Re: [PATCH 1/2] selftests/x86/fsgsbase: Indirect output through a wrapper function

Ingo Molnar
2019-02-11T08:45:50Z

* Mark Brown <broonie@kernel.org> wrote:

> In preparation for a change to make this test run repeatedly which
> would generate huge amounts of output as is indirect all the printf()
> calls in the program through a wrapper and add a quiet flag which can
> be used to suppress the output. This is fairly quick and dirty, I'm not
> 100% sure what would be idiomatic here.
>
> Signed-off-by: Mark Brown <broonie@kernel.org>
> ---
> tools/testing/selftests/x86/fsgsbase.c | 52 ++++++++++++++++----------
> 1 file changed, 32 insertions(+), 20 deletions(-)

So this really loses useful output when there is a failure. After this
patch I get:

dagon:~/tip/tools/testing/selftests/x86> ./fsgsbase_64 -vv
[FAIL] 24 errors detected in 1 tries

Not very helpful, and no real command-line way to see the failures.

While previously it would tell me what's going on:

dagon:~/tip/tools/testing/selftests/x86> ./fsgsbase_64 | grep FAIL
[FAIL] GS/BASE changed from 0x1/0x1 to 0x1/0x0
[FAIL] GS/BASE changed from 0x2/0x1 to 0x2/0x0
[FAIL] GS/BASE changed from 0x3/0x1 to 0x3/0x0
[FAIL] GS/BASE changed from 0x1/0x1 to 0x1/0x0
[FAIL] GS/BASE changed from 0x2/0x1 to 0x2/0x0
[FAIL] GS/BASE changed from 0x3/0x1 to 0x3/0x0
[FAIL] GS/BASE changed from 0x1/0x1 to 0x1/0x0
[FAIL] GS/BASE changed from 0x2/0x1 to 0x2/0x0
[FAIL] GS/BASE changed from 0x3/0x1 to 0x3/0x0
[FAIL] GS/BASE changed from 0x1/0x1 to 0x1/0x0
[FAIL] GS/BASE changed from 0x2/0x1 to 0x2/0x0
[FAIL] GS/BASE changed from 0x3/0x1 to 0x3/0x0
[FAIL] GS/BASE changed from 0x1/0x200000000 to 0x1/0x0
[FAIL] GS/BASE changed from 0x2/0x200000000 to 0x2/0x0
[FAIL] GS/BASE changed from 0x3/0x200000000 to 0x3/0x0
[FAIL] GS/BASE changed from 0x1/0x200000000 to 0x1/0x0
[FAIL] GS/BASE changed from 0x2/0x200000000 to 0x2/0x0
[FAIL] GS/BASE changed from 0x3/0x200000000 to 0x3/0x0
[FAIL] GS/BASE changed from 0x1/0x200000000 to 0x1/0x0
[FAIL] GS/BASE changed from 0x2/0x200000000 to 0x2/0x0
[FAIL] GS/BASE changed from 0x3/0x200000000 to 0x3/0x0
[FAIL] GS/BASE changed from 0x1/0x200000000 to 0x1/0x0
[FAIL] GS/BASE changed from 0x2/0x200000000 to 0x2/0x0
[FAIL] GS/BASE changed from 0x3/0x200000000 to 0x3/0x0

So I believe at least failure messages need to be preserved.

Thanks,

Ingo