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https://gitlab.com/qemu-project/qemu
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![blueswir1](/assets/img/avatar_default.png)
Most 64 bit architectures I'm aware of support running 32 bit code of the same architecture as well. So x86_64 can run i386 code easily and ppc64 can run ppc code. Unfortunately, the current checks are pretty strict. So you can only load e.g. an x86_64 elf binary on qemu-system-x86_64, but no i386 one. This can get really annoying. I first encountered this issue with my multiboot patch, where qemu-system-x86_64 was unable to load an i386 elf binary because the elf loader rejected it. The same thing happened again on PPC64 now. The firmware we're loading is a PPC32 elf binary, as it's shared with PPC32. But the platform is PPC64. Right now there is a hack for this in the ppc cpu.h definition, that simply sets the type to PPC32 in system emulation mode. While that works fine for the firmware, it's no good if you also want to load a PPC64 kernel with -kernel. So in order to solve this mess, I figured the easiest way is to make the elf loader aware of platforms that are backwards compatible. For now I was only sure that x86_64 does i386 and ppc64 does ppc32, but maybe there are other combinations too. This patch is a prerequisite for having a working -kernel option on PPC64. Signed-off-by: Alexander Graf <alex@csgraf.de> git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@6855 c046a42c-6fe2-441c-8c8c-71466251a162
272 lines
7.9 KiB
C
272 lines
7.9 KiB
C
static void glue(bswap_ehdr, SZ)(struct elfhdr *ehdr)
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{
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bswap16s(&ehdr->e_type); /* Object file type */
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bswap16s(&ehdr->e_machine); /* Architecture */
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bswap32s(&ehdr->e_version); /* Object file version */
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bswapSZs(&ehdr->e_entry); /* Entry point virtual address */
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bswapSZs(&ehdr->e_phoff); /* Program header table file offset */
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bswapSZs(&ehdr->e_shoff); /* Section header table file offset */
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bswap32s(&ehdr->e_flags); /* Processor-specific flags */
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bswap16s(&ehdr->e_ehsize); /* ELF header size in bytes */
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bswap16s(&ehdr->e_phentsize); /* Program header table entry size */
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bswap16s(&ehdr->e_phnum); /* Program header table entry count */
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bswap16s(&ehdr->e_shentsize); /* Section header table entry size */
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bswap16s(&ehdr->e_shnum); /* Section header table entry count */
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bswap16s(&ehdr->e_shstrndx); /* Section header string table index */
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}
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static void glue(bswap_phdr, SZ)(struct elf_phdr *phdr)
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{
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bswap32s(&phdr->p_type); /* Segment type */
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bswapSZs(&phdr->p_offset); /* Segment file offset */
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bswapSZs(&phdr->p_vaddr); /* Segment virtual address */
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bswapSZs(&phdr->p_paddr); /* Segment physical address */
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bswapSZs(&phdr->p_filesz); /* Segment size in file */
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bswapSZs(&phdr->p_memsz); /* Segment size in memory */
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bswap32s(&phdr->p_flags); /* Segment flags */
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bswapSZs(&phdr->p_align); /* Segment alignment */
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}
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static void glue(bswap_shdr, SZ)(struct elf_shdr *shdr)
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{
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bswap32s(&shdr->sh_name);
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bswap32s(&shdr->sh_type);
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bswapSZs(&shdr->sh_flags);
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bswapSZs(&shdr->sh_addr);
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bswapSZs(&shdr->sh_offset);
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bswapSZs(&shdr->sh_size);
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bswap32s(&shdr->sh_link);
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bswap32s(&shdr->sh_info);
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bswapSZs(&shdr->sh_addralign);
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bswapSZs(&shdr->sh_entsize);
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}
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static void glue(bswap_sym, SZ)(struct elf_sym *sym)
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{
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bswap32s(&sym->st_name);
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bswapSZs(&sym->st_value);
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bswapSZs(&sym->st_size);
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bswap16s(&sym->st_shndx);
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}
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static struct elf_shdr *glue(find_section, SZ)(struct elf_shdr *shdr_table,
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int n, int type)
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{
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int i;
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for(i=0;i<n;i++) {
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if (shdr_table[i].sh_type == type)
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return shdr_table + i;
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}
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return NULL;
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}
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static int glue(symfind, SZ)(const void *s0, const void *s1)
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{
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struct elf_sym *key = (struct elf_sym *)s0;
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struct elf_sym *sym = (struct elf_sym *)s1;
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int result = 0;
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if (key->st_value < sym->st_value) {
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result = -1;
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} else if (key->st_value > sym->st_value + sym->st_size) {
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result = 1;
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}
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return result;
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}
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static const char *glue(lookup_symbol, SZ)(struct syminfo *s, target_ulong orig_addr)
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{
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struct elf_sym *syms = glue(s->disas_symtab.elf, SZ);
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struct elf_sym key;
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struct elf_sym *sym;
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key.st_value = orig_addr;
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sym = bsearch(&key, syms, s->disas_num_syms, sizeof(*syms), glue(symfind, SZ));
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if (sym != 0) {
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return s->disas_strtab + sym->st_name;
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}
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return "";
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}
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static int glue(symcmp, SZ)(const void *s0, const void *s1)
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{
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struct elf_sym *sym0 = (struct elf_sym *)s0;
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struct elf_sym *sym1 = (struct elf_sym *)s1;
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return (sym0->st_value < sym1->st_value)
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? -1
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: ((sym0->st_value > sym1->st_value) ? 1 : 0);
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}
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static int glue(load_symbols, SZ)(struct elfhdr *ehdr, int fd, int must_swab)
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{
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struct elf_shdr *symtab, *strtab, *shdr_table = NULL;
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struct elf_sym *syms = NULL;
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struct syminfo *s;
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int nsyms, i;
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char *str = NULL;
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shdr_table = load_at(fd, ehdr->e_shoff,
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sizeof(struct elf_shdr) * ehdr->e_shnum);
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if (!shdr_table)
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return -1;
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if (must_swab) {
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for (i = 0; i < ehdr->e_shnum; i++) {
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glue(bswap_shdr, SZ)(shdr_table + i);
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}
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}
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symtab = glue(find_section, SZ)(shdr_table, ehdr->e_shnum, SHT_SYMTAB);
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if (!symtab)
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goto fail;
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syms = load_at(fd, symtab->sh_offset, symtab->sh_size);
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if (!syms)
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goto fail;
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nsyms = symtab->sh_size / sizeof(struct elf_sym);
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i = 0;
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while (i < nsyms) {
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if (must_swab)
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glue(bswap_sym, SZ)(&syms[i]);
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/* We are only interested in function symbols.
