[POWERPC] Make iSeries spin on __secondary_hold_spinloop, like pSeries

Currently all iSeries secondary CPUs spin directly on the cpu_start
field in their paca.  Make them spin on the global
__secondary_hold_spinloop until after the pacas have been initialised.

As Stephen Rothwell points out, this works at the moment because
__secondary_hold_spinloop is being set already, but iSeries isn't
looking at it :)

Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

diff --git a/arch/powerpc/platforms/iseries/exception.S b/arch/powerpc/platforms/iseries/exception.S
index c775cd4..8ff330d 100644 (file)
--- a/arch/powerpc/platforms/iseries/exception.S
+++ b/arch/powerpc/platforms/iseries/exception.S
@@ -59,8 +59,33 @@ system_reset_iSeries:
        andc    r4,r4,r5
        mtspr   SPRN_CTRLT,r4
 
+/* Spin on __secondary_hold_spinloop until it is updated by the boot cpu. */
+/* In the UP case we'll yeild() later, and we will not access the paca anyway */
+#ifdef CONFIG_SMP
 1:
        HMT_LOW
+       LOAD_REG_IMMEDIATE(r23, __secondary_hold_spinloop)
+       ld      r23,0(r23)
+       sync
+       LOAD_REG_IMMEDIATE(r3,current_set)
+       sldi    r28,r24,3               /* get current_set[cpu#] */
+       ldx     r3,r3,r28
+       addi    r1,r3,THREAD_SIZE
+       subi    r1,r1,STACK_FRAME_OVERHEAD
+
+       cmpwi   0,r23,0                 /* Keep poking the Hypervisor until */
+       bne     2f                      /* we're released */
+       /* Let the Hypervisor know we are alive */
+       /* 8002 is a call to HvCallCfg::getLps, a harmless Hypervisor function */
+       lis     r3,0x8002
+       rldicr  r3,r3,32,15             /* r0 = (r3 << 32) & 0xffff000000000000 */
+       li      r0,-1                   /* r0=-1 indicates a Hypervisor call */
+       sc                              /* Invoke the hypervisor via a system call */
+       b       1b
+#endif
+
+2:
+       HMT_LOW
 #ifdef CONFIG_SMP
        lbz     r23,PACAPROCSTART(r13)  /* Test if this processor
                                         * should start */
@@ -91,7 +116,7 @@ iSeries_secondary_smp_loop:
        li      r0,-1                   /* r0=-1 indicates a Hypervisor call */
        sc                              /* Invoke the hypervisor via a system call */
        mfspr   r13,SPRN_SPRG3          /* Put r13 back ???? */
-       b       1b                      /* If SMP not configured, secondaries
+       b       2b                      /* If SMP not configured, secondaries
                                         * loop forever */
 
 /***  ISeries-LPAR interrupt handlers ***/