Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
Ard Biesheuvel | 599 | 100.00% | 1 | 100.00% |
Total | 599 | 1 |
// SPDX-License-Identifier: GPL-2.0-only /* * Copyright (C) 2023 - Google LLC * Author: Ard Biesheuvel <ardb@google.com> */ #include <elf.h> #include <fcntl.h> #include <stdbool.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sys/mman.h> #include <sys/stat.h> #include <sys/types.h> #include <unistd.h> #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__ #define HOST_ORDER ELFDATA2LSB #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__ #define HOST_ORDER ELFDATA2MSB #endif static Elf64_Ehdr *ehdr; static Elf64_Shdr *shdr; static const char *strtab; static bool swap; static uint64_t swab_elfxword(uint64_t val) { return swap ? __builtin_bswap64(val) : val; } static uint32_t swab_elfword(uint32_t val) { return swap ? __builtin_bswap32(val) : val; } static uint16_t swab_elfhword(uint16_t val) { return swap ? __builtin_bswap16(val) : val; } int main(int argc, char *argv[]) { struct stat stat; int fd, ret; if (argc < 3) { fprintf(stderr, "file arguments missing\n"); exit(EXIT_FAILURE); } fd = open(argv[1], O_RDWR); if (fd < 0) { fprintf(stderr, "failed to open %s\n", argv[1]); exit(EXIT_FAILURE); } ret = fstat(fd, &stat); if (ret < 0) { fprintf(stderr, "failed to stat() %s\n", argv[1]); exit(EXIT_FAILURE); } ehdr = mmap(0, stat.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0); if (ehdr == MAP_FAILED) { fprintf(stderr, "failed to mmap() %s\n", argv[1]); exit(EXIT_FAILURE); } swap = ehdr->e_ident[EI_DATA] != HOST_ORDER; shdr = (void *)ehdr + swab_elfxword(ehdr->e_shoff); strtab = (void *)ehdr + swab_elfxword(shdr[swab_elfhword(ehdr->e_shstrndx)].sh_offset); for (int i = 0; i < swab_elfhword(ehdr->e_shnum); i++) { unsigned long info, flags; bool prel64 = false; Elf64_Rela *rela; int numrela; if (swab_elfword(shdr[i].sh_type) != SHT_RELA) continue; /* only consider RELA sections operating on data */ info = swab_elfword(shdr[i].sh_info); flags = swab_elfxword(shdr[info].sh_flags); if ((flags & (SHF_ALLOC | SHF_EXECINSTR)) != SHF_ALLOC) continue; /* * We generally don't permit ABS64 relocations in the code that * runs before relocation processing occurs. If statically * initialized absolute symbol references are unavoidable, they * may be emitted into a *.rodata.prel64 section and they will * be converted to place-relative 64-bit references. This * requires special handling in the referring code. */ if (strstr(strtab + swab_elfword(shdr[info].sh_name), ".rodata.prel64")) { prel64 = true; } rela = (void *)ehdr + swab_elfxword(shdr[i].sh_offset); numrela = swab_elfxword(shdr[i].sh_size) / sizeof(*rela); for (int j = 0; j < numrela; j++) { uint64_t info = swab_elfxword(rela[j].r_info); if (ELF64_R_TYPE(info) != R_AARCH64_ABS64) continue; if (prel64) { /* convert ABS64 into PREL64 */ info ^= R_AARCH64_ABS64 ^ R_AARCH64_PREL64; rela[j].r_info = swab_elfxword(info); } else { fprintf(stderr, "Unexpected absolute relocations detected in %s\n", argv[2]); close(fd); unlink(argv[1]); exit(EXIT_FAILURE); } } } close(fd); return 0; }
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