diff options
Diffstat (limited to 'drivers/of/kexec.c')
| -rw-r--r-- | drivers/of/kexec.c | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/drivers/of/kexec.c b/drivers/of/kexec.c index 8fa8946cda42..6512e25671df 100644 --- a/drivers/of/kexec.c +++ b/drivers/of/kexec.c @@ -11,6 +11,7 @@ #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> @@ -69,6 +70,240 @@ static int fdt_find_and_del_mem_rsv(void *fdt, unsigned long start, unsigned lon 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; +} + +/** + * 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 ima_get_kexec_buffer(void **addr, size_t *size) +{ + int ret, len; + unsigned long tmp_addr; + size_t tmp_size; + const void *prop; + + if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC)) + return -ENOTSUPP; + + 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; + + *addr = __va(tmp_addr); + *size = tmp_size; + + return 0; +} + +/** + * ima_free_kexec_buffer - free memory used by the IMA buffer + */ +int ima_free_kexec_buffer(void) +{ + int ret; + unsigned long addr; + size_t size; + struct property *prop; + + if (!IS_ENABLED(CONFIG_HAVE_IMA_KEXEC)) + return -ENOTSUPP; + + 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; + + return memblock_free(addr, size); + +} + +/** + * 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 +/** + * write_number - Convert number to big-endian format + * + * @p: Buffer to write the number to + * @value: Number to convert + * @cells: Number of cells + * + * Return: 0 on success, or negative errno on error. + */ +static int write_number(void *p, u64 value, int cells) +{ + if (cells == 1) { + u32 tmp; + + if (value > U32_MAX) + return -EINVAL; + + tmp = cpu_to_be32(value); + memcpy(p, &tmp, sizeof(tmp)); + } else if (cells == 2) { + u64 tmp; + + tmp = cpu_to_be64(value); + memcpy(p, &tmp, sizeof(tmp)); + } else + return -EINVAL; + + return 0; +} + +/** + * 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, addr_cells, size_cells, entry_size; + u8 value[16]; + + if (!image->ima_buffer_size) + return 0; + + ret = get_addr_size_cells(&addr_cells, &size_cells); + if (ret) + return ret; + + entry_size = 4 * (addr_cells + size_cells); + + if (entry_size > sizeof(value)) + return -EINVAL; + + ret = write_number(value, image->ima_buffer_addr, addr_cells); + if (ret) + return ret; + + ret = write_number(value + 4 * addr_cells, image->ima_buffer_size, + size_cells); + if (ret) + return ret; + + ret = fdt_setprop(fdt, chosen_node, "linux,ima-kexec-buffer", value, + entry_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 * @@ -254,6 +489,11 @@ void *of_kexec_alloc_and_setup_fdt(const struct kimage *image, } 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) { |