linux/drivers/of/kexec.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2020 Arm Limited
 *
 * Based on arch/arm64/kernel/machine_kexec_file.c:
 *  Copyright (C) 2018 Linaro Limited
 *
 * And arch/powerpc/kexec/file_load.c:
 *  Copyright (C) 2016  IBM Corporation
 */

#include <linux/ima.h>
#include <linux/kernel.h>
#include <linux/kexec.h>
#include <linux/memblock.h>
#include <linux/libfdt.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/types.h>

#define RNG_SEED_SIZE …

/*
 * Additional space needed for the FDT buffer so that we can add initrd,
 * bootargs, kaslr-seed, rng-seed, useable-memory-range and elfcorehdr.
 */
#define FDT_EXTRA_SPACE …

/**
 * fdt_find_and_del_mem_rsv - delete memory reservation with given address and size
 *
 * @fdt:	Flattened device tree for the current kernel.
 * @start:	Starting address of the reserved memory.
 * @size:	Size of the reserved memory.
 *
 * Return: 0 on success, or negative errno on error.
 */
static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned long size)
{ … }

/**
 * get_addr_size_cells - Get address and size of root node
 *
 * @addr_cells: Return address of the root node
 * @size_cells: Return size of the root node
 *
 * Return: 0 on success, or negative errno on error.
 */
static int get_addr_size_cells(int *addr_cells, int *size_cells)
{ … }

/**
 * do_get_kexec_buffer - Get address and size of device tree property
 *
 * @prop: Device tree property
 * @len: Size of @prop
 * @addr: Return address of the node
 * @size: Return size of the node
 *
 * Return: 0 on success, or negative errno on error.
 */
static int do_get_kexec_buffer(const void *prop, int len, unsigned long *addr,
			       size_t *size)
{ … }

#ifdef CONFIG_HAVE_IMA_KEXEC
/**
 * ima_get_kexec_buffer - get IMA buffer from the previous kernel
 * @addr:	On successful return, set to point to the buffer contents.
 * @size:	On successful return, set to the buffer size.
 *
 * Return: 0 on success, negative errno on error.
 */
int __init ima_get_kexec_buffer(void **addr, size_t *size)
{ … }

/**
 * ima_free_kexec_buffer - free memory used by the IMA buffer
 */
int __init ima_free_kexec_buffer(void)
{ … }
#endif

/**
 * remove_ima_buffer - remove the IMA buffer property and reservation from @fdt
 *
 * @fdt: Flattened Device Tree to update
 * @chosen_node: Offset to the chosen node in the device tree
 *
 * The IMA measurement buffer is of no use to a subsequent kernel, so we always
 * remove it from the device tree.
 */
static void remove_ima_buffer(void *fdt, int chosen_node)
{ … }

#ifdef CONFIG_IMA_KEXEC
/**
 * setup_ima_buffer - add IMA buffer information to the fdt
 * @image:		kexec image being loaded.
 * @fdt:		Flattened device tree for the next kernel.
 * @chosen_node:	Offset to the chosen node.
 *
 * Return: 0 on success, or negative errno on error.
 */
static int setup_ima_buffer(const struct kimage *image, void *fdt,
			    int chosen_node)
{ … }
#else /* CONFIG_IMA_KEXEC */
static inline int setup_ima_buffer(const struct kimage *image, void *fdt,
				   int chosen_node)
{
	return 0;
}
#endif /* CONFIG_IMA_KEXEC */

/*
 * of_kexec_alloc_and_setup_fdt - Alloc and setup a new Flattened Device Tree
 *
 * @image:		kexec image being loaded.
 * @initrd_load_addr:	Address where the next initrd will be loaded.
 * @initrd_len:		Size of the next initrd, or 0 if there will be none.
 * @cmdline:		Command line for the next kernel, or NULL if there will
 *			be none.
 * @extra_fdt_size:	Additional size for the new FDT buffer.
 *
 * Return: fdt on success, or NULL errno on error.
 */
void *of_kexec_alloc_and_setup_fdt(const struct kimage *image,
				   unsigned long initrd_load_addr,
				   unsigned long initrd_len,
				   const char *cmdline, size_t extra_fdt_size)
{ … }