The required TEST_COMPARE and C++ changes are included in the
support/ rebase in glibc-rh1418978-1.patch
commit 579396ee082565ab5f42ff166a264891223b7b82
Author: Florian Weimer <fweimer@redhat.com>
Date: Mon Jan 8 14:57:25 2018 +0100
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
Index: glibc-2.17-c758a686/nptl/Makefile
===================================================================
--- glibc-2.17-c758a686.orig/nptl/Makefile
+++ glibc-2.17-c758a686/nptl/Makefile
@@ -199,6 +199,7 @@ CFLAGS-send.c = -fexceptions -fasynchron
CFLAGS-pt-system.c = -fexceptions
CFLAGS-tst-minstack-throw.cc = -std=gnu++11
+CFLAGS-tst-thread-exit-clobber.o = -std=gnu++11
tests = tst-typesizes \
tst-attr1 tst-attr2 tst-attr3 tst-default-attr \
@@ -269,7 +270,8 @@ tests = tst-typesizes \
tst-getpid1 tst-getpid2 tst-getpid3 \
tst-initializers1 $(patsubst %,tst-initializers1-%,c89 gnu89 c99 gnu99) \
tst-mutex-errorcheck \
- tst-minstack-cancel tst-minstack-exit tst-minstack-throw
+ tst-minstack-cancel tst-minstack-exit tst-minstack-throw \
+ tst-thread-exit-clobber
xtests = tst-setuid1 tst-setuid1-static tst-mutexpp1 tst-mutexpp6 tst-mutexpp10
test-srcs = tst-oddstacklimit
@@ -529,6 +531,7 @@ $(objpfx)tst-_res1: $(objpfx)tst-_res1mo
LDLIBS-tst-cancel24 = $(no-as-needed) -lstdc++
LDLIBS-tst-cancel24-static = $(LDLIBS-tst-cancel24)
LDLIBS-tst-minstack-throw = -lstdc++
+LDLIBS-tst-thread-exit-clobber = -lstdc++
extra-B-pthread.so = -B$(common-objpfx)nptl/
$(objpfx)libpthread.so: $(addprefix $(objpfx),$(crti-objs) $(crtn-objs))
Index: glibc-2.17-c758a686/nptl/tst-thread-exit-clobber.cc
===================================================================
--- /dev/null
+++ glibc-2.17-c758a686/nptl/tst-thread-exit-clobber.cc
@@ -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>