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![Paul Burton](/assets/img/avatar_default.png)
It seems that gcc 6.3 at least is smart enough to warn about the _val variable being unassigned in the default case in the set_hdr_field() macro, but not smart enough to figure out that the default case is never taken. This results in warnings such as the following: pfx##hdr32[idx].field = _val; \ ^ ../tools/mips-relocs.c:51:11: note: _val was declared here uint64_t _val; \ ^ ../tools/mips-relocs.c:88:2: note: in expansion of macro set_hdr_field set_hdr_field(p, idx, field, val) ^~~~~~~~~~~~~ ../tools/mips-relocs.c:408:3: note: in expansion of macro set_phdr_field set_phdr_field(i, p_filesz, load_sz); ^~~~~~~~~~~~~~ ../tools/mips-relocs.c: In function main: ../tools/mips-relocs.c:77:25: warning: _val may be used uninitialized in this function [-Wmaybe-uninitialized] Avoid this by assigning _val = 0 in the default case, and asserting that we didn't actually hit it for good measure. For reference gcc 7.1.1 seems to be smart enough to not hit the above warning without this patch. Signed-off-by: Paul Burton <paul.burton@imgtec.com> Fixes: 011dd93ca97a ("MIPS: Stop building position independent code") Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com> Cc: Tom Rini <trini@konsulko.com> Cc: u-boot@lists.denx.de
433 lines
9.5 KiB
C
433 lines
9.5 KiB
C
/*
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* MIPS Relocation Data Generator
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*
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* Copyright (c) 2017 Imagination Technologies Ltd.
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*
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* SPDX-License-Identifier: GPL-2.0+
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*/
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#include <assert.h>
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#include <elf.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include <asm/relocs.h>
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#define hdr_field(pfx, idx, field) ({ \
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uint64_t _val; \
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unsigned int _size; \
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\
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if (is_64) { \
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_val = pfx##hdr64[idx].field; \
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_size = sizeof(pfx##hdr64[0].field); \
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} else { \
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_val = pfx##hdr32[idx].field; \
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_size = sizeof(pfx##hdr32[0].field); \
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} \
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\
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switch (_size) { \
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case 1: \
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break; \
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case 2: \
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_val = is_be ? be16toh(_val) : le16toh(_val); \
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break; \
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case 4: \
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_val = is_be ? be32toh(_val) : le32toh(_val); \
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break; \
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case 8: \
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_val = is_be ? be64toh(_val) : le64toh(_val); \
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break; \
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} \
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\
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_val; \
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})
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#define set_hdr_field(pfx, idx, field, val) ({ \
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uint64_t _val; \
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unsigned int _size; \
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\
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if (is_64) \
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_size = sizeof(pfx##hdr64[0].field); \
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else \
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_size = sizeof(pfx##hdr32[0].field); \
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\
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switch (_size) { \
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case 1: \
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_val = val; \
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break; \
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case 2: \
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_val = is_be ? htobe16(val) : htole16(val); \
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break; \
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case 4: \
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_val = is_be ? htobe32(val) : htole32(val); \
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break; \
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case 8: \
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_val = is_be ? htobe64(val) : htole64(val); \
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break; \
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default: \
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/* We should never reach here */ \
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_val = 0; \
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assert(0); \
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break; \
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} \
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\
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if (is_64) \
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pfx##hdr64[idx].field = _val; \
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else \
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pfx##hdr32[idx].field = _val; \
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})
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#define ehdr_field(field) \
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hdr_field(e, 0, field)
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#define phdr_field(idx, field) \
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hdr_field(p, idx, field)
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#define shdr_field(idx, field) \
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hdr_field(s, idx, field)
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#define set_phdr_field(idx, field, val) \
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set_hdr_field(p, idx, field, val)
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#define set_shdr_field(idx, field, val) \
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set_hdr_field(s, idx, field, val)
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#define shstr(idx) (&shstrtab[idx])
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bool is_64, is_be;
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uint64_t text_base;
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struct mips_reloc {
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uint8_t type;
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uint64_t offset;
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} *relocs;
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size_t relocs_sz, relocs_idx;
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static int add_reloc(unsigned int type, uint64_t off)
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{
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struct mips_reloc *new;
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size_t new_sz;
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switch (type) {
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case R_MIPS_NONE:
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case R_MIPS_LO16:
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case R_MIPS_PC16:
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case R_MIPS_HIGHER:
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case R_MIPS_HIGHEST:
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case R_MIPS_PC21_S2:
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case R_MIPS_PC26_S2:
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/* Skip these relocs */
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return 0;
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default:
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break;
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}
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if (relocs_idx == relocs_sz) {
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new_sz = relocs_sz ? relocs_sz * 2 : 128;
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new = realloc(relocs, new_sz * sizeof(*relocs));
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if (!new) {
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fprintf(stderr, "Out of memory\n");
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return -ENOMEM;
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}
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relocs = new;
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relocs_sz = new_sz;
