x86/UV: Add summary of cpu activity to UV NMI handler

The standard NMI handler dumps the states of all the cpus.  This
includes a full register dump and stack trace.  This can be way
more information than what is needed.  This patch adds a
"summary" dump that is basically a form of the "ps" command.  It
includes the symbolic IP address as well as the command field
and basic process information.

It is enabled when the nmi action is changed to "ips".

Signed-off-by: Mike Travis <travis@sgi.com>
Reviewed-by: Dimitri Sivanich <sivanich@sgi.com>
Reviewed-by: Hedi Berriche <hedi@sgi.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Jason Wessel <jason.wessel@windriver.com>
Link: http://lkml.kernel.org/r/20130923212500.507922930@asylum.americas.sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/platform/uv/uv_nmi.c

@@ -139,6 +139,19 @@ module_param_named(wait_count, uv_nmi_wait_count, int, 0644);
 static int uv_nmi_retry_count = 500;
 module_param_named(retry_count, uv_nmi_retry_count, int, 0644);
 
+/*
+ * Valid NMI Actions:
+ *  "dump"	- dump process stack for each cpu
+ *  "ips"	- dump IP info for each cpu
+ */
+static char uv_nmi_action[8] = "dump";
+module_param_string(action, uv_nmi_action, sizeof(uv_nmi_action), 0644);
+
+static inline bool uv_nmi_action_is(const char *action)
+{
+	return (strncmp(uv_nmi_action, action, strlen(action)) == 0);
+}
+
 /* Setup which NMI support is present in system */
 static void uv_nmi_setup_mmrs(void)
 {
@@ -367,13 +380,38 @@ static void uv_nmi_wait(int master)
 		atomic_read(&uv_nmi_cpus_in_nmi), num_online_cpus());
 }
 
+static void uv_nmi_dump_cpu_ip_hdr(void)
+{
+	printk(KERN_DEFAULT
+		"\nUV: %4s %6s %-32s %s   (Note: PID 0 not listed)\n",
+		"CPU", "PID", "COMMAND", "IP");
+}
+
+static void uv_nmi_dump_cpu_ip(int cpu, struct pt_regs *regs)
+{
+	printk(KERN_DEFAULT "UV: %4d %6d %-32.32s ",
+		cpu, current->pid, current->comm);
+
+	printk_address(regs->ip, 1);
+}
+
 /* Dump this cpu's state */
 static void uv_nmi_dump_state_cpu(int cpu, struct pt_regs *regs)
 {
 	const char *dots = " ................................. ";
 
-	printk(KERN_DEFAULT "UV:%sNMI process trace for CPU %d\n", dots, cpu);
-	show_regs(regs);
+	if (uv_nmi_action_is("ips")) {
+		if (cpu == 0)
+			uv_nmi_dump_cpu_ip_hdr();
+
+		if (current->pid != 0)
+			uv_nmi_dump_cpu_ip(cpu, regs);
+
+	} else if (uv_nmi_action_is("dump")) {
+		printk(KERN_DEFAULT
+			"UV:%sNMI process trace for CPU %d\n", dots, cpu);
+		show_regs(regs);
+	}
 	atomic_set(&uv_cpu_nmi.state, UV_NMI_STATE_DUMP_DONE);
 }
 
@@ -420,7 +458,8 @@ static void uv_nmi_dump_state(int cpu, struct pt_regs *regs, int master)
 		int ignored = 0;
 		int saved_console_loglevel = console_loglevel;
 
-		pr_alert("UV: tracing processes for %d CPUs from CPU %d\n",
+		pr_alert("UV: tracing %s for %d CPUs from CPU %d\n",
+			uv_nmi_action_is("ips") ? "IPs" : "processes",
 			atomic_read(&uv_nmi_cpus_in_nmi), cpu);
 
 		console_loglevel = uv_nmi_loglevel;
@@ -482,7 +521,8 @@ int uv_handle_nmi(unsigned int reason, struct pt_regs *regs)
 	uv_nmi_wait(master);
 
 	/* Dump state of each cpu */
-	uv_nmi_dump_state(cpu, regs, master);
+	if (uv_nmi_action_is("ips") || uv_nmi_action_is("dump"))
+		uv_nmi_dump_state(cpu, regs, master);
 
 	/* Clear per_cpu "in nmi" flag */
 	atomic_set(&uv_cpu_nmi.state, UV_NMI_STATE_OUT);