module.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * OpenRISC module.c
 *
 * Linux architectural port borrowing liberally from similar works of
 * others.  All original copyrights apply as per the original source
 * declaration.
 *
 * Modifications for the OpenRISC architecture:
 * Copyright (C) 2010-2011 Jonas Bonn <[email protected]>
 */

#include <linux/moduleloader.h>
#include <linux/elf.h>

int apply_relocate_add(Elf32_Shdr *sechdrs,
		       const char *strtab,
		       unsigned int symindex,
		       unsigned int relsec,
		       struct module *me)
{
	unsigned int i;
	Elf32_Rela *rel = (void *)sechdrs[relsec].sh_addr;
	Elf32_Sym *sym;
	uint32_t *location;
	uint32_t value;

	pr_debug("Applying relocate section %u to %u\n", relsec,
		 sechdrs[relsec].sh_info);
	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rel); i++) {
		/* This is where to make the change */
		location = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr
			+ rel[i].r_offset;

		/* This is the symbol it is referring to.  Note that all
		   undefined symbols have been resolved.  */
		sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
			+ ELF32_R_SYM(rel[i].r_info);
		value = sym->st_value + rel[i].r_addend;

		switch (ELF32_R_TYPE(rel[i].r_info)) {
		case R_OR1K_32:
			*location = value;
			break;
		case R_OR1K_LO_16_IN_INSN:
			*((uint16_t *)location + 1) = value;
			break;
		case R_OR1K_HI_16_IN_INSN:
			*((uint16_t *)location + 1) = value >> 16;
			break;
		case R_OR1K_INSN_REL_26:
			value -= (uint32_t)location;
			value >>= 2;
			value &= 0x03ffffff;
			value |= *location & 0xfc000000;
			*location = value;
			break;
		case R_OR1K_AHI16:
			/* Adjust the operand to match with a signed LO16.  */
			value += 0x8000;
			*((uint16_t *)location + 1) = value >> 16;
			break;
		case R_OR1K_SLO16:
			/* Split value lower 16-bits.  */
			value = ((value & 0xf800) << 10) | (value & 0x7ff);
			*location = (*location & ~0x3e007ff) | value;
			break;
		default:
			pr_err("module %s: Unknown relocation: %u\n",
			       me->name, ELF32_R_TYPE(rel[i].r_info));
			break;
		}
	}

	return 0;
}