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xemu/include/hw/elf_ops.h
Peter Crosthwaite 7ef295ea5b loader: Add data swap option to load-elf 
Some CPUs are of an opposite data-endianness to other components in the
system. Sometimes elfs have the data sections layed out with this CPU
data-endianness accounting for when loaded via the CPU, so byte swaps
(relative to other system components) will occur.

The leading example, is ARM's BE32 mode, which is is basically LE with
address manipulation on half-word and byte accesses to access the
hw/byte reversed address. This means that word data is invariant
across LE and BE32. This also means that instructions are still LE.
The expectation is that the elf will be loaded via the CPU in this
endianness scheme, which means the data in the elf is reversed at
compile time.

As QEMU loads via the system memory directly, rather than the CPU, we
need a mechanism to reverse elf data endianness to implement this
possibility.

Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
2016-03-04 11:30:21 +00:00

425 lines
13 KiB
C
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static void glue(bswap_ehdr, SZ)(struct elfhdr *ehdr)
{
bswap16s(&ehdr->e_type); /* Object file type */
bswap16s(&ehdr->e_machine); /* Architecture */
bswap32s(&ehdr->e_version); /* Object file version */
bswapSZs(&ehdr->e_entry); /* Entry point virtual address */
bswapSZs(&ehdr->e_phoff); /* Program header table file offset */
bswapSZs(&ehdr->e_shoff); /* Section header table file offset */
bswap32s(&ehdr->e_flags); /* Processor-specific flags */
bswap16s(&ehdr->e_ehsize); /* ELF header size in bytes */
bswap16s(&ehdr->e_phentsize); /* Program header table entry size */
bswap16s(&ehdr->e_phnum); /* Program header table entry count */
bswap16s(&ehdr->e_shentsize); /* Section header table entry size */
bswap16s(&ehdr->e_shnum); /* Section header table entry count */
bswap16s(&ehdr->e_shstrndx); /* Section header string table index */
}
static void glue(bswap_phdr, SZ)(struct elf_phdr *phdr)
{
bswap32s(&phdr->p_type); /* Segment type */
bswapSZs(&phdr->p_offset); /* Segment file offset */
bswapSZs(&phdr->p_vaddr); /* Segment virtual address */
bswapSZs(&phdr->p_paddr); /* Segment physical address */
bswapSZs(&phdr->p_filesz); /* Segment size in file */
bswapSZs(&phdr->p_memsz); /* Segment size in memory */
bswap32s(&phdr->p_flags); /* Segment flags */
bswapSZs(&phdr->p_align); /* Segment alignment */
}
static void glue(bswap_shdr, SZ)(struct elf_shdr *shdr)
{
bswap32s(&shdr->sh_name);
bswap32s(&shdr->sh_type);
bswapSZs(&shdr->sh_flags);
bswapSZs(&shdr->sh_addr);
bswapSZs(&shdr->sh_offset);
bswapSZs(&shdr->sh_size);
bswap32s(&shdr->sh_link);
bswap32s(&shdr->sh_info);
bswapSZs(&shdr->sh_addralign);
bswapSZs(&shdr->sh_entsize);
}
static void glue(bswap_sym, SZ)(struct elf_sym *sym)
{
bswap32s(&sym->st_name);
bswapSZs(&sym->st_value);
bswapSZs(&sym->st_size);
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)
