Martin Michlmayr <firstname.lastname@example.org> writes:
> FYI, but report tht "mips and mipsel personality(2) support is broken"
> * Roger Leigh <email@example.com> [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.
Just a follow up:
There is a twist to the behaviour:
If personality(2) is called with a personality other than 0xffffffff
(query), and it fails, a subsequent call (any persona value) will
I can't see any reason for the behaviour looking at the
kernel/execdomain.c or arch/mips/kernel/linux32.c. ths believes it's
due to a bug in the syscall interface:
<ths> I believe it is related to sign extension.
<ths> o32 queries with 0xffffffff, which is really 0xffffffffffffffff, then the
kernel compares against 0xffffffff.
<rleigh> I haven't heard of that. Is it MIPS-specific, or a 64-bit-specific
<ths> mips uses sign-extended registers for 32bit values.
<ths> There's no 64bit mode switch.
<ths> (The argument for the sys32_personality should be int, not long.)
.''`. Roger Leigh
: :' : Debian GNU/Linux http://people.debian.org/~rleigh/
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