On Thu, 21 Apr 2016, Paul Burton wrote: > diff --git a/arch/mips/kernel/signal.c b/arch/mips/kernel/signal.c > index bf792e2..a304b70 100644 > --- a/arch/mips/kernel/signal.c > +++ b/arch/mips/kernel/signal.c > @@ -195,6 +195,9 @@ static int restore_msa_extcontext(void __user *buf, unsigned int size) > unsigned int csr; > int i, err; > > + if (!config_enabled(CONFIG_CPU_HAS_MSA)) > + return SIGSYS; > + > if (size != sizeof(*msa)) > return -EINVAL; The priciple of your change looks reasonable itself to me, however its call site is ill-formed making it possible to return a nonsensical error code: if (used & USED_EXTCONTEXT) err |= restore_extcontext(sc_to_extcontext(sc)); return err ?: sig; } (`restore_extcontext' takes the result from `restore_msa_extcontext' and passes it on) so if an earlier call has set `err' to -EINVAL (which I take it is the only value expected here or we'd have a preexisting problem), then `protected_restore_fp_context' (which is where this code comes from) will return (-EINVAL | SIGSYS). So you need to redesign this code somehow I'm afraid, maybe just changing the condition to: if (!err && (used & USED_EXTCONTEXT)) will do (although while at it I'd double-check that `err' can really only be -EINVAL here). Maciej
