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tools: relocate-rela: Read rela start/end directly from ELF

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There is no need to pass section information via parameters.
Let's read text base and rela start/end directly from elf.
It will help with reading other information from ELF for others
architecture. Input to relocate-rela is u-boot binary and u-boot ELF.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/ab7ae14a6e058722e8c608089729e98edf20a08d.1655299267.git.michal.simek@amd.com
This commit is contained in:
Michal Simek 2022-06-24 14:14:59 +02:00
parent d8b0444b56
commit 4c9e2d6434
2 changed files with 168 additions and 17 deletions
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4
Makefile
View file

@ -925,9 +925,7 @@ ifneq ($(CONFIG_STATIC_RELA),)
# $(2) is u-boot ELF, $(3) is u-boot bin, $(4) is text base
quiet_cmd_static_rela = RELOC $@
cmd_static_rela = \
start=$$($(NM) $(2) | grep __rel_dyn_start | cut -f 1 -d ' '); \
end=$$($(NM) $(2) | grep __rel_dyn_end | cut -f 1 -d ' '); \
tools/relocate-rela $(3) $(4) $$start $$end
tools/relocate-rela $(3) $(2)
else
quiet_cmd_static_rela =
cmd_static_rela =

181
tools/relocate-rela.c
View file

@ -20,6 +20,8 @@
#define R_AARCH64_RELATIVE 1027
#endif
static int ei_class;
static uint64_t rela_start, rela_end, text_base;
static const bool debug_en;
@ -54,32 +56,183 @@ static bool supported_rela(Elf64_Rela *rela)
}
}
static bool read_num(const char *str, uint64_t *num)
static int decode_elf64(FILE *felf, char **argv)
{
char *endptr;
*num = strtoull(str, &endptr, 16);
return str[0] && !endptr[0];
size_t size;
Elf64_Ehdr header;
uint64_t section_header_base, section_header_size, sh_offset, sh_size;
Elf64_Shdr *sh_table; /* Elf symbol table */
int ret, i, machine;
char *sh_str;
debug("64bit version\n");
/* Make sure we are at start */
rewind(felf);
size = fread(&header, 1, sizeof(header), felf);
if (size != sizeof(header)) {
fclose(felf);
return 25;
}
machine = header.e_machine;
debug("Machine\t%d\n", machine);
text_base = header.e_entry;
section_header_base = header.e_shoff;
section_header_size = header.e_shentsize * header.e_shnum;
sh_table = malloc(section_header_size);
if (!sh_table) {
fprintf(stderr, "%s: Cannot allocate space for section header\n",
argv[0]);
fclose(felf);
return 26;
}
ret = fseek(felf, section_header_base, SEEK_SET);
if (ret) {
fprintf(stderr, "%s: Can't set pointer to section header: %x/%lx\n",
argv[0], ret, section_header_base);
free(sh_table);
fclose(felf);
return 26;
}
size = fread(sh_table, 1, section_header_size, felf);
if (size != section_header_size) {
fprintf(stderr, "%s: Can't read section header: %lx/%lx\n",
argv[0], size, section_header_size);
free(sh_table);
fclose(felf);
return 27;
}
sh_size = sh_table[header.e_shstrndx].sh_size;
debug("e_shstrndx\t0x%08x\n", header.e_shstrndx);
debug("sh_size\t\t0x%08lx\n", sh_size);
sh_str = malloc(sh_size);
if (!sh_str) {
fprintf(stderr, "malloc failed\n");
free(sh_table);
fclose(felf);
return 28;
}
/*
* Specifies the byte offset from the beginning of the file
* to the first byte in the section.
*/
sh_offset = sh_table[header.e_shstrndx].sh_offset;
debug("sh_offset\t0x%08x\n", header.e_shnum);
ret = fseek(felf, sh_offset, SEEK_SET);
if (ret) {
fprintf(stderr, "Setting up sh_offset failed\n");
free(sh_str);
free(sh_table);
fclose(felf);
return 29;
}
size = fread(sh_str, 1, sh_size, felf);
if (size != sh_size) {
fprintf(stderr, "%s: Can't read section: %lx/%lx\n",
argv[0], size, sh_size);
free(sh_str);
free(sh_table);
fclose(felf);
return 30;
}
for (i = 0; i < header.e_shnum; i++) {
/* fprintf(stderr, "%s\n", sh_str + sh_table[i].sh_name); Debug only */
if (!strcmp(".rela.dyn", (sh_str + sh_table[i].sh_name))) {
debug("Found section\t\".rela_dyn\"\n");
debug(" at addr\t0x%08x\n",
(unsigned int)sh_table[i].sh_addr);
debug(" at offset\t0x%08x\n",
(unsigned int)sh_table[i].sh_offset);
debug(" of size\t0x%08x\n",
(unsigned int)sh_table[i].sh_size);
rela_start = sh_table[i].sh_addr;
rela_end = rela_start + sh_table[i].sh_size;
break;
}
}
/* Clean up */
free(sh_str);
free(sh_table);
fclose(felf);
debug("text_base\t0x%08lx\n", text_base);
debug("rela_start\t0x%08lx\n", rela_start);
debug("rela_end\t0x%08lx\n", rela_end);
if (!rela_start)
return 1;
return 0;
}
static int decode_elf(char **argv)
{
FILE *felf;
size_t size;
unsigned char e_ident[EI_NIDENT];
felf = fopen(argv[2], "r+b");
if (!felf) {
fprintf(stderr, "%s: Cannot open %s: %s\n",
argv[0], argv[5], strerror(errno));
return 2;
}
size = fread(e_ident, 1, EI_NIDENT, felf);
if (size != EI_NIDENT) {
fclose(felf);
return 25;
}
/* Check if this is really ELF file */
if (e_ident[0] != 0x7f &&
e_ident[1] != 'E' &&
e_ident[2] != 'L' &&
e_ident[3] != 'F') {
fclose(felf);
return 1;
}
ei_class = e_ident[4];
debug("EI_CLASS(1=32bit, 2=64bit) %d\n", ei_class);
if (ei_class == 2)
return decode_elf64(felf, argv);
return 1;
}
int main(int argc, char **argv)
{
FILE *f;
int i, num;
int i, num, ret;
uint64_t file_size;
if (argc != 5) {
if (argc != 3) {
fprintf(stderr, "Statically apply ELF rela relocations\n");
fprintf(stderr, "Usage: %s <bin file> <text base> " \
"<rela start> <rela end>\n", argv[0]);
fprintf(stderr, "All numbers in hex.\n");
fprintf(stderr, "Usage: %s <bin file> <u-boot ELF>\n",
argv[0]);
return 1;
}
if (!read_num(argv[2], &text_base) ||
!read_num(argv[3], &rela_start) ||
!read_num(argv[4], &rela_end)) {
fprintf(stderr, "%s: bad number\n", argv[0]);
return 3;
ret = decode_elf(argv);
if (ret) {
fprintf(stderr, "ELF decoding failed\n");
return ret;
}
if (rela_start > rela_end || rela_start < text_base) {