From ddd2fe18a0122e6c1f4cb62fead4a396f0051803 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 6e8415d9a6f0ca6832944d73d8926c0997c1fa20 ("MIPS: Emulate the new MIPS R6 B{L,G}T{Z,}{AL,}C instructions") and commit 497a908bb63041e4f60665600d2341a276bd47a2 ("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: 6e8415d9a6f0 ("MIPS: Emulate the new MIPS R6 B{L,G}T{Z,}{AL,}C instructions") Fixes: 497a908bb630 ("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 c0c5e5972256e..d8f9b357b2226 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 22b9b2cb9219f..00c241ae04ce8 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: /* -- 2.39.5