On 10/07/2023 15.13, Ilya Leoshkevich wrote:
> On Mon, 2023-07-10 at 14:09 +0100, Richard Henderson wrote:
>> On 7/10/23 13:15, Thomas Huth wrote:
>>> From: Ilya Leoshkevich <iii@linux.ibm.com>
>>>
>>> Add a small test to prevent regressions.
>>>
>>> Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
>>> Reviewed-by: David Hildenbrand <david@redhat.com>
>>> Message-Id: <20230704081506.276055-13-iii@linux.ibm.com>
>>> Signed-off-by: Thomas Huth <thuth@redhat.com>
>>> ---
>>> tests/tcg/s390x/mie3-mvcrl.c | 46 ++++++++++++++++++++++++++++---
>>> -----
>>> 1 file changed, 36 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/tests/tcg/s390x/mie3-mvcrl.c b/tests/tcg/s390x/mie3-
>>> mvcrl.c
>>> index 93c7b0a290..ec78dd1d49 100644
>>> --- a/tests/tcg/s390x/mie3-mvcrl.c
>>> +++ b/tests/tcg/s390x/mie3-mvcrl.c
>>> @@ -1,29 +1,55 @@
>>> +#include <stdbool.h>
>>> #include <stdint.h>
>>> +#include <stdlib.h>
>>> #include <string.h>
>>>
>>> -
>>> -static inline void mvcrl_8(const char *dst, const char *src)
>>> +static void mvcrl(const char *dst, const char *src, size_t len)
>>> {
>>> + register long r0 asm("r0") = len;
>>> +
>>> asm volatile (
>>> - "llill %%r0, 8\n"
>>> ".insn sse, 0xE50A00000000, 0(%[dst]), 0(%[src])"
>>> - : : [dst] "d" (dst), [src] "d" (src)
>>> - : "r0", "memory");
>>> + : : [dst] "d" (dst), [src] "d" (src), "r" (r0)
>>> + : "memory");
>>> }
>>>
>>> -
>>> -int main(int argc, char *argv[])
>>> +static bool test(void)
>>> {
>>> const char *alpha = "abcdefghijklmnop";
>>>
>>> /* array missing 'i' */
>>> - char tstr[17] = "abcdefghjklmnop\0" ;
>>> + char tstr[17] = "abcdefghjklmnop\0";
>>>
>>> /* mvcrl reference use: 'open a hole in an array' */
>>> - mvcrl_8(tstr + 9, tstr + 8);
>>> + mvcrl(tstr + 9, tstr + 8, 8);
>>>
>>> /* place missing 'i' */
>>> tstr[8] = 'i';
>>>
>>> - return strncmp(alpha, tstr, 16ul);
>>> + return strncmp(alpha, tstr, 16ul) == 0;
>>> +}
>>> +
>>> +static bool test_bad_r0(void)
>>> +{
>>> + char src[256];
>>> +
>>> + /*
>>> + * PoP says: Bits 32-55 of general register 0 should contain
>>> zeros;
>>> + * otherwise, the program may not operate compatibly in the
>>> future.
>>> + *
>>> + * Try it anyway in order to check whether this would crash
>>> QEMU itself.
>>> + */
>>> + mvcrl(src, src, (size_t)-1);
>>> +
>>> + return true;
>>> +}
>>
>> gcc 11 doesn't like this:
>>
>> https://gitlab.com/qemu-project/qemu/-/jobs/4623964826#L3921
>>
>> /home/gitlab-runner/builds/E8PpwMky/0/qemu-
>> project/qemu/tests/tcg/s390x/mie3-mvcrl.c: In
>> function ‘test_bad_r0’:
>> /home/gitlab-runner/builds/E8PpwMky/0/qemu-
>> project/qemu/tests/tcg/s390x/mie3-mvcrl.c:42:5:
>> error: ‘src’ may be used uninitialized [-Werror=maybe-uninitialized]
>> 42 | mvcrl(src, src, (size_t)-1);
>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /home/gitlab-runner/builds/E8PpwMky/0/qemu-
>> project/qemu/tests/tcg/s390x/mie3-mvcrl.c:6:13:
>> note: by argument 1 of type ‘const char *’ to ‘mvcrl’ declared here
>> 6 | static void mvcrl(const char *dst, const char *src, size_t
>> len)
>> | ^~~~~
>> /home/gitlab-runner/builds/E8PpwMky/0/qemu-
>> project/qemu/tests/tcg/s390x/mie3-mvcrl.c:34:10:
>> note: ‘src’ declared here
>> 34 | char src[256];
>> | ^~~
>> /home/gitlab-runner/builds/E8PpwMky/0/qemu-
>> project/qemu/tests/tcg/s390x/mie3-mvcrl.c:42:5:
>> error: ‘src’ may be used uninitialized [-Werror=maybe-uninitialized]
>> 42 | mvcrl(src, src, (size_t)-1);
>> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>> /home/gitlab-runner/builds/E8PpwMky/0/qemu-
>> project/qemu/tests/tcg/s390x/mie3-mvcrl.c:6:13:
>> note: by argument 2 of type ‘const char *’ to ‘mvcrl’ declared here
>> 6 | static void mvcrl(const char *dst, const char *src, size_t
>> len)
>> | ^~~~~
>> /home/gitlab-runner/builds/E8PpwMky/0/qemu-
>> project/qemu/tests/tcg/s390x/mie3-mvcrl.c:34:10:
>> note: ‘src’ declared here
>> 34 | char src[256];
>> | ^~~
>> cc1: all warnings being treated as errors
>>
>> How it sees any use of the structure, initialized or otherwise, I
>> don't know -- it's all
>> hidden within the asm. However, src[256] = { } is enough to silence
>> the error.
>>
>>
>> r~
>
> Thanks for having a look at this. I assume you applied this fixup, and
> I don't need to send a follow-up patch?
No need to respin the patch, I'll fix it up and send a v2 pull request.
Thomas