powerpc: Remove call sites of MSG_ALL_BUT_SELF

The only user of MSG_ALL_BUT_SELF in the whole kernel tree is powerpc,
and it only uses it to start the debugger. Both debuggers always call
smp_send_debugger_break with MSG_ALL_BUT_SELF, and only mpic can do
anything more optimal than a loop over all online cpus, but all message
passing implementations have to code for this special delivery target.

Convert smp_send_debugger_break to take void and loop calling the smp_ops
message_pass function for each of the other cpus in the online cpumask.

Use raw_smp_processor_id() because we are either entering the debugger
or trying to start kdump and the additional warning it not useful were
it to trigger.
Signed-off-by: Milton Miller <miltonm@bga.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

arch/powerpc/include/asm/smp.h

@@ -35,7 +35,7 @@ extern void cpu_die(void);
 
 #ifdef CONFIG_SMP
 
-extern void smp_send_debugger_break(int cpu);
+extern void smp_send_debugger_break(void);
 extern void smp_message_recv(int);
 extern void start_secondary_resume(void);
 

arch/powerpc/kernel/kgdb.c

@@ -109,7 +109,7 @@ static int kgdb_call_nmi_hook(struct pt_regs *regs)
 #ifdef CONFIG_SMP
 void kgdb_roundup_cpus(unsigned long flags)
 {
-	smp_send_debugger_break(MSG_ALL_BUT_SELF);
+	smp_send_debugger_break();
 }
 #endif
 

arch/powerpc/kernel/smp.c

@@ -218,10 +218,17 @@ void arch_send_call_function_ipi_mask(const struct cpumask *mask)
 		smp_ops->message_pass(cpu, PPC_MSG_CALL_FUNCTION);
 }
 
-#ifdef CONFIG_DEBUGGER
-void smp_send_debugger_break(int cpu)
+#if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC)
+void smp_send_debugger_break(void)
 {
-	if (likely(smp_ops))
+	int cpu;
+	int me = raw_smp_processor_id();
+
+	if (unlikely(!smp_ops))
+		return;
+
+	for_each_online_cpu(cpu)
+		if (cpu != me)
 			smp_ops->message_pass(cpu, PPC_MSG_DEBUGGER_BREAK);
 }
 #endif
@@ -230,9 +237,9 @@ void smp_send_debugger_break(int cpu)
 void crash_send_ipi(void (*crash_ipi_callback)(struct pt_regs *))
 {
 	crash_ipi_function_ptr = crash_ipi_callback;
-	if (crash_ipi_callback && smp_ops) {
+	if (crash_ipi_callback) {
 		mb();
-		smp_ops->message_pass(MSG_ALL_BUT_SELF, PPC_MSG_DEBUGGER_BREAK);
+		smp_send_debugger_break();
 	}
 }
 #endif

arch/powerpc/xmon/xmon.c

@@ -437,7 +437,7 @@ static int xmon_core(struct pt_regs *regs, int fromipi)
 		xmon_owner = cpu;
 		mb();
 		if (ncpus > 1) {
-			smp_send_debugger_break(MSG_ALL_BUT_SELF);
+			smp_send_debugger_break();
 			/* wait for other cpus to come in */
 			for (timeout = 100000000; timeout != 0; --timeout) {
 				if (cpumask_weight(&cpus_in_xmon) >= ncpus)