summaryrefslogtreecommitdiffstats
diff options
context:
space:
mode:
-rw-r--r--arch/x86/kernel/nmi.c29
1 files changed, 28 insertions, 1 deletions
diff --git a/arch/x86/kernel/nmi.c b/arch/x86/kernel/nmi.c
index 60308053fdb2..e9bae4c2f2dd 100644
--- a/arch/x86/kernel/nmi.c
+++ b/arch/x86/kernel/nmi.c
@@ -14,6 +14,7 @@
#include <linux/kprobes.h>
#include <linux/kdebug.h>
#include <linux/nmi.h>
+#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/hardirq.h>
#include <linux/slab.h>
@@ -82,6 +83,15 @@ __setup("unknown_nmi_panic", setup_unknown_nmi_panic);
#define nmi_to_desc(type) (&nmi_desc[type])
+static u64 nmi_longest_ns = 1 * NSEC_PER_MSEC;
+static int __init nmi_warning_debugfs(void)
+{
+ debugfs_create_u64("nmi_longest_ns", 0644,
+ arch_debugfs_dir, &nmi_longest_ns);
+ return 0;
+}
+fs_initcall(nmi_warning_debugfs);
+
static int __kprobes nmi_handle(unsigned int type, struct pt_regs *regs, bool b2b)
{
struct nmi_desc *desc = nmi_to_desc(type);
@@ -96,8 +106,25 @@ static int __kprobes nmi_handle(unsigned int type, struct pt_regs *regs, bool b2
* can be latched at any given time. Walk the whole list
* to handle those situations.
*/
- list_for_each_entry_rcu(a, &desc->head, list)
+ list_for_each_entry_rcu(a, &desc->head, list) {
+ u64 before, delta, whole_msecs;
+ int decimal_msecs;
+
+ before = local_clock();
handled += a->handler(type, regs);
+ delta = local_clock() - before;
+
+ if (delta < nmi_longest_ns)
+ continue;
+
+ nmi_longest_ns = delta;
+ whole_msecs = do_div(delta, (1000 * 1000));
+ decimal_msecs = do_div(delta, 1000) % 1000;
+ printk_ratelimited(KERN_INFO
+ "INFO: NMI handler (%ps) took too long to run: "
+ "%lld.%03d msecs\n", a->handler, whole_msecs,
+ decimal_msecs);
+ }
rcu_read_unlock();