Commit d4bd6a1d authored Jun 16, 2017 by Maciej W. Rozycki Committed by Greg Kroah-Hartman Jul 27, 2017

MIPS: Send SIGILL for linked branches in `__compute_return_epc_for_insn'



commit fef40be6da856afead4177aaa9d869a66fb3381f upstream.

Fix commit 319824ea ("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: 319824ea ("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>

parent 99ce7614

arch/mips/kernel/branch.c

+4 −8

Original line number	Diff line number	Diff line
		@@ -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