/* $NetBSD: db_elf.c,v 1.29 2017/11/06 04:08:02 christos Exp $ */ /*- * Copyright (c) 1997, 2009 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, * NASA Ames Research Center, and by Andrew Doran. * * 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ #include __KERNEL_RCSID(0, "$NetBSD: db_elf.c,v 1.29 2017/11/06 04:08:02 christos Exp $"); #include #include #include #include #include #include #ifdef DB_ELF_SYMBOLS #include #include static char *db_elf_find_strtab(db_symtab_t *); #define STAB_TO_SYMSTART(stab) ((Elf_Sym *)((stab)->start)) #define STAB_TO_SYMEND(stab) ((Elf_Sym *)((stab)->end)) #define STAB_TO_EHDR(stab) ((Elf_Ehdr *)((stab)->private)) #define STAB_TO_SHDR(stab, e) ((Elf_Shdr *)((stab)->private + (e)->e_shoff)) static bool db_elf_sym_init(int, void *, void *, const char *); static db_sym_t db_elf_lookup(db_symtab_t *, const char *); static db_sym_t db_elf_search_symbol(db_symtab_t *, db_addr_t, db_strategy_t, db_expr_t *); static void db_elf_symbol_values(db_symtab_t *, db_sym_t, const char **, db_expr_t *); static bool db_elf_line_at_pc(db_symtab_t *, db_sym_t, char **, int *, db_expr_t); static bool db_elf_sym_numargs(db_symtab_t *, db_sym_t, int *, char **); static void db_elf_forall(db_symtab_t *, db_forall_func_t db_forall_func, void *); const db_symformat_t db_symformat_elf = { "ELF", db_elf_sym_init, db_elf_lookup, db_elf_search_symbol, db_elf_symbol_values, db_elf_line_at_pc, db_elf_sym_numargs, db_elf_forall }; static db_symtab_t db_symtabs; /* * Add symbol table, with given name, to symbol tables. */ static int db_add_symbol_table(char *start, char *end, const char *name, char *ref) { db_symtabs.start = start; db_symtabs.end = end; db_symtabs.name = name; db_symtabs.private = ref; return(0); } /* * Find the symbol table and strings; tell ddb about them. */ static bool db_elf_sym_init( int symsize, /* size of symbol table */ void *symtab, /* pointer to start of symbol table */ void *esymtab, /* pointer to end of string table, for checking - rounded up to integer boundary */ const char *name ) { Elf_Ehdr *elf; Elf_Shdr *shp; Elf_Sym *symp, *symtab_start, *symtab_end; char *strtab_start, *strtab_end; int i, j; if (ALIGNED_POINTER(symtab, long) == 0) { printf("[ %s symbol table has bad start address %p ]\n", name, symtab); return (false); } symtab_start = symtab_end = NULL; strtab_start = strtab_end = NULL; /* * The format of the symbols loaded by the boot program is: * * Elf exec header * first section header * . . . * . . . * last section header * first symbol or string table section * . . . * . . . * last symbol or string table section */ /* * Validate the Elf header. */ elf = (Elf_Ehdr *)symtab; if (memcmp(elf->e_ident, ELFMAG, SELFMAG) != 0 || elf->e_ident[EI_CLASS] != ELFCLASS) goto badheader; switch (elf->e_machine) { ELFDEFNNAME(MACHDEP_ID_CASES) default: goto badheader; } /* * Find the first (and, we hope, only) SHT_SYMTAB section in * the file, and the SHT_STRTAB section that goes with it. */ if (elf->e_shoff == 0) goto badheader; shp = (Elf_Shdr *)((char *)symtab + elf->e_shoff); for (i = 0; i < elf->e_shnum; i++) { if (shp[i].sh_type == SHT_SYMTAB) { if (shp[i].sh_offset == 0) continue; /* Got the symbol table. */ symtab_start = (Elf_Sym *)((char *)symtab + shp[i].sh_offset); symtab_end = (Elf_Sym *)((char *)symtab + shp[i].sh_offset + shp[i].sh_size); /* Find the string table to go with it. */ j = shp[i].sh_link; if (shp[j].sh_offset == 0) continue; strtab_start = (char *)symtab + shp[j].sh_offset; strtab_end = (char *)symtab + shp[j].sh_offset + shp[j].sh_size; /* There should only be one symbol table. */ break; } } /* * Now, sanity check the symbols against the string table. */ if (symtab_start == NULL || strtab_start == NULL || ALIGNED_POINTER(symtab_start, long) == 0 || ALIGNED_POINTER(strtab_start, long) == 0) goto badheader; for (symp = symtab_start; symp < symtab_end; symp++) if (symp->st_name + strtab_start > strtab_end) goto badheader; /* * Link the symbol table into the debugger. */ if (db_add_symbol_table((char *)symtab_start, (char *)symtab_end, name, (char *)symtab) != -1) { return (true); } return (false); badheader: printf("[ %s ELF symbol table not valid ]\n", name); return (false); } /* * Internal