[PATCH COMMITTED] Do not require memset elimination in explicit_bzero test

[Stefan Liebler]

On 01/16/2017 04:28 PM, Zack Weinberg wrote:
> On Mon, Jan 16, 2017 at 3:24 AM, Stefan Liebler <stli@linux.vnet.ibm.com> wrote:
>> On 01/10/2017 09:22 AM, Stefan Liebler wrote:
>>>
>>> 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.
>>>
>>> The attached 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.
>>>
>>> If this is okay, I'll commit this patch and clear this bug in the
>>> release blockers list in the release-wiki.
>
> This seems like a reasonable workaround to me.  Please commit.
>
> (Guess we better add "spill slots for callee-save registers, including
> registers saved only by dynamic linker stubs" to the list of things to
> worry about when adding explicit_bzero to the compiler...)
>
> zw
>
Thanks.
Committed, closed bug and cleared entry in the release blockers list in 
the release-wiki.