[0/2] selftests: harness: refactor __constructor_order

Message

Masahiro Yamada May 17, 2024, 11:45 a.m. UTC

This series refactors __constructor_order because
__constructor_order_last() is unneeded.

BTW, the comments in kselftest_harness.h was confusing to me.

As far as I tested, all arches executed constructors in the forward
order.

[test code]

  #include <stdio.h>

  static int x;

  static void __attribute__((constructor)) increment(void)
  {
           x += 1;
  }

  static void __attribute__((constructor)) multiply(void)
  {
          x *= 2;
  }

  int main(void)
  {
          printf("foo = %d\n", x);
          return 0;
  }

It should print 2 for forward order systems, 1 for reverse order systems.

I executed it on some archtes by using QEMU. I always got 2.



Masahiro Yamada (2):
  selftests: harness: remove unneeded __constructor_order_last()
  selftests: harness: rename __constructor_order for clarification

 .../drivers/s390x/uvdevice/test_uvdevice.c     |  6 ------
 tools/testing/selftests/hid/hid_bpf.c          |  6 ------
 tools/testing/selftests/kselftest_harness.h    | 18 ++++--------------
 tools/testing/selftests/rtc/rtctest.c          |  7 -------
 4 files changed, 4 insertions(+), 33 deletions(-)

Comments

Kees Cook May 17, 2024, 9:27 p.m. UTC | #1

On Fri, May 17, 2024 at 08:45:04PM +0900, Masahiro Yamada wrote:
> 
> This series refactors __constructor_order because
> __constructor_order_last() is unneeded.
> 
> BTW, the comments in kselftest_harness.h was confusing to me.
> 
> As far as I tested, all arches executed constructors in the forward
> order.
> 
> [test code]
> 
>   #include <stdio.h>
> 
>   static int x;
> 
>   static void __attribute__((constructor)) increment(void)
>   {
>            x += 1;
>   }
> 
>   static void __attribute__((constructor)) multiply(void)
>   {
>           x *= 2;
>   }
> 
>   int main(void)
>   {
>           printf("foo = %d\n", x);
>           return 0;
>   }
> 
> It should print 2 for forward order systems, 1 for reverse order systems.
> 
> I executed it on some archtes by using QEMU. I always got 2.

IIRC, and it was a long time ago now, it was actually a difference
between libc implementations where I encountered the problem. Maybe
glibc vs Bionic?

-Kees