From: "Maciej W. Rozycki" <macro@imgtec.com>
Date: Fri, 16 Jun 2017 00:12:53 +0100
Subject: [PATCH] MIPS: Send SIGILL for linked branches in
 `__compute_return_epc_for_insn'
References: bnc#1060662
Patch-mainline: v4.12.4
Git-commit: fef40be6da856afead4177aaa9d869a66fb3381f

commit fef40be6da856afead4177aaa9d869a66fb3381f upstream.

Fix commit 319824eabc3f ("MIPS: kernel: branch: Do not emulate the
branch likelies on MIPS R6") and also send SIGILL rather than returning
-SIGILL for BLTZAL, BLTZALL, BGEZAL and BGEZALL instruction encodings no
longer supported in R6, except where emulated.  Returning -SIGILL is
never correct as the API defines this function's result upon error to be
-EFAULT and a signal actually issued.

Fixes: 319824eabc3f ("MIPS: kernel: branch: Do not emulate the branch likelies on MIPS R6")
Signed-off-by: Maciej W. Rozycki <macro@imgtec.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16398/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 arch/mips/kernel/branch.c | 12 ++++--------
 1 file changed, 4 insertions(+), 8 deletions(-)

diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c
index df5c32b38408..64c8360e3d62 100644
--- a/arch/mips/kernel/branch.c
+++ b/arch/mips/kernel/branch.c
@@ -473,10 +473,8 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
 		case bltzal_op:
 		case bltzall_op:
 			if (NO_R6EMU && (insn.i_format.rs ||
-			    insn.i_format.rt == bltzall_op)) {
-				ret = -SIGILL;
-				break;
-			}
+			    insn.i_format.rt == bltzall_op))
+				goto sigill_r2r6;
 			regs->regs[31] = epc + 8;
 			/*
 			 * OK we are here either because we hit a NAL
@@ -507,10 +505,8 @@ int __compute_return_epc_for_insn(struct pt_regs *regs,
 		case bgezal_op:
 		case bgezall_op:
 			if (NO_R6EMU && (insn.i_format.rs ||
-			    insn.i_format.rt == bgezall_op)) {
-				ret = -SIGILL;
-				break;
-			}
+			    insn.i_format.rt == bgezall_op))
+				goto sigill_r2r6;
 			regs->regs[31] = epc + 8;
 			/*
 			 * OK we are here either because we hit a BAL
-- 
2.14.2