Re: [PATCH] efi/libstub: Move efi_relocate_kernel() into its only remaining user

Hi Ard,

On Wed, Apr 29, 2026 at 1:06 AM Ard Biesheuvel <[email protected]> wrote:
>
> From: Ard Biesheuvel <[email protected]>
>
> LoongArch is the only arch that still uses efi_relocate_kernel(), so
> before making changes to it that LoongArch needs, turn it into a private
> function. Move efi_low_alloc_above() into mem.c while at it, and drop
> the relocate.c source file altogether.
>
> Cc: WANG Rui <[email protected]>
> Cc: Huacai Chen <[email protected]>
> Signed-off-by: Ard Biesheuvel <[email protected]>

Tested-by: WANG Rui <[email protected]>

Thanks,
Rui

> ---
> Unless there are any objections, I will queue this up and rebase the
> LoongArch changes adding efi_cache_sync_image() on top of it.
>
>  drivers/firmware/efi/libstub/Makefile         |   2 +-
>  drivers/firmware/efi/libstub/efistub.h        |   7 -
>  drivers/firmware/efi/libstub/loongarch-stub.c |  79 ++++++++++
>  drivers/firmware/efi/libstub/mem.c            |  82 ++++++++++
>  drivers/firmware/efi/libstub/relocate.c       | 166 --------------------
>  5 files changed, 162 insertions(+), 174 deletions(-)
>
> diff --git a/drivers/firmware/efi/libstub/Makefile b/drivers/firmware/efi/libstub/Makefile
> index 983a438e35f3..cfedb3025c26 100644
> --- a/drivers/firmware/efi/libstub/Makefile
> +++ b/drivers/firmware/efi/libstub/Makefile
> @@ -66,7 +66,7 @@ KBUILD_AFLAGS                 := $(KBUILD_CFLAGS) -D__ASSEMBLY__
>  lib-y                          := efi-stub-helper.o gop.o secureboot.o tpm.o \
>                                    file.o mem.o random.o randomalloc.o pci.o \
>                                    skip_spaces.o lib-cmdline.o lib-ctype.o \
> -                                  alignedmem.o relocate.o printk.o vsprintf.o
> +                                  alignedmem.o printk.o vsprintf.o
>
>  # include the stub's libfdt dependencies from lib/ when needed
>  libfdt-deps                    := fdt_rw.c fdt_ro.c fdt_wip.c fdt.c \
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index 979a21818cc1..fd91fc15ec81 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -1104,13 +1104,6 @@ efi_status_t efi_allocate_pages_aligned(unsigned long size, unsigned long *addr,
>  efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
>                                  unsigned long *addr, unsigned long min);
>
> -efi_status_t efi_relocate_kernel(unsigned long *image_addr,
> -                                unsigned long image_size,
> -                                unsigned long alloc_size,
> -                                unsigned long preferred_addr,
> -                                unsigned long alignment,
> -                                unsigned long min_addr);
> -
>  efi_status_t efi_parse_options(char const *cmdline);
>
>  void efi_parse_option_graphics(char *option);
> diff --git a/drivers/firmware/efi/libstub/loongarch-stub.c b/drivers/firmware/efi/libstub/loongarch-stub.c
> index 736b6aae323d..8c538a5243d9 100644
> --- a/drivers/firmware/efi/libstub/loongarch-stub.c
> +++ b/drivers/firmware/efi/libstub/loongarch-stub.c
> @@ -14,6 +14,85 @@ extern int kernel_asize;
>  extern int kernel_fsize;
>  extern int kernel_entry;
>
> +/**
> + * efi_relocate_kernel() - copy memory area
> + * @image_addr:                pointer to address of memory area to copy
> + * @image_size:                size of memory area to copy
> + * @alloc_size:                minimum size of memory to allocate, must be greater or
> + *                     equal to image_size
> + * @preferred_addr:    preferred target address
> + * @alignment:         minimum alignment of the allocated memory area. It
> + *                     should be a power of two.
> + * @min_addr:          minimum target address
> + *
> + * Copy a memory area to a newly allocated memory area aligned according
> + * to @alignment but at least EFI_ALLOC_ALIGN. If the preferred address
> + * is not available, the allocated address will not be below @min_addr.
