Re: Bug#380531: linux-2.6: mips and mipsel personality(2) support is broken

[Martin Michlmayr <tbm@cyrius.com>]

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FYI, but report tht "mips and mipsel personality(2) support is broken"

* Roger Leigh <rleigh@debian.org> [2006-07-30 19:39]:
> personality(2) only works the first time it is called [in the lifetime
> of a process/program].  All subsequent calls return EPERM, which is
> not a documented return value; I can see no mention of it in
> kernel/execdomain.c.  None of the other architectures I have tested
> (amd64, arm, i386, ia64, powerpc) behave this way: personality(2) is
> not a privileged call.
> 
> This happens no matter what the value of persona is, even if it is
> just 0xffffffff to query the current personality.
> 
> The attached testcase demonstrates the breakage.  On a working
> platform (powerpc), the output is like this:
> 
> ------------------------
> $ ./testpersona
> Getting personality
> Get returned '0'
> Setting personality '8'
> Set OK
> Getting personality
> Get returned '8'
> Setting personality '0'
> Set OK
> Getting personality
> Get returned '0'
> ------------------------
> 
> 0 == PER_LINUX
> 8 == PER_LINUX32
> 
> It successfully switched from PER_LINUX to PER_LINUX32 and back again,
> checking the personality before and after each change.
> 
> 
> Regards,
> Roger

-- 
Martin Michlmayr
http://www.cyrius.com/

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#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <sys/personality.h>

int
set_persona (unsigned long p)
{
  fprintf (stderr, "Setting personality '%lu'\n", p);

  int status = personality(p);
  if (status == -1)
    fprintf(stderr, "Set failed: %s\n", strerror(errno));

  fprintf(stderr, "Set OK\n");

  return status;
}

int
get_persona (void)
{
  fprintf (stderr, "Getting personality\n");

  int status = personality(0xffffffff);
  if (status == -1)
    fprintf(stderr, "Get failed: %s\n", strerror(errno));

  fprintf(stderr, "Get returned '%d'\n", status);

  return status;
}

int
main (void)
{
  get_persona();
  set_persona(PER_LINUX32);
  get_persona();
  set_persona(PER_LINUX);
  get_persona();
  return 0;
}