[PATCH v3 2/2] powerpc32: fix check_io_access()

[Christophe Leroy]

On processors like the 8xx, the machine check exception can also
happen directly on the load/store instruction itself, so that case
needs to be handled as well

Signed-off-by: Christophe Leroy <christophe.le...@c-s.fr>
---
 arch/powerpc/include/asm/ppc-opcode.h |  1 +
 arch/powerpc/kernel/traps.c           | 13 +++++++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/ppc-opcode.h 
b/arch/powerpc/include/asm/ppc-opcode.h
index 37e7b9d..5e613b8 100644
--- a/arch/powerpc/include/asm/ppc-opcode.h
+++ b/arch/powerpc/include/asm/ppc-opcode.h
@@ -84,6 +84,7 @@
 /* opcode and xopcode for instructions */
 #define OP_TRAP 3
 #define OP_TRAP_64 2
+#define OP_31          31
 
 #define OP_31_XOP_TRAP      4
 #define OP_31_XOP_LWZX      23
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 255f5cc..27f1a36 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -334,6 +334,7 @@ static inline int check_io_access(struct pt_regs *regs)
 
        if (((msr & 0xffff0000) == 0 || (msr & (0x80000 | 0x40000)))
            && (entry = search_exception_tables(regs->nip)) != NULL) {
+               int op, xop;
                /*
                 * Check that it's a sync instruction, or somewhere
                 * in the twi; isync; nop sequence that inb/inw/inl uses.
@@ -346,10 +347,18 @@ static inline int check_io_access(struct pt_regs *regs)
                        nip -= 2;
                else if (*nip == PPC_INST_ISYNC)
                        --nip;
-               if (*nip == PPC_INST_SYNC || (*nip >> 26) == OP_TRAP) {
+               if (*nip == PPC_INST_SYNC || (*nip >> 26) == OP_TRAP)
+                       --nip;
+               op = *nip >> 26;
+               xop = (*nip >> 1) & 0x3ff;
+               if (op == OP_LWZ || op == OP_LBZ || op == OP_STW ||
+                   op == OP_STB || op == OP_LHZ || op == OP_STH ||
+                   (op == OP_31 &&
+                    (xop == OP_31_XOP_LBZX || xop == OP_31_XOP_LHBRX ||
+                     xop == OP_31_XOP_LWBRX || xop == OP_31_XOP_STBX ||
+                     xop == OP_31_XOP_STHBRX || xop == OP_31_XOP_STWBRX))) {
                        unsigned int rb;
 
-                       --nip;
                        rb = (*nip >> 11) & 0x1f;
                        printk(KERN_DEBUG "%s bad port %lx at %p\n",
                               (*nip & 0x100)? "OUT to": "IN from",
-- 
2.1.0
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