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Re: [Qemu-devel] [PATCH v2 1/2] elf-loader: Provide the possibility to r
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From: |
Thomas Huth |
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Subject: |
Re: [Qemu-devel] [PATCH v2 1/2] elf-loader: Provide the possibility to relocate s390 ELF files |
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Date: |
Mon, 9 Mar 2015 14:30:05 +0100 |
On Mon, 09 Mar 2015 12:11:49 +0100
Christian Borntraeger <address@hidden> wrote:
> Am 09.03.2015 um 11:12 schrieb Thomas Huth:
> > 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 <address@hidden>
>
> I think this was Acked by Alex?
Well, that was on the first version which still had endianess bugs ...
Alex, does your Ack still stand for v2, too?
Thomas
> > ---
> > hw/core/loader.c | 2 +
> > include/elf.h | 2 +
> > include/hw/elf_ops.h | 78
> > ++++++++++++++++++++++++++++++++++++++++++++++++++
> > 3 files changed, 82 insertions(+), 0 deletions(-)
> >
> > diff --git a/hw/core/loader.c b/hw/core/loader.c
> > index e45dc0b..76d8aca 100644
> > --- a/hw/core/loader.c
> > +++ b/hw/core/loader.c
> > @@ -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
> > diff --git a/include/elf.h b/include/elf.h
> > index a516584..3e75f05 100644
> > --- a/include/elf.h
> > +++ b/include/elf.h
> > @@ -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
> > diff --git a/include/hw/elf_ops.h b/include/hw/elf_ops.h
> > index a517753..16a627b 100644
> > --- a/include/hw/elf_ops.h
> > +++ b/include/hw/elf_ops.h
> > @@ -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;
> > }
> >
>