1 files changed, 40 insertions, 16 deletions

diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 67435b9bf98d..f77a104abf9f 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -29,6 +29,7 @@
 #include <linux/nmi.h>
 #include <linux/ctype.h>
 
+#include <asm/debugfs.h>
 #include <asm/ptrace.h>
 #include <asm/smp.h>
 #include <asm/string.h>
@@ -77,6 +78,7 @@ static int xmon_gate;
 #endif /* CONFIG_SMP */
 
 static unsigned long in_xmon __read_mostly = 0;
+static int xmon_on = IS_ENABLED(CONFIG_XMON_DEFAULT);
 
 static unsigned long adrs;
 static int size = 1;
@@ -185,8 +187,6 @@ static void dump_tlb_44x(void);
 static void dump_tlb_book3e(void);
 #endif
 
-static int xmon_no_auto_backtrace;
-
 #ifdef CONFIG_PPC64
 #define REG		"%.16lx"
 #else
@@ -891,10 +891,7 @@ cmds(struct pt_regs *excp)
 	last_cmd = NULL;
 	xmon_regs = excp;
 
-	if (!xmon_no_auto_backtrace) {
-		xmon_no_auto_backtrace = 1;
-		xmon_show_stack(excp->gpr[1], excp->link, excp->nip);
-	}
+	xmon_show_stack(excp->gpr[1], excp->link, excp->nip);
 
 	for(;;) {
 #ifdef CONFIG_SMP
@@ -3392,6 +3389,8 @@ static void sysrq_handle_xmon(int key)
 	/* ensure xmon is enabled */
 	xmon_init(1);
 	debugger(get_irq_regs());
+	if (!xmon_on)
+		xmon_init(0);
 }
 
 static struct sysrq_key_op sysrq_xmon_op = {
@@ -3405,10 +3404,37 @@ static int __init setup_xmon_sysrq(void)
 	register_sysrq_key('x', &sysrq_xmon_op);
 	return 0;
 }
-__initcall(setup_xmon_sysrq);
+device_initcall(setup_xmon_sysrq);
 #endif /* CONFIG_MAGIC_SYSRQ */
 
-static int __initdata xmon_early, xmon_off;
+#ifdef CONFIG_DEBUG_FS
+static int xmon_dbgfs_set(void *data, u64 val)
+{
+	xmon_on = !!val;
+	xmon_init(xmon_on);
+
+	return 0;
+}
+
+static int xmon_dbgfs_get(void *data, u64 *val)
+{
+	*val = xmon_on;
+	return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(xmon_dbgfs_ops, xmon_dbgfs_get,
+			xmon_dbgfs_set, "%llu\n");
+
+static int __init setup_xmon_dbgfs(void)
+{
+	debugfs_create_file("xmon", 0600, powerpc_debugfs_root, NULL,
+				&xmon_dbgfs_ops);
+	return 0;
+}
+device_initcall(setup_xmon_dbgfs);
+#endif /* CONFIG_DEBUG_FS */
+
+static int xmon_early __initdata;
 
 static int __init early_parse_xmon(char *p)
 {
@@ -3416,12 +3442,12 @@ static int __init early_parse_xmon(char *p)
 		/* just "xmon" is equivalent to "xmon=early" */
 		xmon_init(1);
 		xmon_early = 1;
-	} else if (strncmp(p, "on", 2) == 0)
+		xmon_on = 1;
+	} else if (strncmp(p, "on", 2) == 0) {
 		xmon_init(1);
-	else if (strncmp(p, "off", 3) == 0)
-		xmon_off = 1;
-	else if (strncmp(p, "nobt", 4) == 0)
-		xmon_no_auto_backtrace = 1;
+		xmon_on = 1;
+	} else if (strncmp(p, "off", 3) == 0)
+		xmon_on = 0;
 	else
 		return 1;
 
@@ -3431,10 +3457,8 @@ early_param("xmon", early_parse_xmon);
 
 void __init xmon_setup(void)
 {
-#ifdef CONFIG_XMON_DEFAULT
-	if (!xmon_off)
+	if (xmon_on)
 		xmon_init(1);
-#endif
 	if (xmon_early)
 		debugger(NULL);
 }