{
int i;
for(i=0;i<n;i++) {
if (shdr_table[i].sh_type == type)
return shdr_table + i;
}
return NULL;
}
static int glue(symfind, SZ)(const void *s0, const void *s1)
{
hwaddr addr = *(hwaddr *)s0;
struct elf_sym *sym = (struct elf_sym *)s1;
int result = 0;
if (addr < sym->st_value) {
result = -1;
} else if (addr >= sym->st_value + sym->st_size) {
result = 1;
}
return result;
}
static const char *glue(lookup_symbol, SZ)(struct syminfo *s,
hwaddr orig_addr)
{
struct elf_sym *syms = glue(s->disas_symtab.elf, SZ);
struct elf_sym *sym;
sym = bsearch(&orig_addr, syms, s->disas_num_syms, sizeof(*syms),
glue(symfind, SZ));
if (sym != NULL) {
return s->disas_strtab + sym->st_name;
}
return "";
}
static int glue(symcmp, SZ)(const void *s0, const void *s1)
{
struct elf_sym *sym0 = (struct elf_sym *)s0;
struct elf_sym *sym1 = (struct elf_sym *)s1;
return (sym0->st_value < sym1->st_value)
? -1
: ((sym0->st_value > sym1->st_value) ? 1 : 0);
}
static int glue(load_symbols, SZ)(struct elfhdr *ehdr, int fd, int must_swab,
int clear_lsb)
{
struct elf_shdr *symtab, *strtab, *shdr_table = NULL;
struct elf_sym *syms = NULL;
struct syminfo *s;
int nsyms, i;
char *str = NULL;
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);
}
}
symtab = glue(find_section, SZ)(shdr_table, ehdr->e_shnum, SHT_SYMTAB);
if (!symtab)
goto fail;
syms = load_at(fd, symtab->sh_offset, symtab->sh_size);
if (!syms)
goto fail;
nsyms = symtab->sh_size / sizeof(struct elf_sym);
i = 0;
while (i < nsyms) {
if (must_swab)
glue(bswap_sym, SZ)(&syms[i]);
/* We are only interested in function symbols.
Throw everything else away. */
if (syms[i].st_shndx == SHN_UNDEF ||
syms[i].st_shndx >= SHN_LORESERVE ||
ELF_ST_TYPE(syms[i].st_info) != STT_FUNC) {
nsyms--;
if (i < nsyms) {
syms[i] = syms[nsyms];
}
continue;
}
if (clear_lsb) {
/* The bottom address bit marks a Thumb or MIPS16 symbol. */
syms[i].st_value &= ~(glue(glue(Elf, SZ), _Addr))1;
}
i++;
}
syms = g_realloc(syms, nsyms * sizeof(*syms));
qsort(syms, nsyms, sizeof(*syms), glue(symcmp, SZ));
for (i = 0; i < nsyms - 1; i++) {
if (syms[i].st_size == 0) {
syms[i].st_size = syms[i + 1].st_value - syms[i].st_value;
}
}
/* String table */
if (symtab->sh_link >= ehdr->e_shnum)
goto fail;
strtab = &shdr_table[symtab->sh_link];
str = load_at(fd, strtab->sh_offset, strtab->sh_size);
if (!str)
goto fail;
/* Commit */
s = g_malloc0(sizeof(*s));
s->lookup_symbol = glue(lookup_symbol, SZ);
glue(s->disas_symtab.elf, SZ) = syms;
s->disas_num_syms = nsyms;
s->disas_strtab = str;
s->next = syminfos;
syminfos = s;
g_free(shdr_table);
return 0;
fail:
g_free(syms);
g_free(str);
g_free(shdr_table);
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,
int must_swab, uint64_t *pentry,
uint64_t *lowaddr, uint64_t *highaddr,
int elf_machine, int clear_lsb, int data_swab)
{
struct elfhdr ehdr;
struct elf_phdr *phdr = NULL, *ph;
int size, i, total_size;
elf_word mem_size, file_size;
uint64_t addr, low = (uint64_t)-1, high = 0;
