[S390] rework smp code

Define struct pcpu and merge some of the NR_CPUS arrays into it, including
__cpu_logical_map, current_set and smp_cpu_state. Split smp related
functions to those operating on physical cpus and the functions operating
on a logical cpu number. Make the functions for physical cpus use a
pointer to a struct pcpu. This hides the knowledge about cpu addresses in
smp.c, entry[64].S and swsusp_asm64.S, thus remove the sigp.h header.

The PSW restart mechanism is used to start secondary cpus, calling a
function on an online cpu, calling a function on the ipl cpu, and for
the nmi signal. Replace the different assembler functions with a
single function restart_int_handler. The new entry point calls a function
whose pointer is stored in the lowcore of the target cpu and it can wait
for the source cpu to stop. This covers all existing use cases.

Overall the code is now simpler and there are ~380 lines less code.

Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 7 insertions, 36 deletions

diff --git a/arch/s390/kernel/machine_kexec.c b/arch/s390/kernel/machine_kexec.c
index 47b168f..bf6fbc0 100644
--- a/arch/s390/kernel/machine_kexec.c
+++ b/arch/s390/kernel/machine_kexec.c
@@ -49,50 +49,21 @@ static void add_elf_notes(int cpu)
 }
 
 /*
- * Store status of next available physical CPU
- */
-static int store_status_next(int start_cpu, int this_cpu)
-{
-	struct save_area *sa = (void *) 4608 + store_prefix();
-	int cpu, rc;
-
-	for (cpu = start_cpu; cpu < 65536; cpu++) {
-		if (cpu == this_cpu)
-			continue;
-		do {
-			rc = raw_sigp(cpu, sigp_stop_and_store_status);
-		} while (rc == sigp_busy);
-		if (rc != sigp_order_code_accepted)
-			continue;
-		if (sa->pref_reg)
-			return cpu;
-	}
-	return -1;
-}
-
-/*
  * Initialize CPU ELF notes
  */
 void setup_regs(void)
 {
 	unsigned long sa = S390_lowcore.prefixreg_save_area + SAVE_AREA_BASE;
-	int cpu, this_cpu, phys_cpu = 0, first = 1;
+	int cpu, this_cpu;
 
-	this_cpu = stap();
-
-	if (!S390_lowcore.prefixreg_save_area)
-		first = 0;
+	this_cpu = smp_find_processor_id(stap());
+	add_elf_notes(this_cpu);
 	for_each_online_cpu(cpu) {
-		if (first) {
-			add_elf_notes(cpu);
-			first = 0;
+		if (cpu == this_cpu)
+			continue;
+		if (smp_store_status(cpu))
 			continue;
-		}
-		phys_cpu = store_status_next(phys_cpu, this_cpu);
-		if (phys_cpu == -1)
-			break;
 		add_elf_notes(cpu);
-		phys_cpu++;
 	}
 	/* Copy dump CPU store status info to absolute zero */
 	memcpy((void *) SAVE_AREA_BASE, (void *) sa, sizeof(struct save_area));
@@ -255,5 +226,5 @@ void machine_kexec(struct kimage *image)
 		return;
 	tracer_disable();
 	smp_send_stop();
-	smp_switch_to_ipl_cpu(__machine_kexec, image);
+	smp_call_ipl_cpu(__machine_kexec, image);
 }