[igt-dev] [RFT i-g-t] lib/i915: Assert mmap size alignment

[Tvrtko Ursulin]

On 04/03/2019 14:45, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-03-04 14:11:31)
>> From: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>
>> Fishing for fails...
>>
>> /*
>> mmap(2) mandates size is page aligned so check this in our wrappers.
>> */
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>> ---
>>   lib/i915/gem_mman.c |  4 ++++
>>   lib/igt_fb.c        | 14 ++++++++------
>>   tests/kms_ccs.c     | 14 ++++++++------
>>   tests/kms_psr.c     |  8 ++++----
>>   4 files changed, 24 insertions(+), 16 deletions(-)
>>
>> diff --git a/lib/i915/gem_mman.c b/lib/i915/gem_mman.c
>> index 3cf9a6bbdb31..084dbb3b3678 100644
>> --- a/lib/i915/gem_mman.c
>> +++ b/lib/i915/gem_mman.c
>> @@ -57,6 +57,8 @@ void *__gem_mmap__gtt(int fd, uint32_t handle, uint64_t size, unsigned prot)
>>          struct drm_i915_gem_mmap_gtt mmap_arg;
>>          void *ptr;
>>   
>> +       igt_assert(!(size & 4095));
> 
> Fwiw, it's probably best if we had some kind of IGT_BUG_ON() that caused
> a much more visible explosion than a mere test failure.
> 
> #define IGT_BUG_ON(cond) if (!(cond)) raise(SIGILL)

No idea if that would be worthwhile.

But anyway, it seems I have identified all the tests which do 
non-page-aligned mmap. So..

a) leave the assert in low level mmap helpers
b) move the assert to higher level wrappers
c) round up in wrappers is not an option due unmap
d) do nothing in igt

?

Regards,

Tvrtko