/**************************************************************************** * libs/libc/modlib/modlib_symbols.c * * Copyright (C) 2015, 2017 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 "modlib/modlib.h" /**************************************************************************** * Pre-processor Definitions ****************************************************************************/ /* Return values search for exported modules */ #define SYM_NOT_FOUND 0 #define SYM_FOUND 1 /**************************************************************************** * Private Types ****************************************************************************/ struct mod_exportinfo_s { FAR const char *name; /* Symbol name to find */ FAR struct module_s *modp; /* The module that needs the symbol */ FAR const struct symtab_s *symbol; /* Symbol info returned (if found) */ }; /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: modlib_symname * * Description: * Get the symbol name in loadinfo->iobuffer[]. * * Returned Value: * 0 (OK) is returned on success and a negated errno is returned on * failure. * * EINVAL - There is something inconsistent in the symbol table (should only * happen if the file is corrupted). * ESRCH - Symbol has no name * ****************************************************************************/ static int modlib_symname(FAR struct mod_loadinfo_s *loadinfo, FAR const Elf32_Sym *sym) { FAR uint8_t *buffer; off_t offset; size_t readlen; size_t bytesread; int ret; /* Get the file offset to the string that is the name of the symbol. The * st_name member holds an offset into the file's symbol string table. */ if (sym->st_name == 0) { berr("ERROR: Symbol has no name\n"); return -ESRCH; } offset = loadinfo->shdr[loadinfo->strtabidx].sh_offset + sym->st_name; /* Loop until we get the entire symbol name into memory */ bytesread = 0; for (; ; ) { /* Get the number of bytes to read */ readlen = loadinfo->buflen - bytesread; if (offset + readlen > loadinfo->filelen) { if (loadinfo->filelen <= offset) { berr("ERROR: At end of file\n"); return -EINVAL; } readlen = loadinfo->filelen - offset; } /* Read that number of bytes into the array */ buffer = &loadinfo->iobuffer[bytesread]; ret = modlib_read(loadinfo, buffer, readlen, offset); if (ret < 0) { berr("ERROR: modlib_read failed: %d\n", ret); return ret; } bytesread += readlen; /* Did we read the NUL terminator? */ if (memchr(buffer, '\0', readlen) != NULL) { /* Yes, the buffer contains a NUL terminator. */ return OK; } /* No.. then we have to read more */ ret = modlib_reallocbuffer(loadinfo, CONFIG_MODLIB_BUFFERINCR); if (ret < 0) { berr("ERROR: mod_reallocbuffer failed: %d\n", ret); return ret; } } /* We will not get here */ return OK; } /**************************************************************************** * Name: modlib_symcallback * * Description: * modlib_registry_foreach() callback function. Test if the provided module, * modp, exports the symbol of interest. If so, return that symbol value * and setup the module dependency relationship. * * Returned Value: * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ static int modlib_symcallback(FAR struct module_s *modp, FAR void *arg) { FAR struct mod_exportinfo_s *exportinfo = (FAR struct mod_exportinfo_s *)arg; int ret; /* Check if this module exports a symbol of that name */ #ifdef CONFIG_SYMTAB_ORDEREDBYNAME exportinfo->symbol = symtab_findorderedbyname(modp->modinfo.exports, exportinfo->name, modp->modinfo.nexports); #else exportinfo->symbol = symtab_findbyname(modp->modinfo.exports, exportinfo->name, modp->modinfo.nexports); #endif if (exportinfo->symbol != NULL) { /* Yes.. save the dependency relationship and return SYM_FOUND to * stop the traversal. */ ret = modlib_depend(exportinfo->modp, modp); if (ret < 0) { berr("ERROR: modlib_depend failed: %d\n", ret); return ret; } return SYM_FOUND; } return SYM_NOT_FOUND; } /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: modlib_findsymtab * * Description: * Find the symbol table section. * * Returned Value: * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ int modlib_findsymtab(FAR struct mod_loadinfo_s *loadinfo) { int i; /* Find the symbol table section header and its associated string table */ for (i = 1; i < loadinfo->ehdr.e_shnum; i++) { if (loadinfo->shdr[i].sh_type == SHT_SYMTAB) { loadinfo->symtabidx = i; loadinfo->strtabidx = loadinfo->shdr[i].sh_link; break; } } /* Verify that