| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.1 012/123] MIPS: Fix erroneous JR emulation for MIPS R6 | Date | Sat, 8 Aug 2015 15:08:10 -0700 |
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4.1-stable review patch. If anyone has any objections, please let me know.
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From: Markos Chandras <markos.chandras@imgtec.com>
commit 143fefc8f315cd10e046e6860913c421c3385cb1 upstream.
Commit 5f9f41c474befb4ebbc40b27f65bb7d649241581 ("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: 5f9f41c474be ("MIPS: kernel: Prepare the JR instruction for emulation on MIPS R6") Signed-off-by: Markos Chandras <markos.chandras@imgtec.com> Cc: linux-mips@linux-mips.org Patchwork: https://patchwork.linux-mips.org/patch/10583/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- arch/mips/math-emu/cp1emu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/mips/math-emu/cp1emu.c +++ b/arch/mips/math-emu/cp1emu.c @@ -451,7 +451,7 @@ static int isBranchInstr(struct pt_regs /* 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;
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