1 files changed, 40 insertions, 3 deletions

diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c
index f12fde10c8ad..f08a7b4facb9 100644
--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -1142,7 +1142,7 @@ emul:
 
 		case mfhc_op:
 			if (!cpu_has_mips_r2_r6)
-				goto sigill;
+				return SIGILL;
 
 			/* copregister rd -> gpr[rt] */
 			if (MIPSInst_RT(ir) != 0) {
@@ -1153,7 +1153,7 @@ emul:
 
 		case mthc_op:
 			if (!cpu_has_mips_r2_r6)
-				goto sigill;
+				return SIGILL;
 
 			/* copregister rd <- gpr[rt] */
 			SITOHREG(xcp->regs[MIPSInst_RT(ir)], MIPSInst_RD(ir));
@@ -1376,7 +1376,6 @@ branch_common:
 				xcp->regs[MIPSInst_RS(ir)];
 		break;
 	default:
-sigill:
 		return SIGILL;
 	}
 
@@ -2524,6 +2523,35 @@ dcopuop:
 	return 0;
 }
 
+/*
+ * Emulate FPU instructions.
+ *
+ * If we use FPU hardware, then we have been typically called to handle
+ * an unimplemented operation, such as where an operand is a NaN or
+ * denormalized.  In that case exit the emulation loop after a single
+ * iteration so as to let hardware execute any subsequent instructions.
+ *
+ * If we have no FPU hardware or it has been disabled, then continue
+ * emulating floating-point instructions until one of these conditions
+ * has occurred:
+ *
+ * - a non-FPU instruction has been encountered,
+ *
+ * - an attempt to emulate has ended with a signal,
+ *
+ * - the ISA mode has been switched.
+ *
+ * We need to terminate the emulation loop if we got switched to the
+ * MIPS16 mode, whether supported or not, so that we do not attempt
+ * to emulate a MIPS16 instruction as a regular MIPS FPU instruction.
+ * Similarly if we got switched to the microMIPS mode and only the
+ * regular MIPS mode is supported, so that we do not attempt to emulate
+ * a microMIPS instruction as a regular MIPS FPU instruction.  Or if
+ * we got switched to the regular MIPS mode and only the microMIPS mode
+ * is supported, so that we do not attempt to emulate a regular MIPS
+ * instruction that should cause an Address Error exception instead.
+ * For simplicity we always terminate upon an ISA mode switch.
+ */
 int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
 	int has_fpu, void *__user *fault_addr)
 {
@@ -2609,6 +2637,15 @@ int fpu_emulator_cop1Handler(struct pt_regs *xcp, struct mips_fpu_struct *ctx,
 			break;
 		if (sig)
 			break;
+		/*
+		 * We have to check for the ISA bit explicitly here,
+		 * because `get_isa16_mode' may return 0 if support
+		 * for code compression has been globally disabled,
+		 * or otherwise we may produce the wrong signal or
+		 * even proceed successfully where we must not.
+		 */
+		if ((xcp->cp0_epc ^ prevepc) & 0x1)
+			break;
 
 		cond_resched();
 	} while (xcp->cp0_epc > prevepc);