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elf-loader: Provide the possibility to relocate s390 ELF files 

On s390, we would like to load our "BIOS" s390-ccw.img to the end of the
RAM. Therefor we need the possibility to relocate the ELF file so that
it can also run from different addresses. This patch adds the necessary
code to the QEMU ELF loader function.

Signed-off-by: Thomas Huth <thuth@linux.vnet.ibm.com>
Message-Id: <1425895973-15239-2-git-send-email-thuth@linux.vnet.ibm.com>
Acked-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
This commit is contained in:
Thomas Huth 2015-03-09 11:12:52 +01:00 committed by Christian Borntraeger
parent 5c8d542004
commit 5dce07e1cb
3 changed files with 82 additions and 0 deletions
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2
hw/core/loader.c
View File

@ -297,6 +297,7 @@ static void *load_at(int fd, int offset, int size)
#undef elf_phdr
#undef elf_shdr
#undef elf_sym
#undef elf_rela
#undef elf_note
#undef elf_word
#undef elf_sword
@ -307,6 +308,7 @@ static void *load_at(int fd, int offset, int size)
#define elf_note elf64_note
#define elf_shdr elf64_shdr
#define elf_sym elf64_sym
#define elf_rela elf64_rela
#define elf_word uint64_t
#define elf_sword int64_t
#define bswapSZs bswap64s

2
include/elf.h
View File

@ -1508,6 +1508,7 @@ struct elf32_fdpic_loadmap {
#define elf_shdr elf32_shdr
#define elf_sym elf32_sym
#define elf_addr_t Elf32_Off
#define elf_rela elf32_rela
#ifdef ELF_USES_RELOCA
# define ELF_RELOC Elf32_Rela
@ -1523,6 +1524,7 @@ struct elf32_fdpic_loadmap {
#define elf_shdr elf64_shdr
#define elf_sym elf64_sym
#define elf_addr_t Elf64_Off
#define elf_rela elf64_rela
#ifdef ELF_USES_RELOCA
# define ELF_RELOC Elf64_Rela

78
include/hw/elf_ops.h
View File

@ -49,6 +49,13 @@ static void glue(bswap_sym, SZ)(struct elf_sym *sym)
bswap16s(&sym->st_shndx);
}
static void glue(bswap_rela, SZ)(struct elf_rela *rela)
{
bswapSZs(&rela->r_offset);
bswapSZs(&rela->r_info);
bswapSZs((elf_word *)&rela->r_addend);
}
static struct elf_shdr *glue(find_section, SZ)(struct elf_shdr *shdr_table,
int n, int type)
{
@ -182,6 +189,75 @@ static int glue(load_symbols, SZ)(struct elfhdr *ehdr, int fd, int must_swab,
return -1;
}
static int glue(elf_reloc, SZ)(struct elfhdr *ehdr, int fd, int must_swab,
uint64_t (*translate_fn)(void *, uint64_t),
void *translate_opaque, uint8_t *data,
struct elf_phdr *ph, int elf_machine)
{
struct elf_shdr *reltab, *shdr_table = NULL;
struct elf_rela *rels = NULL;
int nrels, i, ret = -1;
elf_word wordval;
void *addr;
shdr_table = load_at(fd, ehdr->e_shoff,
sizeof(struct elf_shdr) * ehdr->e_shnum);
if (!shdr_table) {
return -1;
}
if (must_swab) {
for (i = 0; i < ehdr->e_shnum; i++) {
glue(bswap_shdr, SZ)(&shdr_table[i]);
}
}
reltab = glue(find_section, SZ)(shdr_table, ehdr->e_shnum, SHT_RELA);
if (!reltab) {
goto fail;
}
rels = load_at(fd, reltab->sh_offset, reltab->sh_size);
if (!rels) {
goto fail;
}
nrels = reltab->sh_size / sizeof(struct elf_rela);
for (i = 0; i < nrels; i++) {
if (must_swab) {
glue(bswap_rela, SZ)(&rels[i]);
}
if (rels[i].r_offset < ph->p_vaddr ||
rels[i].r_offset >= ph->p_vaddr + ph->p_filesz) {
continue;
}
addr = &data[rels[i].r_offset - ph->p_vaddr];
switch (elf_machine) {
case EM_S390:
switch (rels[i].r_info) {
case R_390_RELATIVE:
wordval = *(elf_word *)addr;
if (must_swab) {
bswapSZs(&wordval);
}
wordval = translate_fn(translate_opaque, wordval);
if (must_swab) {
bswapSZs(&wordval);
}
*(elf_word *)addr = wordval;
break;
default:
fprintf(stderr, "Unsupported relocation type %i!\n",
(int)rels[i].r_info);
}
}
}
ret = 0;
fail:
g_free(rels);
g_free(shdr_table);
return ret;
}
static int glue(load_elf, SZ)(const char *name, int fd,
uint64_t (*translate_fn)(void *, uint64_t),
void *translate_opaque,
@ -271,6 +347,8 @@ static int glue(load_elf, SZ)(const char *name, int fd,
linked at the wrong physical address. */
if (translate_fn) {
addr = translate_fn(translate_opaque, ph->p_paddr);
glue(elf_reloc, SZ)(&ehdr, fd, must_swab, translate_fn,
translate_opaque, data, ph, elf_machine);
} else {
addr = ph->p_paddr;
}