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}
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relocs[relocs_idx++] = (struct mips_reloc){
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.type = type,
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.offset = off,
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};
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return 0;
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}
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static int parse_mips32_rel(const void *_rel)
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{
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const Elf32_Rel *rel = _rel;
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uint32_t off, type;
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off = is_be ? be32toh(rel->r_offset) : le32toh(rel->r_offset);
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off -= text_base;
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type = is_be ? be32toh(rel->r_info) : le32toh(rel->r_info);
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type = ELF32_R_TYPE(type);
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return add_reloc(type, off);
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}
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static int parse_mips64_rela(const void *_rel)
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{
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const Elf64_Rela *rel = _rel;
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uint64_t off, type;
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off = is_be ? be64toh(rel->r_offset) : le64toh(rel->r_offset);
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off -= text_base;
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type = rel->r_info >> (64 - 8);
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return add_reloc(type, off);
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}
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static void output_uint(uint8_t **buf, uint64_t val)
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{
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uint64_t tmp;
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do {
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tmp = val & 0x7f;
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val >>= 7;
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tmp |= !!val << 7;
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*(*buf)++ = tmp;
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} while (val);
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}
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static int compare_relocs(const void *a, const void *b)
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{
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const struct mips_reloc *ra = a, *rb = b;
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return ra->offset - rb->offset;
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}
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int main(int argc, char *argv[])
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{
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unsigned int i, j, i_rel_shdr, sh_type, sh_entsize, sh_entries;
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size_t rel_size, rel_actual_size, load_sz;
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const char *shstrtab, *sh_name, *rel_pfx;
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int (*parse_fn)(const void *rel);
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uint8_t *buf_start, *buf;
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const Elf32_Ehdr *ehdr32;
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const Elf64_Ehdr *ehdr64;
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uintptr_t sh_offset;
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Elf32_Phdr *phdr32;
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Elf64_Phdr *phdr64;
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Elf32_Shdr *shdr32;
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Elf64_Shdr *shdr64;
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struct stat st;
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int err, fd;
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void *elf;
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bool skip;
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fd = open(argv[1], O_RDWR);
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if (fd == -1) {
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fprintf(stderr, "Unable to open input file %s\n", argv[1]);
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err = errno;
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goto out_ret;
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}
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err = fstat(fd, &st);
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if (err) {
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fprintf(stderr, "Unable to fstat() input file\n");
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goto out_close_fd;
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}
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elf = mmap(NULL, st.st_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
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if (elf == MAP_FAILED) {
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fprintf(stderr, "Unable to mmap() input file\n");
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err = errno;
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goto out_close_fd;
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}
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ehdr32 = elf;
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ehdr64 = elf;
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if (memcmp(&ehdr32->e_ident[EI_MAG0], ELFMAG, SELFMAG)) {
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fprintf(stderr, "Input file is not an ELF\n");
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err = -EINVAL;
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goto out_free_relocs;
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}
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if (ehdr32->e_ident[EI_VERSION] != EV_CURRENT) {
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fprintf(stderr, "Unrecognised ELF version\n");
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err = -EINVAL;
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goto out_free_relocs;
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}
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switch (ehdr32->e_ident[EI_CLASS]) {
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case ELFCLASS32:
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is_64 = false;
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break;
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case ELFCLASS64:
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is_64 = true;
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break;
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default:
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fprintf(stderr, "Unrecognised ELF class\n");
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err = -EINVAL;
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goto out_free_relocs;
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}
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switch (ehdr32->e_ident[EI_DATA]) {
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case ELFDATA2LSB:
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is_be = false;
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break;
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case ELFDATA2MSB:
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is_be = true;
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break;
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default:
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fprintf(stderr, "Unrecognised ELF data encoding\n");
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err = -EINVAL;
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goto out_free_relocs;
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}
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if (ehdr_field(e_type) != ET_EXEC) {
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fprintf(stderr, "Input ELF is not an executable\n");
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printf("type 0x%lx\n", ehdr_field(e_type));
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err = -EINVAL;
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goto out_free_relocs;
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}
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if (ehdr_field(e_machine) != EM_MIPS) {
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fprintf(stderr, "Input ELF does not target MIPS\n");
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err = -EINVAL;
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goto out_free_relocs;
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}
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phdr32 = elf + ehdr_field(e_phoff);
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phdr64 = elf + ehdr_field(e_phoff);
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shdr32 = elf + ehdr_field(e_shoff);
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shdr64 = elf + ehdr_field(e_shoff);