helper function - return a pointer to the string table * for the current symbol table. */ static char * db_elf_find_strtab(db_symtab_t *stab) { Elf_Ehdr *elf = STAB_TO_EHDR(stab); Elf_Shdr *shp = STAB_TO_SHDR(stab, elf); int i; stab = &db_symtabs; /* * We don't load ELF header for ELF modules. * Find out if this is a loadable module. If so, * string table comes right after symbol table. */ if ((Elf_Sym *)elf == STAB_TO_SYMSTART(stab)) { return ((char *)STAB_TO_SYMEND(stab)); } for (i = 0; i < elf->e_shnum; i++) { if (shp[i].sh_type == SHT_SYMTAB) return ((char*)elf + shp[shp[i].sh_link].sh_offset); } return (NULL); } /* * Lookup the symbol with the given name. */ static db_sym_t db_elf_lookup(db_symtab_t *stab, const char *symstr) { Elf_Sym *symp, *symtab_start, *symtab_end; char *strtab; stab = &db_symtabs; symtab_start = STAB_TO_SYMSTART(stab); symtab_end = STAB_TO_SYMEND(stab); strtab = db_elf_find_strtab(stab); if (strtab == NULL) return ((db_sym_t)0); for (symp = symtab_start; symp < symtab_end; symp++) { if (symp->st_name != 0 && db_eqname(strtab + symp->st_name, symstr, 0)) return ((db_sym_t)symp); } return ((db_sym_t)0); } /* * Search for the symbol with the given address (matching within the * provided threshold). */ static db_sym_t db_elf_search_symbol(db_symtab_t *symtab, db_addr_t off, db_strategy_t strategy, db_expr_t *diffp) { Elf_Sym *rsymp, *symp, *symtab_start, *symtab_end; db_addr_t diff = *diffp; symtab = &db_symtabs; symtab_start = STAB_TO_SYMSTART(symtab); symtab_end = STAB_TO_SYMEND(symtab); rsymp = NULL; for (symp = symtab_start; symp < symtab_end; symp++) { if (symp->st_name == 0) continue; #if 0 /* This prevents me from seeing anythin in locore.s -- eeh */ if (ELF_ST_TYPE(symp->st_info) != STT_OBJECT && ELF_ST_TYPE(symp->st_info) != STT_FUNC) continue; #endif if (off >= symp->st_value) { if (off - symp->st_value < diff) { diff = off - symp->st_value; rsymp = symp; if (diff == 0) { if (strategy == DB_STGY_PROC && ELFDEFNNAME(ST_TYPE)(symp->st_info) == STT_FUNC && ELFDEFNNAME(ST_BIND)(symp->st_info) != STB_LOCAL) break; if (strategy == DB_STGY_ANY && ELFDEFNNAME(ST_BIND)(symp->st_info) != STB_LOCAL) break; } } else if (off - symp->st_value == diff) { if (rsymp == NULL) rsymp = symp; else if (ELFDEFNNAME(ST_BIND)(rsymp->st_info) == STB_LOCAL && ELFDEFNNAME(ST_BIND)(symp->st_info) != STB_LOCAL) { /* pick the external symbol */ rsymp = symp; } } } } if (rsymp == NULL) *diffp = off; else *diffp = diff; return ((db_sym_t)rsymp); } /* * Return the name and value for a symbol. */ static void db_elf_symbol_values(db_symtab_t *symtab, db_sym_t sym, const char **namep, db_expr_t *valuep) { Elf_Sym *symp = (Elf_Sym *)sym; char *strtab; symtab = &db_symtabs; if (namep) { strtab = db_elf_find_strtab(symtab); if (strtab == NULL) *namep = NULL; else *namep = strtab + symp->st_name; } if (valuep) *valuep = symp->st_value; } /* * Return the file and line number of the current program counter * if we can find the appropriate debugging symbol. */ static bool db_elf_line_at_pc(db_symtab_t *symtab, db_sym_t cursym, char **filename, int *linenum, db_expr_t off) { /* * XXX We don't support this (yet). */ return (false); } /* * Returns the number of arguments to a function and their * names if we can find the appropriate debugging symbol. */ static bool db_elf_sym_numargs(db_symtab_t *symtab, db_sym_t cursym, int *nargp, char **argnamep) { /* * XXX We don't support this (yet). */ return (false); } static void db_elf_forall(db_symtab_t *stab, db_forall_func_t db_forall_func, void *arg) { char *strtab; static char suffix[2]; Elf_Sym *symp, *symtab_start, *symtab_end; stab = &db_symtabs; symtab_start = STAB_TO_SYMSTART(stab); symtab_end = STAB_TO_SYMEND(stab); strtab = db_elf_find_strtab(stab); if (strtab == NULL) return; for (symp = symtab_start; symp < symtab_end; symp++) if (symp->st_name != 0) { suffix[1] = '\0'; switch (ELFDEFNNAME(ST_TYPE)(symp->st_info)) { case STT_OBJECT: suffix[0] = '+'; break; case STT_FUNC: suffix[0] = '*'; break; case STT_SECTION: suffix[0] = '&'; break; case STT_FILE: suffix[0] = '/'; break; default: suffix[0] = '\0'; } (*db_forall_func)(stab, (db_sym_t)symp, strtab + symp->st_name, suffix, 0, arg); } return; } #endif /* DB_ELF_SYMBOLS */