[U-Boot] [PATCH 4/8] riscv: andes_plic: Fix some wrong configurations

Thu Nov 7 12:22:23 UTC 2019

On Thu, Nov 7, 2019 at 5:11 PM Rick Chen <rickchen36 at gmail.com> wrote:
>
> Hi Anup & Lukas
>
> Anup Patel <anup at brainfault.org> 於 2019年11月7日 週四 下午6:44寫道：
> >
> > On Thu, Nov 7, 2019 at 3:11 PM Auer, Lukas
> > <lukas.auer at aisec.fraunhofer.de> wrote:
> > >
> > > On Thu, 2019-11-07 at 11:48 +0530, Anup Patel wrote:
> > > > On Thu, Nov 7, 2019 at 11:40 AM Rick Chen <rickchen36 at gmail.com> wrote:
> > > > > Hi Anup
> > > > >
> > > > > > On Thu, Nov 7, 2019 at 10:45 AM Anup Patel <anup at brainfault.org> wrote:
> > > > > > > On Thu, Nov 7, 2019 at 7:04 AM Rick Chen <rickchen36 at gmail.com> wrote:
> > > > > > > > Hi Anup
> > > > > > > >
> > > > > > > > > On Wed, Nov 6, 2019 at 2:51 PM Rick Chen <rickchen36 at gmail.com> wrote:
> > > > > > > > > > Hi Anup
> > > > > > > > > >
> > > > > > > > > > > On Wed, Nov 6, 2019 at 2:18 PM Anup Patel <anup at brainfault.org> wrote:
> > > > > > > > > > > > On Wed, Nov 6, 2019 at 12:14 PM Rick Chen <rickchen36 at gmail.com> wrote:
> > > > > > > > > > > > > Hi Anup
> > > > > > > > > > > > >
> > > > > > > > > > > > > > On Tue, Nov 5, 2019 at 7:19 AM Rick Chen <rickchen36 at gmail.com> wrote:
> > > > > > > > > > > > > > > Hi Anup
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > On Thu, Oct 31, 2019 at 1:42 PM Anup Patel <anup at brainfault.org> wrote:
> > > > > > > > > > > > > > > > > > On Thu, Oct 31, 2019 at 6:30 AM Alan Kao <alankao at andestech.com> wrote:
> > > > > > > > > > > > > > > > > > > Hi Bin,
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Thanks for the critics.  Comments below.
> > > > > > > > > > > > > > > > > > > On Wed, Oct 30, 2019 at 06:38:00PM +0800, Bin Meng wrote:
> > > > > > > > > > > > > > > > > > > > Hi Rick,
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > On Wed, Oct 30, 2019 at 10:50 AM Rick Chen <rickchen36 at gmail.com> wrote:
> > > > > > > > > > > > > > > > > > > > > Hi Bin
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > Hi Rick,
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > On Fri, Oct 25, 2019 at 2:18 PM Andes <uboot at andestech.com> wrote:
> > > > > > > > > > > > > > > > > > > > > > > From: Rick Chen <rick at andestech.com>
> > > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > It will work fine due to hart 0 always will be main
> > > > > > > > > > > > > > > > > > > > > > > hart coincidentally. When develop SPL flow, I try to
> > > > > > > > > > > > > > > > > > > > > > > force other harts to be main hart. And it will go
> > > > > > > > > > > > > > > > > > > > > > > wrong in sending IPI flow. So fix it.
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > Fix what? Does this commit contain 2 fixes, or just 1 fix?
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > Yes, it include two fixs. But they will cause one negative result
> > > > > > > > > > > > > > > > > > > > > that only hart 0 can send ipi to other harts.
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > > Having this fix, any hart can be main hart in U-Boot SPL
> > > > > > > > > > > > > > > > > > > > > > > theoretically, but it still fail somewhere. After dig in
> > > > > > > > > > > > > > > > > > > > > > > and found there is an assumption that hart 0 shall be
> > > > > > > > > > > > > > > > > > > > > > > main hart in OpenSbi.
> > > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > > So does this mean there is a bug in OpenSBI too?
> > > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > > I am not sure if it is a bug. Maybe it is a compatible issue.
> > > > > > > > > > > > > > > > > > > > > There is a limitation that only hart 0 can be main hart in OpenSBI.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > > I don't think OpenSBI has such limitation.
> > > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Please check the source.
> > > > > > > > > > > > > > > > > > > https://github.com/riscv/opensbi/blob/master/firmware/fw_base.S#L54
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > Apparently, the FIRST TWO LINEs of the initialization are the
> > > > > > > > > > > > > > > > > > > 1. get hart ID.
> > > > > > > > > > > > > > > > > > > 2. determine which route to take based on their ID respectively.
> > > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > > So, I do think OpenSBI has this signature, if you are not willing to call it
> > > > > > > > > > > > > > > > > > > a limitation.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > This dependency on hart id #0 was not there until we added self-relocation
> > > > > > > > > > > > > > > > > > in OpenSBI for FW_DYNAMIC.
> > > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > > I will try to fix this in OpenSBI but we might end-up having boot_lottery.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > I have send a patch to fix this OpenSBI:
> > > > > > > > > > > > > > > > > "[PATCH] firmware: Introduce relocation lottery"
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > Can you try above patch and see if that helps ?
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > > > It will be great if you can provide Tested-by to my patch as well.
> > > > > > > > > > > > > > > > >
> > > > > > > > > > > > > > >
> > > > > > > > > > > > > > > I can not find this patch in mailing list.
> > > > > > > > > > > > > > > Can you provide a hyperlink ?
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > You can try latest riscv/opensbi master.
> > > > > > > > > > > > > >
> > > > > > > > > > > > > > I have tested the patch on SiFive Unleashed multiple times.
> > > > > > > > > > > > >
> > > > > > > > > > > > > I have tried this patch, but it fail
> > > > > > > > > > > > > firmware: Introduce relocation lottery(
> > > > > > > > > > > > > 98f4a208995b027662a7b04a25e4fa5df5f3eefe)
> > > > > > > > > > > > >
> > > > > > > > > > > > > The scenario was as below:
> > > > > > > > > > > > > There are 4 harts run in U-Boot SPL, hart 0 play as main hart.
> > > > > > > > > > > > > The hart 1 will receive ipi and come into OpenSBI(0x1000000) from
> > > > > > > > > > > > > U-Boot SPL(0x0), meanwhile hart 0,2,3 still run in U-Boot SPL.
> > > > > > > > > > > > > Then hart 1 will do _relocate_copy_to_lower which will copy data from
> > > > > > > > > > > > > 0x1000000 to 0x0.
> > > > > > > > > > > > > And it will corrupt U-Boot SPL.
> > > > > > > > > > > >
> > > > > > > > > > > > The self-relocation in OpenSBI firmwares ensures that OpenSBI firmware
> > > > > > > > > > > > are moved to the FW_TEXT_START before entering C code. This helps
> > > > > > > > > > > > us load OpenSBI firmwares anywhere in RAM.
> > > > > > > > > > > >
> > > > > > > > > > > > However, OpenSBI firmwares don't know where the U-Boot SPL is running.
> > > > > > > > > > > >
> > > > > > > > > > > > In your case, both OpenSBI FW_DYNAMIC and U-Boot SPL are linked to
> > > > > > > > > > > > address same address 0x0. This means secondary HARTs cannot safely
> > > > > > > > > > > > wait while primary HART enters OpenSBI. You should hold secondary HARTs
> > > > > > > > > > > > in U-Boot SPL only till OpenSBI FW_DYNAMIC and U-Boot proper are
> > > > > > > > > > > > loaded in RAM by primary HART. All your HARTs should jump to OpenSBI
> > > > > > > > > > > > at the same time after everything is loaded in RAM.
