Revamp relocation handling.
Move more code to common dl.c. Add missing veneers for arm and arm64. Decreases kernel size by 70 bytes on i386-pc (40-50 compressed)
This commit is contained in:
Vladimir Serbinenko
parent
a846dd4b3a
commit
8c534b85f1
18 changed files with 1097 additions and 987 deletions
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@ -25,6 +25,15 @@
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#include <grub/i18n.h>
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#include <grub/cpu/reloc.h>
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struct trampoline
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{
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#define LDR 0x58000050
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#define BR 0xd61f0200
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grub_uint32_t ldr; /* ldr x16, 8 */
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grub_uint32_t br; /* br x16 */
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grub_uint64_t addr;
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};
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/*
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* Check if EHDR is a valid ELF header.
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*/
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@ -42,59 +51,76 @@ grub_arch_dl_check_header (void *ehdr)
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return GRUB_ERR_NONE;
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}
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#pragma GCC diagnostic ignored "-Wcast-align"
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grub_err_t
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grub_arch_dl_get_tramp_got_size (const void *ehdr, grub_size_t *tramp,
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grub_size_t *got)
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{
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const Elf_Ehdr *e = ehdr;
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const Elf_Shdr *s;
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unsigned i;
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*tramp = 0;
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*got = 0;
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for (i = 0, s = (const Elf_Shdr *) ((grub_addr_t) e + e->e_shoff);
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i < e->e_shnum;
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i++, s = (const Elf_Shdr *) ((grub_addr_t) s + e->e_shentsize))
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if (s->sh_type == SHT_REL || s->sh_type == SHT_RELA)
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{
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const Elf_Rel *rel, *max;
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for (rel = (const Elf_Rel *) ((grub_addr_t) e + s->sh_offset),
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max = rel + s->sh_size / s->sh_entsize;
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rel < max;
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rel = (const Elf_Rel *) ((grub_addr_t) rel + s->sh_entsize))
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switch (ELF_R_TYPE (rel->r_info))
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{
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case R_AARCH64_CALL26:
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case R_AARCH64_JUMP26:
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{
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*tramp += sizeof (struct trampoline);
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break;
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}
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}
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}
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return GRUB_ERR_NONE;
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}
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/*
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* Unified function for both REL and RELA
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*/
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static grub_err_t
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do_relX (Elf_Shdr * relhdr, Elf_Ehdr * e, grub_dl_t mod)
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grub_err_t
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grub_arch_dl_relocate_symbols (grub_dl_t mod, void *ehdr,
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Elf_Shdr *s, grub_dl_segment_t seg)
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{
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grub_err_t retval;
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grub_dl_segment_t segment;
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Elf_Rel *rel;
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Elf_Rela *rela;
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Elf_Sym *symbol;
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int i, entnum;
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unsigned long long entsize;
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Elf_Rel *rel, *max;
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/* Find the target segment for this relocation section. */
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for (segment = mod->segment ; segment != 0 ; segment = segment->next)
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if (segment->section == relhdr->sh_info)
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break;
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if (!segment)
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return grub_error (GRUB_ERR_EOF, N_("relocation segment not found"));
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rel = (Elf_Rel *) ((grub_addr_t) e + relhdr->sh_offset);
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rela = (Elf_Rela *) rel;
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if (relhdr->sh_type == SHT_RELA)
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entsize = sizeof (Elf_Rela);
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else
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entsize = sizeof (Elf_Rel);
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entnum = relhdr->sh_size / entsize;
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retval = GRUB_ERR_NONE;
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grub_dprintf("dl", "Processing %d relocation entries.\n", entnum);
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/* Step through all relocations */
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for (i = 0, symbol = mod->symtab; i < entnum; i++)
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for (rel = (Elf_Rel *) ((char *) ehdr + s->sh_offset),
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max = (Elf_Rel *) ((char *) rel + s->sh_size);
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rel < max;
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rel = (Elf_Rel *) ((char *) rel + s->sh_entsize))
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{
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Elf_Sym *sym;
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void *place;
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grub_uint64_t sym_addr, symidx, reltype;
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grub_uint64_t sym_addr;
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if (rel->r_offset >= segment->size)
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if (rel->r_offset >= seg->size)
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return grub_error (GRUB_ERR_BAD_MODULE,
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"reloc offset is out of the segment");
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symidx = ELF_R_SYM (rel->r_info);
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reltype = ELF_R_TYPE (rel->r_info);
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sym = (Elf_Sym *) ((char *) mod->symtab
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+ mod->symsize * ELF_R_SYM (rel->r_info));
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sym_addr = symbol[symidx].st_value;
