[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>

2 files changed, 131 insertions, 22 deletions

diff --git a/arch/ppc/kernel/misc.S b/arch/ppc/kernel/misc.S
index 3056ede2424d..ae6af29938a1 100644
--- a/arch/ppc/kernel/misc.S
+++ b/arch/ppc/kernel/misc.S
@@ -25,6 +25,11 @@
 #include <asm/thread_info.h>
 #include <asm/asm-offsets.h>
 
+#ifdef CONFIG_8xx
+#define ISYNC_8xx isync
+#else
+#define ISYNC_8xx
+#endif
         .text
 
         .align  5
@@ -800,8 +805,18 @@ _GLOBAL(_insb)
         subi    r4,r4,1
         blelr-
 00:     lbz     r5,0(r3)
-        eieio
-        stbu    r5,1(r4)
+01:     eieio
+02:     stbu    r5,1(r4)
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
@@ -811,8 +826,18 @@ _GLOBAL(_outsb)
         subi    r4,r4,1
         blelr-
 00:     lbzu    r5,1(r4)
-        stb     r5,0(r3)
-        eieio
+01:     stb     r5,0(r3)
+02:     eieio
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
@@ -822,8 +847,18 @@ _GLOBAL(_insw)
         subi    r4,r4,2
         blelr-
 00:     lhbrx   r5,0,r3
-        eieio
-        sthu    r5,2(r4)
+01:     eieio
+02:     sthu    r5,2(r4)
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
@@ -833,8 +868,18 @@ _GLOBAL(_outsw)
         subi    r4,r4,2
         blelr-
 00:     lhzu    r5,2(r4)
-        eieio
-        sthbrx  r5,0,r3
+01:     eieio
+02:     sthbrx  r5,0,r3
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
@@ -844,8 +889,18 @@ _GLOBAL(_insl)
         subi    r4,r4,4
         blelr-
 00:     lwbrx   r5,0,r3
-        eieio
-        stwu    r5,4(r4)
+01:     eieio
+02:     stwu    r5,4(r4)
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
@@ -855,8 +910,18 @@ _GLOBAL(_outsl)
         subi    r4,r4,4
         blelr-
 00:     lwzu    r5,4(r4)
-        stwbrx  r5,0,r3
-        eieio
+01:     stwbrx  r5,0,r3
+02:     eieio
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
@@ -867,8 +932,18 @@ _GLOBAL(_insw_ns)
         subi    r4,r4,2
         blelr-
 00:     lhz     r5,0(r3)
-        eieio
-        sthu    r5,2(r4)
+01:     eieio
+02:     sthu    r5,2(r4)
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
@@ -879,8 +954,18 @@ _GLOBAL(_outsw_ns)
         subi    r4,r4,2
         blelr-
 00:     lhzu    r5,2(r4)
-        sth     r5,0(r3)
-        eieio
+01:     sth     r5,0(r3)
+02:     eieio
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
@@ -891,8 +976,18 @@ _GLOBAL(_insl_ns)
         subi    r4,r4,4
         blelr-
 00:     lwz     r5,0(r3)
-        eieio
-        stwu    r5,4(r4)
+01:     eieio
+02:     stwu    r5,4(r4)
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
@@ -903,8 +998,18 @@ _GLOBAL(_outsl_ns)
         subi    r4,r4,4
         blelr-
 00:     lwzu    r5,4(r4)
-        stw     r5,0(r3)
-        eieio
+01:     stw     r5,0(r3)
+02:     eieio
+        ISYNC_8xx
+        .section .fixup,"ax"
+03:     blr
+        .text
+        .section __ex_table, "a"
+                .align 2
+                .long 00b, 03b
+                .long 01b, 03b
+                .long 02b, 03b
+        .text
         bdnz    00b
         blr
 
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;