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nptl: Add test for callee-saved register restore in pthread_exit

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GCC PR 83641 results in a miscompilation of libpthread, which
causes pthread_exit not to restore callee-saved registers before
running destructors for objects on the stack.  This test detects
this situation:

info: unsigned int, direct pthread_exit call
tst-thread-exit-clobber.cc:80: numeric comparison failure
   left: 4148288912 (0xf741dd90); from: value
  right: 1600833940 (0x5f6ac994); from: magic_values.v2
info: double, direct pthread_exit call
info: unsigned int, indirect pthread_exit call
info: double, indirect pthread_exit call
error: 1 test failures

(cherry picked from commit 579396ee08)
This commit is contained in:
Florian Weimer 2018-01-08 14:57:25 +01:00
parent 771c846a71
commit aedc861c42
3 changed files with 258 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
ChangeLog
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@ -1,3 +1,12 @@
2018-01-08 Florian Weimer <fweimer@redhat.com>
* nptl/tst-thread-exit-clobber.cc: New file.
* nptl/Makefile (CFLAGS-tst-thread-exit-clobber.o): Compile in
C++11 mode.
(LDLIBS-tst-thread-exit-clobber): Link with libstdc++.
(tests): Add tst-thread-exit-clobber.
[!CXX] (tests-unsupported): Add tst-thread-exit-clobber.
2018-01-12 Dmitry V. Levin <ldv@altlinux.org>
[BZ #22679]

8
nptl/Makefile
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@ -219,6 +219,8 @@ CFLAGS-pt-system.c = -fexceptions
LDLIBS-tst-once5 = -lstdc++
CFLAGS-tst-thread_local1.o = -std=gnu++11
LDLIBS-tst-thread_local1 = -lstdc++
CFLAGS-tst-thread-exit-clobber.o = -std=gnu++11
LDLIBS-tst-thread-exit-clobber = -lstdc++
tests = tst-typesizes \
tst-attr1 tst-attr2 tst-attr3 tst-default-attr \
@ -297,7 +299,9 @@ tests = tst-typesizes \
c89 gnu89 c99 gnu99 c11 gnu11) \
tst-bad-schedattr \
tst-thread_local1 tst-mutex-errorcheck tst-robust10 \
tst-robust-fork tst-create-detached
tst-robust-fork tst-create-detached \
tst-thread-exit-clobber
xtests = tst-setuid1 tst-setuid1-static tst-setuid2 \
tst-mutexpp1 tst-mutexpp6 tst-mutexpp10
test-srcs = tst-oddstacklimit
@ -445,7 +449,7 @@ tests-unsupported += tst-cancel24 tst-cancel24-static tst-once5
endif
# These tests require a C++ compiler and runtime with thread_local support.
ifneq ($(have-cxx-thread_local),yes)
tests-unsupported += tst-thread_local1
tests-unsupported += tst-thread_local1 tst-thread-exit-clobber
endif
include ../Rules

