src/lib/rmodule.c

/*
 * This file is part of the coreboot project.
 *
 * Copyright (C) 2012 ChromeOS Authors
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */
#include <assert.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <console/console.h>
#include <rmodule.h>

/* Change this define to get more verbose debugging for module loading. */
#define PK_ADJ_LEVEL BIOS_NEVER

static inline int rmodule_is_loaded(const struct rmodule *module)
{
	return module->location != NULL;
}

/* Calculate a loaded program address based on the blob address. */
static inline void *rmodule_load_addr(const struct rmodule *module,
                                      uintptr_t blob_addr)
{
	char *loc = module->location;
	return &loc[blob_addr - module->header->module_link_start_address];
}

/* Initialize a rmodule structure based on raw data. */
int rmodule_parse(void *ptr, struct rmodule *module)
{
	char *base;
	struct rmodule_header *rhdr;

	base = ptr;
	rhdr = ptr;

	if (rhdr == NULL)
		return -1;

	/* Sanity check the raw data. */
	if (rhdr->magic != RMODULE_MAGIC)
		return -1;
	if (rhdr->version != RMODULE_VERSION_1)
		return -1;

	/* Indicate the module hasn't been loaded yet. */
	module->location = NULL;

	/* The rmodule only needs a reference to the reloc_header. */
	module->header = rhdr;

	/* The payload lives after the header. */
	module->payload = &base[rhdr->payload_begin_offset];
	module->payload_size = rhdr->payload_end_offset -
	                       rhdr->payload_begin_offset;
	module->relocations = &base[rhdr->relocations_begin_offset];

	return 0;
}

int rmodule_memory_size(const struct rmodule *module)
{
	return module->header->module_program_size;
}

void *rmodule_parameters(const struct rmodule *module)
{
	if (!rmodule_is_loaded(module))
		return NULL;

	/* Indicate if there are no parameters. */
	if (module->header->parameters_begin == module->header->parameters_end)
		return NULL;

	return rmodule_load_addr(module, module->header->parameters_begin);
}

int rmodule_entry_offset(const struct rmodule *module)
{
	return module->header->module_entry_point -
	       module->header->module_link_start_address;
}

void *rmodule_entry(const struct rmodule *module)
{
	if (!rmodule_is_loaded(module))
		return NULL;

	return rmodule_load_addr(module, module->header->module_entry_point);
}

static void rmodule_clear_bss(struct rmodule *module)
{
	char *begin;
	int size;

	begin = rmodule_load_addr(module, module->header->bss_begin);
	size = module->header->bss_end - module->header->bss_begin;
	memset(begin, 0, size);
}

static inline size_t rmodule_number_relocations(const struct rmodule *module)
{
	size_t r;

	r = module->header->relocations_end_offset;
	r -= module->header->relocations_begin_offset;
	r /= sizeof(uintptr_t);
	return r;
}

static void rmodule_copy_payload(const struct rmodule *module)
{
	printk(BIOS_DEBUG, "Loading module at %p with entry %p. "
	       "filesize: 0x%x memsize: 0x%x\n",
	       module->location, rmodule_entry(module),
	       module->payload_size, rmodule_memory_size(module));

	/* No need to copy the payload if the load location and the
	 * payload location are the same. */
	if (module->location == module->payload)
		return;

	memcpy(module->location, module->payload, module->payload_size);
}

static int rmodule_relocate(const struct rmodule *module)
{
	size_t num_relocations;
	const uintptr_t *reloc;
	uintptr_t adjustment;

	/* Each relocation needs to be adjusted relative to the beginning of
	 * the loaded program. */
	adjustment = (uintptr_t)rmodule_load_addr(module, 0);

	reloc = module->relocations;
	num_relocations = rmodule_number_relocations(module);

	printk(BIOS_DEBUG, "Processing %zu relocs. Offset value of 0x%08x\n",
	       num_relocations, adjustment);

	while (num_relocations > 0) {
		uintptr_t *adjust_loc;

