sparc64: Only allocate per-cpu areas for possible cpus.

This gets us real close to the generic implementation of
setup_per_cpu_areas() except:

1) We store the per-cpu offset into the trap_block[], whereas
   the generic code has it's own static array.

2) We have to initialize the %g5 register to hold the boot cpu's
   per-cpu area offset.

3) The OBP/MDESC cpu info scan is performed at the end.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 16 deletions

diff --git a/arch/sparc/kernel/smp_64.c b/arch/sparc/kernel/smp_64.c
index 5302344e3cb4..567a6a47ba23 100644
--- a/arch/sparc/kernel/smp_64.c
+++ b/arch/sparc/kernel/smp_64.c
@@ -1373,27 +1373,17 @@ void smp_send_stop(void)
 
 void __init setup_per_cpu_areas(void)
 {
-        unsigned long base, shift, goal, size, i;
+        unsigned long size, i, nr_possible_cpus = num_possible_cpus();
         char *ptr;
 
         /* Copy section for each CPU (we discard the original) */
-        goal = PERCPU_ENOUGH_ROOM;
+        size = ALIGN(PERCPU_ENOUGH_ROOM, PAGE_SIZE);
+        ptr = alloc_bootmem_pages(size * nr_possible_cpus);
 
-        shift = PAGE_SHIFT;
-        for (size = PAGE_SIZE; size < goal; size <<= 1UL)
-                shift++;
-
-        ptr = __alloc_bootmem(size * NR_CPUS, PAGE_SIZE, 0);
-        if (!ptr) {
-                prom_printf("Cannot allocate per-cpu memory.\n");
-                prom_halt();
-        }
-
-        base = ptr - __per_cpu_start;
-
-        for (i = 0; i < NR_CPUS; i++, ptr += size) {
-                __per_cpu_offset(i) = base + (i * size);
+        for_each_possible_cpu(i) {
+                __per_cpu_offset(i) = ptr - __per_cpu_start;
                 memcpy(ptr, __per_cpu_start, __per_cpu_end - __per_cpu_start);
+                ptr += size;
         }
 
         /* Setup %g5 for the boot cpu.  */