/*- * Copyright (c) 1998 Doug Rabson * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $Id: link_elf.c,v 1.1 1998/08/24 08:25:26 dfr Exp $ */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include extern int elf_reloc(linker_file_t lf, const Elf_Rela *rela, const char *sym); static int link_elf_load_file(const char*, linker_file_t*); static int link_elf_lookup_symbol(linker_file_t, const char*, linker_sym_t*); static void link_elf_symbol_values(linker_file_t, linker_sym_t, linker_symval_t*); static int link_elf_search_symbol(linker_file_t, caddr_t value, linker_sym_t* sym, long* diffp); static void link_elf_unload(linker_file_t); /* * The file representing the currently running kernel. This contains * the global symbol table. */ linker_file_t linker_kernel_file; static struct linker_class_ops link_elf_class_ops = { link_elf_load_file, }; static struct linker_file_ops link_elf_file_ops = { link_elf_lookup_symbol, link_elf_symbol_values, link_elf_search_symbol, link_elf_unload, }; typedef struct elf_file { caddr_t address; /* Relocation address */ #ifdef SPARSE_MAPPING vm_object_t object; /* VM object to hold file pages */ #endif const Elf_Dyn* dynamic; /* Symbol table etc. */ Elf_Off nbuckets; /* DT_HASH info */ Elf_Off nchains; const Elf_Off* buckets; const Elf_Off* chains; caddr_t hash; caddr_t strtab; /* DT_STRTAB */ const Elf_Sym* symtab; /* DT_SYMTAB */ Elf_Addr* got; /* DT_PLTGOT */ const Elf_Rel* pltrel; /* DT_JMPREL */ int pltrelsize; /* DT_PLTRELSZ */ const Elf_Rela* pltrela; /* DT_JMPREL */ int pltrelasize; /* DT_PLTRELSZ */ const Elf_Rel* rel; /* DT_REL */ int relsize; /* DT_RELSZ */ const Elf_Rela* rela; /* DT_RELA */ int relasize; /* DT_RELASZ */ } *elf_file_t; static int parse_dynamic(linker_file_t lf); static int load_dependancies(linker_file_t lf); static int relocate_file(linker_file_t lf); /* * The kernel symbol table starts here. */ extern struct _dynamic _DYNAMIC; static void link_elf_init(void* arg) { Elf_Dyn* dp = (Elf_Dyn*) &_DYNAMIC; #if ELF_TARG_CLASS == ELFCLASS32 linker_add_class("elf32", NULL, &link_elf_class_ops); #else linker_add_class("elf64", NULL, &link_elf_class_ops); #endif if (dp) { elf_file_t ef; ef = malloc(sizeof(struct elf_file), M_LINKER, M_NOWAIT); if (ef == NULL) panic("link_elf_init: Can't create linker structures for kernel"); ef->address = 0; #ifdef SPARSE_MAPPING ef->object = 0; #endif ef->dynamic = dp; linker_kernel_file = linker_make_file(kernelname, ef, &link_elf_file_ops); if (linker_kernel_file == NULL) panic("link_elf_init: Can't create linker structures for kernel"); parse_dynamic(linker_kernel_file); /* * XXX there must be a better way of getting these constants. */ #ifdef __alpha__ linker_kernel_file->address = (caddr_t) 0xfffffc0000300000; #else linker_kernel_file->address = (caddr_t) 0xf0100000; #endif linker_kernel_file->size = -(long)linker_kernel_file->address; linker_current_file = linker_kernel_file; } } SYSINIT(link_elf, SI_SUB_KMEM, SI_ORDER_THIRD, link_elf_init, 0); static int parse_dynamic(linker_file_t lf) { elf_file_t ef = lf->priv; const Elf_Dyn *dp; int plttype = DT_REL; for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { switch (dp->d_tag) { case DT_HASH: { /* From src/libexec/rtld-elf/rtld.c */ const Elf_Off *hashtab = (const Elf_Off *) (ef->address + dp->d_un.d_ptr); ef->nbuckets = hashtab[0]; ef->nchains = hashtab[1]; ef->buckets = hashtab + 2; ef->chains = ef->buckets + ef->nbuckets; break; } case DT_STRTAB: ef->strtab = (caddr_t) (ef->address + dp->d_un.d_ptr); break; case DT_SYMTAB: ef->symtab = (Elf_Sym*) (ef->address + dp->d_un.d_ptr); break; case DT_SYMENT: if (dp->d_un.d_val != sizeof(Elf_Sym)) return ENOEXEC; break; case DT_PLTGOT: ef->got = (Elf_Addr *) (ef->address + dp->d_un.d_ptr); break; case