> > > > > > > > > > >
> > > > > > > > > > > I see the issue now.
> > > > > > > > > > >
> > > > > > > > > > > The U-Boot SPL is first letting secondary HART jump to OpenSBI and primary
> > > > > > > > > > > HART jumps to OpenSBI at the end.
> > > > > > > > > > > (Refer, jump_to_image_no_args() in arch/riscv/lib/spl.c)
> > > > > > > > > > >
> > > > > > > > > > > The real issue is FW_TEXT_START being same as U-Boot SPL TEXT_START.
> > > > > > > > > > >
> > > > > > > > > > > If possible please change TEXT base for U-Boot SPL or OpenSBI. I think
> > > > > > > > > > > changing U-Boot SPL TEXT_START would be convenient since this series
> > > > > > > > > > > is under review. Thoughts ?
> > > > > > > > > >
> > > > > > > > > > Yes.
> > > > > > > > > > I know it can avoid corrupting issue with changing  U-Boot SPL
> > > > > > > > > > TEXT_START not equal to OpenSBI TEXT base.
> > > > > > > > >
> > > > > > > > > I think this issue will be seen on U-Boot SPL running on QEMU as well.
> > > > > > > > >
> > > > > > > > > > With the following changes, U-Boot SPL text base can equal to OpenSBI text base
> > > > > > > > > > 1 U-Boot pass main hart information (a2) when jumping to OpenSBI
> > > > > > > > > > 2 OpenSBI pick up $a2 to keep playing as main hart, other harts go to
> > > > > > > > > > _wait_relocate_copy_done
> > > > > > > > >
> > > > > > > > > Overall it's a good suggestion but we cannot use a2 register because this
> > > > > > > > > will break FW_JUMP and FW_PAYLOAD. Instead, we should pass preferred
> > > > > > > > > boot HART id in struct fw_dynamic_info.
> > > > > > > >
> > > > > > > > Sorry, what I want to say shall be a3.
> > > > > > > >
> > > > > > > > > I have a patch for this in preferred_boot_hart_v1 branch of
> > > > > > > > > https://github.com/avpatel/opensbi.git
> > > > > > > > >
> > > > > > > > > Can you try OpenSBI from above branch ?
> > > > > > > > >
> > > > > > > > > You will have to update the "struct fw_dynamic_info" passed to
> > > > > > > > > OpenSBI by U-Boot SPL.
> > > > > > > >
> > > > > > > > Main hart will pass struct "fw_dynamic_info" to OpenSBI by U-Boot SPL.
> > > > > > > > But other harts will NOT pass struct "fw_dynamic_info" to OpenSBI by U-Boot SPL.
> > > > > > >
> > > > > > > That's wrong in U-Boot SPL.
> > > > > > >
> > > > > > > All HARTs have to follow FW_DYNAMIC protocol and pass
> > > > > > > "struct fw_dynamic_info" pointer in 'a2' register.
> > > > > > >
> > > > > > > > So if U-Boot SPL can pass main hart information via a3, OpenSBI just
> > > > > > > > have the following change
> > > > > > > > blt zero, a6, _wait_relocate_copy_done
> > > > > > > > change to
> > > > > > > > bne a3, a6, _wait_relocate_copy_done
> > > > > > > > before this commit
> > > > > > > > 98f4a208995b027662a7b04a25e4fa5df5f3eefe
> > > > > > > > firmware: Introduce relocation lottery
> > > > > > >
> > > > > > > What about FW_JUMP and FW_PAYLOAD? We have no way of passing
> > > > > > > value in a3 for these firmwares because these are not booted by U-Boot
> > > > > > > SPL.
> > > > > > >
> > > > > > > Also, U-Boot-2019.10 already uses U-Boot SPL support which does not
> > > > > > > pass anything in 'a3' register.
