From e9d92d223381f1f3be5d87322b576721d3b93612 Mon Sep 17 00:00:00 2001 From: Markos Chandras Date: Wed, 24 Jun 2015 09:52:00 +0100 Subject: [PATCH] MIPS: Fix branch emulation for BLTC and BGEC instructions Commits f1b44067c19258b7614e3cd09dfe8d8e12ff5895 ("MIPS: Emulate the new MIPS R6 B{L,G}T{Z,}{AL,}C instructions") and commit a8ff66f52d3f17b5ae793955270675c197f73d6c ("MIPS: Emulate the new MIPS R6 B{L,G}E{Z,}{AL,}C instructions") added support for emulating various branch compact instructions. However, it missed the case for those which use the old BLEZL and BGTZL opcodes leading to random crashes when the R6 emulator is disabled. We fix this by ensuring that the 'rt' field is not zero which is always true for these branch compact instructions. Fixes: f1b44067c192 ("MIPS: Emulate the new MIPS R6 B{L,G}T{Z,}{AL,}C instructions") Fixes: a8ff66f52d3f ("MIPS: Emulate the new MIPS R6 B{L,G}E{Z,}{AL,}C instructions") Cc: # 4.0+ Signed-off-by: Markos Chandras Cc: linux-mips@linux-mips.org Cc: Markos Chandras Patchwork: https://patchwork.linux-mips.org/patch/10582/ Signed-off-by: Ralf Baechle --- arch/mips/kernel/branch.c | 4 ++-- arch/mips/math-emu/cp1emu.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/arch/mips/kernel/branch.c b/arch/mips/kernel/branch.c index c0c5e5972256..d8f9b357b222 100644 --- a/arch/mips/kernel/branch.c +++ b/arch/mips/kernel/branch.c @@ -600,7 +600,7 @@ int __compute_return_epc_for_insn(struct pt_regs *regs, break; case blezl_op: /* not really i_format */ - if (NO_R6EMU) + if (!insn.i_format.rt && NO_R6EMU) goto sigill_r6; case blez_op: /* @@ -635,7 +635,7 @@ int __compute_return_epc_for_insn(struct pt_regs *regs, break; case bgtzl_op: - if (NO_R6EMU) + if (!insn.i_format.rt && NO_R6EMU) goto sigill_r6; case bgtz_op: /* diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c index 22b9b2cb9219..00c241ae04ce 100644 --- a/arch/mips/math-emu/cp1emu.c +++ b/arch/mips/math-emu/cp1emu.c @@ -551,7 +551,7 @@ static int isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn, dec_insn.next_pc_inc; return 1; case blezl_op: - if (NO_R6EMU) + if (!insn.i_format.rt && NO_R6EMU) break; case blez_op: @@ -588,7 +588,7 @@ static int isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn, dec_insn.next_pc_inc; return 1; case bgtzl_op: - if (NO_R6EMU) + if (!insn.i_format.rt && NO_R6EMU) break; case bgtz_op: /* -- 2.20.1