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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@ -25,45 +25,113 @@
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#include <grub/i18n.h>
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#include <grub/arm/reloc.h>
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struct trampoline_arm
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{
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#define ARM_LOAD_IP 0xe59fc000
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#define ARM_BX 0xe12fff1c
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#define ARM_MOV_PC 0xe1a0f00c
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grub_uint32_t load_ip; /* ldr ip, [pc] */
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grub_uint32_t bx; /* bx ip or mov pc, ip*/
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grub_uint32_t addr;
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};
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static grub_uint16_t thumb_template[8] =
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{
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0x468c, /* mov ip, r1 */
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0x4903, /* ldr r1, [pc, #12] ; (10 <.text+0x10>) */
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/* Exchange R1 and IP in limited Thumb instruction set.
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IP gets negated but we compensate it by C code. */
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/* R1 IP */
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/* -A R1 */
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0x4461, /* add r1, ip */ /* R1-A R1 */
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0x4249, /* negs r1, r1 */ /* A-R1 R1 */
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0x448c, /* add ip, r1 */ /* A-R1 A */
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0x4249, /* negs r1, r1 */ /* R1-A A */
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0x4461, /* add r1, ip */ /* R1 A */
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0x4760 /* bx ip */
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};
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struct trampoline_thumb
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{
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grub_uint16_t template[8];
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grub_uint32_t neg_addr;
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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)
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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++)
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switch (ELF_R_TYPE (rel->r_info))
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{
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case R_ARM_CALL:
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case R_ARM_JUMP24:
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{
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*tramp += sizeof (struct trampoline_arm);
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break;
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}
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case R_ARM_THM_CALL:
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case R_ARM_THM_JUMP24:
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case R_ARM_THM_JUMP19:
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{
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*tramp += sizeof (struct trampoline_thumb);
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break;
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}
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}
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}
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grub_dprintf ("dl", "trampoline size %x\n", *tramp);
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return GRUB_ERR_NONE;
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}
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/*************************************************
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* Runtime dynamic linker with helper functions. *
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*************************************************/
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static grub_err_t
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do_relocations (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_dl_segment_t seg;
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Elf_Rel *rel;
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Elf_Sym *sym;
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int i, entnum;
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Elf_Rel *rel, *max;
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entnum = relhdr->sh_size / sizeof (Elf_Rel);
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/* Find the target segment for this relocation section. */
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for (seg = mod->segment ; seg ; seg = seg->next)
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if (seg->section == relhdr->sh_info)
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break;
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if (!seg)
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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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/* Step through all relocations */
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for (i = 0, sym = 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_Addr *target, sym_addr;
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int relsym, reltype;
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grub_err_t retval;
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Elf_Sym *sym;
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if (seg->size < rel[i].r_offset)
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if (seg->size < rel->r_offset)
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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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relsym = ELF_R_SYM (rel[i].r_info);
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reltype = ELF_R_TYPE (rel[i].r_info);
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target = (void *) ((grub_addr_t) seg->addr + rel[i].r_offset);
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target = (void *) ((char *) seg->addr + rel->r_offset);
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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 = sym[relsym].st_value;
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sym_addr = sym->st_value;
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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_ARM_ABS32:
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{
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@ -76,16 +144,58 @@ do_relocations (Elf_Shdr * relhdr, Elf_Ehdr * e, grub_dl_t mod)
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case R_ARM_CALL:
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case R_ARM_JUMP24:
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{
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retval = grub_arm_reloc_jump24 (target, sym_addr);
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if (retval != GRUB_ERR_NONE)
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return retval;
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grub_int32_t offset;
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sym_addr += grub_arm_jump24_get_offset (target);
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offset = sym_addr - (grub_uint32_t) target;
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if ((sym_addr & 1) || !grub_arm_jump24_check_offset (offset))
