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33 results

efi-stub-helper.c

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  • efi-stub-helper.c 16.12 KiB
    /*
     * Helper functions used by the EFI stub on multiple
     * architectures. This should be #included by the EFI stub
     * implementation files.
     *
     * Copyright 2011 Intel Corporation; author Matt Fleming
     *
     * This file is part of the Linux kernel, and is made available
     * under the terms of the GNU General Public License version 2.
     *
     */
    
    #include <linux/efi.h>
    #include <asm/efi.h>
    
    #include "efistub.h"
    
    /*
     * Some firmware implementations have problems reading files in one go.
     * A read chunk size of 1MB seems to work for most platforms.
     *
     * Unfortunately, reading files in chunks triggers *other* bugs on some
     * platforms, so we provide a way to disable this workaround, which can
     * be done by passing "efi=nochunk" on the EFI boot stub command line.
     *
     * If you experience issues with initrd images being corrupt it's worth
     * trying efi=nochunk, but chunking is enabled by default because there
     * are far more machines that require the workaround than those that
     * break with it enabled.
     */
    #define EFI_READ_CHUNK_SIZE	(1024 * 1024)
    
    static unsigned long __chunk_size = EFI_READ_CHUNK_SIZE;
    
    /*
     * Allow the platform to override the allocation granularity: this allows
     * systems that have the capability to run with a larger page size to deal
     * with the allocations for initrd and fdt more efficiently.
     */
    #ifndef EFI_ALLOC_ALIGN
    #define EFI_ALLOC_ALIGN		EFI_PAGE_SIZE
    #endif
    
    struct file_info {
    	efi_file_handle_t *handle;
    	u64 size;
    };
    
    void efi_printk(efi_system_table_t *sys_table_arg, char *str)
    {
    	char *s8;
    
    	for (s8 = str; *s8; s8++) {
    		efi_char16_t ch[2] = { 0 };
    
    		ch[0] = *s8;
    		if (*s8 == '\n') {
    			efi_char16_t nl[2] = { '\r', 0 };
    			efi_char16_printk(sys_table_arg, nl);
    		}
    
    		efi_char16_printk(sys_table_arg, ch);
    	}
    }
    
    efi_status_t efi_get_memory_map(efi_system_table_t *sys_table_arg,
    				efi_memory_desc_t **map,
    				unsigned long *map_size,
    				unsigned long *desc_size,
    				u32 *desc_ver,
    				unsigned long *key_ptr)
    {
    	efi_memory_desc_t *m = NULL;
    	efi_status_t status;
    	unsigned long key;
    	u32 desc_version;
    
    	*map_size = sizeof(*m) * 32;
    again:
    	/*
    	 * Add an additional efi_memory_desc_t because we're doing an
    	 * allocation which may be in a new descriptor region.
    	 */
    	*map_size += sizeof(*m);
    	status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
    				*map_size, (void **)&m);
    	if (status != EFI_SUCCESS)
    		goto fail;
    
    	*desc_size = 0;
    	key = 0;
    	status = efi_call_early(get_memory_map, map_size, m,
    				&key, desc_size, &desc_version);
    	if (status == EFI_BUFFER_TOO_SMALL) {
    		efi_call_early(free_pool, m);
    		goto again;
    	}
    
    	if (status != EFI_SUCCESS)
    		efi_call_early(free_pool, m);
    
    	if (key_ptr && status == EFI_SUCCESS)
    		*key_ptr = key;
    	if (desc_ver && status == EFI_SUCCESS)
    		*desc_ver = desc_version;
    
    fail:
    	*map = m;
    	return status;
    }
    
    
    unsigned long get_dram_base(efi_system_table_t *sys_table_arg)
    {
    	efi_status_t status;
    	unsigned long map_size;
    	unsigned long membase  = EFI_ERROR;
    	struct efi_memory_map map;
    	efi_memory_desc_t *md;
    
    	status = efi_get_memory_map(sys_table_arg, (efi_memory_desc_t **)&map.map,
    				    &map_size, &map.desc_size, NULL, NULL);
    	if (status != EFI_SUCCESS)
    		return membase;
    
    	map.map_end = map.map + map_size;
    
    	for_each_efi_memory_desc_in_map(&map, md) {
    		if (md->attribute & EFI_MEMORY_WB) {
    			if (membase > md->phys_addr)
    				membase = md->phys_addr;
    		}
    	}
    
