[PATCH 4.2 020/134] MIPS: math-emu: Emulate missing BC1{EQ,NE}Z instructions

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

4.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Markos Chandras <markos.chandras@xxxxxxxxxx>

commit c909ca718e8f50cf484ef06a8dd935e738e8e53d upstream.

Commit c8a34581ec09 ("MIPS: Emulate the BC1{EQ,NE}Z FPU instructions")
added support for emulating the new R6 BC1{EQ,NE}Z branches but it missed
the case where the instruction that caused the exception was not on a DS.

Signed-off-by: Markos Chandras <markos.chandras@xxxxxxxxxx>
Fixes: c8a34581ec09 ("MIPS: Emulate the BC1{EQ,NE}Z FPU instructions")
Cc: linux-mips@xxxxxxxxxxxxxx
Patchwork: https://patchwork.linux-mips.org/patch/10738/
Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 arch/mips/math-emu/cp1emu.c |   20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

--- a/arch/mips/math-emu/cp1emu.c
+++ b/arch/mips/math-emu/cp1emu.c
@@ -1181,6 +1181,24 @@ emul:
 			}
 			break;
 
+		case bc1eqz_op:
+		case bc1nez_op:
+			if (!cpu_has_mips_r6 || delay_slot(xcp))
+				return SIGILL;
+
+			cond = likely = 0;
+			switch (MIPSInst_RS(ir)) {
+			case bc1eqz_op:
+				if (get_fpr32(&current->thread.fpu.fpr[MIPSInst_RT(ir)], 0) & 0x1)
+				    cond = 1;
+				break;
+			case bc1nez_op:
+				if (!(get_fpr32(&current->thread.fpu.fpr[MIPSInst_RT(ir)], 0) & 0x1))
+				    cond = 1;
+				break;
+			}
+			goto branch_common;
+
 		case bc_op:
 			if (delay_slot(xcp))
 				return SIGILL;
@@ -1207,7 +1225,7 @@ emul:
 			case bct_op:
 				break;
 			}
-
+branch_common:
 			set_delay_slot(xcp);
 			if (cond) {
 				/*