text: // SPDX-License-Identifier: GPL-2.0
  #include <linux/moduleloader.h>
  #include <linux/elf.h>
  #include <linux/vmalloc.h>
  #include <linux/fs.h>
  #include <linux/string.h>
  #include <linux/kernel.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 *rela = (void *)sechdrs[relsec].sh_addr;
  
  	pr_debug("Applying relocate section %u to %u\n", relsec,
  	       sechdrs[relsec].sh_info);
  	for (i = 0; i < sechdrs[relsec].sh_size / sizeof(*rela); i++) {
  		/* This is where to make the change */
  		uint32_t *loc =
  			(uint32_t *)(sechdrs[sechdrs[relsec].sh_info].sh_addr
  					     + rela[i].r_offset);
  		/* This is the symbol it is referring to.  Note that all
  		   undefined symbols have been resolved.  */
  		Elf32_Sym *sym = (Elf32_Sym *)sechdrs[symindex].sh_addr
  			+ ELF32_R_SYM(rela[i].r_info);
  		uint32_t v = sym->st_value + rela[i].r_addend;
  
  		switch (ELF32_R_TYPE(rela[i].r_info)) {
  		case R_H8_DIR24R8:
  			loc = (uint32_t *)((uint32_t)loc - 1);
  			*loc = (*loc & 0xff000000) | ((*loc & 0xffffff) + v);
  			break;
  		case R_H8_DIR24A8:
  			if (ELF32_R_SYM(rela[i].r_info))
  				*loc += v;
  			break;
  		case R_H8_DIR32:
  		case R_H8_DIR32A16:
  			*loc += v;
  			break;
  		case R_H8_PCREL16:
  			v -= (unsigned long)loc + 2;
  			if ((Elf32_Sword)v > 0x7fff ||
  			    (Elf32_Sword)v < -(Elf32_Sword)0x8000)
  				goto overflow;
  			else
  				*(unsigned short *)loc = v;
  			break;
  		case R_H8_PCREL8:
  			v -= (unsigned long)loc + 1;
  			if ((Elf32_Sword)v > 0x7f ||
  			    (Elf32_Sword)v < -(Elf32_Sword)0x80)
  				goto overflow;
  			else
  				*(unsigned char *)loc = v;
  			break;
  		default:
  			pr_err("module %s: Unknown relocation: %u\n",
  			       me->name, ELF32_R_TYPE(rela[i].r_info));
  			return -ENOEXEC;
  		}
  	}
  	return 0;
   overflow:
  	pr_err("module %s: relocation offset overflow: %08x\n",
  	       me->name, rela[i].r_offset);
  	return -ENOEXEC;
  }
  