/**************************************************************************** * binfmt/libelf/libelf_bind.c * * Copyright (C) 2012, 2014, 2019 Gregory Nutt. All rights reserved. * Author: Gregory Nutt * * 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. * 3. Neither the name NuttX nor the names of its contributors may be * used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 * COPYRIGHT OWNER 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. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include #include "libelf.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* CONFIG_DEBUG_FEATURES, CONFIG_DEBUG_INFO, and CONFIG_DEBUG_BINFMT have to be * defined or CONFIG_ELF_DUMPBUFFER does nothing. */ #if !defined(CONFIG_DEBUG_INFO) || !defined (CONFIG_DEBUG_BINFMT) # undef CONFIG_ELF_DUMPBUFFER #endif #ifdef CONFIG_ELF_DUMPBUFFER # define elf_dumpbuffer(m,b,n) binfodumpbuffer(m,b,n) #else # define elf_dumpbuffer(m,b,n) #endif /**************************************************************************** * Private Types ****************************************************************************/ struct elf32_symcache_s { dq_entry_t entry; Elf32_Sym sym; int idx; }; typedef struct elf32_symcache_s elf32_symcache_t; /**************************************************************************** * Private Data ****************************************************************************/ /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: elf_readrels * * Description: * Read the (ELF32_Rel structure * buffer count) into memory. * ****************************************************************************/ static inline int elf_readrels(FAR struct elf_loadinfo_s *loadinfo, FAR const Elf32_Shdr *relsec, int index, FAR Elf32_Rel *rels, int count) { off_t offset; int size; /* Verify that the symbol table index lies within symbol table */ if (index < 0 || index > (relsec->sh_size / sizeof(Elf32_Rel))) { berr("Bad relocation symbol index: %d\n", index); return -EINVAL; } /* Get the file offset to the symbol table entry */ offset = sizeof(Elf32_Rel) * index; size = sizeof(Elf32_Rel) * count; if (offset + size > relsec->sh_size) { size = relsec->sh_size - offset; } /* And, finally, read the symbol table entry into memory */ return elf_read(loadinfo, (FAR uint8_t *)rels, size, relsec->sh_offset + offset); } /**************************************************************************** * Name: elf_relocate and elf_relocateadd * * Description: * Perform all relocations associated with a section. * * Returned Value: * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ static int elf_relocate(FAR struct elf_loadinfo_s *loadinfo, int relidx, FAR const struct symtab_s *exports, int nexports) { FAR Elf32_Shdr *relsec = &loadinfo->shdr[relidx]; FAR Elf32_Shdr *dstsec = &loadinfo->shdr[relsec->sh_info]; FAR Elf32_Rel *rels; FAR Elf32_Rel *rel; FAR elf32_symcache_t *cache; FAR Elf32_Sym *sym; FAR dq_entry_t *e; dq_queue_t q; uintptr_t addr; int symidx; int ret; int i; int j; rels = kmm_malloc(CONFIG_ELF_RELOCATION_BUFFERCOUNT * sizeof(Elf32_Rel)); if (rels == NULL) { berr("Failed to allocate memory for elf relocation\n"); return -ENOMEM; } dq_init(&q); /* Examine each relocation in the section. 'relsec' is the section * containing the relations. 'dstsec' is the section containing the data * to be relocated. */ ret = OK; for (i = j = 0; i < relsec->sh_size / sizeof(Elf32_Rel); i++) { /* Read the relocation entry into memory */ rel = &rels[i % CONFIG_ELF_RELOCATION_BUFFERCOUNT]; if (!(i % CONFIG_ELF_RELOCATION_BUFFERCOUNT)) { ret = elf_readrels(loadinfo, relsec, i, rels, CONFIG_ELF_RELOCATION_BUFFERCOUNT); if (ret < 0) { berr("Section %d reloc %d: Failed to read relocation entry: %d\n", relidx, i, ret); break; } } /* Get the symbol table index for the relocation. This is contained * in a bit-field within the r_info element. */ symidx = ELF32_R_SYM(rel->r_info); /* First try the cache */ sym = NULL; for (e = dq_peek(&q); e; e = dq_next(e)) { cache = (FAR elf32_symcache_t *)e; if (cache->idx == symidx) { dq_rem(&cache->entry, &q); dq_addfirst(&cache->entry, &q); sym = &cache->sym; break; } } /* If the symbol was not found in the cache, we will need to read the * symbol from the file. */ if (sym == NULL) { if (j < CONFIG_ELF_SYMBOL_CACHECOUNT) { cache = kmm_malloc(sizeof(elf32_symcache_t)); if (!cache) { berr("Failed to allocate memory for elf symbols\n"); ret = -ENOMEM; break; } j++; } else { cache = (FAR elf32_symcache_t *)dq_remlast(&q); } sym = &cache->sym; /* Read the symbol table entry into memory */ ret = elf_readsym(loadinfo, symidx, sym); if (ret < 0) { berr("Section %d reloc %d: Failed to read symbol[%d]: %d\n", relidx, i, symidx, ret); kmm_free(cache); break; } /* Get the value of the symbol (in sym.st_value) */ ret = elf_symvalue(loadinfo, sym, exports, nexports); if (ret < 0) { /* The special error -ESRCH is returned only in one condition: The * symbol has no name. * * There are a few relocations for a few architectures that do * no depend upon a named symbol. We don't know if that is the * case here, but we will use a NULL symbol pointer to indicate * that case to up_relocate(). That function can then do what * is best. */ if (ret == -ESRCH) { berr("Section %d reloc %d: Undefined symbol[%d] has no name: %d\n", relidx, i, symidx, ret); } else { berr("Section %d reloc %d: Failed to get value of symbol[%d]: %d\n", relidx, i, symidx, ret); kmm_free(cache); break; } } cache->idx = symidx; dq_addfirst(&cache->entry, &q); } if (sym->st_shndx == SHN_UNDEF && sym->st_name == 0) { sym = NULL; } /* Calculate the relocation address. */ if (rel->r_offset < 0 || rel->r_offset > dstsec->sh_size - sizeof(uint32_t)) { berr("Section %d reloc %d: Relocation address out of range, offset %d size %d\n", relidx, i, rel->r_offset, dstsec->sh_size); ret = -EINVAL; break; } addr = dstsec->sh_addr + rel->r_offset; /* Now perform the architecture-specific relocation */ ret = up_relocate(rel, sym, addr); if (ret < 0) { berr("ERROR: Section %d reloc %d: Relocation failed: %d\n", relidx, i, ret); break; } } kmm_free(rels); while ((e = dq_peek(&q))) { dq_rem(e, &q); kmm_free(e); } return ret; } static int elf_relocateadd(FAR struct elf_loadinfo_s *loadinfo, int relidx, FAR const struct symtab_s *exports, int nexports) { berr("Not implemented\n"); return -ENOSYS; } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: elf_bind * * Description: * Bind the imported symbol names in the loaded module described by * 'loadinfo' using the exported symbol values provided by 'symtab'. * * Returned Value: * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ int elf_bind(FAR struct elf_loadinfo_s *loadinfo, FAR const struct symtab_s *exports, int nexports) { #ifdef CONFIG_ARCH_ADDRENV int status; #endif int ret; int i; /* Find the symbol and string tables */ ret = elf_findsymtab(loadinfo); if (ret < 0) { return ret; } /* Allocate an I/O buffer. This buffer is used by elf_symname() to * accumulate the variable length symbol name. */ ret = elf_allocbuffer(loadinfo); if (ret < 0) { berr("elf_allocbuffer failed: %d\n", ret); return ret; } #ifdef CONFIG_ARCH_ADDRENV /* If CONFIG_ARCH_ADDRENV=y, then the loaded ELF lies in a virtual address * space that may not be in place now. elf_addrenv_select() will * temporarily instantiate that address space. */ ret = elf_addrenv_select(loadinfo); if (ret < 0) { berr("ERROR: elf_addrenv_select() failed: %d\n", ret); return ret; } #endif /* Process relocations in every allocated section */ for (i = 1; i < loadinfo->ehdr.e_shnum; i++) { /* Get the index to the relocation section */ int infosec = loadinfo->shdr[i].sh_info; if (infosec >= loadinfo->ehdr.e_shnum) { continue; } /* Make sure that the section is allocated. We can't relocated * sections that were not loaded into memory. */ if ((loadinfo->shdr[infosec].sh_flags & SHF_ALLOC) == 0) { continue; } /* Process the relocations by type */ if (loadinfo->shdr[i].sh_type == SHT_REL) { ret = elf_relocate(loadinfo, i, exports, nexports); } else if (loadinfo->shdr[i].sh_type == SHT_RELA) { ret = elf_relocateadd(loadinfo, i, exports, nexports); } if (ret < 0) { break; } } #if defined(CONFIG_ARCH_ADDRENV) /* Ensure that the I and D caches are coherent before starting the newly * loaded module by cleaning the D cache (i.e., flushing the D cache * contents to memory and invalidating the I cache). */ #if 0 /* REVISIT... has some problems */ (void)up_addrenv_coherent(&loadinfo->addrenv); #else up_coherent_dcache(loadinfo->textalloc, loadinfo->textsize); up_coherent_dcache(loadinfo->dataalloc, loadinfo->datasize); #endif /* Restore the original address environment */ status = elf_addrenv_restore(loadinfo); if (status < 0) { berr("ERROR: elf_addrenv_restore() failed: %d\n", status); if (ret == OK) { ret = status; } } #else /* Ensure that the I and D caches are coherent before starting the newly * loaded module by cleaning the D cache (i.e., flushing the D cache * contents to memory and invalidating the I cache). */ up_coherent_dcache(loadinfo->textalloc, loadinfo->textsize); up_coherent_dcache(loadinfo->dataalloc, loadinfo->datasize); #endif return ret; }