1 files changed, 64 insertions, 11 deletions

diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c
index 9c7419e459d6..54bd1b2fb4c0 100644
--- a/arch/x86/kernel/cpu/mcheck/mce.c
+++ b/arch/x86/kernel/cpu/mcheck/mce.c
@@ -204,6 +204,9 @@ static void print_mce_tail(void)
 
 static atomic_t mce_paniced;
 
+static int fake_panic;
+static atomic_t mce_fake_paniced;
+
 /* Panic in progress. Enable interrupts and wait for final IPI */
 static void wait_for_panic(void)
 {
@@ -221,15 +224,21 @@ static void mce_panic(char *msg, struct mce *final, char *exp)
 {
         int i;
 
-        /*
-         * Make sure only one CPU runs in machine check panic
-         */
-        if (atomic_inc_return(&mce_paniced) > 1)
-                wait_for_panic();
-        barrier();
+        if (!fake_panic) {
+                /*
+                 * Make sure only one CPU runs in machine check panic
+                 */
+                if (atomic_inc_return(&mce_paniced) > 1)
+                        wait_for_panic();
+                barrier();
 
-        bust_spinlocks(1);
-        console_verbose();
+                bust_spinlocks(1);
+                console_verbose();
+        } else {
+                /* Don't log too much for fake panic */
+                if (atomic_inc_return(&mce_fake_paniced) > 1)
+                        return;
+        }
         print_mce_head();
         /* First print corrected ones that are still unlogged */
         for (i = 0; i < MCE_LOG_LEN; i++) {
@@ -256,9 +265,12 @@ static void mce_panic(char *msg, struct mce *final, char *exp)
         print_mce_tail();
         if (exp)
                 printk(KERN_EMERG "Machine check: %s\n", exp);
-        if (panic_timeout == 0)
-                panic_timeout = mce_panic_timeout;
-        panic(msg);
+        if (!fake_panic) {
+                if (panic_timeout == 0)
+                        panic_timeout = mce_panic_timeout;
+                panic(msg);
+        } else
+                printk(KERN_EMERG "Fake kernel panic: %s\n", msg);
 }
 
 /* Support code for software error injection */
@@ -2015,4 +2027,45 @@ struct dentry *mce_get_debugfs_dir(void)
 
         return dmce;
 }
+
+static void mce_reset(void)
+{
+        cpu_missing = 0;
+        atomic_set(&mce_fake_paniced, 0);
+        atomic_set(&mce_executing, 0);
+        atomic_set(&mce_callin, 0);
+        atomic_set(&global_nwo, 0);
+}
+
+static int fake_panic_get(void *data, u64 *val)
+{
+        *val = fake_panic;
+        return 0;
+}
+
+static int fake_panic_set(void *data, u64 val)
+{
+        mce_reset();
+        fake_panic = val;
+        return 0;
+}
+
+DEFINE_SIMPLE_ATTRIBUTE(fake_panic_fops, fake_panic_get,
+                        fake_panic_set, "%llu\n");
+
+static int __init mce_debugfs_init(void)
+{
+        struct dentry *dmce, *ffake_panic;
+
+        dmce = mce_get_debugfs_dir();
+        if (!dmce)
+                return -ENOMEM;
+        ffake_panic = debugfs_create_file("fake_panic", 0444, dmce, NULL,
+                                          &fake_panic_fops);
+        if (!ffake_panic)
+                return -ENOMEM;
+
+        return 0;
+}
+late_initcall(mce_debugfs_init);
 #endif