    	efi_call_early(free_pool, map.map);
    
    	return membase;
    }
    
    /*
     * Allocate at the highest possible address that is not above 'max'.
     */
    efi_status_t efi_high_alloc(efi_system_table_t *sys_table_arg,
    			    unsigned long size, unsigned long align,
    			    unsigned long *addr, unsigned long max)
    {
    	unsigned long map_size, desc_size;
    	efi_memory_desc_t *map;
    	efi_status_t status;
    	unsigned long nr_pages;
    	u64 max_addr = 0;
    	int i;
    
    	status = efi_get_memory_map(sys_table_arg, &map, &map_size, &desc_size,
    				    NULL, NULL);
    	if (status != EFI_SUCCESS)
    		goto fail;
    
    	/*
    	 * Enforce minimum alignment that EFI requires when requesting
    	 * a specific address.  We are doing page-based allocations,
    	 * so we must be aligned to a page.
    	 */
    	if (align < EFI_ALLOC_ALIGN)
    		align = EFI_ALLOC_ALIGN;
    
    	nr_pages = round_up(size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
    again:
    	for (i = 0; i < map_size / desc_size; i++) {
    		efi_memory_desc_t *desc;
    		unsigned long m = (unsigned long)map;
    		u64 start, end;
    
    		desc = (efi_memory_desc_t *)(m + (i * desc_size));
    		if (desc->type != EFI_CONVENTIONAL_MEMORY)
    			continue;
    
    		if (desc->num_pages < nr_pages)
    			continue;
    
    		start = desc->phys_addr;
    		end = start + desc->num_pages * (1UL << EFI_PAGE_SHIFT);
    
    		if (end > max)
    			end = max;
    
    		if ((start + size) > end)
    			continue;
    
    		if (round_down(end - size, align) < start)
    			continue;
    
    		start = round_down(end - size, align);
    
    		/*
    		 * Don't allocate at 0x0. It will confuse code that
    		 * checks pointers against NULL.
    		 */
    		if (start == 0x0)
    			continue;
    
    		if (start > max_addr)
    			max_addr = start;
    	}
    
    	if (!max_addr)
    		status = EFI_NOT_FOUND;
    	else {
    		status = efi_call_early(allocate_pages,
    					EFI_ALLOCATE_ADDRESS, EFI_LOADER_DATA,
    					nr_pages, &max_addr);
    		if (status != EFI_SUCCESS) {
    			max = max_addr;
    			max_addr = 0;
    			goto again;
    		}
    
    		*addr = max_addr;
    	}
    
    	efi_call_early(free_pool, map);
    fail:
    	return status;
    }
    
    /*
     * Allocate at the lowest possible address.
     */
    efi_status_t efi_low_alloc(efi_system_table_t *sys_table_arg,
    			   unsigned long size, unsigned long align,
    			   unsigned long *addr)
    {
    	unsigned long map_size, desc_size;
    	efi_memory_desc_t *map;
    	efi_status_t status;
    	unsigned long nr_pages;
    	int i;
    
    	status = efi_get_memory_map(sys_table_arg, &map, &map_size, &desc_size,
    				    NULL, NULL);
    	if (status != EFI_SUCCESS)
    		goto fail;
    
    	/*
    	 * Enforce minimum alignment that EFI requires when requesting
    	 * a specific address.  We are doing page-based allocations,
    	 * so we must be aligned to a page.
    	 */
    	if (align < EFI_ALLOC_ALIGN)
    		align = EFI_ALLOC_ALIGN;
    
    	nr_pages = round_up(size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
    	for (i = 0; i < map_size / desc_size; i++) {
    		efi_memory_desc_t *desc;
    		unsigned long m = (unsigned long)map;
    		u64 start, end;
    
    		desc = (efi_memory_desc_t *)(m + (i * desc_size));
    
    		if (desc->type != EFI_CONVENTIONAL_MEMORY)
    			continue;
    
    		if (desc->num_pages < nr_pages)
    			continue;
    
    		start = desc->phys_addr;
    		end = start + desc->num_pages * (1UL << EFI_PAGE_SHIFT);
    
