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MIPS: Fix erroneous JR emulation for MIPS R6 

Commit 5f9f41c474 ("MIPS: kernel: Prepare
the JR instruction for emulation on MIPS R6") added support for
emulating the JR instruction on MIPS R6 cores but that introduced a bug
which could be triggered when hitting a JALR opcode because the code used
the wrong field in the 'r_format' struct to determine the instruction
opcode. This lead to crashes because an emulated JALR instruction was
treated as a JR one when the R6 emulator was turned off.

Fixes: 5f9f41c474 ("MIPS: kernel: Prepare the JR instruction for emulation on MIPS R6")
Cc: <stable@vger.kernel.org> # 4.0+
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Cc: linux-mips@linux-mips.org
Cc: stable@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/10583/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Markos Chandras 2015-06-24 09:52:01 +01:00 committed by Ralf Baechle
parent e9d92d2233
commit 143fefc8f3
1 changed files with 1 additions and 1 deletions
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2
arch/mips/math-emu/cp1emu.c
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@ -451,7 +451,7 @@ static int isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn,
/* Fall through */
case jr_op:
/* For R6, JR already emulated in jalr_op */
if (NO_R6EMU && insn.r_format.opcode == jr_op)
if (NO_R6EMU && insn.r_format.func == jr_op)
break;
*contpc = regs->regs[insn.r_format.rs];
return 1;