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-rw-r--r--arch/x86/Kconfig.debug12
-rw-r--r--arch/x86/include/asm/smp.h6
-rw-r--r--arch/x86/kernel/Makefile1
-rw-r--r--arch/x86/kernel/nmi_selftest.c179
-rw-r--r--arch/x86/kernel/smpboot.c1
5 files changed, 199 insertions, 0 deletions
diff --git a/arch/x86/Kconfig.debug b/arch/x86/Kconfig.debug
index 4caec1261f1..97da3c17b42 100644
--- a/arch/x86/Kconfig.debug
+++ b/arch/x86/Kconfig.debug
@@ -287,4 +287,16 @@ config DEBUG_STRICT_USER_COPY_CHECKS
If unsure, or if you run an older (pre 4.4) gcc, say N.
+config DEBUG_NMI_SELFTEST
+ bool "NMI Selftest"
+ depends on DEBUG_KERNEL
+ ---help---
+ Enabling this option turns on a quick NMI selftest to verify
+ that the NMI behaves correctly.
+
+ This might help diagnose strange hangs that rely on NMI to
+ function properly.
+
+ If unsure, say N.
+
endmenu
diff --git a/arch/x86/include/asm/smp.h b/arch/x86/include/asm/smp.h
index 73b11bc0ae6..0434c400287 100644
--- a/arch/x86/include/asm/smp.h
+++ b/arch/x86/include/asm/smp.h
@@ -225,5 +225,11 @@ extern int hard_smp_processor_id(void);
#endif /* CONFIG_X86_LOCAL_APIC */
+#ifdef CONFIG_DEBUG_NMI_SELFTEST
+extern void nmi_selftest(void);
+#else
+#define nmi_selftest() do { } while (0)
+#endif
+
#endif /* __ASSEMBLY__ */
#endif /* _ASM_X86_SMP_H */
diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
index 8baca3c4871..02b2f05b371 100644
--- a/arch/x86/kernel/Makefile
+++ b/arch/x86/kernel/Makefile
@@ -80,6 +80,7 @@ obj-$(CONFIG_APB_TIMER) += apb_timer.o
obj-$(CONFIG_AMD_NB) += amd_nb.o
obj-$(CONFIG_DEBUG_RODATA_TEST) += test_rodata.o
obj-$(CONFIG_DEBUG_NX_TEST) += test_nx.o
+obj-$(CONFIG_DEBUG_NMI_SELFTEST) += nmi_selftest.o
obj-$(CONFIG_KVM_GUEST) += kvm.o
obj-$(CONFIG_KVM_CLOCK) += kvmclock.o
diff --git a/arch/x86/kernel/nmi_selftest.c b/arch/x86/kernel/nmi_selftest.c
new file mode 100644
index 00000000000..572adb62225
--- /dev/null
+++ b/arch/x86/kernel/nmi_selftest.c
@@ -0,0 +1,179 @@
+/*
+ * arch/x86/kernel/nmi-selftest.c
+ *
+ * Testsuite for NMI: IPIs
+ *
+ * Started by Don Zickus:
+ * (using lib/locking-selftest.c as a guide)
+ *
+ * Copyright (C) 2011 Red Hat, Inc., Don Zickus <dzickus@redhat.com>
+ */
+
+#include <linux/smp.h>
+#include <linux/cpumask.h>
+#include <linux/delay.h>
+
+#include <asm/apic.h>
+#include <asm/nmi.h>
+
+#define SUCCESS 0
+#define FAILURE 1
+#define TIMEOUT 2
+
+static int nmi_fail;
+
+/* check to see if NMI IPIs work on this machine */
+static DECLARE_BITMAP(nmi_ipi_mask, NR_CPUS) __read_mostly;
+
+static int testcase_total;
+static int testcase_successes;
+static int expected_testcase_failures;
+static int unexpected_testcase_failures;
+static int unexpected_testcase_unknowns;
+
+static int nmi_unk_cb(unsigned int val, struct pt_regs *regs)
+{
+ unexpected_testcase_unknowns++;
+ return NMI_HANDLED;
+}
+
+static void init_nmi_testsuite(void)
+{
+ /* trap all the unknown NMIs we may generate */
+ register_nmi_handler(NMI_UNKNOWN, nmi_unk_cb, 0, "nmi_selftest_unk");
+}
+
+static void cleanup_nmi_testsuite(void)
+{
+ unregister_nmi_handler(NMI_UNKNOWN, "nmi_selftest_unk");
+}
+
+static int test_nmi_ipi_callback(unsigned int val, struct pt_regs *regs)
+{
+ int cpu = raw_smp_processor_id();
+
+ if (cpumask_test_and_clear_cpu(cpu, to_cpumask(nmi_ipi_mask)))
