[PATCH 11/15] KDB: add new system NMI entry code to KDB

[Mike Travis]

This patch adds a new "KDB_REASON" code (KDB_REASON_SYSTEM_NMI).
This is purely cosmetic to distinguish it from the other various
reasons that NMI may occur and are usually after an error occurred.
Also the dumping of registers is not done to more closely match
what happens when KDB is entered manually via the sysreq 'g' key.

Reviewed-by: Dimitri Sivanich <sivanich@xxxxxxx>
Signed-off-by: Mike Travis <travis@xxxxxxx>
---
 include/linux/kdb.h             |    1 +
 include/linux/kgdb.h            |    1 +
 kernel/debug/debug_core.c       |    5 +++++
 kernel/debug/kdb/kdb_debugger.c |    5 ++++-
 kernel/debug/kdb/kdb_main.c     |    3 +++
 5 files changed, 14 insertions(+), 1 deletion(-)

--- linux.orig/include/linux/kdb.h
+++ linux/include/linux/kdb.h
@@ -110,6 +110,7 @@ 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;
--- linux.orig/include/linux/kgdb.h
+++ linux/include/linux/kgdb.h
@@ -52,6 +52,7 @@ extern int kgdb_connected;
 extern int kgdb_io_module_registered;
 
 extern atomic_t			kgdb_setting_breakpoint;
+extern atomic_t			kgdb_system_nmi;
 extern atomic_t			kgdb_cpu_doing_single_step;
 
 extern struct task_struct	*kgdb_usethread;
--- linux.orig/kernel/debug/debug_core.c
+++ linux/kernel/debug/debug_core.c
@@ -125,6 +125,7 @@ static atomic_t			masters_in_kgdb;
 static atomic_t			slaves_in_kgdb;
 static atomic_t			kgdb_break_tasklet_var;
 atomic_t			kgdb_setting_breakpoint;
+atomic_t			kgdb_system_nmi;
 
 struct task_struct		*kgdb_usethread;
 struct task_struct		*kgdb_contthread;
@@ -760,7 +761,11 @@ int kgdb_nmicallin(int cpu, int trapnr,
 
 		/* Indicate there are slaves waiting */
 		kgdb_info[cpu].send_ready = send_ready;
+
+		/* Use new reason code "SYSTEM_NMI" */
+		atomic_inc(&kgdb_system_nmi);
 		kgdb_cpu_enter(ks, regs, DCPU_WANT_MASTER);
+		atomic_dec(&kgdb_system_nmi);
 		kgdb_do_roundup = save_kgdb_do_roundup;
 		kgdb_info[cpu].send_ready = NULL;
 
--- linux.orig/kernel/debug/kdb/kdb_debugger.c
+++ linux/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 (atomic_read(&kgdb_system_nmi))
+		reason = KDB_REASON_SYSTEM_NMI;
+
+	else if (in_nmi())
 		reason = KDB_REASON_NMI;
 
 	for (i = 0, bp = kdb_breakpoints; i < KDB_MAXBPT; i++, bp++) {
--- linux.orig/kernel/debug/kdb/kdb_main.c
+++ linux/kernel/debug/kdb/kdb_main.c
@@ -1216,6 +1216,9 @@ static int kdb_local(kdb_reason_t reason
 			   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",

-- 
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