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// 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/kernel.h>
#include <linux/kexec.h>
#include <linux/libfdt.h>
#include <linux/of.h>
#include <linux/of_fdt.h>
#include <linux/random.h>
#include <linux/types.h>
/* relevant device tree properties */
#define FDT_PROP_KEXEC_ELFHDR "linux,elfcorehdr"
#define FDT_PROP_MEM_RANGE "linux,usable-memory-range"
#define FDT_PROP_INITRD_START "linux,initrd-start"
#define FDT_PROP_INITRD_END "linux,initrd-end"
#define FDT_PROP_BOOTARGS "bootargs"
#define FDT_PROP_KASLR_SEED "kaslr-seed"
#define FDT_PROP_RNG_SEED "rng-seed"
#define RNG_SEED_SIZE 128
/*
* 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 0x1000
/**
* 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)
{
int i, ret, num_rsvs = fdt_num_mem_rsv(fdt);
for (i = 0; i < num_rsvs; i++) {
u64 rsv_start, rsv_size;
ret = fdt_get_mem_rsv(fdt, i, &rsv_start, &rsv_size);
if (ret) {
pr_err("Malformed device tree.\n");
return -EINVAL;
}
if (rsv_start == start && rsv_size == size) {
ret = fdt_del_mem_rsv(fdt, i);
if (ret) {
pr_err("Error deleting device tree reservation.\n");
return -EINVAL;
}
return 0;
}
}
return -ENOENT;
}
/*
* 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)
{
void *fdt;
int ret, chosen_node;
const void *prop;
size_t fdt_size;
fdt_size = fdt_totalsize(initial_boot_params) +
(cmdline ? strlen(cmdline) : 0) +
FDT_EXTRA_SPACE +
extra_fdt_size;
fdt = kvmalloc(fdt_size, GFP_KERNEL);
if (!fdt)
return NULL;
ret = fdt_open_into(initial_boot_params, fdt, fdt_size);
if (ret < 0) {
pr_err("Error %d setting up the new device tree.\n", ret);
goto out;
}
/* Remove memory reservation for the current device tree. */
ret = fdt_find_and_del_mem_rsv(fdt, __pa(initial_boot_params),
fdt_totalsize(initial_boot_params));
if (ret == -EINVAL) {
pr_err("Error removing memory reservation.\n");
goto out;
}
chosen_node = fdt_path_offset(fdt, "/chosen");
if (chosen_node == -FDT_ERR_NOTFOUND)
chosen_node = fdt_add_subnode(fdt, fdt_path_offset(fdt, "/"),
"chosen");
if (chosen_node < 0) {
ret = chosen_node;
goto out;
}
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_KEXEC_ELFHDR);
if (ret && ret != -FDT_ERR_NOTFOUND)
goto out;
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_MEM_RANGE);
if (ret && ret != -FDT_ERR_NOTFOUND)
goto out;
/* Did we boot using an initrd? */
prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", NULL);
if (prop) {
u64 tmp_start, tmp_end, tmp_size;
tmp_start = fdt64_to_cpu(*((const fdt64_t *) prop));
prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", NULL);
if (!prop) {
ret = -EINVAL;
goto out;
}
tmp_end = fdt64_to_cpu(*((const fdt64_t *) prop));
/*
* kexec reserves exact initrd size, while firmware may
* reserve a multiple of PAGE_SIZE, so check for both.
*/
tmp_size = tmp_end - tmp_start;
ret = fdt_find_and_del_mem_rsv(fdt, tmp_start, tmp_size);
if (ret == -ENOENT)
ret = fdt_find_and_del_mem_rsv(fdt, tmp_start,
round_up(tmp_size, PAGE_SIZE));
if (ret == -EINVAL)
goto out;
}
/* add initrd-* */
if (initrd_load_addr) {
ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_INITRD_START,
initrd_load_addr);
if (ret)
goto out;
ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_INITRD_END,
initrd_load_addr + initrd_len);
if (ret)
goto out;
ret = fdt_add_mem_rsv(fdt, initrd_load_addr, initrd_len);
if (ret)
goto out;
} else {
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_INITRD_START);
if (ret && (ret != -FDT_ERR_NOTFOUND))
goto out;
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_INITRD_END);
if (ret && (ret != -FDT_ERR_NOTFOUND))
goto out;
}
if (image->type == KEXEC_TYPE_CRASH) {
/* add linux,elfcorehdr */
ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
FDT_PROP_KEXEC_ELFHDR,
image->elf_load_addr,
image->elf_headers_sz);
if (ret)
goto out;
/*
* Avoid elfcorehdr from being stomped on in kdump kernel by
* setting up memory reserve map.
*/
ret = fdt_add_mem_rsv(fdt, image->elf_load_addr,
image->elf_headers_sz);
if (ret)
goto out;
/* add linux,usable-memory-range */
ret = fdt_appendprop_addrrange(fdt, 0, chosen_node,
FDT_PROP_MEM_RANGE,
crashk_res.start,
crashk_res.end - crashk_res.start + 1);
if (ret)
goto out;
}
/* add bootargs */
if (cmdline) {
ret = fdt_setprop_string(fdt, chosen_node, FDT_PROP_BOOTARGS, cmdline);
if (ret)
goto out;
} else {
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_BOOTARGS);
if (ret && (ret != -FDT_ERR_NOTFOUND))
goto out;
}
/* add kaslr-seed */
ret = fdt_delprop(fdt, chosen_node, FDT_PROP_KASLR_SEED);
if (ret == -FDT_ERR_NOTFOUND)
ret = 0;
else if (ret)
goto out;
if (rng_is_initialized()) {
u64 seed = get_random_u64();
ret = fdt_setprop_u64(fdt, chosen_node, FDT_PROP_KASLR_SEED, seed);
if (ret)
goto out;
} else {
pr_notice("RNG is not initialised: omitting \"%s\" property\n",
FDT_PROP_KASLR_SEED);
}
/* add rng-seed */
if (rng_is_initialized()) {
void *rng_seed;
ret = fdt_setprop_placeholder(fdt, chosen_node, FDT_PROP_RNG_SEED,
RNG_SEED_SIZE, &rng_seed);
if (ret)
goto out;
get_random_bytes(rng_seed, RNG_SEED_SIZE);
} else {
pr_notice("RNG is not initialised: omitting \"%s\" property\n",
FDT_PROP_RNG_SEED);
}
ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0);
out:
if (ret) {
kvfree(fdt);
fdt = NULL;
}
return fdt;
}
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