Primary Git Repository for the Zephyr Project. Zephyr is a new generation, scalable, optimized, secure RTOS for multiple hardware architectures.
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/*
* Copyright (c) 2024 Intel Corporation
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <zephyr/llext/elf.h>
#include <zephyr/llext/llext.h>
#include <zephyr/llext/llext_internal.h>
#include <zephyr/llext/loader.h>
#include <zephyr/logging/log.h>
#include <zephyr/sys/util.h>
LOG_MODULE_REGISTER(elf, CONFIG_LLEXT_LOG_LEVEL);
#define R_ARC_32 4
#define R_ARC_B26 5 /* AKA R_ARC_64 */
#define R_ARC_S25W_PCREL 17
#define R_ARC_32_ME 27
/* ARCompact insns packed in memory have Middle Endian encoding */
#define ME(x) (((x & 0xffff0000) >> 16) | ((x & 0xffff) << 16))
/**
* @brief Architecture specific function for relocating shared elf
*
* Elf files contain a series of relocations described in multiple sections.
* These relocation instructions are architecture specific and each architecture
* supporting modules must implement this.
*
* The relocation codes are well documented:
* https://github.com/foss-for-synopsys-dwc-arc-processors/arc-ABI-manual/blob/master/ARCv2_ABI.pdf
* https://github.com/zephyrproject-rtos/binutils-gdb
*/
int arch_elf_relocate(struct llext_loader *ldr, struct llext *ext, elf_rela_t *rel,
const elf_shdr_t *shdr)
{
int ret = 0;
uint32_t value;
const uintptr_t loc = llext_get_reloc_instruction_location(ldr, ext, shdr->sh_info, rel);
uint32_t insn = UNALIGNED_GET((uint32_t *)loc);
elf_sym_t sym;
uintptr_t sym_base_addr;
const char *sym_name;
ret = llext_read_symbol(ldr, ext, rel, &sym);
if (ret != 0) {
LOG_ERR("Could not read symbol from binary!");
return ret;
}
sym_name = llext_symbol_name(ldr, ext, &sym);
ret = llext_lookup_symbol(ldr, ext, &sym_base_addr, rel, &sym, sym_name, shdr);
if (ret != 0) {
LOG_ERR("Could not find symbol %s!", sym_name);
return ret;
}
sym_base_addr += rel->r_addend;
int reloc_type = ELF32_R_TYPE(rel->r_info);
switch (reloc_type) {
case R_ARC_32:
case R_ARC_B26:
UNALIGNED_PUT(sym_base_addr, (uint32_t *)loc);
break;
case R_ARC_S25W_PCREL:
/* ((S + A) - P) >> 2
* S = symbol address
* A = addend
* P = relative offset to PCL
*/
value = (sym_base_addr + rel->r_addend - (loc & ~0x3)) >> 2;
insn = ME(insn);
/* disp25w */
insn = insn & ~0x7fcffcf;
insn |= ((value >> 0) & 0x01ff) << 18;
insn |= ((value >> 9) & 0x03ff) << 6;
insn |= ((value >> 19) & 0x000f) << 0;
insn = ME(insn);
UNALIGNED_PUT(insn, (uint32_t *)loc);
break;
case R_ARC_32_ME:
UNALIGNED_PUT(ME(sym_base_addr), (uint32_t *)loc);
break;
default:
LOG_ERR("unknown relocation: %u\n", reloc_type);
ret = -ENOEXEC;
break;
}
return ret;
}