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IABSD.fr/src/sys/ddb/db_elf.c
miod
- sys/ddb/db_elf.c
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/* $OpenBSD: db_elf.c,v 1.34 2024/11/07 16:02:29 miod Exp $ */ /* $NetBSD: db_elf.c,v 1.13 2000/07/07 21:55:18 jhawk Exp $ */ /*- * Copyright (c) 1997 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. * * 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 <sys/param.h> #include <sys/stdint.h> #include <sys/systm.h> #include <sys/exec.h> #include <machine/db_machdep.h> #include <ddb/db_elf.h> #include <ddb/db_sym.h> #include <ddb/db_output.h> #include <sys/exec_elf.h> db_symtab_t db_symtab; Elf_Sym *db_elf_sym_lookup(const char *); /* * Find the symbol table and strings; tell ddb about them. * * symsize: size of symbol table * symtab: pointer to start of symbol table * esymtab: pointer to end of string table, for checking - rounded up to * integer boundary */ int db_elf_sym_init(int symsize, void *symtab, void *esymtab, const char *name) { Elf_Ehdr *elf; Elf_Shdr *shp; Elf_Sym *symp, *symtab_start, *symtab_end; char *shstrtab, *strtab_start, *strtab_end; int i; char *errstr = ""; if (ALIGNED_POINTER(symtab, long) == 0) { db_printf("[ %s symbol table has bad start address %p ]\n", name, symtab); return (0); } 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, string, or line table section * . . . * . . . * last symbol, string, or line table section */ /* * Validate the Elf header. */ elf = (Elf_Ehdr *)symtab; if (memcmp(elf->e_ident, ELFMAG, SELFMAG) != 0 || elf->e_ident[EI_CLASS] != ELFCLASS) { errstr = "bad magic"; goto badheader; } if (elf->e_machine != ELF_TARG_MACH) { errstr = "bad e_machine"; goto badheader; } /* * Find the section header string table (.shstrtab), and look up * the symbol table (.symtab) and string table (.strtab) via their * names in shstrtab, rather than by table type. * This works in the presence of multiple string tables, such as * stabs data found when booting bsd.gdb. */ shp = (Elf_Shdr *)((char *)symtab + elf->e_shoff); shstrtab = (char *)symtab + shp[elf->e_shstrndx].sh_offset; for (i = 0; i < elf->e_shnum; i++) { if (shp[i].sh_type == SHT_SYMTAB) { int j; if (shp[i].sh_offset == 0) continue; symtab_start = (Elf_Sym *)((char *)symtab + shp[i].sh_offset); symtab_end = (Elf_Sym *)((char *)symtab + shp[i].sh_offset + shp[i].sh_size); 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; break; } /* * This is the old way of doing things. * XXX - verify that it's not needed. */ if (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0) { strtab_start = (char *)symtab + shp[i].sh_offset; strtab_end = (char *)symtab + shp[i].sh_offset + shp[i].sh_size; } else if (strcmp(".symtab", shstrtab+shp[i].sh_name) == 0) { symtab_start = (Elf_Sym *)((char *)symtab + shp[i].sh_offset); symtab_end = (Elf_Sym *)((char *)symtab + shp[i].sh_offset + shp[i].sh_size); } } /* * Now, sanity check the symbols against the string table. */ if (symtab_start == NULL || strtab_start == NULL || ALIGNED_POINTER(symtab_start, long) == 0) { errstr = "symtab unaligned"; goto badheader; } for (symp = symtab_start; symp < symtab_end; symp++) if (symp->st_name + strtab_start > strtab_end) { errstr = "symtab corrupted"; goto badheader; } /* * Link the symbol table into the debugger. */ db_symtab.start = (char *)symtab_start; db_symtab.end = (char *)symtab_end; db_symtab.name = name; db_symtab.private = (char *)symtab; db_printf("[ using %lu bytes of %s ELF symbol table ]\n", (u_long)roundup(((char *)esymtab - (char *)symtab), sizeof(u_long)), name); return (1); badheader: db_printf("[ %s ELF symbol table not valid: %s ]\n", name, errstr); return (0); } /* * Internal helper function - return a pointer to the string table * for the current symbol table. */ const char * db_elf_find_strtab(db_symtab_t *stab) { Elf_Ehdr *elf = STAB_TO_EHDR(stab); Elf_Shdr *shp = STAB_TO_SHDR(stab, elf); const char *shstrtab; int i; shstrtab = (const char *)elf + shp[elf->e_shstrndx].sh_offset; for (i = 0; i < elf->e_shnum; i++) { if (shp[i].sh_type == SHT_SYMTAB) return ((const char *)elf + shp[shp[i].sh_link].sh_offset); if (strcmp(".strtab", shstrtab+shp[i].sh_name) == 0) return ((const char *)elf + shp[i].sh_offset); } return (NULL); } /* * Internal helper function - return a pointer to the section * named ``sname''. */ const char * db_elf_find_section(db_symtab_t *stab, size_t *size, const char *sname) { Elf_Ehdr *elf = STAB_TO_EHDR(stab); Elf_Shdr *shp = STAB_TO_SHDR(stab, elf); char *shstrtab; int i; shstrtab = (char *)elf + shp[elf->e_shstrndx].sh_offset; for (i = 0; i < elf->e_shnum; i++) { if ((shp[i].sh_flags & SHF_ALLOC) != 0 && strcmp(sname, shstrtab+shp[i].sh_name) == 0) { *size = shp[i].sh_size; return ((char *)elf + shp[i].sh_offset); } } return (NULL); } /* * Lookup the symbol with the given name. */ Elf_Sym * db_elf_sym_lookup(const char *symstr) { db_symtab_t *stab = &db_symtab; Elf_Sym *symp, *symtab_start, *symtab_end; const char *strtab; if (stab->private == NULL) return (NULL); symtab_start = STAB_TO_SYMSTART(stab); symtab_end = STAB_TO_SYMEND(stab); strtab = db_elf_find_strtab(stab); if (strtab == NULL) return (NULL); for (symp = symtab_start; symp < symtab_end; symp++) { if (symp->st_name != 0 && db_eqname(strtab + symp->st_name, symstr, 0)) return (symp); } return (NULL); } /* * Search for the symbol with the given address (matching within the * provided threshold). */ Elf_Sym * db_elf_sym_search(vaddr_t off, db_strategy_t strategy, db_expr_t *diffp) { db_symtab_t *stab = &db_symtab; Elf_Sym *rsymp, *symp, *symtab_start, *symtab_end; db_expr_t diff = *diffp; if (stab->private == NULL) return (NULL); symtab_start = STAB_TO_SYMSTART(stab); symtab_end = STAB_TO_SYMEND(stab); rsymp = NULL; for (symp = symtab_start; symp < symtab_end; symp++) { if (symp->st_name == 0) continue; #if 0 /* This prevents me from seeing anything in locore.s -- eeh */ if (ELF_SYM_TYPE(symp->st_info) != Elf_estt_object && ELF_SYM_TYPE(symp->st_info) != Elf_estt_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 && ELF_ST_TYPE(symp->st_info) == STT_FUNC && ELF_ST_BIND(symp->st_info) != STB_LOCAL) break; if (strategy == DB_STGY_ANY && ELF_ST_BIND(symp->st_info) != STB_LOCAL) break; } } else if ((off - symp->st_value) == diff) { if (rsymp == NULL) rsymp = symp; else if (ELF_ST_BIND(rsymp->st_info) == STB_LOCAL && ELF_ST_BIND(symp->st_info) != STB_LOCAL) { /* pick the external symbol */ rsymp = symp; } } } } if (rsymp == NULL) *diffp = off; else *diffp = diff; return (rsymp); } /* * Return the name and value for a symbol. */ void db_symbol_values(Elf_Sym *sym, const char **namep, db_expr_t *valuep) { db_symtab_t *stab = &db_symtab; Elf_Sym *symp = (Elf_Sym *)sym; const char *strtab; if (sym == NULL) { *namep = NULL; return; } if (stab->private == NULL) return; if (namep) { strtab = db_elf_find_strtab(stab); 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. */ int db_elf_line_at_pc(Elf_Sym *cursym, const char **filename, int *linenum, db_expr_t off) { db_symtab_t *stab = &db_symtab; static char path[PATH_MAX]; const char *linetab, *dirname, *basename; size_t linetab_size; if (stab->private == NULL) return (0); linetab = db_elf_find_section(stab, &linetab_size, ".debug_line"); if (linetab == NULL) return (0); if (!db_dwarf_line_at_pc(linetab, linetab_size, off, &dirname, &basename, linenum)) return (0); if (dirname == NULL) strlcpy(path, basename, sizeof(path)); else snprintf(path, sizeof(path), "%s/%s", dirname, basename); *filename = path; return (1); } void db_elf_sym_forall(db_forall_func_t db_forall_func, void *arg) { db_symtab_t *stab = &db_symtab; const char *strtab; static char suffix[2]; Elf_Sym *symp, *symtab_start, *symtab_end; if (stab->private == NULL) return; 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 (ELF_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)(symp, strtab + symp->st_name, suffix, arg); } } Elf_Sym * db_symbol_by_name(const char *name, db_expr_t *valuep) { Elf_Sym *sym; sym = db_elf_sym_lookup(name); if (sym == NULL) return (NULL); db_symbol_values(sym, &name, valuep); return (sym); }