sh: Fix PC adjustments for varying opcode length.

There are a few different cases for figuring out how to
size the instruction. We read in the instruction located
at regs->pc - 4 when rewinding the opcode to figure out if
there's a 32-bit opcode before the faulting instruction, with
a default of a - 2 adjustment on a mismatch. In practice this
works for the cases where pc - 4 is just another 16-bit opcode,
or we happen to have a 32-bit and a 16-bit immediately
preceeding the pc value.

In the cases where we aren't rewinding, this is much less ugly..

We also don't bother fixing up the places where we're explicitly
dealing with 16-bit instructions, since this might lead to
confusion regarding the encoding size possibilities on other
CPU variants.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/arch/sh/kernel/process.c b/arch/sh/kernel/process.c
index 209cc9b4218..9005b2f12aa 100644
--- a/arch/sh/kernel/process.c
+++ b/arch/sh/kernel/process.c
@@ -498,7 +498,7 @@ asmlinkage void debug_trap_handler(unsigned long r4, unsigned long r5,
         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
 
         /* Rewind */
-        regs->pc -= instruction_size(regs->pc);
+        regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));
 
         if (notify_die(DIE_TRAP, regs, regs->tra & 0xff,
                        SIGTRAP) == NOTIFY_STOP)
@@ -517,7 +517,7 @@ asmlinkage void bug_trap_handler(unsigned long r4, unsigned long r5,
         struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
 
         /* Rewind */
-        regs->pc -= instruction_size(regs->pc);
+        regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));
 
         if (notify_die(DIE_TRAP, regs, TRAPA_BUG_OPCODE & 0xff,
                        SIGTRAP) == NOTIFY_STOP)