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Subject[RFC PATCH v3 3/4] objtool: correct rebuilding of reloc sections
From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Currently relocations generated in elf_rebuild_rel_reloc_section/
elf_rebuild_rela_reloc_section functions are broken if the objtool is
built and run on big endian system. E.g. the following errors pop up
during x86 cross compilation:
x86_64-9.1.0-ld: fs/efivarfs/inode.o: bad reloc symbol index (0x2000000 >=
0x22) for offset 0 in section `.orc_unwind_ip'
x86_64-9.1.0-ld: final link failed: bad value

To address that convert those functions to do things similar to
elf_write_reloc(), reuse gelf_update_rel/gelf_update_rela libelf library
functions.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Co-developed-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
---
tools/objtool/elf.c | 34 +++++++++++++++++++---------------
1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
index 4e1d7460574b..5c0341b0cde3 100644
--- a/tools/objtool/elf.c
+++ b/tools/objtool/elf.c
@@ -829,25 +829,27 @@ static int elf_rebuild_rel_reloc_section(struct section *sec, int nr)
{
struct reloc *reloc;
int idx = 0, size;
- GElf_Rel *relocs;
+ void *buf;

/* Allocate a buffer for relocations */
- size = nr * sizeof(*relocs);
- relocs = malloc(size);
- if (!relocs) {
+ size = nr * sizeof(GElf_Rel);
+ buf = malloc(size);
+ if (!buf) {
perror("malloc");
return -1;
}

- sec->data->d_buf = relocs;
+ sec->data->d_buf = buf;
sec->data->d_size = size;
+ sec->data->d_type = ELF_T_REL;

sec->sh.sh_size = size;

idx = 0;
list_for_each_entry(reloc, &sec->reloc_list, list) {
- relocs[idx].r_offset = reloc->offset;
- relocs[idx].r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+ reloc->rel.r_offset = reloc->offset;
+ reloc->rel.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+ gelf_update_rel(sec->data, idx, &reloc->rel);
idx++;
}

@@ -858,26 +860,28 @@ static int elf_rebuild_rela_reloc_section(struct section *sec, int nr)
{
struct reloc *reloc;
int idx = 0, size;
- GElf_Rela *relocs;
+ void *buf;

/* Allocate a buffer for relocations with addends */
- size = nr * sizeof(*relocs);
- relocs = malloc(size);
- if (!relocs) {
+ size = nr * sizeof(GElf_Rela);
+ buf = malloc(size);
+ if (!buf) {
perror("malloc");
return -1;
}

- sec->data->d_buf = relocs;
+ sec->data->d_buf = buf;
sec->data->d_size = size;
+ sec->data->d_type = ELF_T_RELA;

sec->sh.sh_size = size;

idx = 0;
list_for_each_entry(reloc, &sec->reloc_list, list) {
- relocs[idx].r_offset = reloc->offset;
- relocs[idx].r_addend = reloc->addend;
- relocs[idx].r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+ reloc->rela.r_offset = reloc->offset;
+ reloc->rela.r_addend = reloc->addend;
+ reloc->rela.r_info = GELF_R_INFO(reloc->sym->idx, reloc->type);
+ gelf_update_rela(sec->data, idx, &reloc->rela);
idx++;
}

--
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