90 lines
2.4 KiB
C
90 lines
2.4 KiB
C
/*
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* Copyright (c) 2023 Intel Corporation
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*
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* SPDX-License-Identifier: Apache-2.0
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*/
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#include <zephyr/llext/elf.h>
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#include <zephyr/llext/llext.h>
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#include <zephyr/llext/llext_internal.h>
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#include <zephyr/llext/loader.h>
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#include <zephyr/logging/log.h>
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LOG_MODULE_DECLARE(llext);
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#define R_XTENSA_NONE 0
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#define R_XTENSA_32 1
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#define R_XTENSA_RTLD 2
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#define R_XTENSA_GLOB_DAT 3
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#define R_XTENSA_JMP_SLOT 4
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#define R_XTENSA_RELATIVE 5
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#define R_XTENSA_PLT 6
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#define R_XTENSA_SLOT0_OP 20
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/**
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* @brief Architecture specific function for relocating shared elf
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*
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* Elf files contain a series of relocations described in multiple sections.
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* These relocation instructions are architecture specific and each architecture
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* supporting modules must implement this.
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*/
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void arch_elf_relocate_local(struct llext_loader *ldr, struct llext *ext,
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const elf_rela_t *rel, const elf_sym_t *sym, size_t got_offset)
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{
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uint8_t *text = ext->mem[LLEXT_MEM_TEXT];
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int type = ELF32_R_TYPE(rel->r_info);
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elf_word *got_entry = (elf_word *)(text + got_offset);
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uintptr_t sh_addr;
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if (ELF_ST_TYPE(sym->st_info) == STT_SECTION) {
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elf_shdr_t *shdr = llext_peek(ldr, ldr->hdr.e_shoff +
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sym->st_shndx * ldr->hdr.e_shentsize);
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sh_addr = shdr->sh_addr ? : (uintptr_t)llext_peek(ldr, shdr->sh_offset);
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} else {
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sh_addr = ldr->sects[LLEXT_MEM_TEXT].sh_addr;
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}
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switch (type) {
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case R_XTENSA_RELATIVE:
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/* Relocate a local symbol: Xtensa specific */
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*got_entry += (uintptr_t)text - sh_addr;
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break;
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case R_XTENSA_32:
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*got_entry += sh_addr;
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break;
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case R_XTENSA_SLOT0_OP:
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;
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uint8_t *opc = (uint8_t *)got_entry;
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/* Check the opcode: is this an L32R? And does it have to be relocated? */
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if ((opc[0] & 0xf) != 1 || opc[1] || opc[2])
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break;
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elf_sym_t rsym;
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int ret = llext_seek(ldr, ldr->sects[LLEXT_MEM_SYMTAB].sh_offset +
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ELF_R_SYM(rel->r_info) * sizeof(elf_sym_t));
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if (!ret) {
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ret = llext_read(ldr, &rsym, sizeof(elf_sym_t));
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}
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if (ret)
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return;
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uintptr_t link_addr = (uintptr_t)llext_loaded_sect_ptr(ldr, ext, rsym.st_shndx) +
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rsym.st_value;
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ssize_t value = (link_addr - (((uintptr_t)got_entry + 3) & ~3)) >> 2;
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opc[1] = value & 0xff;
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opc[2] = (value >> 8) & 0xff;
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break;
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default:
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LOG_DBG("unsupported relocation type %u", type);
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return;
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}
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LOG_DBG("relocation to %#x type %u at %p", *got_entry, type, (void *)got_entry);
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}
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