[patch 31/61] lock validator: SMP alternatives workaround

[Ingo Molnar]

From: Ingo Molnar <mingo@xxxxxxx>

disable SMP alternatives fixups (the patching in of NOPs on 1-CPU
systems) if the lock validator is enabled: there is a binutils
section handling bug that causes corrupted instructions when
UP instructions are patched in.

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
Signed-off-by: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
---
 arch/i386/kernel/alternative.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

Index: linux/arch/i386/kernel/alternative.c
===================================================================
--- linux.orig/arch/i386/kernel/alternative.c
+++ linux/arch/i386/kernel/alternative.c
@@ -301,6 +301,16 @@ void alternatives_smp_switch(int smp)
 	struct smp_alt_module *mod;
 	unsigned long flags;
 
+#ifdef CONFIG_LOCKDEP
+	/*
+	 * A not yet fixed binutils section handling bug prevents
+	 * alternatives-replacement from working reliably, so turn
+	 * it off:
+	 */
+	printk("lockdep: not fixing up alternatives.\n");
+	return;
+#endif
+
 	if (no_replacement || smp_alt_once)
 		return;
 	BUG_ON(!smp && (num_online_cpus() > 1));
-
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