+ return NMI_HANDLED;
+
+ return NMI_DONE;
+}
+
+static void test_nmi_ipi(struct cpumask *mask)
+{
+ unsigned long timeout;
+
+ if (register_nmi_handler(NMI_LOCAL, test_nmi_ipi_callback,
+ NMI_FLAG_FIRST, "nmi_selftest")) {
+ nmi_fail = FAILURE;
+ return;
+ }
+
+ /* sync above data before sending NMI */
+ wmb();
+
+ apic->send_IPI_mask(mask, NMI_VECTOR);
+
+ /* Don't wait longer than a second */
+ timeout = USEC_PER_SEC;
+ while (!cpumask_empty(mask) && timeout--)
+ udelay(1);
+
+ /* What happens if we timeout, do we still unregister?? */
+ unregister_nmi_handler(NMI_LOCAL, "nmi_selftest");
+
+ if (!timeout)
+ nmi_fail = TIMEOUT;
+ return;
+}
+
+static void remote_ipi(void)
+{
+ cpumask_copy(to_cpumask(nmi_ipi_mask), cpu_online_mask);
+ cpumask_clear_cpu(smp_processor_id(), to_cpumask(nmi_ipi_mask));
+ test_nmi_ipi(to_cpumask(nmi_ipi_mask));
+}
+
+static void local_ipi(void)
+{
+ cpumask_clear(to_cpumask(nmi_ipi_mask));
+ cpumask_set_cpu(smp_processor_id(), to_cpumask(nmi_ipi_mask));
+ test_nmi_ipi(to_cpumask(nmi_ipi_mask));
+}
+
+static void reset_nmi(void)
+{
+ nmi_fail = 0;
+}
+
+static void dotest(void (*testcase_fn)(void), int expected)
+{
+ testcase_fn();
+ /*
+ * Filter out expected failures:
+ */
+ if (nmi_fail != expected) {
+ unexpected_testcase_failures++;
+
+ if (nmi_fail == FAILURE)
+ printk("FAILED |");
+ else if (nmi_fail == TIMEOUT)
+ printk("TIMEOUT|");
+ else
+ printk("ERROR |");
+ dump_stack();
+ } else {
+ testcase_successes++;
+ printk(" ok |");
+ }
+ testcase_total++;
+
+ reset_nmi();
+}
+
+static inline void print_testname(const char *testname)
+{
+ printk("%12s:", testname);
+}
+
+void nmi_selftest(void)
+{
+ init_nmi_testsuite();
+
+ /*
+ * Run the testsuite:
+ */
+ printk("----------------\n");
+ printk("| NMI testsuite:\n");
+ printk("--------------------\n");
+
+ print_testname("remote IPI");
+ dotest(remote_ipi, SUCCESS);
+ printk("\n");
+ print_testname("local IPI");
+ dotest(local_ipi, SUCCESS);
+ printk("\n");
+
+ cleanup_nmi_testsuite();
+
+ if (unexpected_testcase_failures) {
+ printk("--------------------\n");
+ printk("BUG: %3d unexpected failures (out of %3d) - debugging disabled! |\n",
+ unexpected_testcase_failures, testcase_total);
+ printk("-----------------------------------------------------------------\n");
+ } else if (expected_testcase_failures && testcase_successes) {
+ printk("--------------------\n");
+ printk("%3d out of %3d testcases failed, as expected. |\n",
+ expected_testcase_failures, testcase_total);
+ printk("----------------------------------------------------\n");
+ } else if (expected_testcase_failures && !testcase_successes) {
+ printk("--------------------\n");
+ printk("All %3d testcases failed, as expected. |\n",
+ expected_testcase_failures);
+ printk("----------------------------------------\n");
+ } else {
+ printk("--------------------\n");
+ printk("Good, all %3d testcases passed! |\n",
+ testcase_successes);
+ printk("---------------------------------\n");
+ }
+}
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 9f548cb4a95..19277817eff 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1142,6 +1142,7 @@ void __init native_smp_cpus_done(unsigned int max_cpus)
{
pr_debug("Boot done.\n");
+ nmi_selftest();
impress_friends();
#ifdef CONFIG_X86_IO_APIC
setup_ioapic_dest();