4xx tlbmiss renables interrupts while in kgdb

[David Blythe <blythe@routefree.com>]

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The 4xx tlbmiss handler reenables interrupts while handling a page
fault.  Sometimes kgdb generates faults (that are ignored) while
grubbing around in memory for backtraces and such and has the side
effect of leaving interrupts enabled.  Makes debugging drivers more
entertaining.

Here is a small, but not particularly elegant patch to fix it (against
the mvista 010216 release for the 405).
	david

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Index: arch/ppc/mm/4xx_tlb.c
===================================================================
diff -u -r1.2 4xx_tlb.c
--- arch/ppc/mm/4xx_tlb.c	2001/03/16 20:18:16	1.2
+++ arch/ppc/mm/4xx_tlb.c	2001/04/13 23:27:12
@@ -50,6 +50,9 @@


 /* Global Variables */
+#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
+extern void (*debugger_fault_handler)(struct pt_regs *);
+#endif

 static pin_entry_t    pin_table[PPC4XX_TLB_SIZE];
 static unsigned long  tlb_next_replace = 0;
@@ -347,6 +350,10 @@
 	dtlb_miss_count++;

 	if (tlbMiss(regs, badaddr, wasWrite, 1)) {
+#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
+		/* don't enable interrupts while in the debugger */
+		if (!debugger_fault_handler)
+#endif
 		sti();
 		do_page_fault(regs, badaddr, wasWrite);
 		cli();
@@ -362,6 +369,9 @@
 	itlb_miss_count++;

 	if (!current) {
+#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
+		if (!debugger_fault_handler)
+#endif
 		sti();
 		bad_page_fault(regs, regs->nip);
 		cli();
@@ -369,6 +379,9 @@
 	}

 	if (tlbMiss(regs, regs->nip, 0, 1)) {
+#if defined(CONFIG_XMON) || defined(CONFIG_KGDB)
+		if (!debugger_fault_handler)
+#endif
 		sti();
 		do_page_fault(regs, regs->nip, 0);
 		cli();