The facility unavailable exception can be triggered from userspace by
accessing PMU registers when EBB is not enabled.  This causes the
included pr_err() to run, hence spamming the kernel log buffer.

This avoids this by rate limiting these messages.

Signed-off-by: Michael Neuling <mi...@neuling.org>
---
We can bike shed the hell out of this one.  We could just remove it, or
we could put it under the control of show_unhandled_signals.

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index e435bc0..7836de3f 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -1340,8 +1340,9 @@ void facility_unavailable_exception(struct pt_regs *regs)
        if (!arch_irq_disabled_regs(regs))
                local_irq_enable();
 
-       pr_err("%sFacility '%s' unavailable, exception at 0x%lx, MSR=%lx\n",
-              hv ? "Hypervisor " : "", facility, regs->nip, regs->msr);
+       pr_err_ratelimited(
+               "%sFacility '%s' unavailable, exception at 0x%lx, MSR=%lx\n",
+               hv ? "Hypervisor " : "", facility, regs->nip, regs->msr);
 
        if (user_mode(regs)) {
                _exception(SIGILL, regs, ILL_ILLOPC, regs->nip);
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