[PATCH] ppc32: handle access to non-present IO ports on 8xx

This adds exception table entries for I/O instructions on and
changes MachineCheckException() slightly to cover 8xx specifics (on
8xx the MCE can be generated while executing the IO access instruction
itself, which is not the case on PowerMac's, as the comment on traps.c
details).

Signed-off-by: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/ppc/kernel/traps.c b/arch/ppc/kernel/traps.c
index 16adde6b429d..42d980e82bdc 100644
--- a/arch/ppc/kernel/traps.c
+++ b/arch/ppc/kernel/traps.c
@@ -159,7 +159,7 @@ void _exception(int signr, struct pt_regs *regs, int code, unsigned long addr)
  */
 static inline int check_io_access(struct pt_regs *regs)
 {
-#ifdef CONFIG_PPC_PMAC
+#if defined CONFIG_PPC_PMAC || defined CONFIG_8xx
         unsigned long msr = regs->msr;
         const struct exception_table_entry *entry;
         unsigned int *nip = (unsigned int *)regs->nip;
@@ -178,7 +178,11 @@ static inline int check_io_access(struct pt_regs *regs)
                         nip -= 2;
                 else if (*nip == 0x4c00012c)    /* isync */
                         --nip;
-                if (*nip == 0x7c0004ac || (*nip >> 26) == 3) {
+                /* eieio from I/O string functions */
+                else if ((*nip) == 0x7c0006ac || *(nip+1) == 0x7c0006ac)
+                        nip += 2;
+                if (*nip == 0x7c0004ac || (*nip >> 26) == 3 ||
+                        (*(nip+1) >> 26) == 3) {
                         /* sync or twi */
                         unsigned int rb;