DT_REL: ef->rel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); break; case DT_RELSZ: ef->relsize = dp->d_un.d_val; break; case DT_RELENT: if (dp->d_un.d_val != sizeof(Elf_Rel)) return ENOEXEC; break; case DT_JMPREL: ef->pltrel = (const Elf_Rel *) (ef->address + dp->d_un.d_ptr); break; case DT_PLTRELSZ: ef->pltrelsize = dp->d_un.d_val; break; case DT_RELA: ef->rela = (const Elf_Rela *) (ef->address + dp->d_un.d_ptr); break; case DT_RELASZ: ef->relasize = dp->d_un.d_val; break; case DT_RELAENT: if (dp->d_un.d_val != sizeof(Elf_Rela)) return ENOEXEC; break; case DT_PLTREL: plttype = dp->d_un.d_val; if (plttype != DT_REL && plttype != DT_RELA) return ENOEXEC; break; } } if (plttype == DT_RELA) { ef->pltrela = (const Elf_Rela *) ef->pltrel; ef->pltrel = NULL; ef->pltrelasize = ef->pltrelsize; ef->pltrelsize = 0; } return 0; } static void link_elf_error(const char *s) { printf("kldload: %s\n", s); } static int link_elf_load_file(const char* filename, linker_file_t* result) { struct nameidata nd; struct proc* p = curproc; /* XXX */ union { Elf_Ehdr hdr; char buf[PAGE_SIZE]; } u; int nbytes, i; Elf_Phdr *phdr; Elf_Phdr *phlimit; Elf_Phdr *segs[2]; int nsegs; Elf_Phdr *phdyn; Elf_Phdr *phphdr; caddr_t mapbase; size_t mapsize; Elf_Off base_offset; Elf_Addr base_vaddr; Elf_Addr base_vlimit; caddr_t base_addr; Elf_Off data_offset; Elf_Addr data_vaddr; Elf_Addr data_vlimit; caddr_t data_addr; Elf_Addr clear_vaddr; caddr_t clear_addr; size_t nclear; Elf_Addr bss_vaddr; Elf_Addr bss_vlimit; caddr_t bss_addr; int error = 0; int resid; elf_file_t ef; linker_file_t lf; NDINIT(&nd, LOOKUP, FOLLOW, UIO_SYSSPACE, filename, p); error = vn_open(&nd, FREAD, 0); if (error) return error; /* * Read the elf header from the file. */ error = vn_rdwr(UIO_READ, nd.ni_vp, (void*) &u, sizeof u, 0, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); nbytes = sizeof u - resid; if (error) goto out; if (!IS_ELF(u.hdr)) { error = ENOEXEC; goto out; } if (u.hdr.e_ident[EI_CLASS] != ELF_TARG_CLASS || u.hdr.e_ident[EI_DATA] != ELF_TARG_DATA) { link_elf_error("Unsupported file layout"); error = ENOEXEC; goto out; } if (u.hdr.e_ident[EI_VERSION] != EV_CURRENT || u.hdr.e_version != EV_CURRENT) { link_elf_error("Unsupported file version"); error = ENOEXEC; goto out; } if (u.hdr.e_type != ET_EXEC && u.hdr.e_type != ET_DYN) { link_elf_error("Unsupported file type"); error = ENOEXEC; goto out; } if (u.hdr.e_machine != ELF_TARG_MACH) { link_elf_error("Unsupported machine"); error = ENOEXEC; goto out; } if (!ELF_MACHINE_OK(u.hdr.e_machine)) { link_elf_error("Incompatibile elf machine type"); error = ENOEXEC; goto out; } /* * We rely on the program header being in the first page. This is * not strictly required by the ABI specification, but it seems to * always true in practice. And, it simplifies things considerably. */ if (!((u.hdr.e_phentsize == sizeof(Elf_Phdr)) || (u.hdr.e_phoff + u.hdr.e_phnum*sizeof(Elf_Phdr) <= PAGE_SIZE) || (u.hdr.e_phoff + u.hdr.e_phnum*sizeof(Elf_Phdr) <= nbytes))) link_elf_error("Unreadable program headers"); /* * Scan the program header entries, and save key information. * * We rely on there being exactly two load segments, text and data, * in that order. */ phdr = (Elf_Phdr *) (u.buf + u.hdr.e_phoff); phlimit = phdr + u.hdr.e_phnum; nsegs = 0; phdyn = NULL; phphdr = NULL; while (phdr < phlimit) { switch (phdr->p_type) { case PT_LOAD: if (nsegs == 2) { link_elf_error("Too many sections"); error = ENOEXEC; goto out; } segs[nsegs] = phdr; ++nsegs; break; case PT_PHDR: phphdr = phdr; break; case PT_DYNAMIC: phdyn = phdr; break; } ++phdr; } if (phdyn == NULL) { link_elf_error("Object is not dynamically-linked"); error = ENOEXEC; goto out; } /* * Allocate the entire address space of the object, to stake out our * contiguous region, and to establish the base address for relocation. */ base_offset = trunc_page(segs[0]->p_offset); base_vaddr = trunc_page(segs[0]->p_vaddr); base_vlimit = round_page(segs[1]->p_vaddr + segs[1]->p_memsz); mapsize = base_vlimit - base_vaddr; ef = malloc(sizeof(struct elf_file), M_LINKER, M_WAITOK); #ifdef SPARSE_MAPPING ef->object = vm_object_allocate(OBJT_DEFAULT, mapsize >> PAGE_SHIFT); if (ef->object == NULL) { free(ef, M_LINKER); error = ENOMEM; goto out; } vm_object_reference(ef->object); ef->address = (caddr_t) vm_map_min(kernel_map); error = vm_map_find(kernel_map, ef->object, 0, (vm_offset_t *) &ef->address, mapsize, 1, VM_PROT_ALL, VM_PROT_ALL, 0); if (error) { vm_object_deallocate(ef->object); free(ef, M_LINKER); goto out; } #else ef->address = malloc(mapsize, M_LINKER, M_WAITOK); #endif mapbase = ef->address; /* * Read the text and data sections and zero the bss. */ for (i = 0; i < 2; i++) { caddr_t segbase = mapbase + segs[i]->p_vaddr - base_vaddr; error = vn_rdwr(UIO_READ, nd.ni_vp, segbase, segs[i]->p_filesz, segs[i]->p_offset, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &resid, p); if (error) { #ifdef SPARSE_MAPPING vm_map_remove(kernel_map, (vm_offset_t) ef->address, (vm_offset_t) ef->address + (ef->object->size << PAGE_SHIFT)); vm_object_deallocate(ef->object); #else free(ef->address, M_LINKER); #endif free(ef, M_LINKER); goto out; } bzero(segbase + segs[i]->p_filesz, segs[i]->p_memsz - segs[i]->p_filesz); #ifdef SPARSE_MAPPING /* * Wire down the pages */ vm_map_pageable(kernel_map, (vm_offset_t) segbase, (vm_offset_t) segbase + segs[i]->p_memsz, FALSE); #endif } ef->dynamic = (const Elf_Dyn *) (mapbase + phdyn->p_vaddr - base_vaddr); lf = linker_make_file(filename, ef, &link_elf_file_ops); if (lf == NULL) { #ifdef SPARSE_MAPPING vm_map_remove(kernel_map, (vm_offset_t) ef->address, (vm_offset_t) ef->address + (ef->object->size << PAGE_SHIFT)); vm_object_deallocate(ef->object); #else free(ef->address, M_LINKER); #endif free(ef, M_LINKER); error = ENOMEM; goto out; } lf->address = ef->address; lf->size = mapsize; if ((error = parse_dynamic(lf)) != 0 || (error = load_dependancies(lf)) != 0 || (error = relocate_file(lf)) != 0) { linker_file_unload(lf); goto out; } *result = lf; out: VOP_UNLOCK(nd.ni_vp, 0, p); vn_close(nd.ni_vp, FREAD, p->p_ucred, p); return error; } static void link_elf_unload(linker_file_t file) { elf_file_t ef = file->priv; if (ef) { #ifdef SPARSE_MAPPING if (ef->object) { vm_map_remove(kernel_map, (vm_offset_t) ef->address, (vm_offset_t) ef->address + (ef->object->size << PAGE_SHIFT)); vm_object_deallocate(ef->object); } #else free(ef->address, M_LINKER); #endif free(ef, M_LINKER); } } static int load_dependancies(linker_file_t lf) { elf_file_t ef = lf->priv; linker_file_t lfdep; char* name; char* filename = 0; const Elf_Dyn *dp; int error = 0; /* * All files are dependant on /kernel. */ linker_kernel_file->refs++; linker_file_add_dependancy(lf, linker_kernel_file); for (dp = ef->dynamic; dp->d_tag != DT_NULL; dp++) { if (dp->d_tag == DT_NEEDED) { name = ef->strtab + dp->d_un.d_val; /* * Prepend pathname if dep is not an absolute filename. */ if (name[0] != '/') { char* p; if (!filename) { filename = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); if (!filename) { error = ENOMEM; goto out; } } p = lf->filename + strlen(lf->filename) - 1; while (p >= lf->filename && *p != '/') p--; if (p >= lf->filename) { strncpy(filename, lf->filename, p - lf->filename); filename[p - lf->filename] = '\0'; strcat(filename, "/"); strcat(filename, name); name = filename; } } error = linker_load_file(name, &lfdep); if (error) goto out; error = linker_file_add_dependancy(lf, lfdep); if (error) goto out; } } out: if (filename) free(filename, M_TEMP); return