    		/*
    		 * Don't allocate at 0x0. It will confuse code that
    		 * checks pointers against NULL. Skip the first 8
    		 * bytes so we start at a nice even number.
    		 */
    		if (start == 0x0)
    			start += 8;
    
    		start = round_up(start, align);
    		if ((start + size) > end)
    			continue;
    
    		status = efi_call_early(allocate_pages,
    					EFI_ALLOCATE_ADDRESS, EFI_LOADER_DATA,
    					nr_pages, &start);
    		if (status == EFI_SUCCESS) {
    			*addr = start;
    			break;
    		}
    	}
    
    	if (i == map_size / desc_size)
    		status = EFI_NOT_FOUND;
    
    	efi_call_early(free_pool, map);
    fail:
    	return status;
    }
    
    void efi_free(efi_system_table_t *sys_table_arg, unsigned long size,
    	      unsigned long addr)
    {
    	unsigned long nr_pages;
    
    	if (!size)
    		return;
    
    	nr_pages = round_up(size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
    	efi_call_early(free_pages, addr, nr_pages);
    }
    
    /*
     * Parse the ASCII string 'cmdline' for EFI options, denoted by the efi=
     * option, e.g. efi=nochunk.
     *
     * It should be noted that efi= is parsed in two very different
     * environments, first in the early boot environment of the EFI boot
     * stub, and subsequently during the kernel boot.
     */
    efi_status_t efi_parse_options(char *cmdline)
    {
    	char *str;
    
    	/*
    	 * If no EFI parameters were specified on the cmdline we've got
    	 * nothing to do.
    	 */
    	str = strstr(cmdline, "efi=");
    	if (!str)
    		return EFI_SUCCESS;
    
    	/* Skip ahead to first argument */
    	str += strlen("efi=");
    
    	/*
    	 * Remember, because efi= is also used by the kernel we need to
    	 * skip over arguments we don't understand.
    	 */
    	while (*str) {
    		if (!strncmp(str, "nochunk", 7)) {
    			str += strlen("nochunk");
    			__chunk_size = -1UL;
    		}
    
    		/* Group words together, delimited by "," */
    		while (*str && *str != ',')
    			str++;
    
    		if (*str == ',')
    			str++;
    	}
    
    	return EFI_SUCCESS;
    }
    
    /*
     * Check the cmdline for a LILO-style file= arguments.
     *
     * We only support loading a file from the same filesystem as
     * the kernel image.
     */
    efi_status_t handle_cmdline_files(efi_system_table_t *sys_table_arg,
    				  efi_loaded_image_t *image,
    				  char *cmd_line, char *option_string,
    				  unsigned long max_addr,
    				  unsigned long *load_addr,
    				  unsigned long *load_size)
    {
    	struct file_info *files;
    	unsigned long file_addr;
    	u64 file_size_total;
    	efi_file_handle_t *fh = NULL;
    	efi_status_t status;
    	int nr_files;
    	char *str;
    	int i, j, k;
    
    	file_addr = 0;
    	file_size_total = 0;
    
    	str = cmd_line;
    
    	j = 0;			/* See close_handles */
    
    	if (!load_addr || !load_size)
    		return EFI_INVALID_PARAMETER;
    
    	*load_addr = 0;
    	*load_size = 0;
    
    	if (!str || !*str)
    		return EFI_SUCCESS;
    
    	for (nr_files = 0; *str; nr_files++) {
    		str = strstr(str, option_string);
    		if (!str)
    			break;
    
    		str += strlen(option_string);
    
    		/* Skip any leading slashes */
    		while (*str == '/' || *str == '\\')
    			str++;
    
    		while (*str && *str != ' ' && *str != '\n')
    			str++;
    	}
    
    	if (!nr_files)
    		return EFI_SUCCESS;
    
    	status = efi_call_early(allocate_pool, EFI_LOADER_DATA,
    				nr_files * sizeof(*files), (void **)&files);
    	if (status != EFI_SUCCESS) {
    		pr_efi_err(sys_table_arg, "Failed to alloc mem for file handle list\n");
    		goto fail;
    	}
    
    	str = cmd_line;
    	for (i = 0; i < nr_files; i++) {
    		struct file_info *file;
    		efi_char16_t filename_16[256];
    		efi_char16_t *p;
    
    		str = strstr(str, option_string);
    		if (!str)
    			break;
    
    		str += strlen(option_string);
    
    		file = &files[i];
    		p = filename_16;
    
    		/* Skip any leading slashes */
    		while (*str == '/' || *str == '\\')
    			str++;
    
    		while (*str && *str != ' ' && *str != '\n') {
    			if ((u8 *)p >= (u8 *)filename_16 + sizeof(filename_16))
    				break;
    
    			if (*str == '/') {
    				*p++ = '\\';
    				str++;
    			} else {
    				*p++ = *str++;
    			}
    		}
    
