[PATCH] x86_64: x86_64 version of the smp alternative patch.

Changes are largely identical to the i386 version:

 * alternative #define are moved to the new alternative.h file.
 * one new elf section with pointers to the lock prefixes which can be
   nop'ed out for non-smp.
 * two new elf sections simliar to the "classic" alternatives to
   replace SMP code with simpler UP code.
 * fixup headers to use alternative.h instead of defining their own
   LOCK / LOCK_PREFIX macros.

The patch reuses the i386 version of the alternatives code to avoid code
duplication.  The code in alternatives.c was shuffled around a bit to
reduce the number of #ifdefs needed.  It also got some tweaks needed for
x86_64 (vsyscall page handling) and new features (noreplacement option
which was x86_64 only up to now).  Debug printk's are changed from
compile-time to runtime.

Loosely based on a early version from Bastian Blank <waldi@debian.org>

Signed-off-by: Gerd Hoffmann <kraxel@suse.de>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index 71a7222cf9ce..06535e7687ce 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -797,6 +797,8 @@ static int __cpuinit do_boot_cpu(int cpu, int apicid)
         }
 
 
+        alternatives_smp_switch(1);
+
         c_idle.idle = get_idle_for_cpu(cpu);
 
         if (c_idle.idle) {
@@ -1259,6 +1261,8 @@ void __cpu_die(unsigned int cpu)
                 /* They ack this in play_dead by setting CPU_DEAD */
                 if (per_cpu(cpu_state, cpu) == CPU_DEAD) {
                         printk ("CPU %d is now offline\n", cpu);
+                        if (1 == num_online_cpus())
+                                alternatives_smp_switch(0);
                         return;
                 }
                 msleep(100);