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  • /*
     * Read a coreboot rmodule and execute it.
     * The rmodule_header struct is from coreboot.
     *
     * Copyright (c) 2016 Google, Inc
     *
     * SPDX-License-Identifier:	GPL-2.0
     */
    
    #include <common.h>
    #include <errno.h>
    #include <asm/arch/pei_data.h>
    
    #define RMODULE_MAGIC		0xf8fe
    #define RMODULE_VERSION_1	1
    
    /*
     * All fields with '_offset' in the name are byte offsets into the flat blob.
     * The linker and the linker script takes are of assigning the values.
     */
    struct rmodule_header {
    	uint16_t magic;
    	uint8_t version;
    	uint8_t type;
    	/* The payload represents the program's loadable code and data */
    	uint32_t payload_begin_offset;
    	uint32_t payload_end_offset;
    	/* Begin and of relocation information about the program module */
    	uint32_t relocations_begin_offset;
    	uint32_t relocations_end_offset;
    	/*
    	 * The starting address of the linked program. This address is vital
    	 * for determining relocation offsets as the relocation info and other
    	 * symbols (bss, entry point) need this value as a basis to calculate
    	 * the offsets.
    	 */
    	uint32_t module_link_start_address;
    	/*
    	 * The module_program_size is the size of memory used while running
    	 * the program. The program is assumed to consume a contiguous amount
    	 * of memory
    	 */
    	uint32_t module_program_size;
    	/* This is program's execution entry point */
    	uint32_t module_entry_point;
    	/*
    	 * Optional parameter structure that can be used to pass data into
    	 * the module
    	 */
    	uint32_t parameters_begin;
    	uint32_t parameters_end;
    	/* BSS section information so the loader can clear the bss */
    	uint32_t bss_begin;
    	uint32_t bss_end;
    	/* Add some room for growth */
    	uint32_t padding[4];
    } __packed;
    
    int cpu_run_reference_code(void)
    {
    	struct pei_data _pei_data __aligned(8);
    	struct pei_data *pei_data = &_pei_data;
    	asmlinkage int (*func)(void *);
    	struct rmodule_header *hdr;
    	char *src, *dest;
    	int ret, dummy;
    	int size;
    
    	hdr = (struct rmodule_header *)CONFIG_X86_REFCODE_ADDR;
    	debug("Extracting code from rmodule at %p\n", hdr);
    	if (hdr->magic != RMODULE_MAGIC) {
    		debug("Invalid rmodule magic\n");
    		return -EINVAL;
    	}
    	if (hdr->module_link_start_address != 0) {
    		debug("Link start address must be 0\n");
    		return -EPERM;
    	}
    	if (hdr->module_entry_point != 0) {
    		debug("Entry point must be 0\n");
    		return -EPERM;
    	}
    
    	memset(pei_data, '\0', sizeof(struct pei_data));
    	broadwell_fill_pei_data(pei_data);
    	mainboard_fill_pei_data(pei_data);
    	pei_data->saved_data = (void *)&dummy;
    
    	src = (char *)hdr + hdr->payload_begin_offset;
    	dest = (char *)CONFIG_X86_REFCODE_RUN_ADDR;
    
    	size = hdr->payload_end_offset - hdr->payload_begin_offset;
    	debug("Copying refcode from %p to %p, size %x\n", src, dest, size);
    	memcpy(dest, src, size);
    
    	size = hdr->bss_end - hdr->bss_begin;
    	debug("Zeroing BSS at %p, size %x\n", dest + hdr->bss_begin, size);
    	memset(dest + hdr->bss_begin, '\0', size);
    
    	func = (asmlinkage int (*)(void *))dest;
    	debug("Running reference code at %p\n", func);
    #ifdef DEBUG
    	print_buffer(CONFIG_X86_REFCODE_RUN_ADDR, (void *)func, 1, 0x40, 0);
    #endif
    	ret = func(pei_data);
    	if (ret != 0) {
    		debug("Reference code returned %d\n", ret);
    		return -EL2HLT;
    	}
    	debug("Refereence code completed\n");
    
    	return 0;
    }