243
nptl/tst-thread-exit-clobber.cc Normal file
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@ -0,0 +1,243 @@
/* Test that pthread_exit does not clobber callee-saved registers.
Copyright (C) 2018 Free Software Foundation, Inc.
This file is part of the GNU C Library.
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
<http://www.gnu.org/licenses/>. */
#include <stdio.h>
#include <support/check.h>
#include <support/xthread.h>
/* This test attempts to check that callee-saved registers are
restored to their original values when destructors are run after
pthread_exit is called. GCC PR 83641 causes this test to fail.
The constants have been chosen randomly and are magic values which
are used to detect whether registers have been clobbered. The idea
is that these values are hidden behind a compiler barrier and only
present in .rodata initially, so that it is less likely that they
are in a register by accident.
The checker class can be stored in registers, and the magic values
are directly loaded into these registers. The checker destructor
is eventually invoked by pthread_exit and calls one of the
check_magic functions to verify that the class contents (that is,
register value) is correct.
These tests are performed both for unsigned int and double values,
to cover different calling conventions. */
template <class T>
struct values
{
T v0;
T v1;
T v2;
T v3;
T v4;
};
static const values<unsigned int> magic_values =
{
0x57f7fc72,
0xe582daba,
0x5f6ac994,
0x35efddb7,
0x1fbf5a74,
};
static const values<double> magic_values_double =
{
0.6764041905675465,
0.9533336788140494,
0.6091161359041452,
0.7668653957125336,
0.010374520235509666,
};
/* Special index value which tells check_magic that no check should be
performed. */
enum { no_check = -1 };
/* Check that VALUE is the magic value for INDEX, behind a compiler
barrier. */
__attribute__ ((noinline, noclone, weak))
void
check_magic (int index, unsigned int value)
{
switch (index)
{
case 0:
TEST_COMPARE (value, magic_values.v0);
break;
case 1:
TEST_COMPARE (value, magic_values.v1);
break;
case 2:
TEST_COMPARE (value, magic_values.v2);
break;
case 3:
TEST_COMPARE (value, magic_values.v3);
break;
case 4:
TEST_COMPARE (value, magic_values.v4);
break;
case no_check:
break;
default:
FAIL_EXIT1 ("invalid magic value index %d", index);
}
}
/* Check that VALUE is the magic value for INDEX, behind a compiler
barrier. Double variant. */
__attribute__ ((noinline, noclone, weak))
void
check_magic (int index, double value)
{
switch (index)
{
case 0:
TEST_VERIFY (value == magic_values_double.v0);
break;
case 1:
TEST_VERIFY (value == magic_values_double.v1);
break;
case 2:
TEST_VERIFY (value == magic_values_double.v2);
break;
case 3:
TEST_VERIFY (value == magic_values_double.v3);
break;
case 4:
TEST_VERIFY (value == magic_values_double.v4);
break;
case no_check:
break;
default:
FAIL_EXIT1 ("invalid magic value index %d", index);
}
}
/* Store a magic value and check, via the destructor, that it has the
expected value. */
template <class T, int I>
struct checker
{
T value;
checker (T v)
: value (v)
{
}
~checker ()
{
check_magic (I, value);
}
};
/* The functions call_pthread_exit_0, call_pthread_exit_1,
call_pthread_exit are used to call pthread_exit indirectly, with
the intent of clobbering the register values. */
__attribute__ ((noinline, noclone, weak))
void
call_pthread_exit_0 (const values<unsigned int> *pvalues)
{
checker<unsigned int, no_check> c0 (pvalues->v0);
checker<unsigned int, no_check> c1 (pvalues->v1);
checker<unsigned int, no_check> c2 (pvalues->v2);
checker<unsigned int, no_check> c3 (pvalues->v3);
checker<unsigned int, no_check> c4 (pvalues->v4);
pthread_exit (NULL);
}
__attribute__ ((noinline, noclone, weak))
void
call_pthread_exit_1 (const values<double> *pvalues)
{
checker<double, no_check> c0 (pvalues->v0);
checker<double, no_check> c1 (pvalues->v1);
checker<double, no_check> c2 (pvalues->v2);
checker<double, no_check> c3 (pvalues->v3);
checker<double, no_check> c4 (pvalues->v4);
values<unsigned int> other_values = { 0, };
call_pthread_exit_0 (&other_values);
}
__attribute__ ((noinline, noclone, weak))
void
call_pthread_exit ()
{
values<double> other_values = { 0, };
call_pthread_exit_1 (&other_values);
}
/* Create on-stack objects and check that their values are restored by
pthread_exit. If Nested is true, call pthread_exit indirectly via
call_pthread_exit. */
template <class T, bool Nested>
__attribute__ ((noinline, noclone, weak))
void *
threadfunc (void *closure)
{
const values<T> *pvalues = static_cast<const values<T> *> (closure);
checker<T, 0> c0 (pvalues->v0);
checker<T, 1> c1 (pvalues->v1);
checker<T, 2> c2 (pvalues->v2);
checker<T, 3> c3 (pvalues->v3);
checker<T, 4> c4 (pvalues->v4);
if (Nested)
call_pthread_exit ();
else
pthread_exit (NULL);
/* This should not be reached. */
return const_cast<char *> ("");
}
static int
do_test ()
{
puts ("info: unsigned int, direct pthread_exit call");
pthread_t thr
= xpthread_create (NULL, &threadfunc<unsigned int, false>,
const_cast<values<unsigned int> *> (&magic_values));
TEST_VERIFY (xpthread_join (thr) == NULL);
puts ("info: double, direct pthread_exit call");
thr = xpthread_create (NULL, &threadfunc<double, false>,
const_cast<values<double> *> (&magic_values_double));
TEST_VERIFY (xpthread_join (thr) == NULL);
puts ("info: unsigned int, indirect pthread_exit call");
thr = xpthread_create (NULL, &threadfunc<unsigned int, true>,
const_cast<values<unsigned int> *> (&magic_values));
TEST_VERIFY (xpthread_join (thr) == NULL);
puts ("info: double, indirect pthread_exit call");
thr = xpthread_create (NULL, &threadfunc<double, true>,
const_cast<values<double> *> (&magic_values_double));
TEST_VERIFY (xpthread_join (thr) == NULL);
return 0;
}
#include <support/test-driver.c>