nptl: Add test for callee-saved register restore in pthread_exit
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
This commit is contained in:
Florian Weimer
parent
dabd75b6a1
commit
579396ee08
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@ -1,3 +1,12 @@
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2018-01-08 Florian Weimer <fweimer@redhat.com>
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* nptl/tst-thread-exit-clobber.cc: New file.
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* nptl/Makefile (CFLAGS-tst-thread-exit-clobber.o): Compile in
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C++11 mode.
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(LDLIBS-tst-thread-exit-clobber): Link with libstdc++.
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(tests): Add tst-thread-exit-clobber.
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[!CXX] (tests-unsupported): Add tst-thread-exit-clobber.
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2018-01-08 Florian Weimer <fweimer@redhat.com>
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* support/check.h (support_static_assert): Define.
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@ -229,6 +229,8 @@ CFLAGS-pt-system.c += -fexceptions
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LDLIBS-tst-once5 = -lstdc++
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CFLAGS-tst-thread_local1.o = -std=gnu++11
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LDLIBS-tst-thread_local1 = -lstdc++
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CFLAGS-tst-thread-exit-clobber.o = -std=gnu++11
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LDLIBS-tst-thread-exit-clobber = -lstdc++
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tests = tst-attr1 tst-attr2 tst-attr3 tst-default-attr \
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tst-mutex1 tst-mutex2 tst-mutex3 tst-mutex4 tst-mutex5 tst-mutex6 \
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@ -304,7 +306,8 @@ tests = tst-attr1 tst-attr2 tst-attr3 tst-default-attr \
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c89 gnu89 c99 gnu99 c11 gnu11) \
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tst-bad-schedattr \
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tst-thread_local1 tst-mutex-errorcheck tst-robust10 \
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tst-robust-fork tst-create-detached tst-memstream
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tst-robust-fork tst-create-detached tst-memstream \
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tst-thread-exit-clobber
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tests-internal := tst-rwlock19 tst-rwlock20 \
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tst-sem11 tst-sem12 tst-sem13 \
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@ -458,7 +461,7 @@ tests-unsupported += tst-cancel24 tst-cancel24-static tst-once5
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endif
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# These tests require a C++ compiler and runtime with thread_local support.
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ifneq ($(have-cxx-thread_local),yes)
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tests-unsupported += tst-thread_local1
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tests-unsupported += tst-thread_local1 tst-thread-exit-clobber
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endif
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include ../Rules
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@ -0,0 +1,243 @@
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/* Test that pthread_exit does not clobber callee-saved registers.
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Copyright (C) 2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <stdio.h>
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#include <support/check.h>
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#include <support/xthread.h>
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/* This test attempts to check that callee-saved registers are
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restored to their original values when destructors are run after
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pthread_exit is called. GCC PR 83641 causes this test to fail.
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The constants have been chosen randomly and are magic values which
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are used to detect whether registers have been clobbered. The idea
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is that these values are hidden behind a compiler barrier and only
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present in .rodata initially, so that it is less likely that they
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are in a register by accident.
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The checker class can be stored in registers, and the magic values
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are directly loaded into these registers. The checker destructor
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is eventually invoked by pthread_exit and calls one of the
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check_magic functions to verify that the class contents (that is,
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register value) is correct.
