[PATCH] powerpc: Fixups for kernel linked at 32 MB

There's a few places where we need to fix things up for the kernel to work
if it's linked at 32MB:

 - platforms/powermac/smp.c
   To start secondary cpus on pmac we patch the reset vector, which is fine.
   Except if we're above 32MB we don't have enough bits for an absolute branch,
   it needs to relative.
 - kernel/head_64.s
    - A few branches in the cpu hold code need to load the full target address
      and do a bctr.
    - after_prom_start needs to load PHYSICAL_START as the dest address, not 0.
    - The exception prolog needs to load the low word of the target adddress,
      not just the low halfword.
    - Fixup handling of the initial stab address.
 - kernel/setup_64.c
   smp_release_cpus() needs to write 1 to the spinloop flag near 0, not 32 MB.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 7 insertions, 9 deletions

diff --git a/arch/powerpc/platforms/powermac/smp.c b/arch/powerpc/platforms/powermac/smp.c
index fb2a7c798e82..862f1e985c19 100644
--- a/arch/powerpc/platforms/powermac/smp.c
+++ b/arch/powerpc/platforms/powermac/smp.c
@@ -753,14 +753,15 @@ static int __init smp_core99_probe(void)
 static void __devinit smp_core99_kick_cpu(int nr)
 {
         unsigned int save_vector;
-        unsigned long new_vector;
-        unsigned long flags;
+        unsigned long target, flags;
         volatile unsigned int *vector
                  = ((volatile unsigned int *)(KERNELBASE+0x100));
 
         if (nr < 0 || nr > 3)
                 return;
-        if (ppc_md.progress) ppc_md.progress("smp_core99_kick_cpu", 0x346);
+
+        if (ppc_md.progress)
+                ppc_md.progress("smp_core99_kick_cpu", 0x346);
 
         local_irq_save(flags);
         local_irq_disable();
@@ -768,14 +769,11 @@ static void __devinit smp_core99_kick_cpu(int nr)
         /* Save reset vector */
         save_vector = *vector;
 
-        /* Setup fake reset vector that does    
+        /* Setup fake reset vector that does
          *   b __secondary_start_pmac_0 + nr*8 - KERNELBASE
          */
-        new_vector = (unsigned long) __secondary_start_pmac_0 + nr * 8;
-        *vector = 0x48000002 + new_vector - KERNELBASE;
-
-        /* flush data cache and inval instruction cache */
-        flush_icache_range((unsigned long) vector, (unsigned long) vector + 4);
+        target = (unsigned long) __secondary_start_pmac_0 + nr * 8;
+        create_branch((unsigned long)vector, target, BRANCH_SET_LINK);
 
         /* Put some life in our friend */
         pmac_call_feature(PMAC_FTR_RESET_CPU, NULL, nr, 0);