[PATCH] ARM: imx: Enable kaslrseed command on DH i.MX8M Plus DHCOM

[Tim Harvey]

On Tue, Apr 23, 2024 at 4:18 PM Marek Vasut <marex at denx.de> wrote:
>
> On 4/19/24 5:24 PM, Tim Harvey wrote:
> > On Thu, Apr 18, 2024 at 11:42 AM Marek Vasut <marex at denx.de> wrote:
> >>
> >> On 4/18/24 8:02 PM, Fabio Estevam wrote:
> >>> Hi Tim,
> >>>
> >>> On Thu, Apr 18, 2024 at 2:54 PM Tim Harvey <tharvey at gateworks.com> wrote:
> >>>
> >>>> Fabio, if you enable CONFIG_DM_RNG on an imx8m{m,p}_evk do you get the
> >>>> following in the SPL?
> >>>> Couldn't bind rng driver (-96)
> >>>> SEC0:  RNG instantiated
> >>>>
> >>>> sec_init failed!
> >>>
> >>> Yes, if I add CONFIG_DM_RNG=y to imx8mm_evk_defconfig I get:
> >>>
> >>> U-Boot SPL 2024.04-00793-g3434b88d2c2f-dirty (Apr 18 2024 - 14:58:57 -0300)
> >>> No pmic
> >>> Couldn't bind rng driver (-96)
> >>> SEC0:  RNG instantiated
> >>>
> >>> sec_init failed!
> >>
> >> Interesting. Which TFA blob version do you use ? I used the mainline
> >> 2.10 for my tests.
> >
> > Marek,
> >
> > Were you able to reproduce this as well with the board you enabled
> > DM_RNG for? If it does work fine what dtb were you using... perhaps
> > there is something in its u-boot.dtsi that we need?
>
> This one arch/arm/dts/imx8mp-dhcom-pdk3.dts , see log below. The build
> has a few extra patches in it, but nothing which affects the KASLR:
>
> $ export SOURCE_DATE_EPOCH=1672531200 ; echo tst > .scmversion
> $ make imx8mp_dhcom_pdk3_defconfig ; make
>
> U-Boot SPL 2024.07-rc1tst (Jan 01 2023 - 00:00:00 +0000)
> DDR:   4096 MiB [0x5]
> DDR:   Inline ECC enabled
> WDT:   Started watchdog at 30280000 with servicing every 1000ms (60s timeout)
> Trying to boot from BOOTROM
> Boot Stage: Primary boot
> image offset 0x1000, pagesize 0x1, ivt offset 0x0
> NOTICE:  Do not release JR0 to NS as it can be used by HAB
> NOTICE:  BL31: v2.10.0  (release):v2.10.0-5-gfb51ca229
> NOTICE:  BL31: Built : 20:30:36, Apr 23 2024
>
>
> U-Boot 2024.07-rc1tst (Jan 01 2023 - 00:00:00 +0000)
>
> CPU:   Freescale i.MX8MP[8] rev1.1 1600 MHz (running at 1200 MHz)
> CPU:   Industrial temperature grade (-40C to 105C) at 70C
> Reset cause: POR
> Model: DH electronics i.MX8M Plus DHCOM Premium Developer Kit (3)
> DRAM:  3.5 GiB
> Core:  183 devices, 34 uclasses, devicetree: separate
> WDT:   Started watchdog at 30280000 with servicing every 1000ms (60s timeout)
> MMC:   FSL_SDHC: 0, FSL_SDHC: 1
> Loading Environment from SPIFlash... SF: Detected w25q128jw with page
> size 256 Bytes, erase size 4 KiB, total 16 MiB
> OK
> In:    serial
> Out:   serial
> Err:   serial
> SEC0:  RNG instantiated
> Net:   eth1: ethernet at 30be0000, eth0: ethernet at 30bf0000
> ...
>
> > The error -EPFNOSUPPORT is interesting and helps point to the only
> > place it can be where the comment says the strange errno is to make
> > this easier to find:
> > https://elixir.bootlin.com/u-boot/latest/source/drivers/core/uclass.c#L70:
> >          if (!uc_drv) {
> >                  debug("Cannot find uclass for id %d: please add the
> > UCLASS_DRIVER() declaration for this UCLASS_... id\n",
> >                        id);
> >                  /*
> >                   * Use a strange error to make this case easier to find. When
> >                   * a uclass is not available it can prevent driver model from
> >                   * starting up and this failure is otherwise hard to debug.
> >                   */
> >                  return -EPFNOSUPPORT;
> >          }
> >
> > I'm not very familiar with the dm driver binding - does the
> > U-BOOT_DRIVER usage in drivers/crypto/fsl/rng.c need to be refactored
> > to use UCLASS_DRIVER for it to be usable in both SPL and U-Boot?
>
> I don't think you need the CAAM RNG in SPL in the first place, or do you ?
>
> > Honestly I don't know why we need DM_RNG in SPL anyway and we could
> > just add support for disabling it there to avoid unwanted bloat.
>
> I think you can disable it , yes.

Marek,

Would it be advantageous for the kaslr-seed to be added automatically
from image_setup_libfdt?

I notice arch/arm/cpu/armv8/fsl-layerscape/fdt.c:ft_cpu_setup does
this and board/raspberrypi/rpi/rpi.c looks like it copies kaslr-seed
from the control fdt which I assume was added by an earlier layer for
that target.

I'm not clear if there is a disadvantage to automatically adding this
node if DM_RNG is enabled.

Best Regards,

Tim