> + * On exit, @image_addr is updated to the target copy address that was used.
> + *
> + * This function is used to copy the Linux kernel verbatim. It does not apply
> + * any relocation changes.
> + *
> + * Return:             status code
> + */
> +static
> +efi_status_t efi_relocate_kernel(unsigned long *image_addr,
> +                                unsigned long image_size,
> +                                unsigned long alloc_size,
> +                                unsigned long preferred_addr,
> +                                unsigned long alignment,
> +                                unsigned long min_addr)
> +{
> +       unsigned long cur_image_addr;
> +       unsigned long new_addr = 0;
> +       efi_status_t status;
> +       unsigned long nr_pages;
> +       efi_physical_addr_t efi_addr = preferred_addr;
> +
> +       if (!image_addr || !image_size || !alloc_size)
> +               return EFI_INVALID_PARAMETER;
> +       if (alloc_size < image_size)
> +               return EFI_INVALID_PARAMETER;
> +
> +       cur_image_addr = *image_addr;
> +
> +       /*
> +        * The EFI firmware loader could have placed the kernel image
> +        * anywhere in memory, but the kernel has restrictions on the
> +        * max physical address it can run at.  Some architectures
> +        * also have a preferred address, so first try to relocate
> +        * to the preferred address.  If that fails, allocate as low
> +        * as possible while respecting the required alignment.
> +        */
> +       nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
> +       status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
> +                            EFI_LOADER_DATA, nr_pages, &efi_addr);
> +       new_addr = efi_addr;
> +       /*
> +        * If preferred address allocation failed allocate as low as
> +        * possible.
> +        */
> +       if (status != EFI_SUCCESS) {
> +               status = efi_low_alloc_above(alloc_size, alignment, &new_addr,
> +                                            min_addr);
> +       }
> +       if (status != EFI_SUCCESS) {
> +               efi_err("Failed to allocate usable memory for kernel.\n");
> +               return status;
> +       }
> +
> +       /*
> +        * We know source/dest won't overlap since both memory ranges
> +        * have been allocated by UEFI, so we can safely use memcpy.
> +        */
> +       memcpy((void *)new_addr, (void *)cur_image_addr, image_size);
> +
> +       /* Return the new address of the relocated image. */
> +       *image_addr = new_addr;
> +
> +       return status;
> +}
> +
>  efi_status_t handle_kernel_image(unsigned long *image_addr,
>                                  unsigned long *image_size,
>                                  unsigned long *reserve_addr,
> diff --git a/drivers/firmware/efi/libstub/mem.c b/drivers/firmware/efi/libstub/mem.c
> index 9c82259eea81..59f3f83de50c 100644
> --- a/drivers/firmware/efi/libstub/mem.c
> +++ b/drivers/firmware/efi/libstub/mem.c
> @@ -124,3 +124,85 @@ void efi_free(unsigned long size, unsigned long addr)
>         nr_pages = round_up(size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
>         efi_bs_call(free_pages, addr, nr_pages);
>  }
> +
> +/**
> + * efi_low_alloc_above() - allocate pages at or above given address
> + * @size:      size of the memory area to allocate
> + * @align:     minimum alignment of the allocated memory area. It should
> + *             a power of two.
> + * @addr:      on exit the address of the allocated memory
> + * @min:       minimum address to used for the memory allocation
> + *
> + * Allocate at the lowest possible address that is not below @min as
> + * EFI_LOADER_DATA. The allocated pages are aligned according to @align but at
> + * least EFI_ALLOC_ALIGN. The first allocated page will not below the address
> + * given by @min.
> + *
> + * Return:     status code
> + */
> +efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
> +                                unsigned long *addr, unsigned long min)
> +{
> +       struct efi_boot_memmap *map __free(efi_pool) = NULL;
> +       efi_status_t status;
> +       unsigned long nr_pages;
> +       int i;
> +
> +       status = efi_get_memory_map(&map, false);
> +       if (status != EFI_SUCCESS)
> +               return status;
> +
> +       /*
> +        * Enforce minimum alignment that EFI or Linux requires when
> +        * requesting a specific address.  We are doing page-based (or
> +        * larger) allocations, and both the address and size must meet
> +        * alignment constraints.
