| Message ID | 1465482910-23593-1-git-send-email-kamal@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/arch/mips/math-emu/cp1emu.c b/arch/mips/math-emu/cp1emu.c index f0f1b98..2bf9209 100644 --- a/arch/mips/math-emu/cp1emu.c +++ b/arch/mips/math-emu/cp1emu.c @@ -445,9 +445,11 @@ static int isBranchInstr(struct pt_regs *regs, struct mm_decoded_insn dec_insn, case spec_op: switch (insn.r_format.func) { case jalr_op: - regs->regs[insn.r_format.rd] = - regs->cp0_epc + dec_insn.pc_inc + - dec_insn.next_pc_inc; + if (insn.r_format.rd != 0) { + regs->regs[insn.r_format.rd] = + regs->cp0_epc + dec_insn.pc_inc + + dec_insn.next_pc_inc; + } /* Fall through */ case jr_op: /* For R6, JR already emulated in jalr_op */
This is a note to let you know that I have just added a patch titled MIPS: math-emu: Fix jalr emulation when rd == $0 to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: https://git.launchpad.net/~canonical-kernel/linux/+git/linux-stable-ckt/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt12. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From e4a68a824140f11f989e262c1929658b2b179e95 Mon Sep 17 00:00:00 2001 From: Paul Burton <paul.burton@imgtec.com> Date: Thu, 21 Apr 2016 14:04:55 +0100 Subject: MIPS: math-emu: Fix jalr emulation when rd == $0 commit ab4a92e66741b35ca12f8497896bafbe579c28a1 upstream. When emulating a jalr instruction with rd == $0, the code in isBranchInstr was incorrectly writing to GPR $0 which should actually always remain zeroed. This would lead to any further instructions emulated which use $0 operating on a bogus value until the task is next context switched, at which point the value of $0 in the task context would be restored to the correct zero by a store in SAVE_SOME. Fix this by not writing to rd if it is $0. Fixes: 102cedc32a6e ("MIPS: microMIPS: Floating point support.") Signed-off-by: Paul Burton <paul.burton@imgtec.com> Cc: Maciej W. Rozycki <macro@imgtec.com> Cc: James Hogan <james.hogan@imgtec.com> Cc: linux-mips@linux-mips.org Cc: linux-kernel@vger.kernel.org Patchwork: https://patchwork.linux-mips.org/patch/13160/ Signed-off-by: Ralf Baechle <ralf@linux-mips.org> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/mips/math-emu/cp1emu.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) -- 2.7.4