6 files changed, 42 insertions, 3 deletions

diff --git a/include/linux/kdb.h b/include/linux/kdb.h
index 7f6fe6e015bc..290db1269c4c 100644
--- a/include/linux/kdb.h
+++ b/include/linux/kdb.h
@@ -109,6 +109,7 @@ typedef enum {
         KDB_REASON_RECURSE,     /* Recursive entry to kdb;
                                  * regs probably valid */
         KDB_REASON_SSTEP,       /* Single Step trap. - regs valid */
+        KDB_REASON_SYSTEM_NMI,  /* In NMI due to SYSTEM cmd; regs valid */
 } kdb_reason_t;
 
 extern int kdb_trap_printk;
diff --git a/include/linux/kgdb.h b/include/linux/kgdb.h
index c6e091bf39a5..dfb4f2ffdaa2 100644
--- a/include/linux/kgdb.h
+++ b/include/linux/kgdb.h
@@ -310,6 +310,7 @@ extern int
 kgdb_handle_exception(int ex_vector, int signo, int err_code,
                       struct pt_regs *regs);
 extern int kgdb_nmicallback(int cpu, void *regs);
+extern int kgdb_nmicallin(int cpu, int trapnr, void *regs, atomic_t *snd_rdy);
 extern void gdbstub_exit(int status);
 
 extern int                      kgdb_single_step;
diff --git a/kernel/debug/debug_core.c b/kernel/debug/debug_core.c
index 0506d447aed2..7d2f35e5df2f 100644
--- a/kernel/debug/debug_core.c
+++ b/kernel/debug/debug_core.c
@@ -575,8 +575,12 @@ return_normal:
                 raw_spin_lock(&dbg_slave_lock);
 
 #ifdef CONFIG_SMP
+        /* If send_ready set, slaves are already waiting */
+        if (ks->send_ready)
+                atomic_set(ks->send_ready, 1);
+
         /* Signal the other CPUs to enter kgdb_wait() */
-        if ((!kgdb_single_step) && kgdb_do_roundup)
+        else if ((!kgdb_single_step) && kgdb_do_roundup)
                 kgdb_roundup_cpus(flags);
 #endif
 
@@ -678,11 +682,11 @@ kgdb_handle_exception(int evector, int signo, int ecode, struct pt_regs *regs)
         if (arch_kgdb_ops.enable_nmi)
                 arch_kgdb_ops.enable_nmi(0);
 
+        memset(ks, 0, sizeof(struct kgdb_state));
         ks->cpu                 = raw_smp_processor_id();
         ks->ex_vector           = evector;
         ks->signo               = signo;
         ks->err_code            = ecode;
-        ks->kgdb_usethreadid    = 0;
         ks->linux_regs          = regs;
 
         if (kgdb_reenter_check(ks))
@@ -732,6 +736,30 @@ int kgdb_nmicallback(int cpu, void *regs)
         return 1;
 }
 
+int kgdb_nmicallin(int cpu, int trapnr, void *regs, atomic_t *send_ready)
+{
+#ifdef CONFIG_SMP
+        if (!kgdb_io_ready(0) || !send_ready)
+                return 1;
+
+        if (kgdb_info[cpu].enter_kgdb == 0) {
+                struct kgdb_state kgdb_var;
+                struct kgdb_state *ks = &kgdb_var;
+
+                memset(ks, 0, sizeof(struct kgdb_state));
+                ks->cpu                 = cpu;
+                ks->ex_vector           = trapnr;
+                ks->signo               = SIGTRAP;
+                ks->err_code            = KGDB_KDB_REASON_SYSTEM_NMI;
+                ks->linux_regs          = regs;
+                ks->send_ready          = send_ready;
+                kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+                return 0;
+        }
+#endif
+        return 1;
+}
+
 static void kgdb_console_write(struct console *co, const char *s,
    unsigned count)
 {
diff --git a/kernel/debug/debug_core.h b/kernel/debug/debug_core.h
index 2235967e78b0..572aa4f5677c 100644
--- a/kernel/debug/debug_core.h
+++ b/kernel/debug/debug_core.h
@@ -26,6 +26,7 @@ struct kgdb_state {
         unsigned long           threadid;
         long                    kgdb_usethreadid;
         struct pt_regs          *linux_regs;
+        atomic_t                *send_ready;
 };
 
 /* Exception state values */
@@ -74,11 +75,13 @@ extern int kdb_stub(struct kgdb_state *ks);
 extern int kdb_parse(const char *cmdstr);
 extern int kdb_common_init_state(struct kgdb_state *ks);
 extern int kdb_common_deinit_state(void);
+#define KGDB_KDB_REASON_SYSTEM_NMI KDB_REASON_SYSTEM_NMI
 #else /* ! CONFIG_KGDB_KDB */
 static inline int kdb_stub(struct kgdb_state *ks)
 {
         return DBG_PASS_EVENT;
 }
+#define KGDB_KDB_REASON_SYSTEM_NMI 0
 #endif /* CONFIG_KGDB_KDB */
 
 #endif /* _DEBUG_CORE_H_ */
diff --git a/kernel/debug/kdb/kdb_debugger.c b/kernel/debug/kdb/kdb_debugger.c
index 328d18ef31e4..8859ca34dcfe 100644
--- a/kernel/debug/kdb/kdb_debugger.c
+++ b/kernel/debug/kdb/kdb_debugger.c
@@ -69,7 +69,10 @@ int kdb_stub(struct kgdb_state *ks)
         if (atomic_read(&kgdb_setting_breakpoint))
                 reason = KDB_REASON_KEYBOARD;
 
-        if (in_nmi())
+        if (ks->err_code == KDB_REASON_SYSTEM_NMI && ks->signo == SIGTRAP)
+                reason = KDB_REASON_SYSTEM_NMI;
+
+        else if (in_nmi())
                 reason = KDB_REASON_NMI;
 
         for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 00eb8f7fbf41..0b097c8a1e50 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1200,6 +1200,9 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs,
                            instruction_pointer(regs));
                 kdb_dumpregs(regs);
                 break;
+        case KDB_REASON_SYSTEM_NMI:
+                kdb_printf("due to System NonMaskable Interrupt\n");
+                break;
         case KDB_REASON_NMI:
                 kdb_printf("due to NonMaskable Interrupt @ "
                            kdb_machreg_fmt "\n",