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Throw everything else away. */
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if (syms[i].st_shndx == SHN_UNDEF ||
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syms[i].st_shndx >= SHN_LORESERVE ||
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ELF_ST_TYPE(syms[i].st_info) != STT_FUNC) {
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nsyms--;
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if (i < nsyms) {
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syms[i] = syms[nsyms];
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}
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continue;
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}
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#if defined(TARGET_ARM) || defined (TARGET_MIPS)
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/* The bottom address bit marks a Thumb or MIPS16 symbol. */
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syms[i].st_value &= ~(target_ulong)1;
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#endif
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i++;
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}
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syms = qemu_realloc(syms, nsyms * sizeof(*syms));
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qsort(syms, nsyms, sizeof(*syms), glue(symcmp, SZ));
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/* String table */
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if (symtab->sh_link >= ehdr->e_shnum)
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goto fail;
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strtab = &shdr_table[symtab->sh_link];
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str = load_at(fd, strtab->sh_offset, strtab->sh_size);
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if (!str)
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goto fail;
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/* Commit */
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s = qemu_mallocz(sizeof(*s));
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s->lookup_symbol = glue(lookup_symbol, SZ);
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glue(s->disas_symtab.elf, SZ) = syms;
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s->disas_num_syms = nsyms;
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s->disas_strtab = str;
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s->next = syminfos;
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syminfos = s;
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qemu_free(shdr_table);
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return 0;
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fail:
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qemu_free(syms);
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qemu_free(str);
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qemu_free(shdr_table);
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return -1;
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}
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static int glue(load_elf, SZ)(int fd, int64_t address_offset,
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int must_swab, uint64_t *pentry,
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uint64_t *lowaddr, uint64_t *highaddr)
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{
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struct elfhdr ehdr;
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struct elf_phdr *phdr = NULL, *ph;
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int size, i, total_size;
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elf_word mem_size;
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uint64_t addr, low = 0, high = 0;
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uint8_t *data = NULL;
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if (read(fd, &ehdr, sizeof(ehdr)) != sizeof(ehdr))
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goto fail;
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if (must_swab) {
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glue(bswap_ehdr, SZ)(&ehdr);
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}
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switch (ELF_MACHINE) {
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case EM_PPC64:
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if (EM_PPC64 != ehdr.e_machine)
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if (EM_PPC != ehdr.e_machine)
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goto fail;
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break;
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case EM_X86_64:
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if (EM_X86_64 != ehdr.e_machine)
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if (EM_386 != ehdr.e_machine)
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goto fail;
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break;
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default:
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if (ELF_MACHINE != ehdr.e_machine)
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goto fail;
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}
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if (pentry)
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*pentry = (uint64_t)(elf_sword)ehdr.e_entry;
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glue(load_symbols, SZ)(&ehdr, fd, must_swab);
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size = ehdr.e_phnum * sizeof(phdr[0]);
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lseek(fd, ehdr.e_phoff, SEEK_SET);
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phdr = qemu_mallocz(size);
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if (!phdr)
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goto fail;
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if (read(fd, phdr, size) != size)
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goto fail;
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if (must_swab) {
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for(i = 0; i < ehdr.e_phnum; i++) {
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ph = &phdr[i];
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glue(bswap_phdr, SZ)(ph);
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}
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}
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total_size = 0;
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for(i = 0; i < ehdr.e_phnum; i++) {
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ph = &phdr[i];
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if (ph->p_type == PT_LOAD) {
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mem_size = ph->p_memsz;
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/* XXX: avoid allocating */
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data = qemu_mallocz(mem_size);
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if (ph->p_filesz > 0) {
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if (lseek(fd, ph->p_offset, SEEK_SET) < 0)
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goto fail;
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if (read(fd, data, ph->p_filesz) != ph->p_filesz)
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goto fail;
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}
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/* address_offset is hack for kernel images that are
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linked at the wrong physical address. */
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addr = ph->p_paddr + address_offset;
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cpu_physical_memory_write_rom(addr, data, mem_size);
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total_size += mem_size;
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if (!low || addr < low)
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low = addr;
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if (!high || (addr + mem_size) > high)
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high = addr + mem_size;
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qemu_free(data);
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data = NULL;
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}
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}
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qemu_free(phdr);
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if (lowaddr)
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*lowaddr = (uint64_t)(elf_sword)low;
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if (highaddr)
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*highaddr = (uint64_t)(elf_sword)high;
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return total_size;
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fail:
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qemu_free(data);
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qemu_free(phdr);
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return -1;
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}
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