linux/drivers/firmware/efi/memmap.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Common EFI memory map functions.
 */

#define pr_fmt(fmt) …

#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/efi.h>
#include <linux/io.h>
#include <linux/memblock.h>
#include <linux/slab.h>

#include <asm/early_ioremap.h>
#include <asm/efi.h>

/**
 * __efi_memmap_init - Common code for mapping the EFI memory map
 * @data: EFI memory map data
 *
 * This function takes care of figuring out which function to use to
 * map the EFI memory map in efi.memmap based on how far into the boot
 * we are.
 *
 * During bootup EFI_MEMMAP_LATE in data->flags should be clear since we
 * only have access to the early_memremap*() functions as the vmalloc
 * space isn't setup.  Once the kernel is fully booted we can fallback
 * to the more robust memremap*() API.
 *
 * Returns: zero on success, a negative error code on failure.
 */
int __init __efi_memmap_init(struct efi_memory_map_data *data)
{ … }

/**
 * efi_memmap_init_early - Map the EFI memory map data structure
 * @data: EFI memory map data
 *
 * Use early_memremap() to map the passed in EFI memory map and assign
 * it to efi.memmap.
 *
 * Returns: zero on success, a negative error code on failure.
 */
int __init efi_memmap_init_early(struct efi_memory_map_data *data)
{ … }

void __init efi_memmap_unmap(void)
{ … }

/**
 * efi_memmap_init_late - Map efi.memmap with memremap()
 * @addr: Physical address of the new EFI memory map
 * @size: Size in bytes of the new EFI memory map
 *
 * Setup a mapping of the EFI memory map using ioremap_cache(). This
 * function should only be called once the vmalloc space has been
 * setup and is therefore not suitable for calling during early EFI
 * initialise, e.g. in efi_init(). Additionally, it expects
 * efi_memmap_init_early() to have already been called.
 *
 * The reason there are two EFI memmap initialisation
 * (efi_memmap_init_early() and this late version) is because the
 * early EFI memmap should be explicitly unmapped once EFI
 * initialisation is complete as the fixmap space used to map the EFI
 * memmap (via early_memremap()) is a scarce resource.
 *
 * This late mapping is intended to persist for the duration of
 * runtime so that things like efi_mem_desc_lookup() and
 * efi_mem_attributes() always work.
 *
 * Returns: zero on success, a negative error code on failure.
 */
int __init efi_memmap_init_late(phys_addr_t addr, unsigned long size)
{ … }