Re: test: misc/tst-personality broken on 32-bit hosts

On 27/08/26 09:34, Yury Khrustalev wrote:
> The misc/tst-personality test incorrectly processes errors returned from
> the personality() function on 32-bit hosts. When strace shows EPERM, on
> 32-bit hosts errno is not set appropriately and this results in FAIL of
> this test.

The issue is not really 32-bit/64-bit, but how the syscall wrapper is defined:

* If the port uses the wordsize-64 syscalls.list definition it will set errno
  on failure - aarch64, x86_64 (and x32 via the x86_64 Implies), powerpc64, 
  s390x, alpha, loongarch64, riscv64.  They are two exceptions: sparc64 which
  overrides it and use the generic implementation instead, and mips64 which
  does not have wordsize-64 in implies.

* Otherwise the port uses the generic Linux implementation it will not touch 
  errno.

> 
> The simple yet clumsy fix is:
> 
>   -      if (errno == EPERM)
>   +      if (errno == EPERM || errno == 0xdefaced)

This seems to be  the simpler solution for now, the '64-bit-syscall-abi' would
require arch-specific wrapper to be really robust.

> 
> The second condition will be true on 32-bit hosts because in this case
> errno will remain unchanged.
> 
> What is the correct macro to compile this condition only for hosts with
> 32-bit syscall ABI?
> 
> Ideally, it should be something like:
> 
>   -      if (errno == EPERM)
>   +      if (
>   + #if 64-bit-syscall-abi
>   +          errno == EPERM
>   + #else
>   +          errno == 0xdefaced
>   + #endif
>   +      )
> 
> Thanks,
> Yury