Re: [edk2-devel] Conflicting virtual addresses causing Runtime Services issues

["Jon Nettleton" <jon@solid-run.com>]

On Wed, Mar 10, 2021 at 3:52 PM Laszlo Ersek <lersek@redhat.com> wrote:
>
> On 03/10/21 09:04, Jon Nettleton wrote:
> > I am debugging a failure that I am seeing while using the HoneyComb's
> > spi-nor flash for runtime variable storage.  I am hoping someone on
> > the list can give me some insight as what may be the problem.
> >
> > The problem showed up when we switched the MMIO region for the fspi
> > flash device to be marked as non executable.  reading variables is
> > fine, however writes began throwing an error.
> >
> > [  556.709828] Unable to handle kernel execute from non-executable
> > memory at virtual address 00000000206a3968
> >
> > I have patched the kernel and removed the X86 requirement and enabled
> > the sysfs runtime mappings kernel config so I can get an easy view of
> > the mappings the kernel carries for runtime services.  I then track
> > that virtual address to the MMIO region of nor flash, which makes
> > sense that region is marked as non executable.  The question is why is
> > code being executed from this address range
> >
> > attribute
> > ::::::::::::::
> > 0x8000000000000001
> > ::::::::::::::
> > num_pages
> > ::::::::::::::
> > 0x40
> > ::::::::::::::
> > phys_addr
> > ::::::::::::::
> > 0x20500000
> > ::::::::::::::
> > type
> > ::::::::::::::
> > 0xb
> > ::::::::::::::
> > virt_addr
> > ::::::::::::::
> > 0x20680000
> >
> > So then I patched the PL011 serial driver to be able to log to the
> > console in runtime and I track down the access to Status =
> > Fvb->GetPhysicalAddress(Fvb, &FvVolHdr); in UpdateVariableStore().
> > What I don't understand is why EfiConvertPointer is mapping that
> > pointer into the Virtual address space occupied by the runtime mmio of
> > the flash.  The pointer is being properly remapped.  Here are the
> > pointer addresses in EFI and Kernel Runtime
> >
> > EFI:
> > UpdateVariableStore:156 ECE33968
> > FvbGetPhysicalAddress(BaseAddress=0x20000000)
> >
> > KERNEL:
> > UpdateVariableStore:156 206A3968
> > [  556.709828] Unable to handle kernel execute from non-executable
> > memory at virtual address 00000000206a3968
> >
> > Any insight that anyone could provide would be much appreciated.
>
> Your platform appears misconfigured -- the flash MMIO range appears to
> overlap runtime services code even before SetVirtualAddressMap. The
> virtual address conflict is likely the result of the original physical
> address conflict.

There is no physical address conflict.  Running in physical mode the pointer
for GetPhysicalAddress is at 0xECE33968 and the MMIO physical
region is 0x20000000 - 0x2FFFFFFF.  Shown as the BaseAddress above.
Obviously I don't use that full MMIO region because our flash is not
256MB.

>
> After the virtual address updates, the EfiMemoryMappedIO (0xb) type
> range is mapped at virtual address range [0x20680000, 0x206C0000). The
> GetPhysicalAddress function seems to be located at offset 0x23968 in
> that range (with 0x1C698 bytes to go in the range). That's inexplicable.

Yes, exactly why I am reaching out.

>
> What is the physical base address of the flash? What are the PCDs used
> in "ArmPlatformPkg/Drivers/NorFlashDxe/NorFlashFvb.c"?

We don't use the ArmPlatformPkg

The code is available here.
https://github.com/SolidRun/edk2-platforms/tree/LX2160_UEFI_ACPI_EAR3-lx2160cex7/Silicon/NXP/Drivers/SpiNorFlashDxe

Thanks
>
> Laszlo
>