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S390: Fix FAIL in test string/tst-xbzero-opt [BZ #21006]

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On s390x this test failed with:
FAIL: explicit clear/test: expected 0 got 1

In setup_explicit_clear, the buffer is filled with the test_pattern.
On s390x the memcpy in prepare_test_buffer is done by loading
r4 / r5 with the test_pattern and using store multiple instruction
to store r4 / r5 to buf.
If explicit_bzero is resolved in setup_explicit_clear, r4 / r5 is
stored to stack by _dl_runtime_resolve and the call to memmem in
count_test_patterns finds a hit of the test_pattern on the stack.

This patch resolves all symbols at program startup by linking with
-z now.  This omits the call of _dl_runtime_resolve within
setup_explicit_clear and the test passes.

ChangeLog:

	[BZ #21006]
	* string/Makefile (LDFLAGS-tst-xbzero-opt): New variable.
This commit is contained in:
Stefan Liebler 2017-01-17 08:54:58 +01:00
parent b040e1b084
commit 570c443352
2 changed files with 13 additions and 0 deletions
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5
ChangeLog
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@ -1,3 +1,8 @@
2017-01-17 Stefan Liebler <stli@linux.vnet.ibm.com>
[BZ #21006]
* string/Makefile (LDFLAGS-tst-xbzero-opt): New variable.
2017-01-16 Joseph Myers <joseph@codesourcery.com>
[BZ #21045]

8
string/Makefile
View File

@ -74,6 +74,14 @@ CFLAGS-stratcliff.c = -fno-builtin
CFLAGS-test-ffs.c = -fno-builtin
CFLAGS-tst-inlcall.c = -fno-builtin
CFLAGS-tst-xbzero-opt.c = -O3
# BZ 21006: Resolve all functions but at least explicit_bzero at startup.
# Otherwise the test fails on s390x as the memcpy in prepare_test_buffer is
# done by loading r4 / r5 with the test_pattern and using store multiple
# instruction to store r4 / r5 to buf. If explicit_bzero would be resolved in
# setup_explicit_clear, r4 / r5 would be stored to stack by _dl_runtime_resolve
# and the call to memmem in count_test_patterns will find a hit of the
# test_pattern on the stack.
LDFLAGS-tst-xbzero-opt = -z now
# Called during TLS initialization.
CFLAGS-memcpy.c = $(no-stack-protector)