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

From: Christophe Leroy
Date: Tue May 17 2016 - 08:01:50 EST


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.leroy@xxxxxx>
---
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