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shstrtab = elf + shdr_field(ehdr_field(e_shstrndx), sh_offset);
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i_rel_shdr = UINT_MAX;
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for (i = 0; i < ehdr_field(e_shnum); i++) {
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sh_name = shstr(shdr_field(i, sh_name));
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if (!strcmp(sh_name, ".rel")) {
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i_rel_shdr = i;
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continue;
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}
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if (!strcmp(sh_name, ".text")) {
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text_base = shdr_field(i, sh_addr);
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continue;
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}
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}
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if (i_rel_shdr == UINT_MAX) {
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fprintf(stderr, "Unable to find .rel section\n");
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err = -EINVAL;
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goto out_free_relocs;
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}
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if (!text_base) {
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fprintf(stderr, "Unable to find .text base address\n");
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err = -EINVAL;
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goto out_free_relocs;
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}
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rel_pfx = is_64 ? ".rela." : ".rel.";
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for (i = 0; i < ehdr_field(e_shnum); i++) {
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sh_type = shdr_field(i, sh_type);
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if ((sh_type != SHT_REL) && (sh_type != SHT_RELA))
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continue;
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sh_name = shstr(shdr_field(i, sh_name));
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if (strncmp(sh_name, rel_pfx, strlen(rel_pfx))) {
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if (strcmp(sh_name, ".rel") && strcmp(sh_name, ".rel.dyn"))
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fprintf(stderr, "WARNING: Unexpected reloc section name '%s'\n", sh_name);
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continue;
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}
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/*
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* Skip reloc sections which either don't correspond to another
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* section in the ELF, or whose corresponding section isn't
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* loaded as part of the U-Boot binary (ie. doesn't have the
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* alloc flags set).
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*/
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skip = true;
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for (j = 0; j < ehdr_field(e_shnum); j++) {
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if (strcmp(&sh_name[strlen(rel_pfx) - 1], shstr(shdr_field(j, sh_name))))
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continue;
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skip = !(shdr_field(j, sh_flags) & SHF_ALLOC);
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break;
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}
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if (skip)
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continue;
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sh_offset = shdr_field(i, sh_offset);
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sh_entsize = shdr_field(i, sh_entsize);
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sh_entries = shdr_field(i, sh_size) / sh_entsize;
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if (sh_type == SHT_REL) {
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if (is_64) {
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fprintf(stderr, "REL-style reloc in MIPS64 ELF?\n");
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err = -EINVAL;
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goto out_free_relocs;
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} else {
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parse_fn = parse_mips32_rel;
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}
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} else {
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if (is_64) {
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parse_fn = parse_mips64_rela;
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} else {
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fprintf(stderr, "RELA-style reloc in MIPS32 ELF?\n");
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err = -EINVAL;
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goto out_free_relocs;
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}
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}
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for (j = 0; j < sh_entries; j++) {
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err = parse_fn(elf + sh_offset + (j * sh_entsize));
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if (err)
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goto out_free_relocs;
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}
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}
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/* Sort relocs in ascending order of offset */
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qsort(relocs, relocs_idx, sizeof(*relocs), compare_relocs);
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/* Make reloc offsets relative to their predecessor */
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for (i = relocs_idx - 1; i > 0; i--)
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relocs[i].offset -= relocs[i - 1].offset;
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/* Write the relocations to the .rel section */
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buf = buf_start = elf + shdr_field(i_rel_shdr, sh_offset);
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for (i = 0; i < relocs_idx; i++) {
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output_uint(&buf, relocs[i].type);
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output_uint(&buf, relocs[i].offset >> 2);
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}
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/* Write a terminating R_MIPS_NONE (0) */
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output_uint(&buf, R_MIPS_NONE);
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/* Ensure the relocs didn't overflow the .rel section */
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rel_size = shdr_field(i_rel_shdr, sh_size);
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rel_actual_size = buf - buf_start;
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if (rel_actual_size > rel_size) {
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fprintf(stderr, "Relocs overflowed .rel section\n");
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return -ENOMEM;
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}
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/* Update the .rel section's size */
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set_shdr_field(i_rel_shdr, sh_size, rel_actual_size);
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/* Shrink the PT_LOAD program header filesz (ie. shrink u-boot.bin) */
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for (i = 0; i < ehdr_field(e_phnum); i++) {
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if (phdr_field(i, p_type) != PT_LOAD)
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continue;
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load_sz = phdr_field(i, p_filesz);
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load_sz -= rel_size - rel_actual_size;
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set_phdr_field(i, p_filesz, load_sz);
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break;
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}
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/* Make sure data is written back to the file */
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err = msync(elf, st.st_size, MS_SYNC);
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if (err) {
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fprintf(stderr, "Failed to msync: %d\n", errno);
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goto out_free_relocs;
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}
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out_free_relocs:
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free(relocs);
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munmap(elf, st.st_size);
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out_close_fd:
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close(fd);
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out_ret:
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return err;
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}
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