> > > > > > >
> > > > > > > We should definitely use "struct fw_dynamic_info" for this so that we can
> > > > > > > maintain backward compatibility as well.
> > > > > > >
> > > > > > > Please make sure that U-Boot SPL passes "struct fw_dynamic_info"
> > > > > > > pointer in 'a2' register for all HARTs.
> > > > > > >
> > > > > > > > But after this commit 98f4a, main hart become chosen from lottery mechanism.
> > > > > > > > Maybe I will prefer to change U-Boot SPL text base not overlap with
> > > > > > > > OpenSBI text start. :)
> > > > > > >
> > > > > > > Like I mentioned, we have this issue for U-Boot SPL on QEMU as well. It's
> > > > > > > just that most of us did not notice it for U-Boot SPL on QEMU.
> > > > > > >
> > > > > > > Let's fix this in the right way from start itself.
> > > > > >
> > > > > > I double checked spl_invoke_opensbi() and it is doing the right thing
> > > > > > by passing "struct fw_dyanmic_info" pointer in 'a2' register.
> > > > > > (Refer, common/spl/spl_opensbi.c)
> > > > > >
> > > > > > Not sure, why it is not passing 'a2' register correctly for you ??
> > > > > >
> > > > >
> > > > > Yes, you are right. I reply too quickly.
> > > > > Other harts will pass struct fw_dyanmic_info in a2 to OpenSBI.
> > > > >
> > > > > Thanks for your corrections
> > > >
> > > > No problem, I am happy to help.
> > > >
> > > > BTW, I tried to play around with U-Boot SPL on QEMU.
> > > >
> > > > Maybe below changes can help you...
> > >
> > > Thanks for looking into this issue! I successfully tested it on QEMU, I
> > > had to add a short delay between sending the IPIs to trigger the
> > > problem.
> > >
> > > We might still run into problems however. Right now, we are assuming
> > > that the main hart is the last one to enter OpenSBI. If this is not the
> > > case (some delay when handling the IPI), we will have the same problem
> > > again. To fix this we could pass the hart mask, containing all harts
> > > that have entered U-Boot, to OpenSBI and wait for all harts to be
> > > running in OpenSBI. I am not sure how realistic this scenario is, so
> > > this might not be needed.
> >
> > I agree that we might still run into this issue if primary HART enters
> > OpenSBI before secondary HARTs. I think this situation can only
> > happen on QEMU where each CPU is a thread running on host but
> > very unlikely/impossible on real HW.
> >
> > Maybe a delay on primary HART in U-Boot SPL after SMP calls to
> > secondary HARTs and before jumping to OpenSBI ?
> >
> > Regarding hart_mask in fw_dynamic_info, I think the issue will be the
> > size of the hart_mask. It is possible in-future SOC vendors come-up
> > with SOC having huge number of HARTs OR SOC with discontinuous
> > HART IDs which can cause a 64bit hart_mask to be not sufficient for
> > all HARTs.
> >
> > Also, waiting for all HARTs to enter OpenSBI will be one more wait-loop
> > in fw_base.S which will add to the boot-time as well.
> >
> > I still think the root cause of the issue is that TEXT_START of
> > U-Boot SPL and OpenSBI FW_DYNAMIC is same. Maybe we can
> > insist SOC vendors to not use same TEXT_START ?
>
> I have try your changes about boot_hart for U-Boot SPL with OpenSBI,
> preferred_boot_hart_v2 branch
> It still encounter some booting problems. I try to find out the root
> cause but in vain.
>
> I am very agree with options of Lukas.
> After modifying U-Boot SPL text base not equal to zero and the booting
> progress will be pass.

No problem, it will be your decision to go with different TEXT_BASE for
AndesTech platform.

We will keep the "boot_hart" field in OpenSBI for U-Boot SPL on QEMU
and I will wait for Lukas to add more checks and small delay in U-Boot SPL
(like he mentioned).

Thanks,
Anup