From mboxrd@z Thu Jan 1 00:00:00 1970 From: santosh.shilimkar@ti.com (Santosh Shilimkar) Date: Mon, 5 Aug 2013 10:38:13 -0400 Subject: [PATCH v2 4/6] ARM: mm: LPAE: Correct virt_to_phys patching for 64 bit physical addresses In-Reply-To: References: <1375289086-5315-1-git-send-email-santosh.shilimkar@ti.com> <1375289086-5315-5-git-send-email-santosh.shilimkar@ti.com> <51FCFBE1.5090000@ti.com> <51FD5922.1060705@ti.com> Message-ID: <51FFB8D5.8070506@ti.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sunday 04 August 2013 01:32 AM, Nicolas Pitre wrote: > On Sat, 3 Aug 2013, Santosh Shilimkar wrote: > >> On Saturday 03 August 2013 10:01 AM, Nicolas Pitre wrote: >>> On Sat, 3 Aug 2013, Sricharan R wrote: >>> >>>> On Saturday 03 August 2013 08:58 AM, Nicolas Pitre wrote: >>>>> ... meaning that, instead of using 0x81 for the stub value on the mov >>>>> instruction, it only has to be 0x83. Bits 7 and 0 still act as anchors >>>>> for the rotation field in the opcode, while bit 1 indicates which value >>>>> to patch in. >>>> I started with this kind of augmenting with the immediate operand >>>> while starting V2. But the problem was, we do the runtime patching twice. >>> >>> Ahhh... Bummer. >>> >> Sorry if it wasn't clear but I thought we discussed why patching is >> done twice. > > Yeah, I know the reasons. I just had forgotten about the effects on the > anchor bits. > I see. >> This was purely based on the discussion where RMK suggested to follow >> that approach to minimize code changes. >> >> Looks like we need to revisit that now based on Russell's latest >> comment. > > Note that my comments on this particular patch are still valid and > independent from whatever approach is used globally to deal with the > memory alias. I do think that the value to patch should be selected > depending on the opcode's rotation field which makes it compatible with > a double patching approach as well. > Completely agree. Regards, Santosh