s390: simplify disabled_wait

The disabled_wait() function uses its argument as the PSW address when
it stops the CPU with a wait PSW that is disabled for interrupts.
The different callers sometimes use a specific number like 0xdeadbeef
to indicate a specific failure, the early boot code uses 0 and some
other calls sites use __builtin_return_address(0).

At the time a dump is created the current PSW and the registers of a
CPU are written to lowcore to make them avaiable to the dump analysis
tool. For a CPU stopped with disabled_wait the PSW and the registers
do not really make sense together, the PSW address does not point to
the function the registers belong to.

Simplify disabled_wait() by using _THIS_IP_ for the PSW address and
drop the argument to the function.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/boot/als.c

@@ -99,7 +99,7 @@ static void facility_mismatch(void)
 	print_machine_type();
 	print_missing_facilities();
 	sclp_early_printk("See Principles of Operations for facility bits\n");
-	disabled_wait(0x8badcccc);
+	disabled_wait();
 }
 
 void verify_facilities(void)

arch/s390/boot/startup.c

@@ -57,7 +57,7 @@ void error(char *x)
 	sclp_early_printk(x);
 	sclp_early_printk("\n\n -- System halted");
 
-	disabled_wait(0xdeadbeef);
+	disabled_wait();
 }
 
 #ifdef CONFIG_KERNEL_UNCOMPRESSED

arch/s390/include/asm/processor.h

@@ -315,12 +315,12 @@ void enabled_wait(void);
 /*
  * Function to drop a processor into disabled wait state
  */
-static inline void __noreturn disabled_wait(unsigned long code)
+static inline void __noreturn disabled_wait(void)
 {
 	psw_t psw;
 
 	psw.mask = PSW_MASK_BASE | PSW_MASK_WAIT | PSW_MASK_BA | PSW_MASK_EA;
-	psw.addr = code;
+	psw.addr = _THIS_IP_;
 	__load_psw(psw);
 	while (1);
 }

arch/s390/kernel/early.c

@@ -141,7 +141,7 @@ static void early_pgm_check_handler(void)
 	addr = S390_lowcore.program_old_psw.addr;
 	fixup = s390_search_extables(addr);
 	if (!fixup)
-		disabled_wait(0);
+		disabled_wait();
 	/* Disable low address protection before storing into lowcore. */
 	__ctl_store(cr0, 0, 0);
 	cr0_new = cr0 & ~(1UL << 28);
@@ -298,7 +298,7 @@ static void __init check_image_bootable(void)
 	sclp_early_printk("Linux kernel boot failure: An attempt to boot a vmlinux ELF image failed.\n");
 	sclp_early_printk("This image does not contain all parts necessary for starting up. Use\n");
 	sclp_early_printk("bzImage or arch/s390/boot/compressed/vmlinux instead.\n");
-	disabled_wait(0xbadb007);
+	disabled_wait();
 }
 
 void __init startup_init(void)

arch/s390/kernel/early_nobss.c

@@ -25,7 +25,7 @@ static void __init reset_tod_clock(void)
 		return;
 	/* TOD clock not running. Set the clock to Unix Epoch. */
 	if (set_tod_clock(TOD_UNIX_EPOCH) != 0 || store_tod_clock(&time) != 0)
-		disabled_wait(0);
+		disabled_wait();
 
 	memset(tod_clock_base, 0, 16);
 	*(__u64 *) &tod_clock_base[1] = TOD_UNIX_EPOCH;

arch/s390/kernel/ipl.c

@@ -920,7 +920,7 @@ static void __reipl_run(void *unused)
 	case IPL_TYPE_FCP_DUMP:
 		break;
 	}
-	disabled_wait((unsigned long) __builtin_return_address(0));
+	disabled_wait();
 }
 
 static void reipl_run(struct shutdown_trigger *trigger)
@@ -1375,7 +1375,7 @@ static void stop_run(struct shutdown_trigger *trigger)
 {
 	if (strcmp(trigger->name, ON_PANIC_STR) == 0 ||
 	    strcmp(trigger->name, ON_RESTART_STR) == 0)
-		disabled_wait((unsigned long) __builtin_return_address(0));
+		disabled_wait();
 	smp_stop_cpu();
 }
 

arch/s390/kernel/machine_kexec.c

@@ -96,7 +96,7 @@ static void __do_machine_kdump(void *image)
 	start_kdump(1);
 
 	/* Die if start_kdump returns */
-	disabled_wait((unsigned long) __builtin_return_address(0));
+	disabled_wait();
 }
 
 /*
@@ -284,7 +284,7 @@ static void __do_machine_kexec(void *data)
 	(*data_mover)(&image->head, image->start);
 
 	/* Die if kexec returns */
-	disabled_wait((unsigned long) __builtin_return_address(0));
+	disabled_wait();
 }
 
 /*

arch/s390/kernel/nmi.c

@@ -125,7 +125,7 @@ void nmi_free_per_cpu(struct lowcore *lc)
 static notrace void s390_handle_damage(void)
 {
 	smp_emergency_stop();
-	disabled_wait((unsigned long) __builtin_return_address(0));
+	disabled_wait();
 	while (1);
 }
 NOKPROBE_SYMBOL(s390_handle_damage);

kernel/panic.c

@@ -318,12 +318,7 @@ void panic(const char *fmt, ...)
 	}
 #endif
 #if defined(CONFIG_S390)
-	{
+	disabled_wait();
-		unsigned long caller;
-
-		caller = (unsigned long)__builtin_return_address(0);
-		disabled_wait(caller);
-	}
 #endif
 	pr_emerg("---[ end Kernel panic - not syncing: %s ]---\n", buf);
 	local_irq_enable();