uint8_t *data = NULL;
char label[128];
int ret = ELF_LOAD_FAILED;
if (read(fd, &ehdr, sizeof(ehdr)) != sizeof(ehdr))
goto fail;
if (must_swab) {
glue(bswap_ehdr, SZ)(&ehdr);
}
switch (elf_machine) {
case EM_PPC64:
if (ehdr.e_machine != EM_PPC64) {
if (ehdr.e_machine != EM_PPC) {
ret = ELF_LOAD_WRONG_ARCH;
goto fail;
}
}
break;
case EM_X86_64:
if (ehdr.e_machine != EM_X86_64) {
if (ehdr.e_machine != EM_386) {
ret = ELF_LOAD_WRONG_ARCH;
goto fail;
}
}
break;
case EM_MICROBLAZE:
if (ehdr.e_machine != EM_MICROBLAZE) {
if (ehdr.e_machine != EM_MICROBLAZE_OLD) {
ret = ELF_LOAD_WRONG_ARCH;
goto fail;
}
}
break;
case EM_MOXIE:
if (ehdr.e_machine != EM_MOXIE) {
if (ehdr.e_machine != EM_MOXIE_OLD) {
ret = ELF_LOAD_WRONG_ARCH;
goto fail;
}
}
break;
default:
if (elf_machine != ehdr.e_machine) {
ret = ELF_LOAD_WRONG_ARCH;
goto fail;
}
}
if (pentry)
*pentry = (uint64_t)(elf_sword)ehdr.e_entry;
glue(load_symbols, SZ)(&ehdr, fd, must_swab, clear_lsb);
size = ehdr.e_phnum * sizeof(phdr[0]);
if (lseek(fd, ehdr.e_phoff, SEEK_SET) != ehdr.e_phoff) {
goto fail;
}
phdr = g_malloc0(size);
if (!phdr)
goto fail;
if (read(fd, phdr, size) != size)
goto fail;
if (must_swab) {
for(i = 0; i < ehdr.e_phnum; i++) {
ph = &phdr[i];
glue(bswap_phdr, SZ)(ph);
}
}
total_size = 0;
for(i = 0; i < ehdr.e_phnum; i++) {
ph = &phdr[i];
if (ph->p_type == PT_LOAD) {
mem_size = ph->p_memsz; /* Size of the ROM */
file_size = ph->p_filesz; /* Size of the allocated data */
data = g_malloc0(file_size);
if (ph->p_filesz > 0) {
if (lseek(fd, ph->p_offset, SEEK_SET) < 0) {
goto fail;
}
if (read(fd, data, file_size) != file_size) {
goto fail;
}
}
/* address_offset is hack for kernel images that are
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;
}
if (data_swab) {
int j;
for (j = 0; j < file_size; j += (1 << data_swab)) {
uint8_t *dp = data + j;
switch (data_swab) {
case (1):
*(uint16_t *)dp = bswap16(*(uint16_t *)dp);
break;
case (2):
*(uint32_t *)dp = bswap32(*(uint32_t *)dp);
break;
case (3):
*(uint64_t *)dp = bswap64(*(uint64_t *)dp);
break;
default:
g_assert_not_reached();
}
}
}
/* the entry pointer in the ELF header is a virtual
* address, if the text segments paddr and vaddr differ
* we need to adjust the entry */
if (pentry && !translate_fn &&
ph->p_vaddr != ph->p_paddr &&
ehdr.e_entry >= ph->p_vaddr &&
ehdr.e_entry < ph->p_vaddr + ph->p_filesz &&
ph->p_flags & PF_X) {
*pentry = ehdr.e_entry - ph->p_vaddr + ph->p_paddr;
}
snprintf(label, sizeof(label), "phdr #%d: %s", i, name);
/* rom_add_elf_program() seize the ownership of 'data' */
rom_add_elf_program(label, data, file_size, mem_size, addr);
total_size += mem_size;
if (addr < low)
low = addr;
if ((addr + mem_size) > high)
high = addr + mem_size;
data = NULL;
}
}
g_free(phdr);
if (lowaddr)
*lowaddr = (uint64_t)(elf_sword)low;
if (highaddr)
*highaddr = (uint64_t)(elf_sword)high;
return total_size;
fail:
g_free(data);
g_free(phdr);
return ret;
}
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