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{
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struct trampoline_arm *tp = mod->trampptr;
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mod->trampptr = tp + 1;
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tp->load_ip = ARM_LOAD_IP;
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tp->bx = (sym_addr & 1) ? ARM_BX : ARM_MOV_PC;
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tp->addr = sym_addr + 8;
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offset = (grub_uint8_t *) tp - (grub_uint8_t *) target - 8;
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}
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if (!grub_arm_jump24_check_offset (offset))
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return grub_error (GRUB_ERR_BAD_MODULE,
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"trampoline out of range");
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grub_arm_jump24_set_offset (target, offset);
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}
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break;
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case R_ARM_THM_CALL:
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case R_ARM_THM_JUMP24:
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{
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/* Thumb instructions can be 16-bit aligned */
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retval = grub_arm_reloc_thm_call ((grub_uint16_t *) target, sym_addr);
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grub_int32_t offset;
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sym_addr += grub_arm_thm_call_get_offset ((grub_uint16_t *) target);
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grub_dprintf ("dl", " sym_addr = 0x%08x\n", sym_addr);
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offset = sym_addr - (grub_uint32_t) target;
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grub_dprintf("dl", " BL*: target=%p, sym_addr=0x%08x, offset=%d\n",
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target, sym_addr, offset);
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if (!(sym_addr & 1) || (offset < -0x200000 || offset >= 0x200000))
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{
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struct trampoline_thumb *tp = mod->trampptr;
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mod->trampptr = tp + 1;
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grub_memcpy (tp->template, thumb_template, sizeof (tp->template));
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tp->neg_addr = -sym_addr - 4;
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offset = ((grub_uint8_t *) tp - (grub_uint8_t *) target - 4) | 1;
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}
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if (offset < -0x200000 || offset >= 0x200000)
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return grub_error (GRUB_ERR_BAD_MODULE,
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"trampoline out of range");
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grub_dprintf ("dl", " relative destination = %p\n",
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(char *) target + offset);
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retval = grub_arm_thm_call_set_offset ((grub_uint16_t *) target, offset);
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if (retval != GRUB_ERR_NONE)
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return retval;
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}
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@ -98,15 +208,37 @@ do_relocations (Elf_Shdr * relhdr, Elf_Ehdr * e, grub_dl_t mod)
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case R_ARM_THM_JUMP19:
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{
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/* Thumb instructions can be 16-bit aligned */
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retval = grub_arm_reloc_thm_jump19 ((grub_uint16_t *) target, sym_addr);
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if (retval != GRUB_ERR_NONE)
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return retval;
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grub_int32_t offset;
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if (!(sym_addr & 1))
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return grub_error (GRUB_ERR_BAD_MODULE,
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N_("Relocation targeting wrong execution state"));
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sym_addr += grub_arm_thm_jump19_get_offset ((grub_uint16_t *) target);
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offset = sym_addr - (grub_uint32_t) target;
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if (!grub_arm_thm_jump19_check_offset (offset)
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|| !(sym_addr & 1))
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{
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struct trampoline_thumb *tp = mod->gotptr;
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mod->gotptr = tp + 1;
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grub_memcpy (tp->template, thumb_template, sizeof (tp->template));
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tp->neg_addr = -sym_addr - 4;
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offset = ((grub_uint8_t *) tp - (grub_uint8_t *) target - 4) | 1;
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}
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if (!grub_arm_thm_jump19_check_offset (offset))
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return grub_error (GRUB_ERR_BAD_MODULE,
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"trampoline out of range");
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grub_arm_thm_jump19_set_offset ((grub_uint16_t *) target, 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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ELF_R_TYPE (rel->r_info));
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}
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}
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@ -130,77 +262,3 @@ grub_arch_dl_check_header (void *ehdr)
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return GRUB_ERR_NONE;
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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_uint32_t) e + e->e_shoff);
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i < e->e_shnum;
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i++, s = (Elf_Shdr *) ((grub_uint32_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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* Only externally visible function in this file.
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* Locates the relocations section of the ELF object, and calls
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* do_relocations() 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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{
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/* Relocations, no addends */
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ret = do_relocations (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_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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case SHT_NOBITS:
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case SHT_ARM_ATTRIBUTES:
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break;
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case SHT_RELA:
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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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}
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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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