> +        */
> +       if (align < EFI_ALLOC_ALIGN)
> +               align = EFI_ALLOC_ALIGN;
> +
> +       size = round_up(size, EFI_ALLOC_ALIGN);
> +       nr_pages = size / EFI_PAGE_SIZE;
> +       for (i = 0; i < map->map_size / map->desc_size; i++) {
> +               efi_memory_desc_t *desc;
> +               unsigned long m = (unsigned long)map->map;
> +               u64 start, end;
> +
> +               desc = efi_memdesc_ptr(m, map->desc_size, i);
> +
> +               if (desc->type != EFI_CONVENTIONAL_MEMORY)
> +                       continue;
> +
> +               if (desc->attribute & EFI_MEMORY_HOT_PLUGGABLE)
> +                       continue;
> +
> +               if (efi_soft_reserve_enabled() &&
> +                   (desc->attribute & EFI_MEMORY_SP))
> +                       continue;
> +
> +               if (desc->num_pages < nr_pages)
> +                       continue;
> +
> +               start = desc->phys_addr;
> +               end = start + desc->num_pages * EFI_PAGE_SIZE;
> +
> +               if (start < min)
> +                       start = min;
> +
> +               start = round_up(start, align);
> +               if ((start + size) > end)
> +                       continue;
> +
> +               status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
> +                                    EFI_LOADER_DATA, nr_pages, &start);
> +               if (status == EFI_SUCCESS) {
> +                       *addr = start;
> +                       break;
> +               }
> +       }
> +
> +       if (i == map->map_size / map->desc_size)
> +               return EFI_NOT_FOUND;
> +
> +       return EFI_SUCCESS;
> +}
> diff --git a/drivers/firmware/efi/libstub/relocate.c b/drivers/firmware/efi/libstub/relocate.c
> deleted file mode 100644
> index d4264bfb6dc1..000000000000
> --- a/drivers/firmware/efi/libstub/relocate.c
> +++ /dev/null
> @@ -1,166 +0,0 @@
> -// SPDX-License-Identifier: GPL-2.0
> -
> -#include <linux/efi.h>
> -#include <asm/efi.h>
> -
> -#include "efistub.h"
> -
> -/**
> - * efi_low_alloc_above() - allocate pages at or above given address
> - * @size:      size of the memory area to allocate
> - * @align:     minimum alignment of the allocated memory area. It should
> - *             a power of two.
> - * @addr:      on exit the address of the allocated memory
> - * @min:       minimum address to used for the memory allocation
> - *
> - * Allocate at the lowest possible address that is not below @min as
> - * EFI_LOADER_DATA. The allocated pages are aligned according to @align but at
> - * least EFI_ALLOC_ALIGN. The first allocated page will not below the address
> - * given by @min.
> - *
> - * Return:     status code
> - */
> -efi_status_t efi_low_alloc_above(unsigned long size, unsigned long align,
> -                                unsigned long *addr, unsigned long min)
> -{
> -       struct efi_boot_memmap *map __free(efi_pool) = NULL;
> -       efi_status_t status;
> -       unsigned long nr_pages;
> -       int i;
> -
> -       status = efi_get_memory_map(&map, false);
> -       if (status != EFI_SUCCESS)
> -               return status;
> -
> -       /*
> -        * Enforce minimum alignment that EFI or Linux requires when
> -        * requesting a specific address.  We are doing page-based (or
> -        * larger) allocations, and both the address and size must meet
> -        * alignment constraints.
