[LTP] [PATCH v5] Add a test case for mmap MAP_GROWSDOWN flag

[Li Wang]

On Mon, Sep 14, 2020 at 11:06 AM Li Wang <liwang@redhat.com> wrote:

>
> ...
>
>
>> But still the code wasn't exactly right, because the lowest address of
>> the stack in the previous code was stack - stack_size, which would be
>> start of the unmapped region and the size of the stack would be 2 *
>> stack_size, as we expected the mapping to grow.
>>
>
> No, I don't think so, the lowest address of the stack in the previous code
> is:
>     stack = start + total_size - size;
> and we pass this stack pointer to ptrehad_attr_setstack() is correct here,
> indeed the stack really starts at stack + stack_size, that's internal
> steps.
>

Here print debug info to verify that stack grows down from 'stack + size'
address:

mmap18.c:99: INFO: start = 0x7f4831293000, stack - size = 0x7f4831393000,
stack = 0x7f48313b3000, stack + size = 0x7f48313d3000
mmap18.c:110: INFO: &limit = 0x7f48313d1ee8, limit = 0x7f4831397000
mmap18.c:110: INFO: &limit = 0x7f48313d1ec8, limit = 0x7f4831397000
mmap18.c:110: INFO: &limit = 0x7f48313d1ea8, limit = 0x7f4831397000
mmap18.c:110: INFO: &limit = 0x7f48313d1e88, limit = 0x7f4831397000
mmap18.c:110: INFO: &limit = 0x7f48313d1e68, limit = 0x7f4831397000
mmap18.c:110: INFO: &limit = 0x7f48313d1e48, limit = 0x7f4831397000
mmap18.c:110: INFO: &limit = 0x7f48313d1e28, limit = 0x7f4831397000
mmap18.c:110: INFO: &limit = 0x7f48313d1e08, limit = 0x7f4831397000
mmap18.c:110: INFO: &limit = 0x7f48313d1de8, limit = 0x7f4831397000
...

-- 
Regards,
Li Wang
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