MIPS: Trap exception handling fixes

2a0b24f56c2492b932f1aed617ae80fb23500d21 broke Trap exception handling in
the standard MIPS mode.  Additionally the microMIPS-mode trap code mask is
wrong, as it's a 4-bit field.  Here's a fix.

Signed-off-by: Maciej W. Rozycki <macro@codesourcery.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/5309/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

1 files changed, 15 insertions, 13 deletions

diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index e3be67012d78..a75ae40184aa 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -897,22 +897,24 @@ out_sigsegv:
 
 asmlinkage void do_tr(struct pt_regs *regs)
 {
-        unsigned int opcode, tcode = 0;
+        u32 opcode, tcode = 0;
         u16 instr[2];
-        unsigned long epc = exception_epc(regs);
+        unsigned long epc = msk_isa16_mode(exception_epc(regs));
 
-        if ((__get_user(instr[0], (u16 __user *)msk_isa16_mode(epc))) ||
-                (__get_user(instr[1], (u16 __user *)msk_isa16_mode(epc + 2))))
+        if (get_isa16_mode(regs->cp0_epc)) {
+                if (__get_user(instr[0], (u16 __user *)(epc + 0)) ||
+                    __get_user(instr[1], (u16 __user *)(epc + 2)))
                         goto out_sigsegv;
-        opcode = (instr[0] << 16) | instr[1];
-
-        /* Immediate versions don't provide a code.  */
-        if (!(opcode & OPCODE)) {
-                if (get_isa16_mode(regs->cp0_epc))
-                        /* microMIPS */
-                        tcode = (opcode >> 12) & 0x1f;
-                else
-                        tcode = ((opcode >> 6) & ((1 << 10) - 1));
+                opcode = (instr[0] << 16) | instr[1];
+                /* Immediate versions don't provide a code.  */
+                if (!(opcode & OPCODE))
+                        tcode = (opcode >> 12) & ((1 << 4) - 1);
+        } else {
+                if (__get_user(opcode, (u32 __user *)epc))
+                        goto out_sigsegv;
+                /* Immediate versions don't provide a code.  */
+                if (!(opcode & OPCODE))
+                        tcode = (opcode >> 6) & ((1 << 10) - 1);
         }
 
         do_trap_or_bp(regs, tcode, "Trap");