error; } static const char * symbol_name(elf_file_t ef, const Elf_Rela *rela) { const Elf_Sym *ref; if (ELF_R_SYM(rela->r_info)) { ref = ef->symtab + ELF_R_SYM(rela->r_info); return ef->strtab + ref->st_name; } else return NULL; } static int relocate_file(linker_file_t lf) { elf_file_t ef = lf->priv; const Elf_Rel *rellim; const Elf_Rel *rel; const Elf_Rela *relalim; const Elf_Rela *rela; /* Perform relocations without addend if there are any: */ rellim = (const Elf_Rel *) ((caddr_t) ef->rel + ef->relsize); for (rel = ef->rel; ef->rel != NULL && rel < rellim; rel++) { Elf_Rela locrela; locrela.r_info = rel->r_info; locrela.r_offset = rel->r_offset; locrela.r_addend = 0; if (elf_reloc(lf, &locrela, symbol_name(ef, &locrela))) return ENOENT; } /* Perform relocations with addend if there are any: */ relalim = (const Elf_Rela *) ((caddr_t) ef->rela + ef->relasize); for (rela = ef->rela; ef->rela != NULL && rela < relalim; rela++) { if (elf_reloc(lf, rela, symbol_name(ef, rela))) return ENOENT; } /* Perform PLT relocations without addend if there are any: */ rellim = (const Elf_Rel *) ((caddr_t) ef->pltrel + ef->pltrelsize); for (rel = ef->pltrel; ef->pltrel != NULL && rel < rellim; rel++) { Elf_Rela locrela; locrela.r_info = rel->r_info; locrela.r_offset = rel->r_offset; locrela.r_addend = 0; if (elf_reloc(lf, &locrela, symbol_name(ef, &locrela))) return ENOENT; } /* Perform relocations with addend if there are any: */ relalim = (const Elf_Rela *) ((caddr_t) ef->pltrela + ef->pltrelasize); for (rela = ef->pltrela; ef->pltrela != NULL && rela < relalim; rela++) { if (elf_reloc(lf, rela, symbol_name(ef, rela))) return ENOENT; } return 0; } /* * Hash function for symbol table lookup. Don't even think about changing * this. It is specified by the System V ABI. */ static unsigned long elf_hash(const char *name) { const unsigned char *p = (const unsigned char *) name; unsigned long h = 0; unsigned long g; while (*p != '\0') { h = (h << 4) + *p++; if ((g = h & 0xf0000000) != 0) h ^= g >> 24; h &= ~g; } return h; } int link_elf_lookup_symbol(linker_file_t lf, const char* name, linker_sym_t* sym) { elf_file_t ef = lf->priv; unsigned long symnum; const Elf_Sym* es; unsigned long hash; int i; hash = elf_hash(name); symnum = ef->buckets[hash % ef->nbuckets]; while (symnum != STN_UNDEF) { const Elf_Sym *symp; const char *strp; if (symnum >= ef->nchains) { printf("link_elf_lookup_symbol: corrupt symbol table\n"); return ENOENT; } symp = ef->symtab + symnum; if (symp->st_name == 0) { printf("link_elf_lookup_symbol: corrupt symbol table\n"); return ENOENT; } strp = ef->strtab + symp->st_name; if (strcmp(name, strp) == 0) { if (symp->st_shndx != SHN_UNDEF || (symp->st_value != 0 && ELF_ST_TYPE(symp->st_info) == STT_FUNC)) { *sym = (linker_sym_t) symp; return 0; } else return ENOENT; } symnum = ef->chains[symnum]; } return ENOENT; } static void link_elf_symbol_values(linker_file_t lf, linker_sym_t sym, linker_symval_t* symval) { elf_file_t ef = lf->priv; Elf_Sym* es = (Elf_Sym*) sym; symval->name = ef->strtab + es->st_name; symval->value = (caddr_t) ef->address + es->st_value; symval->size = es->st_size; } static int link_elf_search_symbol(linker_file_t lf, caddr_t value, linker_sym_t* sym, long* diffp) { elf_file_t ef = lf->priv; u_long off = (u_long) value; u_long diff = off; int symcount = ef->nchains; const Elf_Sym* es; const Elf_Sym* best = 0; int i; for (i = 0, es = ef->symtab; i < ef->nchains; i++, es++) { if (es->st_name == 0) continue; if (off >= es->st_value) { if (off - es->st_value < diff) { diff = off - es->st_value; best = es; if (diff == 0) break; } else if (off - es->st_value == diff) { best = es; } } } if (best == 0) *diffp = off; else *diffp = diff; *sym = (linker_sym_t) best; return 0; }