Martin Michlmayr <tbm@xxxxxxxxxx> writes: > FYI, but report tht "mips and mipsel personality(2) support is broken" > > * Roger Leigh <rleigh@xxxxxxxxxx> [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 succeed. 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 thing? <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/ `. `' Printing on GNU/Linux? http://gutenprint.sourceforge.net/ `- GPG Public Key: 0x25BFB848 Please sign and encrypt your mail.
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