MIPS: kernel: Prepare the JR instruction for emulation on MIPS R6

The MIPS R6 JR instruction is an alias to the JALR one, so it may
need emulation for non-R6 userlands.

Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
index 4d7d99d601cc..5736949896d1 100644
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -417,6 +417,8 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
                         regs->regs[insn.r_format.rd] = epc + 8;
                         /* Fall through */
                 case jr_op:
+                        if (NO_R6EMU && insn.r_format.func == jr_op)
+                                goto sigill_r6;
                         regs->cp0_epc = regs->regs[insn.r_format.rs];
                         break;
                 }
@@ -477,7 +479,7 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
 
                 case bposge32_op:
                         if (!cpu_has_dsp)
-                                goto sigill;
+                                goto sigill_dsp;
 
                         dspcontrol = rddsp(0x01);
 
@@ -631,10 +633,15 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
 
         return ret;
 
-sigill:
+sigill_dsp:
         printk("%s: DSP branch but not DSP ASE - sending SIGBUS.\n", current->comm);
         force_sig(SIGBUS, current);
         return -EFAULT;
+sigill_r6:
+        pr_info("%s: R2 branch but r2-to-r6 emulator is not preset - sending SIGILL.\n",
+                current->comm);
+        force_sig(SIGILL, current);
+        return -EFAULT;
 }
 EXPORT_SYMBOL_GPL(__compute_return_epc_for_insn);