there is a symbol and string table */ if (loadinfo->symtabidx == 0) { berr("ERROR: No symbols in ELF file\n"); return -EINVAL; } return OK; } /**************************************************************************** * Name: modlib_readsym * * Description: * Read the ELF symbol structure at the specified index into memory. * * Input Parameters: * loadinfo - Load state information * index - Symbol table index * sym - Location to return the table entry * * Returned Value: * 0 (OK) is returned on success and a negated errno is returned on * failure. * ****************************************************************************/ int modlib_readsym(FAR struct mod_loadinfo_s *loadinfo, int index, FAR Elf32_Sym *sym) { FAR Elf32_Shdr *symtab = &loadinfo->shdr[loadinfo->symtabidx]; off_t offset; /* Verify that the symbol table index lies within symbol table */ if (index < 0 || index > (symtab->sh_size / sizeof(Elf32_Sym))) { berr("ERROR: Bad relocation symbol index: %d\n", index); return -EINVAL; } /* Get the file offset to the symbol table entry */ offset = symtab->sh_offset + sizeof(Elf32_Sym) * index; /* And, finally, read the symbol table entry into memory */ return modlib_read(loadinfo, (FAR uint8_t *)sym, sizeof(Elf32_Sym), offset); } /**************************************************************************** * Name: modlib_symvalue * * Description: * Get the value of a symbol. The updated value of the symbol is returned * in the st_value field of the symbol table entry. * * Input Parameters: * modp - Module state information * loadinfo - Load state information * sym - Symbol table entry (value might be undefined) * * Returned Value: * 0 (OK) is returned on success and a negated errno is returned on * failure. * * EINVAL - There is something inconsistent in the symbol table (should only * happen if the file is corrupted). * ENOSYS - Symbol lies in common * ESRCH - Symbol has no name * ENOENT - Symbol undefined and not provided via a symbol table * ****************************************************************************/ int modlib_symvalue(FAR struct module_s *modp, FAR struct mod_loadinfo_s *loadinfo, FAR Elf32_Sym *sym) { FAR const struct symtab_s *symbol; struct mod_exportinfo_s exportinfo; uintptr_t secbase; int nsymbols; int ret; switch (sym->st_shndx) { case SHN_COMMON: { /* NuttX ELF modules should be compiled with -fno-common. */ berr("ERROR: SHN_COMMON: Re-compile with -fno-common\n"); return -ENOSYS; } case SHN_ABS: { /* st_value already holds the correct value */ binfo("SHN_ABS: st_value=%08lx\n", (long)sym->st_value); return OK; } case SHN_UNDEF: { /* Get the name of the undefined symbol */ ret = modlib_symname(loadinfo, sym); if (ret < 0) { /* 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 return and special error to the caller to * indicate the nameless symbol. */ berr("ERROR: SHN_UNDEF: Failed to get symbol name: %d\n", ret); return ret; } /* First check if the symbol is exported by an installed module. * Newest modules are installed at the head of the list. Therefore, * if the symbol is exported by numerous modules, then the most * recently installed will take precedence. */ exportinfo.name = (FAR const char *)loadinfo->iobuffer; exportinfo.modp = modp; exportinfo.symbol = NULL; ret = modlib_registry_foreach(modlib_symcallback, (FAR void *)&exportinfo); if (ret < 0) { berr("ERROR: modlib_symcallback failed: \n", ret); return ret; } symbol = exportinfo.symbol; /* If the symbol is not exported by any module, then check if the * base code exports a symbol of this name. */ if (symbol == NULL) { modlib_getsymtab(&symbol, &nsymbols); #ifdef CONFIG_SYMTAB_ORDEREDBYNAME symbol = symtab_findorderedbyname(symbol, exportinfo.name, nsymbols); #else symbol = symtab_findbyname(symbol, exportinfo.name, nsymbols); #endif } /* Was the symbol found from any exporter? */ if (symbol == NULL) { berr("ERROR: SHN_UNDEF: Exported symbol \"%s\" not found\n", loadinfo->iobuffer); return -ENOENT; } /* Yes... add the exported symbol value to the ELF symbol table entry */ binfo("SHN_UNDEF: name=%s %08x+%08x=%08x\n", loadinfo->iobuffer, sym->st_value, symbol->sym_value, sym->st_value + symbol->sym_value); sym->st_value += (Elf32_Word)((uintptr_t)symbol->sym_value); } break; default: { secbase = loadinfo->shdr[sym->st_shndx].sh_addr; binfo("Other: %08x+%08x=%08x\n", sym->st_value, secbase, sym->st_value + secbase); sym->st_value += secbase; } break; } return OK; }