Re: one problem about using kdb 'ss' command

Keith Owens (on Tue, 27 Feb 2007 00:42:54 +1100) wrote:
>"Zhou, Water" (on Mon, 26 Feb 2007 14:13:24 +0800) wrote:
>>    Entering kdb (current=3D0xc460b550, pid 1125) duo to Breakpoint @0xc016ca90
>>    kdb> ss
>>
>>    kdb_ss: pt_regs not available
>>
>>I think the problem is because of get_irq_regs() inline function
>>return NULL when the breakpoint is touched. I don't know why ?
>
>Correct, there are a couple of paths that do not call set_irq_regs().
>Could you try this patch, it is against kdb-v4.4-2.6.20-common-4 but
>should apply to 2.6.19 as well.  The patch compiles but I will not be
>able to test it for for several hours.

After testing, this is the correct patch.  It is included in
kdb-v4.4-2.6.20-common-5.

Index: linux/kdb/kdbmain.c
===================================================================
--- linux.orig/kdb/kdbmain.c	2007-02-27 10:51:18.403100729 +1100
+++ linux/kdb/kdbmain.c	2007-02-27 10:44:43.146860775 +1100
@@ -1735,7 +1735,8 @@ kdb(kdb_reason_t reason, int error, stru
 	kdb_intstate_t int_state;	/* Interrupt state */
 	kdb_reason_t reason2 = reason;
 	int result = 0;	/* Default is kdb did not handle it */
-	int ss_event;
+	int ss_event, old_regs_saved = 0;
+	struct pt_regs *old_regs = NULL;
 	kdb_dbtrap_t db_result=KDB_DB_NOBPT;
 	preempt_disable();
 	atomic_inc(&kdb_event);
@@ -1748,6 +1749,23 @@ kdb(kdb_reason_t reason, int error, stru
 	default:
 		break;
 	}
+	switch(reason) {
+	case KDB_REASON_ENTER:
+	case KDB_REASON_ENTER_SLAVE:
+	case KDB_REASON_BREAK:
+	case KDB_REASON_DEBUG:
+	case KDB_REASON_OOPS:
+	case KDB_REASON_SWITCH:
+	case KDB_REASON_KEYBOARD:
+	case KDB_REASON_NMI:
+		if (regs && regs != get_irq_regs()) {
+			old_regs = set_irq_regs(regs);
+			old_regs_saved = 1;
+		}
+		break;
+	default:
+		break;
+	}
 	if (kdb_continue_catastrophic > 2) {
 		kdb_printf("kdb_continue_catastrophic is out of range, setting to 2\n");
 		kdb_continue_catastrophic = 2;
@@ -2060,6 +2078,8 @@ kdb(kdb_reason_t reason, int error, stru
 	if (!(KDB_STATE(DOING_SS) || KDB_STATE(SSBPT) || KDB_STATE(RECURSE))) {
 		KDB_DEBUG_STATE("kdb 15", result);
 		kdb_bp_install_local(regs);
+		if (old_regs_saved)
+			set_irq_regs(old_regs);
 		KDB_STATE_CLEAR(KDB_CONTROL);
 	}
 

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