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
-------------- next part --------------
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();
