq area comes before or after the tls
blocks depending on the TLS model. */
static __thread char tls_var __attribute__ ((tls_model ("initial-exec")));
/* Check that rseq can be registered and has not been taken by glibc. */
static void
check_rseq_disabled (void)
{
struct rseq *rseq_abi = (struct rseq *) ((char *) __thread_pointer () +
__rseq_offset);
#if TLS_TCB_AT_TP
/* The rseq area block should come before the thread pointer and be at least
32 bytes. */
TEST_VERIFY (__rseq_offset <= -RSEQ_AREA_SIZE_INITIAL);
/* The rseq area block should come before TLS variables. */
TEST_VERIFY ((intptr_t) rseq_abi < (intptr_t) &tls_var);
#elif TLS_DTV_AT_TP
/* The rseq area block should come after the TCB, add the TLS block offset to
the rseq offset to get a value relative to the TCB and test that it's
non-negative. */
TEST_VERIFY (__rseq_offset + TLS_TP_OFFSET >= 0);
/* The rseq area block should come after TLS variables. */
TEST_VERIFY ((intptr_t) rseq_abi > (intptr_t) &tls_var);
#else
# error "Either TLS_TCB_AT_TP or TLS_DTV_AT_TP must be defined"
#endif
/* __rseq_flags is unused and should always be '0'. */
TEST_COMPARE (__rseq_flags, 0);
/* When rseq is not registered, __rseq_size should always be '0'. */
TEST_COMPARE (__rseq_size, 0);
/* When rseq is not registered, the 'cpu_id' field should be set to
RSEQ_CPU_ID_REGISTRATION_FAILED. */
TEST_COMPARE ((int) rseq_abi->cpu_id, RSEQ_CPU_ID_REGISTRATION_FAILED);
/* Test a rseq registration which should succeed since the internal
registration is disabled. */
int ret = syscall (__NR_rseq, &local_rseq, RSEQ_AREA_SIZE_INITIAL, 0, RSEQ_SIG);
if (ret == 0)
{
/* A successful registration should set the cpu id. */
TEST_VERIFY (local_rseq.cpu_id >= 0);
/* Test we can also unregister rseq. */
ret = syscall (__NR_rseq, &local_rseq, RSEQ_AREA_SIZE_INITIAL,
RSEQ_FLAG_UNREGISTER, RSEQ_SIG);
TEST_COMPARE (ret, 0);
}
else
{
/* Check if we failed with EINVAL which would mean an invalid rseq flags,
a mis-aligned rseq area address or an incorrect rseq size. */
TEST_VERIFY (errno != EINVAL);
/* Check if we failed with EBUSY which means an existing rseq
registration. */
TEST_VERIFY (errno != EBUSY);
/* Check if we failed with EFAULT which means an invalid rseq area
address. */
TEST_VERIFY (errno != EFAULT);
}
}
static void *
thread_func (void *ignored)
{
check_rseq_disabled ();
return NULL;
}
static void
proc_func (void *ignored)
{
check_rseq_disabled ();
}
static int
do_test (void)
{
printf ("info: __rseq_size: %u\n", __rseq_size);
printf ("info: __rseq_offset: %td\n", __rseq_offset);
printf ("info: __rseq_flags: %u\n", __rseq_flags);
printf ("info: getauxval (AT_RSEQ_FEATURE_SIZE): %ld\n",
getauxval (AT_RSEQ_FEATURE_SIZE));
printf ("info: getauxval (AT_RSEQ_ALIGN): %ld\n", getauxval (AT_RSEQ_ALIGN));
puts ("info: checking main thread");
check_rseq_disabled ();
puts ("info: checking main thread (2)");
check_rseq_disabled ();
puts ("info: checking new thread");
xpthread_join (xpthread_create (NULL, thread_func, NULL));
puts ("info: checking subprocess");
support_isolate_in_subprocess (proc_func, NULL);
return 0;
}
#else /* !RSEQ_SIG */
static int
do_test (void)
{
FAIL_UNSUPPORTED ("glibc does not define RSEQ_SIG, skipping test");
}
#endif
#include <support/test-driver.c>
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