sh: Bring SMP support back from the dead.

There was a very preliminary bunch of SMP code scattered around for the
SH7604 microcontrollers from way back when, and it has mostly suffered
bitrot since then. With the tree already having been slowly getting
prepped for SMP, this plugs in most of the remaining platform-independent
bits.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 12 insertions, 6 deletions

diff --git a/arch/sh/kernel/head.S b/arch/sh/kernel/head.S
index 0bccc0ca5a0f..3338239717f1 100644
--- a/arch/sh/kernel/head.S
+++ b/arch/sh/kernel/head.S
@@ -54,8 +54,8 @@ ENTRY(_stext)
         mov.l   1f, r0          ! MD=1, RB=0, BL=0, IMASK=0xF
         ldc     r0, sr
         !                       Initialize global interrupt mask
-        mov     #0, r0
 #ifdef CONFIG_CPU_HAS_SR_RB
+        mov     #0, r0
         ldc     r0, r6_bank
 #endif
         
@@ -72,15 +72,18 @@ ENTRY(_stext)
         !
         mov.l   2f, r0
         mov     r0, r15         ! Set initial r15 (stack pointer)
-        mov     #(THREAD_SIZE >> 10), r1
-        shll8   r1              ! r1 = THREAD_SIZE
-        shll2   r1
-        sub     r1, r0          !
 #ifdef CONFIG_CPU_HAS_SR_RB
+        mov.l   7f, r0
         ldc     r0, r7_bank     ! ... and initial thread_info
 #endif
         
         !                       Clear BSS area
+#ifdef CONFIG_SMP       
+        mov.l   3f, r0
+        cmp/eq  #0, r0          ! skip clear if set to zero
+        bt      10f
+#endif
+        
         mov.l   3f, r1
         add     #4, r1
         mov.l   4f, r2
@@ -89,13 +92,14 @@ ENTRY(_stext)
         bf/s    9b              ! while (r1 < r2)
          mov.l  r0,@-r2
 
+10:             
         !                       Additional CPU initialization
         mov.l   6f, r0
         jsr     @r0
          nop
 
         SYNCO()                 ! Wait for pending instructions..
-
+        
         !                       Start kernel
         mov.l   5f, r0
         jmp     @r0
@@ -107,8 +111,10 @@ ENTRY(_stext)
 #else
 1:      .long   0x400080F0              ! MD=1, RB=0, BL=0, FD=1, IMASK=0xF
 #endif
+ENTRY(stack_start)
 2:      .long   init_thread_union+THREAD_SIZE
 3:      .long   __bss_start
 4:      .long   _end
 5:      .long   start_kernel
 6:      .long   sh_cpu_init
+7:      .long   init_thread_union