[PATCH v4 04/23] tools: relocate-rela: Read rela start/end directly from ELF
Michal Simek
monstr at monstr.eu
Wed Jun 15 15:21:00 CEST 2022
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 at amd.com>
---
(no changes since v1)
Makefile | 4 +-
tools/relocate-rela.c | 181 ++++++++++++++++++++++++++++++++++++++----
2 files changed, 168 insertions(+), 17 deletions(-)
diff --git a/Makefile b/Makefile
index 2270ec5c7938..55c55dbb7e2b 100644
--- a/Makefile
+++ b/Makefile
@@ -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 =
diff --git a/tools/relocate-rela.c b/tools/relocate-rela.c
index 67a138aa67d7..36065edb3f01 100644
--- a/tools/relocate-rela.c
+++ b/tools/relocate-rela.c
@@ -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)
+{
+ 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)
{
- char *endptr;
- *num = strtoull(str, &endptr, 16);
- return str[0] && !endptr[0];
+ 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) {
--
2.36.1
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