[S390] smp: always reboot on cpu 0
Always reboot on logical cpu 0. This makes sure that the IPL cpu is
always the same and usually avoids strange numbering schemes between
physical and logical cpus.
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
diff --git a/arch/s390/kernel/switch_cpu.S b/arch/s390/kernel/switch_cpu.S
new file mode 100644
index 0000000..c05ee6c
--- /dev/null
+++ b/arch/s390/kernel/switch_cpu.S
@@ -0,0 +1,59 @@
+/*
+ * 31-bit switch cpu code
+ *
+ * Copyright IBM Corp. 2009
+ *
+ */
+
+#include <asm/asm-offsets.h>
+#include <asm/lowcore.h>
+#include <asm/ptrace.h>
+
+# smp_switch_to_cpu switches to destination cpu and executes the passed function
+# Parameter: %r2 - function to call
+# %r3 - function parameter
+# %r4 - stack poiner
+# %r5 - current cpu
+# %r6 - destination cpu
+
+ .section .text
+ .align 4
+ .globl smp_switch_to_cpu
+smp_switch_to_cpu:
+ stm %r6,%r15,__SF_GPRS(%r15)
+ lr %r1,%r15
+ ahi %r15,-STACK_FRAME_OVERHEAD
+ st %r1,__SF_BACKCHAIN(%r15)
+ basr %r13,0
+0: la %r1,.gprregs_addr-0b(%r13)
+ l %r1,0(%r1)
+ stm %r0,%r15,0(%r1)
+1: sigp %r0,%r6,__SIGP_RESTART /* start destination CPU */
+ brc 2,1b /* busy, try again */
+2: sigp %r0,%r5,__SIGP_STOP /* stop current CPU */
+ brc 2,2b /* busy, try again */
+3: j 3b
+
+ .globl smp_restart_cpu
+smp_restart_cpu:
+ basr %r13,0
+0: la %r1,.gprregs_addr-0b(%r13)
+ l %r1,0(%r1)
+ lm %r0,%r15,0(%r1)
+1: sigp %r0,%r5,__SIGP_SENSE /* Wait for calling CPU */
+ brc 10,1b /* busy, accepted (status 0), running */
+ tmll %r0,0x40 /* Test if calling CPU is stopped */
+ jz 1b
+ ltr %r4,%r4 /* New stack ? */
+ jz 1f
+ lr %r15,%r4
+1: basr %r14,%r2
+
+.gprregs_addr:
+ .long .gprregs
+
+ .section .data,"aw",@progbits
+.gprregs:
+ .rept 16
+ .long 0
+ .endr