[LTP] max_map_count fail in arm64 system which support lib32

[Cyril Hrubis]

Hi!
> ./max_map_count_32
> max_map_count    0  TINFO  :  set overcommit_memory to 2
> max_map_count    0  TINFO  :  set max_map_count to 64
> max_map_count    1  TFAIL  :  max_map_count.c:233: 64 map entries in total, but expected 64 entries
> max_map_count    0  TINFO  :  set max_map_count to 256
> max_map_count    2  TFAIL  :  max_map_count.c:233: 256 map entries in total, but expected 256 entries
> max_map_count    0  TINFO  :  set max_map_count to 1024
> max_map_count    3  TFAIL  :  max_map_count.c:233: 1024 map entries in total, but expected 1024 entries
> max_map_count    0  TINFO  :  set max_map_count to 4096
> max_map_count    4  TFAIL  :  max_map_count.c:233: 4096 map entries in total, but expected 4096 entries
> max_map_count    0  TINFO  :  set max_map_count to 16384
> max_map_count    5  TFAIL  :  max_map_count.c:233: 16384 map entries in total, but expected 16384 entries
> max_map_count    0  TINFO  :  set max_map_count to 65536
> max_map_count    6  TFAIL  :  max_map_count.c:233: 65536 map entries in total, but expected 65536 entries
> max_map_count    0  TINFO  :  set overcommit_memory to 0
> max_map_count    0  TINFO  :  set max_map_count to 65530
> 
>     When I use 32-bit SDK, it will compile at:
> 
> 	#elif defined(__arm__)
>         	/* Older arm kernels didn't label their vdso maps */
>         	if (!strncmp(line, "ffff0000-ffff1000", 17))
>                 	return true;

So you compile 32bit binary and run it on 64bit arm kernel and it
wrongly skips one mapping?

>     and not:
> 	#elif defined(__ia64__)
>         	/* On ia64, the vdso is not a proper mapping */
>         	if (!strcmp(buf, "[vdso]"))
>                 	return true;

__ia64__ is itanium, I guess that the function always returns false when
compiled for 64bit arm.

The solution may be runtime detection for 32bit/64bit kernel on arm. We
can look at the machine string in the struct utsname returned from
uname(2) to get that information.

-- 
Cyril Hrubis
chrubis@suse.cz