Relocation overflow on RISC-V with multi-range memory layout

From: "Wu, Fei" <fei2.wu@intel.com>
To: <grub-devel@gnu.org>, <agraf@suse.de>,
	Alistair Francis <alistair.francis@wdc.com>
Subject: Relocation overflow on RISC-V with multi-range memory layout
Date: Mon, 25 Sep 2023 16:51:46 +0800	[thread overview]
Message-ID: <6bc32199-1d4e-c366-e589-2198804824b5@intel.com> (raw)

Hi All,

I'm enabling PCIe passthrough on qemu riscv, the physical memory
range between 3GB and 4GB is reserved. Therefore if guest has 4GB ram,
two ranges are created as [2G, 3G) and [4G, 7G). More details can be
found here:
https://lore.kernel.org/all/CAKmqyKMtAzt5saCUMd4vXYfgAQibpzQJAhtTSuSb+yeKhcYpfw@mail.gmail.com/T/

When run grub.efi from uefi shell, a relocation problem happened in
grub_arch_dl_relocate_symbols() of grub-core/kern/riscv/dl.c:

        case R_RISCV_CALL:
        case R_RISCV_CALL_PLT:
          {
            grub_uint32_t *abs_place = place;
            grub_ssize_t off = sym_addr - (grub_addr_t) place;
            grub_uint32_t hi20, lo12;

            if (off != (grub_int32_t) off)
              return grub_error (GRUB_ERR_BAD_MODULE, "relocation
overflow");

It requires `off' in the range of int32, but it's not enforced since the
>4GB memory can be used. I'm not familiar with grub, but this patch does
work for me:

--- a/include/grub/riscv64/efi/memory.h
+++ b/include/grub/riscv64/efi/memory.h
@@ -1,6 +1,6 @@
 #ifndef GRUB_MEMORY_CPU_HEADER
 #include <grub/efi/memory.h>

-#define GRUB_EFI_MAX_USABLE_ADDRESS 0xffffffffffffULL
+#define GRUB_EFI_MAX_USABLE_ADDRESS 0xffffffffULL

Any comments?

Thanks,
Fei.

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