This is a note to let you know that I've just added the patch titled MIPS: Fix unaligned PC interpretation in `compute_return_epc' to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: mips-fix-unaligned-pc-interpretation-in-compute_return_epc.patch and it can be found in the queue-3.18 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 11a3799dbeb620bf0400b1fda5cc2c6bea55f20a Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" <macro@xxxxxxxxxx> Date: Fri, 16 Jun 2017 00:07:34 +0100 Subject: MIPS: Fix unaligned PC interpretation in `compute_return_epc' From: Maciej W. Rozycki <macro@xxxxxxxxxx> commit 11a3799dbeb620bf0400b1fda5cc2c6bea55f20a upstream. Fix a regression introduced with commit fb6883e5809c ("MIPS: microMIPS: Support handling of delay slots.") and defer to `__compute_return_epc' if the ISA bit is set in EPC with non-MIPS16, non-microMIPS hardware, which will then arrange for a SIGBUS due to an unaligned instruction reference. Returning EPC here is never correct as the API defines this function's result to be either a negative error code on failure or one of 0 and BRANCH_LIKELY_TAKEN on success. Fixes: fb6883e5809c ("MIPS: microMIPS: Support handling of delay slots.") Signed-off-by: Maciej W. Rozycki <macro@xxxxxxxxxx> Cc: James Hogan <james.hogan@xxxxxxxxxx> Cc: linux-mips@xxxxxxxxxxxxxx Patchwork: https://patchwork.linux-mips.org/patch/16395/ Signed-off-by: Ralf Baechle <ralf@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/mips/include/asm/branch.h | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) --- a/arch/mips/include/asm/branch.h +++ b/arch/mips/include/asm/branch.h @@ -74,10 +74,7 @@ static inline int compute_return_epc(str return __microMIPS_compute_return_epc(regs); if (cpu_has_mips16) return __MIPS16e_compute_return_epc(regs); - return regs->cp0_epc; - } - - if (!delay_slot(regs)) { + } else if (!delay_slot(regs)) { regs->cp0_epc += 4; return 0; } Patches currently in stable-queue which might be from macro@xxxxxxxxxx are queue-3.18/mips-actually-decode-jalx-in-__compute_return_epc_for_insn.patch queue-3.18/mips-fix-unaligned-pc-interpretation-in-compute_return_epc.patch queue-3.18/mips-math-emu-prevent-wrong-isa-mode-instruction-emulation.patch