[PATCH] lockdep: x86 smp alternatives workaround

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@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/arch/i386/kernel/alternative.c b/arch/i386/kernel/alternative.c
index 7b421b3a053e..28ab80649764 100644
--- a/arch/i386/kernel/alternative.c
+++ b/arch/i386/kernel/alternative.c
@@ -303,6 +303,16 @@ 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));