[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>

6 files changed, 179 insertions, 11 deletions

diff --git a/arch/s390/kernel/Makefile b/arch/s390/kernel/Makefile
index 683f6381cc59..20f861256774 100644
--- a/arch/s390/kernel/Makefile
+++ b/arch/s390/kernel/Makefile
@@ -32,6 +32,8 @@ extra-y				+= head.o init_task.o vmlinux.lds
 
 obj-$(CONFIG_MODULES)           += s390_ksyms.o module.o
 obj-$(CONFIG_SMP)               += smp.o topology.o
+obj-$(CONFIG_SMP)               += $(if $(CONFIG_64BIT),switch_cpu64.o, \
+                                                        switch_cpu.o)
 obj-$(CONFIG_HIBERNATION)       += suspend.o swsusp_asm64.o
 obj-$(CONFIG_AUDIT)             += audit.o
 compat-obj-$(CONFIG_AUDIT)      += compat_audit.o
diff --git a/arch/s390/kernel/ipl.c b/arch/s390/kernel/ipl.c
index 4d73296fed74..0a7c39dee6b7 100644
--- a/arch/s390/kernel/ipl.c
+++ b/arch/s390/kernel/ipl.c
@@ -553,7 +553,7 @@ out:
         return rc;
 }
 
-static void ipl_run(struct shutdown_trigger *trigger)
+static void __ipl_run(void *unused)
 {
         diag308(DIAG308_IPL, NULL);
         if (MACHINE_IS_VM)
@@ -562,6 +562,11 @@ static void ipl_run(struct shutdown_trigger *trigger)
                 reipl_ccw_dev(&ipl_info.data.ccw.dev_id);
 }
 
+static void ipl_run(struct shutdown_trigger *trigger)
+{
+        smp_switch_to_ipl_cpu(__ipl_run, NULL);
+}
+
 static int __init ipl_init(void)
 {
         int rc;
@@ -1039,7 +1044,7 @@ static void get_ipl_string(char *dst, struct ipl_parameter_block *ipb,
                 sprintf(dst + pos, " PARM %s", vmparm);
 }
 
-static void reipl_run(struct shutdown_trigger *trigger)
+static void __reipl_run(void *unused)
 {
         struct ccw_dev_id devid;
         static char buf[128];
@@ -1087,6 +1092,11 @@ static void reipl_run(struct shutdown_trigger *trigger)
         disabled_wait((unsigned long) __builtin_return_address(0));
 }
 
+static void reipl_run(struct shutdown_trigger *trigger)
+{
+        smp_switch_to_ipl_cpu(__reipl_run, NULL);
+}
+
 static void reipl_block_ccw_init(struct ipl_parameter_block *ipb)
 {
         ipb->hdr.len = IPL_PARM_BLK_CCW_LEN;
@@ -1369,20 +1379,18 @@ static struct kobj_attribute dump_type_attr =
 
 static struct kset *dump_kset;
 
-static void dump_run(struct shutdown_trigger *trigger)
+static void __dump_run(void *unused)
 {
         struct ccw_dev_id devid;
         static char buf[100];
 
         switch (dump_method) {
         case DUMP_METHOD_CCW_CIO:
-                smp_send_stop();
                 devid.devno = dump_block_ccw->ipl_info.ccw.devno;
                 devid.ssid  = 0;
                 reipl_ccw_dev(&devid);
                 break;
         case DUMP_METHOD_CCW_VM:
-                smp_send_stop();
                 sprintf(buf, "STORE STATUS");
                 __cpcmd(buf, NULL, 0, NULL);
                 sprintf(buf, "IPL %X", dump_block_ccw->ipl_info.ccw.devno);
@@ -1396,10 +1404,17 @@ static void dump_run(struct shutdown_trigger *trigger)
                 diag308(DIAG308_SET, dump_block_fcp);
                 diag308(DIAG308_DUMP, NULL);
                 break;
-        case DUMP_METHOD_NONE:
-                return;
+        default:
+                break;
         }
-        printk(KERN_EMERG "Dump failed!\n");
+}
+
+static void dump_run(struct shutdown_trigger *trigger)
+{
+        if (dump_method == DUMP_METHOD_NONE)
+                return;
+        smp_send_stop();
+        smp_switch_to_ipl_cpu(__dump_run, NULL);
 }
 
 static int __init dump_ccw_init(void)
diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index 131d7ee8b416..a922d51df6bf 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -54,11 +54,11 @@ void machine_shutdown(void)
 {
 }
 
