[tip: objtool/core] objtool: Fix reloc generation on big endian cross compiles

[tip-bot2 for Martin Schwidefsky]

The following commit has been merged into the objtool/core branch of tip:

Commit-ID:     317664a7fcc99d9bcc0cb33ac05e27764f3024e4
Gitweb:        
https://git.kernel.org/tip/317664a7fcc99d9bcc0cb33ac05e27764f3024e4
Author:        Martin Schwidefsky <schwidef...@de.ibm.com>
AuthorDate:    Sun, 04 Oct 2020 16:30:50 +02:00
Committer:     Josh Poimboeuf <jpoim...@redhat.com>
CommitterDate: Tue, 06 Oct 2020 09:36:48 -05:00

objtool: Fix reloc generation on big endian cross compiles

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 <schwidef...@de.ibm.com>
Co-developed-by: Vasily Gorbik <g...@linux.ibm.com>
Signed-off-by: Vasily Gorbik <g...@linux.ibm.com>
Signed-off-by: Josh Poimboeuf <jpoim...@redhat.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 4e1d746..5c0341b 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++;
        }