		/* If the adjustment location is non-NULL adjust it. */
		adjust_loc = rmodule_load_addr(module, *reloc);
		printk(PK_ADJ_LEVEL, "Adjusting %p: 0x%08x -> 0x%08x\n",
			       adjust_loc, *adjust_loc,
			       *adjust_loc + adjustment);
			*adjust_loc += adjustment;

		reloc++;
		num_relocations--;
	}

	return 0;
}

int rmodule_load_alignment(const struct rmodule *module)
{
	/* The load alignment is the start of the program's linked address.
	 * The base address where the program is loaded needs to be a multiple
	 * of the program's starting link address. That way all data alignment
	 * in the program is preserved. Default to 4KiB. */
	return 4096;
}

int rmodule_load(void *base, struct rmodule *module)
{
	/*
	 * In order to load the module at a given address, the following steps
	 * take place:
	 *  1. Copy payload to base address.
	 *  2. Adjust relocations within the module to new base address.
	 *  3. Clear the bss segment last since the relocations live where
	 *     the bss is. If an rmodule is being loaded from its load
	 *     address the relocations need to be processed before the bss.
	 */
	module->location = base;
	rmodule_copy_payload(module);
	if (rmodule_relocate(module))
		return -1;
	rmodule_clear_bss(module);
	return 0;
}

int rmodule_calc_region(unsigned int region_alignment, size_t rmodule_size,
                        size_t *region_size, int *load_offset)
{
	/* region_alignment must be a power of 2. */
	if (region_alignment & (region_alignment - 1))
		BUG();

	if (region_alignment < 4096)
		region_alignment = 4096;

	/* Sanity check rmodule_header size. The code below assumes it is less
	 * than the minimum alignment required. */
	if (region_alignment < sizeof(struct rmodule_header))
		BUG();

	/* Place the rmodule according to alignment. The rmodule files
	 * themselves are packed as a header and a payload, however the rmodule
	 * itself is linked along with the header. The header starts at address
	 * 0. Immediately following the header in the file is the program,
	 * however its starting address is determined by the rmodule linker
	 * script. In short, sizeof(struct rmodule_header) can be less than
	 * or equal to the linked address of the program. Therefore we want
	 * to place the rmodule so that the program falls on the aligned
	 * address with the header just before it. Therefore, we need at least
	 * a page to account for the size of the header. */
	*region_size = ALIGN(rmodule_size + region_alignment, 4096);
	/* The program starts immediately after the header. However,
	 * it needs to be aligned to a 4KiB boundary. Therefore, adjust the
	 * program location so that the program lands on a page boundary.  The
	 * layout looks like the following:
	 *
	 * +--------------------------------+  region_alignment + region_size
	 * |  >= 0 bytes from alignment     |
	 * +--------------------------------+  program end (4KiB aligned)
	 * |  program size                  |
	 * +--------------------------------+  program_begin (4KiB aligned)
	 * |  sizeof(struct rmodule_header) |
	 * +--------------------------------+  rmodule header start
	 * |  >= 0 bytes from alignment     |
	 * +--------------------------------+  region_alignment
	 */
	*load_offset = region_alignment;

	return region_alignment - sizeof(struct rmodule_header);
}

#if CONFIG_DYNAMIC_CBMEM
#include <cbmem.h>
#include <cbfs_core.h>

int rmodule_stage_load(struct rmod_stage_load *rsl, struct cbfs_stage *stage)
{
	struct rmodule rmod_stage;
	size_t region_size;
	char *stage_region;
	int rmodule_offset;
	int load_offset;
	const struct cbmem_entry *cbmem_entry;

	if (stage == NULL || rsl->name == NULL)
		return -1;

	rmodule_offset =
		rmodule_calc_region(DYN_CBMEM_ALIGN_SIZE,
		                    stage->memlen, &region_size, &load_offset);

	cbmem_entry = cbmem_entry_add(rsl->cbmem_id, region_size);

	if (cbmem_entry == NULL)
		return -1;

	stage_region = cbmem_entry_start(cbmem_entry);

	printk(BIOS_INFO, "Decompressing stage %s @ 0x%p (%d bytes)\n",
	       rsl->name, &stage_region[rmodule_offset], stage->memlen);

	if (!cbfs_decompress(stage->compression, &stage[1],
	                    &stage_region[rmodule_offset], stage->len))
		return -1;

	if (rmodule_parse(&stage_region[rmodule_offset], &rmod_stage))
		return -1;

	if (rmodule_load(&stage_region[load_offset], &rmod_stage))
		return -1;

	rsl->cbmem_entry = cbmem_entry;
	rsl->entry = rmodule_entry(&rmod_stage);

	return 0;
}

int rmodule_stage_load_from_cbfs(struct rmod_stage_load *rsl)
{
	struct cbfs_stage *stage;

	stage = cbfs_get_file_content(CBFS_DEFAULT_MEDIA,
	                              rsl->name, CBFS_TYPE_STAGE, NULL);

	if (stage == NULL)
		return -1;

	return rmodule_stage_load(rsl, stage);
}

#endif /* DYNAMIC_CBMEM */