> -        */
> -       if (align < EFI_ALLOC_ALIGN)
> -               align = EFI_ALLOC_ALIGN;
> -
> -       size = round_up(size, EFI_ALLOC_ALIGN);
> -       nr_pages = size / EFI_PAGE_SIZE;
> -       for (i = 0; i < map->map_size / map->desc_size; i++) {
> -               efi_memory_desc_t *desc;
> -               unsigned long m = (unsigned long)map->map;
> -               u64 start, end;
> -
> -               desc = efi_memdesc_ptr(m, map->desc_size, i);
> -
> -               if (desc->type != EFI_CONVENTIONAL_MEMORY)
> -                       continue;
> -
> -               if (desc->attribute & EFI_MEMORY_HOT_PLUGGABLE)
> -                       continue;
> -
> -               if (efi_soft_reserve_enabled() &&
> -                   (desc->attribute & EFI_MEMORY_SP))
> -                       continue;
> -
> -               if (desc->num_pages < nr_pages)
> -                       continue;
> -
> -               start = desc->phys_addr;
> -               end = start + desc->num_pages * EFI_PAGE_SIZE;
> -
> -               if (start < min)
> -                       start = min;
> -
> -               start = round_up(start, align);
> -               if ((start + size) > end)
> -                       continue;
> -
> -               status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
> -                                    EFI_LOADER_DATA, nr_pages, &start);
> -               if (status == EFI_SUCCESS) {
> -                       *addr = start;
> -                       break;
> -               }
> -       }
> -
> -       if (i == map->map_size / map->desc_size)
> -               return EFI_NOT_FOUND;
> -
> -       return EFI_SUCCESS;
> -}
> -
> -/**
> - * efi_relocate_kernel() - copy memory area
> - * @image_addr:                pointer to address of memory area to copy
> - * @image_size:                size of memory area to copy
> - * @alloc_size:                minimum size of memory to allocate, must be greater or
> - *                     equal to image_size
> - * @preferred_addr:    preferred target address
> - * @alignment:         minimum alignment of the allocated memory area. It
> - *                     should be a power of two.
> - * @min_addr:          minimum target address
> - *
> - * Copy a memory area to a newly allocated memory area aligned according
> - * to @alignment but at least EFI_ALLOC_ALIGN. If the preferred address
> - * is not available, the allocated address will not be below @min_addr.
> - * On exit, @image_addr is updated to the target copy address that was used.
> - *
> - * This function is used to copy the Linux kernel verbatim. It does not apply
> - * any relocation changes.
> - *
> - * Return:             status code
> - */
> -efi_status_t efi_relocate_kernel(unsigned long *image_addr,
> -                                unsigned long image_size,
> -                                unsigned long alloc_size,
> -                                unsigned long preferred_addr,
> -                                unsigned long alignment,
> -                                unsigned long min_addr)
> -{
> -       unsigned long cur_image_addr;
> -       unsigned long new_addr = 0;
> -       efi_status_t status;
> -       unsigned long nr_pages;
> -       efi_physical_addr_t efi_addr = preferred_addr;
> -
> -       if (!image_addr || !image_size || !alloc_size)
> -               return EFI_INVALID_PARAMETER;
> -       if (alloc_size < image_size)
> -               return EFI_INVALID_PARAMETER;
> -
> -       cur_image_addr = *image_addr;
> -
> -       /*
> -        * The EFI firmware loader could have placed the kernel image
> -        * anywhere in memory, but the kernel has restrictions on the
> -        * max physical address it can run at.  Some architectures
> -        * also have a preferred address, so first try to relocate
> -        * to the preferred address.  If that fails, allocate as low
> -        * as possible while respecting the required alignment.
> -        */
> -       nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
> -       status = efi_bs_call(allocate_pages, EFI_ALLOCATE_ADDRESS,
> -                            EFI_LOADER_DATA, nr_pages, &efi_addr);
> -       new_addr = efi_addr;
> -       /*
> -        * If preferred address allocation failed allocate as low as
> -        * possible.
> -        */
> -       if (status != EFI_SUCCESS) {
> -               status = efi_low_alloc_above(alloc_size, alignment, &new_addr,
> -                                            min_addr);
> -       }
> -       if (status != EFI_SUCCESS) {
> -               efi_err("Failed to allocate usable memory for kernel.\n");
> -               return status;
> -       }
> -
> -       /*
> -        * We know source/dest won't overlap since both memory ranges
> -        * have been allocated by UEFI, so we can safely use memcpy.
> -        */
> -       memcpy((void *)new_addr, (void *)cur_image_addr, image_size);
> -
> -       /* Return the new address of the relocated image. */
> -       *image_addr = new_addr;
> -
> -       return status;
> -}
> --
> 2.54.0.545.g6539524ca2-goog
>