    		*p = '\0';
    
    		/* Only open the volume once. */
    		if (!i) {
    			status = efi_open_volume(sys_table_arg, image,
    						 (void **)&fh);
    			if (status != EFI_SUCCESS)
    				goto free_files;
    		}
    
    		status = efi_file_size(sys_table_arg, fh, filename_16,
    				       (void **)&file->handle, &file->size);
    		if (status != EFI_SUCCESS)
    			goto close_handles;
    
    		file_size_total += file->size;
    	}
    
    	if (file_size_total) {
    		unsigned long addr;
    
    		/*
    		 * Multiple files need to be at consecutive addresses in memory,
    		 * so allocate enough memory for all the files.  This is used
    		 * for loading multiple files.
    		 */
    		status = efi_high_alloc(sys_table_arg, file_size_total, 0x1000,
    				    &file_addr, max_addr);
    		if (status != EFI_SUCCESS) {
    			pr_efi_err(sys_table_arg, "Failed to alloc highmem for files\n");
    			goto close_handles;
    		}
    
    		/* We've run out of free low memory. */
    		if (file_addr > max_addr) {
    			pr_efi_err(sys_table_arg, "We've run out of free low memory\n");
    			status = EFI_INVALID_PARAMETER;
    			goto free_file_total;
    		}
    
    		addr = file_addr;
    		for (j = 0; j < nr_files; j++) {
    			unsigned long size;
    
    			size = files[j].size;
    			while (size) {
    				unsigned long chunksize;
    				if (size > __chunk_size)
    					chunksize = __chunk_size;
    				else
    					chunksize = size;
    
    				status = efi_file_read(files[j].handle,
    						       &chunksize,
    						       (void *)addr);
    				if (status != EFI_SUCCESS) {
    					pr_efi_err(sys_table_arg, "Failed to read file\n");
    					goto free_file_total;
    				}
    				addr += chunksize;
    				size -= chunksize;
    			}
    
    			efi_file_close(files[j].handle);
    		}
    
    	}
    
    	efi_call_early(free_pool, files);
    
    	*load_addr = file_addr;
    	*load_size = file_size_total;
    
    	return status;
    
    free_file_total:
    	efi_free(sys_table_arg, file_size_total, file_addr);
    
    close_handles:
    	for (k = j; k < i; k++)
    		efi_file_close(files[k].handle);
    free_files:
    	efi_call_early(free_pool, files);
    fail:
    	*load_addr = 0;
    	*load_size = 0;
    
    	return status;
    }
    /*
     * Relocate a kernel image, either compressed or uncompressed.
     * In the ARM64 case, all kernel images are currently
     * uncompressed, and as such when we relocate it we need to
     * allocate additional space for the BSS segment. Any low
     * memory that this function should avoid needs to be
     * unavailable in the EFI memory map, as if the preferred
     * address is not available the lowest available address will
     * be used.
     */
    efi_status_t efi_relocate_kernel(efi_system_table_t *sys_table_arg,
    				 unsigned long *image_addr,
    				 unsigned long image_size,
    				 unsigned long alloc_size,
    				 unsigned long preferred_addr,
    				 unsigned long alignment)
    {
    	unsigned long cur_image_addr;
    	unsigned long new_addr = 0;
    	efi_status_t status;
    	unsigned long nr_pages;
    	efi_physical_addr_t efi_addr = preferred_addr;
    
    	if (!image_addr || !image_size || !alloc_size)
    		return EFI_INVALID_PARAMETER;
    	if (alloc_size < image_size)
    		return EFI_INVALID_PARAMETER;
    
    	cur_image_addr = *image_addr;
    
    	/*
    	 * The EFI firmware loader could have placed the kernel image
    	 * anywhere in memory, but the kernel has restrictions on the
    	 * max physical address it can run at.  Some architectures
    	 * also have a prefered address, so first try to relocate
    	 * to the preferred address.  If that fails, allocate as low
    	 * as possible while respecting the required alignment.
    	 */
    	nr_pages = round_up(alloc_size, EFI_ALLOC_ALIGN) / EFI_PAGE_SIZE;
    	status = efi_call_early(allocate_pages,
    				EFI_ALLOCATE_ADDRESS, EFI_LOADER_DATA,
    				nr_pages, &efi_addr);
    	new_addr = efi_addr;
    	/*
    	 * If preferred address allocation failed allocate as low as
    	 * possible.
    	 */
    	if (status != EFI_SUCCESS) {
    		status = efi_low_alloc(sys_table_arg, alloc_size, alignment,
    				       &new_addr);
    	}
    	if (status != EFI_SUCCESS) {
    		pr_efi_err(sys_table_arg, "Failed to allocate usable memory for kernel.\n");
    		return status;
    	}
    
