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