diff options
Diffstat (limited to 'drivers/of/kexec.c')
| -rw-r--r-- | drivers/of/kexec.c | 472 |
1 files changed, 472 insertions, 0 deletions
diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c new file mode 100644 index 0000000000..68278340ce --- /dev/null +++ b/drivers/of/kexec.c @@ -0,0 +1,472 @@ +// 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 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; +} + +/** + * 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) +{ + struct device_node *root; + + root = of_find_node_by_path("/"); + if (!root) + return -EINVAL; + + *addr_cells = of_n_addr_cells(root); + *size_cells = of_n_size_cells(root); + + of_node_put(root); + + return 0; +} + +/** + * 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) +{ + int ret, addr_cells, size_cells; + + ret = get_addr_size_cells(&addr_cells, &size_cells); + if (ret) + return ret; + + if (len < 4 * (addr_cells + size_cells)) + return -ENOENT; + + *addr = of_read_number(prop, addr_cells); + *size = of_read_number(prop + 4 * addr_cells, size_cells); + + return 0; +} + +#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) +{ + int ret, len; + unsigned long tmp_addr; + unsigned long start_pfn, end_pfn; + size_t tmp_size; + const void *prop; + + prop = of_get_property(of_chosen, "linux,ima-kexec-buffer", &len); + if (!prop) + return -ENOENT; + + ret = do_get_kexec_buffer(prop, len, &tmp_addr, &tmp_size); + if (ret) + return ret; + + /* Do some sanity on the returned size for the ima-kexec buffer */ + if (!tmp_size) + return -ENOENT; + + /* + * Calculate the PFNs for the buffer and ensure + * they are with in addressable memory. + */ + start_pfn = PHYS_PFN(tmp_addr); + end_pfn = PHYS_PFN(tmp_addr + tmp_size - 1); + if (!page_is_ram(start_pfn) || !page_is_ram(end_pfn)) { + pr_warn("IMA buffer at 0x%lx, size = 0x%zx beyond memory\n", + tmp_addr, tmp_size); + return -EINVAL; + } + + *addr = __va(tmp_addr); + *size = tmp_size; + + return 0; +} + +/** + * ima_free_kexec_buffer - free memory used by the IMA buffer + */ +int __init ima_free_kexec_buffer(void) +{ + int ret; + unsigned long addr; + size_t size; + struct property *prop; + + prop = of_find_property(of_chosen, "linux,ima-kexec-buffer", NULL); + if (!prop) + return -ENOENT; + + ret = do_get_kexec_buffer(prop->value, prop->length, &addr, &size); + if (ret) + return ret; + + ret = of_remove_property(of_chosen, prop); + if (ret) + return ret; + + memblock_free_late(addr, size); + return 0; +} +#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) +{ + int ret, len; + unsigned long addr; + size_t size; + const void *prop; + + if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC)) + return; + + prop = fdt_getprop(fdt, chosen_node, "linux,ima-kexec-buffer", &len); + if (!prop) + return; + + ret = do_get_kexec_buffer(prop, len, &addr, &size); + fdt_delprop(fdt, chosen_node, "linux,ima-kexec-buffer"); + if (ret) + return; + + ret = fdt_find_and_del_mem_rsv(fdt, addr, size); + if (!ret) + pr_debug("Removed old IMA buffer reservation.\n"); +} + +#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) +{ + int ret; + + if (!image->ima_buffer_size) + return 0; + + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, + "linux,ima-kexec-buffer", + image->ima_buffer_addr, + image->ima_buffer_size); + if (ret < 0) + return -EINVAL; + + ret = fdt_add_mem_rsv(fdt, image->ima_buffer_addr, + image->ima_buffer_size); + if (ret) + return -EINVAL; + + pr_debug("IMA buffer at 0x%llx, size = 0x%zx\n", + image->ima_buffer_addr, image->ima_buffer_size); + + return 0; +} +#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) +{ + void *fdt; + int ret, chosen_node, len; + 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, "linux,elfcorehdr"); + if (ret && ret != -FDT_ERR_NOTFOUND) + goto out; + ret = fdt_delprop(fdt, chosen_node, "linux,usable-memory-range"); + if (ret && ret != -FDT_ERR_NOTFOUND) + goto out; + + /* Did we boot using an initrd? */ + prop = fdt_getprop(fdt, chosen_node, "linux,initrd-start", &len); + if (prop) { + u64 tmp_start, tmp_end, tmp_size; + + tmp_start = of_read_number(prop, len / 4); + + prop = fdt_getprop(fdt, chosen_node, "linux,initrd-end", &len); + if (!prop) { + ret = -EINVAL; + goto out; + } + + tmp_end = of_read_number(prop, len / 4); + + /* + * 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, "linux,initrd-start", + initrd_load_addr); + if (ret) + goto out; + + ret = fdt_setprop_u64(fdt, chosen_node, "linux,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, "linux,initrd-start"); + if (ret && (ret != -FDT_ERR_NOTFOUND)) + goto out; + + ret = fdt_delprop(fdt, chosen_node, "linux,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, + "linux,elfcorehdr", 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, + "linux,usable-memory-range", crashk_res.start, + crashk_res.end - crashk_res.start + 1); + if (ret) + goto out; + + if (crashk_low_res.end) { + ret = fdt_appendprop_addrrange(fdt, 0, chosen_node, + "linux,usable-memory-range", + crashk_low_res.start, + crashk_low_res.end - crashk_low_res.start + 1); + if (ret) + goto out; + } + } + + /* add bootargs */ + if (cmdline) { + ret = fdt_setprop_string(fdt, chosen_node, "bootargs", cmdline); + if (ret) + goto out; + } else { + ret = fdt_delprop(fdt, chosen_node, "bootargs"); + if (ret && (ret != -FDT_ERR_NOTFOUND)) + goto out; + } + + /* add kaslr-seed */ + ret = fdt_delprop(fdt, chosen_node, "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, "kaslr-seed", seed); + if (ret) + goto out; + } else { + pr_notice("RNG is not initialised: omitting \"%s\" property\n", + "kaslr-seed"); + } + + /* add rng-seed */ + if (rng_is_initialized()) { + void *rng_seed; + + ret = fdt_setprop_placeholder(fdt, chosen_node, "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", + "rng-seed"); + } + + ret = fdt_setprop(fdt, chosen_node, "linux,booted-from-kexec", NULL, 0); + if (ret) + goto out; + + remove_ima_buffer(fdt, chosen_node); + ret = setup_ima_buffer(image, fdt, fdt_path_offset(fdt, "/chosen")); + +out: + if (ret) { + kvfree(fdt); + fdt = NULL; + } + + return fdt; +} |