[PATCH] Revert "efi_memory: do not add U-Boot memory to the memory map"

[Sughosh Ganu]

On Tue, 12 Nov 2024 at 18:48, Simon Glass <sjg at chromium.org> wrote:
>
> A bisect of Ubuntu 2022.04 boot-failure on qemu-x86_64 resulted in this
> patch. I am not sure how to investigate it.
>
> The boot hangs at some point during booting of the install image, before
> the Ubuntu logo appears.
>
> I will sent a series with a script showing how it is run.
>
> This reverts commit a68c9ac5d8afc51c619c5d3e865fcf147bea90cb.
>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---

I did some digging into this issue, and it turns out that the revert
is only masking the real issue. What this revert does is mark the
memory region occupied by U-Boot as EFI_BOOT_SERVICES_CODE. The x86
kernel seems to mark memory regions other than
EFI_{BOOT,RUNTIME}_SERVICES_CODE as not executable -- and this is
precisely why this crash shows up only on x86. The actual cause of
this issue is in the efi runtime functionality of U-Boot. The kernel
is calling the SetVirtualAddressMap() runtime service function, and
that seems to be calling some of the boot service code of U-Boot,
which it shouldn't. We do not get the crash after disabling the
ConvertPointer() and SetVirtualAddressMap() runtime functions.

-sughosh

>
>  lib/efi_loader/efi_memory.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/lib/efi_loader/efi_memory.c b/lib/efi_loader/efi_memory.c
> index d2f5d563f2a..c7400ec9854 100644
> --- a/lib/efi_loader/efi_memory.c
> +++ b/lib/efi_loader/efi_memory.c
> @@ -809,6 +809,16 @@ static void add_u_boot_and_runtime(void)
>  {
>         unsigned long runtime_start, runtime_end, runtime_pages;
>         unsigned long runtime_mask = EFI_PAGE_MASK;
> +       unsigned long uboot_start, uboot_pages;
> +       unsigned long uboot_stack_size = CONFIG_STACK_SIZE;
> +
> +       /* Add U-Boot */
> +       uboot_start = ((uintptr_t)map_sysmem(gd->start_addr_sp, 0) -
> +                      uboot_stack_size) & ~EFI_PAGE_MASK;
> +       uboot_pages = ((uintptr_t)map_sysmem(gd->ram_top - 1, 0) -
> +                      uboot_start + EFI_PAGE_MASK) >> EFI_PAGE_SHIFT;
> +       efi_add_memory_map_pg(uboot_start, uboot_pages, EFI_BOOT_SERVICES_CODE,
> +                             false);
>
>  #if defined(__aarch64__)
>         /*
> --
> 2.34.1
>