/* Kernel module help for Alpha. Copyright (C) 2002 Richard Henderson. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ #include #include #include #include #include #include #include #if 0 #define DEBUGP printk #else #define DEBUGP(fmt...) #endif void * module_alloc(unsigned long size) { if (size == 0) return NULL; return vmalloc(size); } void module_free(struct module *mod, void *module_region) { vfree(module_region); } /* Allocate the GOT at the end of the core sections. */ struct got_entry { struct got_entry *next; Elf64_Addr r_offset; int got_offset; }; static inline void process_reloc_for_got(Elf64_Rela *rela, struct got_entry *chains, Elf64_Xword *poffset) { unsigned long r_sym = ELF64_R_SYM (rela->r_info); unsigned long r_type = ELF64_R_TYPE (rela->r_info); Elf64_Addr r_offset = rela->r_offset; struct got_entry *g; if (r_type != R_ALPHA_LITERAL) return; for (g = chains + r_sym; g ; g = g->next) if (g->r_offset == r_offset) { if (g->got_offset == 0) { g->got_offset = *poffset; *poffset += 8; } goto found_entry; } g = kmalloc (sizeof (*g), GFP_KERNEL); g->next = chains[r_sym].next; g->r_offset = r_offset; g->got_offset = *poffset; *poffset += 8; chains[r_sym].next = g; found_entry: /* Trick: most of the ELF64_R_TYPE field is unused. There are 42 valid relocation types, and a 32-bit field. Co-opt the bits above 256 to store the got offset for this reloc. */ rela->r_info |= g->got_offset << 8; } int module_frob_arch_sections(Elf64_Ehdr *hdr, Elf64_Shdr *sechdrs, char *secstrings, struct module *me) { struct got_entry *chains; Elf64_Rela *rela; Elf64_Shdr *esechdrs, *symtab, *s, *got; unsigned long nsyms, nrela, i; esechdrs = sechdrs + hdr->e_shnum; symtab = got = NULL; /* Find out how large the symbol table is. Allocate one got_entry head per symbol. Normally this will be enough, but not always. We'll chain different offsets for the symbol down each head. */ for (s = sechdrs; s < esechdrs; ++s) if (s->sh_type == SHT_SYMTAB) symtab = s; else if (!strcmp(".got", secstrings + s->sh_name)) { got = s; me->arch.gotsecindex = s - sechdrs; } if (!symtab) { printk(KERN_ERR "module %s: no symbol table\n", me->name); return -ENOEXEC; } if (!got) { printk(KERN_ERR "module %s: no got section\n", me->name); return -ENOEXEC; } nsyms = symtab->sh_size / sizeof(Elf64_Sym); chains = kmalloc(nsyms * sizeof(struct got_entry), GFP_KERNEL); memset(chains, 0, nsyms * sizeof(struct got_entry)); got->sh_size = 0; got->sh_addralign = 8; got->sh_type = SHT_NOBITS; /* Examine all LITERAL relocations to find out what GOT entries are required. This sizes the GOT section as well. */ for (s = sechdrs; s < esechdrs; ++s) if (s->sh_type == SHT_RELA) { nrela = s->sh_size / sizeof(Elf64_Rela); rela = (void *)hdr + s->sh_offset; for (i = 0; i < nrela; ++i) process_reloc_for_got(rela+i, chains, &got->sh_size); } /* Free the memory we allocated. */ for (i = 0; i < nsyms; ++i) { struct got_entry *g, *n; for (g = chains[i].next; g ; g = n) { n = g->next; kfree(g); } } kfree(chains); return 0; } int apply_relocate(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, struct module *me) { printk(KERN_ERR "module %s: REL relocation unsupported\n", me->name); return -ENOEXEC; } int apply_relocate_add(Elf64_Shdr *sechdrs, const char *strtab, unsigned int symindex, unsigned int relsec, struct module *me) { Elf64_Rela *rela = (void *)sechdrs[relsec].sh_addr; unsigned long i, n = sechdrs[relsec].sh_size / sizeof(*rela); Elf64_Sym *symtab, *sym; void *base, *location; unsigned long got, gp; DEBUGP("Applying relocate section %u to %u\n", relsec, sechdrs[relsec].sh_info); base = (void *)sechdrs[sechdrs[relsec].sh_info].sh_addr; symtab = (Elf64_Sym *)sechdrs[symindex].sh_addr; /* The small sections were sorted to the end of the segment. The following should definitely cover them. */ gp = (u64)me->module_core + me->core_size - 0x8000; got = sechdrs[me->arch.gotsecindex].sh_addr; for (i = 0; i < n; i++) { unsigned long r_sym = ELF64_R_SYM (rela[i].r_info); unsigned long r_type = ELF64_R_TYPE (rela[i].r_info); unsigned long r_got_offset = r_type >> 8; unsigned long value, hi, lo; r_type &= 0xff; /* This is where to make the change. */ location = base + rela[i].r_offset; /* This is the symbol it is referring to. Note that all unresolved symbols have been resolved. */ sym = symtab + r_sym; value = sym->st_value + rela[i].r_addend; switch (r_type) { case R_ALPHA_NONE: break; case R_ALPHA_REFQUAD: /* BUG() can produce misaligned relocations. */ ((u32 *)location)[0] = value; ((u32 *)location)[1] = value >> 32; break; case R_ALPHA_GPREL32: value -= gp; if ((int)value != value) goto reloc_overflow; *(u32 *)location = value; break; case R_ALPHA_LITERAL: hi = got + r_got_offset; lo = hi - gp; if ((short)lo != lo) goto reloc_overflow; *(u16 *)location = lo; *(u64 *)hi = value; break; case R_ALPHA_LITUSE: break; case R_ALPHA_GPDISP: value = gp - (u64)location; lo = (short)value; hi = (int)(value - lo); if (hi + lo != value) goto reloc_overflow; *(u16 *)location = hi >> 16; *(u16 *)(location + rela[i].r_addend) = lo; break; case R_ALPHA_BRSGP: /* BRSGP is only allowed to bind to local symbols. If the section is undef, this means that the value was resolved from somewhere else. */ if (sym->st_shndx == SHN_UNDEF) goto reloc_overflow; if ((sym->st_other & STO_ALPHA_STD_GPLOAD) == STO_ALPHA_STD_GPLOAD) /* Omit the prologue. */ value += 8; /* FALLTHRU */ case R_ALPHA_BRADDR: value -= (u64)location + 4; if (value & 3) goto reloc_overflow; value = (long)value >> 2; if (value + (1<<21) >= 1<<22) goto reloc_overflow; value &= 0x1fffff; value |= *(u32 *)location & ~0x1fffff; *(u32 *)location = value; break; case R_ALPHA_HINT: break; case R_ALPHA_SREL32: value -= (u64)location; if ((int)value != value) goto reloc_overflow; *(u32 *)location = value; break; case R_ALPHA_SREL64: value -= (u64)location; *(u64 *)location = value; break; case R_ALPHA_GPRELHIGH: value = (long)(value - gp + 0x8000) >> 16; if ((short) value != value) goto reloc_overflow; *(u16 *)location = value; break; case R_ALPHA_GPRELLOW: value -= gp; *(u16 *)location = value; break; case R_ALPHA_GPREL16: value -= gp; if ((short) value != value) goto reloc_overflow; *(u16 *)location = value; break; default: printk(KERN_ERR "module %s: Unknown relocation: %lu\n", me->name, r_type); return -ENOEXEC; reloc_overflow: if (ELF64_ST_TYPE (sym->st_info) == STT_SECTION) printk(KERN_ERR "module %s: Relocation overflow vs section %d\n", me->name, sym->st_shndx); else printk(KERN_ERR "module %s: Relocation overflow vs %s\n", me->name, strtab + sym->st_name); return -ENOEXEC; } } return 0; } int module_finalize(const Elf_Ehdr *hdr, const Elf_Shdr *sechdrs, struct module *me) { return 0; } void module_arch_cleanup(struct module *mod) { }