    	/*
    	 * We know source/dest won't overlap since both memory ranges
    	 * have been allocated by UEFI, so we can safely use memcpy.
    	 */
    	memcpy((void *)new_addr, (void *)cur_image_addr, image_size);
    
    	/* Return the new address of the relocated image. */
    	*image_addr = new_addr;
    
    	return status;
    }
    
    /*
     * Get the number of UTF-8 bytes corresponding to an UTF-16 character.
     * This overestimates for surrogates, but that is okay.
     */
    static int efi_utf8_bytes(u16 c)
    {
    	return 1 + (c >= 0x80) + (c >= 0x800);
    }
    
    /*
     * Convert an UTF-16 string, not necessarily null terminated, to UTF-8.
     */
    static u8 *efi_utf16_to_utf8(u8 *dst, const u16 *src, int n)
    {
    	unsigned int c;
    
    	while (n--) {
    		c = *src++;
    		if (n && c >= 0xd800 && c <= 0xdbff &&
    		    *src >= 0xdc00 && *src <= 0xdfff) {
    			c = 0x10000 + ((c & 0x3ff) << 10) + (*src & 0x3ff);
    			src++;
    			n--;
    		}
    		if (c >= 0xd800 && c <= 0xdfff)
    			c = 0xfffd; /* Unmatched surrogate */
    		if (c < 0x80) {
    			*dst++ = c;
    			continue;
    		}
    		if (c < 0x800) {
    			*dst++ = 0xc0 + (c >> 6);
    			goto t1;
    		}
    		if (c < 0x10000) {
    			*dst++ = 0xe0 + (c >> 12);
    			goto t2;
    		}
    		*dst++ = 0xf0 + (c >> 18);
    		*dst++ = 0x80 + ((c >> 12) & 0x3f);
    	t2:
    		*dst++ = 0x80 + ((c >> 6) & 0x3f);
    	t1:
    		*dst++ = 0x80 + (c & 0x3f);
    	}
    
    	return dst;
    }
    
    #ifndef MAX_CMDLINE_ADDRESS
    #define MAX_CMDLINE_ADDRESS	ULONG_MAX
    #endif
    
    /*
     * Convert the unicode UEFI command line to ASCII to pass to kernel.
     * Size of memory allocated return in *cmd_line_len.
     * Returns NULL on error.
     */
    char *efi_convert_cmdline(efi_system_table_t *sys_table_arg,
    			  efi_loaded_image_t *image,
    			  int *cmd_line_len)
    {
    	const u16 *s2;
    	u8 *s1 = NULL;
    	unsigned long cmdline_addr = 0;
    	int load_options_chars = image->load_options_size / 2; /* UTF-16 */
    	const u16 *options = image->load_options;
    	int options_bytes = 0;  /* UTF-8 bytes */
    	int options_chars = 0;  /* UTF-16 chars */
    	efi_status_t status;
    	u16 zero = 0;
    
    	if (options) {
    		s2 = options;
    		while (*s2 && *s2 != '\n'
    		       && options_chars < load_options_chars) {
    			options_bytes += efi_utf8_bytes(*s2++);
    			options_chars++;
    		}
    	}
    
    	if (!options_chars) {
    		/* No command line options, so return empty string*/
    		options = &zero;
    	}
    
    	options_bytes++;	/* NUL termination */
    
    	status = efi_high_alloc(sys_table_arg, options_bytes, 0,
    				&cmdline_addr, MAX_CMDLINE_ADDRESS);
    	if (status != EFI_SUCCESS)
    		return NULL;
    
    	s1 = (u8 *)cmdline_addr;
    	s2 = (const u16 *)options;
    
    	s1 = efi_utf16_to_utf8(s1, s2, options_chars);
    	*s1 = '\0';
    
    	*cmd_line_len = options_bytes;
    	return (char *)cmdline_addr;
    }