-void machine_kexec(struct kimage *image)
+static void __machine_kexec(void *data)
 {
         relocate_kernel_t data_mover;
+        struct kimage *image = data;
 
-        smp_send_stop();
         pfault_fini();
         s390_reset_system();
 
@@ -68,3 +68,9 @@ void machine_kexec(struct kimage *image)
         (*data_mover)(&image->head, image->start);
         for (;;);
 }
+
+void machine_kexec(struct kimage *image)
+{
+        smp_send_stop();
+        smp_switch_to_ipl_cpu(__machine_kexec, image);
+}
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index 384a6846a65e..b39f596d71bd 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -90,6 +90,39 @@ static int cpu_stopped(int cpu)
         return 0;
 }
 
+void smp_switch_to_ipl_cpu(void (*func)(void *), void *data)
+{
+        struct _lowcore *lc, *current_lc;
+        struct stack_frame *sf;
+        struct pt_regs *regs;
+        unsigned long sp;
+
+        if (smp_processor_id() == 0)
+                func(data);
+        __load_psw_mask(PSW_BASE_BITS | PSW_DEFAULT_KEY);
+        /* Disable lowcore protection */
+        __ctl_clear_bit(0, 28);
+        current_lc = lowcore_ptr[smp_processor_id()];
+        lc = lowcore_ptr[0];
+        if (!lc)
+                lc = current_lc;
+        lc->restart_psw.mask = PSW_BASE_BITS | PSW_DEFAULT_KEY;
+        lc->restart_psw.addr = PSW_ADDR_AMODE | (unsigned long) smp_restart_cpu;
+        if (!cpu_online(0))
+                smp_switch_to_cpu(func, data, 0, stap(), __cpu_logical_map[0]);
+        while (signal_processor(0, sigp_stop_and_store_status) == sigp_busy)
+                cpu_relax();
+        sp = lc->panic_stack;
+        sp -= sizeof(struct pt_regs);
+        regs = (struct pt_regs *) sp;
+        memcpy(&regs->gprs, &current_lc->gpregs_save_area, sizeof(regs->gprs));
+        memcpy(&regs->psw, &current_lc->st_status_fixed_logout, sizeof(psw_t));
+        sp -= STACK_FRAME_OVERHEAD;
+        sf = (struct stack_frame *) sp;
+        sf->back_chain = regs->gprs[15];
+        smp_switch_to_cpu(func, data, sp, stap(), __cpu_logical_map[0]);
+}
+
 void smp_send_stop(void)
 {
         int cpu, rc;
@@ -752,7 +785,8 @@ static ssize_t cpu_configure_store(struct sys_device *dev,
         get_online_cpus();
         mutex_lock(&smp_cpu_state_mutex);
         rc = -EBUSY;
-        if (cpu_online(cpu))
+        /* disallow configuration changes of online cpus and cpu 0 */
+        if (cpu_online(cpu) || cpu == 0)
                 goto out;
         rc = 0;
         switch (val) {
diff --git a/arch/s390/kernel/switch_cpu.S b/arch/s390/kernel/switch_cpu.S
new file mode 100644
index 000000000000..c05ee6c221d8
--- /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
diff --git a/arch/s390/kernel/switch_cpu64.S b/arch/s390/kernel/switch_cpu64.S
new file mode 100644
index 000000000000..c73ede3c1d68
--- /dev/null
+++ b/arch/s390/kernel/switch_cpu64.S
@@ -0,0 +1,52 @@
+/*
+ * 64-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:
+        stmg    %r6,%r15,__SF_GPRS(%r15)
+        lgr     %r1,%r15
+        aghi    %r15,-STACK_FRAME_OVERHEAD
+        stg     %r1,__SF_BACKCHAIN(%r15)
+        larl    %r1,.gprregs
+        stmg    %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:
+        larl    %r1,.gprregs
+        lmg     %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
+        ltgr    %r4,%r4                 /* New stack ? */
+        jz      1f
+        lgr     %r15,%r4
+1:      basr    %r14,%r2
+
+        .section .data,"aw",@progbits
+.gprregs:
+        .rept   16
+        .quad   0
+        .endr