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if (relhdr->sh_type == SHT_RELA)
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sym_addr += rela->r_addend;
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sym_addr = sym->st_value;
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if (s->sh_type == SHT_RELA)
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sym_addr += ((Elf_Rela *) rel)->r_addend;
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place = (void *) ((grub_addr_t) segment->addr + rel->r_offset);
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place = (void *) ((grub_addr_t) seg->addr + rel->r_offset);
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switch (reltype)
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switch (ELF_R_TYPE (rel->r_info))
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{
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case R_AARCH64_ABS64:
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{
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@ -108,92 +134,32 @@ do_relX (Elf_Shdr * relhdr, Elf_Ehdr * e, grub_dl_t mod)
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break;
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case R_AARCH64_CALL26:
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case R_AARCH64_JUMP26:
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retval = grub_arm64_reloc_xxxx26 (place, sym_addr);
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{
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grub_int64_t offset = sym_addr - (grub_uint64_t) place;
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if (!grub_arm_64_check_xxxx26_offset (offset))
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{
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struct trampoline *tp = mod->trampptr;
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mod->trampptr = tp + 1;
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tp->ldr = LDR;
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tp->br = BR;
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tp->addr = sym_addr;
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offset = (grub_uint8_t *) tp - (grub_uint8_t *) place;
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}
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if (!grub_arm_64_check_xxxx26_offset (offset))
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return grub_error (GRUB_ERR_BAD_MODULE,
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N_("Trampoline out of range"));
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grub_arm64_set_xxxx26_offset (place, offset);
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}
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break;
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default:
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return grub_error (GRUB_ERR_NOT_IMPLEMENTED_YET,
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N_("relocation 0x%x is not implemented yet"),
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reltype);
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}
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if (retval != GRUB_ERR_NONE)
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break;
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rel = (Elf_Rel *) ((grub_addr_t) rel + entsize);
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rela++;
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}
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return retval;
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}
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/*
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* Verify that provided ELF header contains reference to a symbol table
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*/
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static int
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has_symtab (Elf_Ehdr * e)
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{
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int i;
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Elf_Shdr *s;
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for (i = 0, s = (Elf_Shdr *) ((grub_addr_t) e + e->e_shoff);
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i < e->e_shnum;
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i++, s = (Elf_Shdr *) ((grub_addr_t) s + e->e_shentsize))
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if (s->sh_type == SHT_SYMTAB)
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return 1;
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return 0;
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}
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/*
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* grub_arch_dl_relocate_symbols():
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* Locates the relocations section of the ELF object, and calls
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* do_relX() to deal with it.
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*/
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grub_err_t
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grub_arch_dl_relocate_symbols (grub_dl_t mod, void *ehdr)
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{
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Elf_Ehdr *e = ehdr;
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Elf_Shdr *s;
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unsigned i;
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if (!has_symtab (e))
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return grub_error (GRUB_ERR_BAD_MODULE, N_("no symbol table"));
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#define FIRST_SHDR(x) ((Elf_Shdr *) ((grub_addr_t)(x) + (x)->e_shoff))
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#define NEXT_SHDR(x, y) ((Elf_Shdr *) ((grub_addr_t)(y) + (x)->e_shentsize))
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for (i = 0, s = FIRST_SHDR (e); i < e->e_shnum; i++, s = NEXT_SHDR (e, s))
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{
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grub_err_t ret;
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switch (s->sh_type)
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{
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case SHT_REL:
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case SHT_RELA:
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{
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ret = do_relX (s, e, mod);
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if (ret != GRUB_ERR_NONE)
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return ret;
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}
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break;
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case SHT_ARM_ATTRIBUTES:
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case SHT_NOBITS:
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case SHT_NULL:
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case SHT_PROGBITS:
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case SHT_SYMTAB:
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case SHT_STRTAB:
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break;
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default:
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{
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grub_dprintf ("dl", "unhandled section_type: %d (0x%08x)\n",
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s->sh_type, s->sh_type);
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return GRUB_ERR_NOT_IMPLEMENTED_YET;
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};
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ELF_R_TYPE (rel->r_info));
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}
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}
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#undef FIRST_SHDR
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#undef NEXT_SHDR
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return GRUB_ERR_NONE;
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}
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