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These tests are performed both for unsigned int and double values,
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to cover different calling conventions. */
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template <class T>
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struct values
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{
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T v0;
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T v1;
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T v2;
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T v3;
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T v4;
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};
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static const values<unsigned int> magic_values =
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{
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0x57f7fc72,
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0xe582daba,
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0x5f6ac994,
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0x35efddb7,
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0x1fbf5a74,
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};
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static const values<double> magic_values_double =
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{
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0.6764041905675465,
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0.9533336788140494,
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0.6091161359041452,
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0.7668653957125336,
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0.010374520235509666,
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};
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/* Special index value which tells check_magic that no check should be
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performed. */
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enum { no_check = -1 };
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/* Check that VALUE is the magic value for INDEX, behind a compiler
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barrier. */
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__attribute__ ((noinline, noclone, weak))
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void
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check_magic (int index, unsigned int value)
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{
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switch (index)
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{
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case 0:
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TEST_COMPARE (value, magic_values.v0);
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break;
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case 1:
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TEST_COMPARE (value, magic_values.v1);
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break;
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case 2:
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TEST_COMPARE (value, magic_values.v2);
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break;
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case 3:
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TEST_COMPARE (value, magic_values.v3);
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break;
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case 4:
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TEST_COMPARE (value, magic_values.v4);
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break;
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case no_check:
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break;
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default:
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FAIL_EXIT1 ("invalid magic value index %d", index);
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}
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}
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/* Check that VALUE is the magic value for INDEX, behind a compiler
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barrier. Double variant. */
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__attribute__ ((noinline, noclone, weak))
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void
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check_magic (int index, double value)
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{
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switch (index)
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{
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case 0:
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TEST_VERIFY (value == magic_values_double.v0);
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break;
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case 1:
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TEST_VERIFY (value == magic_values_double.v1);
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break;
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case 2:
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TEST_VERIFY (value == magic_values_double.v2);
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break;
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case 3:
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TEST_VERIFY (value == magic_values_double.v3);
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break;
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case 4:
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TEST_VERIFY (value == magic_values_double.v4);
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break;
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case no_check:
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break;
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default:
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FAIL_EXIT1 ("invalid magic value index %d", index);
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}
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}
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/* Store a magic value and check, via the destructor, that it has the
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expected value. */
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template <class T, int I>
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struct checker
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{
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T value;
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checker (T v)
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: value (v)
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{
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}
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~checker ()
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{
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check_magic (I, value);
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}
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};
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/* The functions call_pthread_exit_0, call_pthread_exit_1,
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call_pthread_exit are used to call pthread_exit indirectly, with
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the intent of clobbering the register values. */
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__attribute__ ((noinline, noclone, weak))
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void
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call_pthread_exit_0 (const values<unsigned int> *pvalues)
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{
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checker<unsigned int, no_check> c0 (pvalues->v0);
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checker<unsigned int, no_check> c1 (pvalues->v1);
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checker<unsigned int, no_check> c2 (pvalues->v2);
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checker<unsigned int, no_check> c3 (pvalues->v3);
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checker<unsigned int, no_check> c4 (pvalues->v4);
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pthread_exit (NULL);
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}
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__attribute__ ((noinline, noclone, weak))
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void
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call_pthread_exit_1 (const values<double> *pvalues)
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{
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checker<double, no_check> c0 (pvalues->v0);
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checker<double, no_check> c1 (pvalues->v1);
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checker<double, no_check> c2 (pvalues->v2);
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checker<double, no_check> c3 (pvalues->v3);
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checker<double, no_check> c4 (pvalues->v4);
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values<unsigned int> other_values = { 0, };
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call_pthread_exit_0 (&other_values);
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}
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__attribute__ ((noinline, noclone, weak))
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void
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call_pthread_exit ()
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{
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values<double> other_values = { 0, };
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call_pthread_exit_1 (&other_values);
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}
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/* Create on-stack objects and check that their values are restored by
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pthread_exit. If Nested is true, call pthread_exit indirectly via
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call_pthread_exit. */
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template <class T, bool Nested>
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__attribute__ ((noinline, noclone, weak))
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void *
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threadfunc (void *closure)
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{
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const values<T> *pvalues = static_cast<const values<T> *> (closure);
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checker<T, 0> c0 (pvalues->v0);
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checker<T, 1> c1 (pvalues->v1);
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checker<T, 2> c2 (pvalues->v2);
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checker<T, 3> c3 (pvalues->v3);
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checker<T, 4> c4 (pvalues->v4);
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if (Nested)
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call_pthread_exit ();
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else
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pthread_exit (NULL);
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/* This should not be reached. */
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return const_cast<char *> ("");
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}
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static int
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do_test ()
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{
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puts ("info: unsigned int, direct pthread_exit call");
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pthread_t thr
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= xpthread_create (NULL, &threadfunc<unsigned int, false>,
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const_cast<values<unsigned int> *> (&magic_values));
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TEST_VERIFY (xpthread_join (thr) == NULL);
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puts ("info: double, direct pthread_exit call");
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thr = xpthread_create (NULL, &threadfunc<double, false>,
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const_cast<values<double> *> (&magic_values_double));
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TEST_VERIFY (xpthread_join (thr) == NULL);
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puts ("info: unsigned int, indirect pthread_exit call");
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thr = xpthread_create (NULL, &threadfunc<unsigned int, true>,
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const_cast<values<unsigned int> *> (&magic_values));
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TEST_VERIFY (xpthread_join (thr) == NULL);
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puts ("info: double, indirect pthread_exit call");
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thr = xpthread_create (NULL, &threadfunc<double, true>,
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const_cast<values<double> *> (&magic_values_double));
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TEST_VERIFY (xpthread_join (thr) == NULL);
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return 0;
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}
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#include <support/test-driver.c>
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